2017-11-27 15:37:16 +00:00
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/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
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* Copyright (c) 2019 Google LLC
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2001-07-09 10:35:18 +00:00
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* Copyright (C) 1995, 1996, 1997 Wolfgang Solfrank
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* Copyright (c) 1995 Martin Husemann
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* Some structure declaration borrowed from Paul Popelka
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* (paulp@uts.amdahl.com), see /sys/msdosfs/ for reference.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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2012-10-21 12:01:11 +00:00
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__RCSID("$NetBSD: dir.c,v 1.20 2006/06/05 16:51:18 christos Exp $");
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2001-07-09 10:35:18 +00:00
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static const char rcsid[] =
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"$FreeBSD$";
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#endif /* not lint */
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2019-04-03 07:09:28 +00:00
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#include <assert.h>
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2019-03-28 18:20:47 +00:00
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#include <inttypes.h>
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2001-07-09 10:35:18 +00:00
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#include <unistd.h>
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#include <time.h>
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#include <sys/param.h>
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#include "ext.h"
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#include "fsutil.h"
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#define SLOT_EMPTY 0x00 /* slot has never been used */
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#define SLOT_E5 0x05 /* the real value is 0xe5 */
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#define SLOT_DELETED 0xe5 /* file in this slot deleted */
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#define ATTR_NORMAL 0x00 /* normal file */
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#define ATTR_READONLY 0x01 /* file is readonly */
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#define ATTR_HIDDEN 0x02 /* file is hidden */
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#define ATTR_SYSTEM 0x04 /* file is a system file */
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#define ATTR_VOLUME 0x08 /* entry is a volume label */
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#define ATTR_DIRECTORY 0x10 /* entry is a directory name */
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#define ATTR_ARCHIVE 0x20 /* file is new or modified */
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#define ATTR_WIN95 0x0f /* long name record */
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/*
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* This is the format of the contents of the deTime field in the direntry
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* structure.
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* We don't use bitfields because we don't know how compilers for
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* arbitrary machines will lay them out.
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*/
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#define DT_2SECONDS_MASK 0x1F /* seconds divided by 2 */
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#define DT_2SECONDS_SHIFT 0
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#define DT_MINUTES_MASK 0x7E0 /* minutes */
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#define DT_MINUTES_SHIFT 5
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#define DT_HOURS_MASK 0xF800 /* hours */
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#define DT_HOURS_SHIFT 11
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/*
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* This is the format of the contents of the deDate field in the direntry
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* structure.
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*/
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#define DD_DAY_MASK 0x1F /* day of month */
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#define DD_DAY_SHIFT 0
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#define DD_MONTH_MASK 0x1E0 /* month */
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#define DD_MONTH_SHIFT 5
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#define DD_YEAR_MASK 0xFE00 /* year - 1980 */
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#define DD_YEAR_SHIFT 9
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/* dir.c */
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2002-03-20 22:57:10 +00:00
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static struct dosDirEntry *newDosDirEntry(void);
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static void freeDosDirEntry(struct dosDirEntry *);
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static struct dirTodoNode *newDirTodo(void);
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static void freeDirTodo(struct dirTodoNode *);
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static char *fullpath(struct dosDirEntry *);
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static u_char calcShortSum(u_char *);
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
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static int delete(struct fat_descriptor *, cl_t, int, cl_t, int, int);
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static int removede(struct fat_descriptor *, u_char *, u_char *,
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cl_t, cl_t, cl_t, char *, int);
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static int checksize(struct fat_descriptor *, u_char *, struct dosDirEntry *);
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static int readDosDirSection(struct fat_descriptor *, struct dosDirEntry *);
|
2001-07-09 10:35:18 +00:00
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/*
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* Manage free dosDirEntry structures.
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*/
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static struct dosDirEntry *freede;
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static struct dosDirEntry *
|
2002-03-20 22:57:10 +00:00
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newDosDirEntry(void)
|
2001-07-09 10:35:18 +00:00
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|
{
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struct dosDirEntry *de;
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if (!(de = freede)) {
|
2019-04-15 06:33:05 +00:00
|
|
|
if (!(de = malloc(sizeof *de)))
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
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return (NULL);
|
2001-07-09 10:35:18 +00:00
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} else
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freede = de->next;
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return de;
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}
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static void
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2002-03-20 22:57:10 +00:00
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freeDosDirEntry(struct dosDirEntry *de)
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2001-07-09 10:35:18 +00:00
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{
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de->next = freede;
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freede = de;
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}
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/*
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* The same for dirTodoNode structures.
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*/
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static struct dirTodoNode *freedt;
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static struct dirTodoNode *
|
2002-03-20 22:57:10 +00:00
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newDirTodo(void)
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2001-07-09 10:35:18 +00:00
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{
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struct dirTodoNode *dt;
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if (!(dt = freedt)) {
|
2019-04-15 06:33:05 +00:00
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if (!(dt = malloc(sizeof *dt)))
|
2001-07-09 10:35:18 +00:00
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return 0;
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} else
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freedt = dt->next;
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return dt;
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}
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static void
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2002-03-20 22:57:10 +00:00
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freeDirTodo(struct dirTodoNode *dt)
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2001-07-09 10:35:18 +00:00
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{
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dt->next = freedt;
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freedt = dt;
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}
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/*
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* The stack of unread directories
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|
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|
*/
|
2011-11-04 13:36:02 +00:00
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|
|
static struct dirTodoNode *pendingDirectories = NULL;
|
2001-07-09 10:35:18 +00:00
|
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|
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/*
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|
* Return the full pathname for a directory entry.
|
|
|
|
*/
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|
static char *
|
2002-03-20 22:57:10 +00:00
|
|
|
fullpath(struct dosDirEntry *dir)
|
2001-07-09 10:35:18 +00:00
|
|
|
{
|
|
|
|
static char namebuf[MAXPATHLEN + 1];
|
|
|
|
char *cp, *np;
|
|
|
|
int nl;
|
|
|
|
|
2019-09-04 04:44:03 +00:00
|
|
|
cp = namebuf + sizeof namebuf;
|
|
|
|
*--cp = '\0';
|
|
|
|
|
|
|
|
for(;;) {
|
2001-07-09 10:35:18 +00:00
|
|
|
np = dir->lname[0] ? dir->lname : dir->name;
|
|
|
|
nl = strlen(np);
|
2019-09-04 04:44:03 +00:00
|
|
|
if (cp <= namebuf + 1 + nl) {
|
|
|
|
*--cp = '?';
|
2001-07-09 10:35:18 +00:00
|
|
|
break;
|
2019-09-04 04:44:03 +00:00
|
|
|
}
|
|
|
|
cp -= nl;
|
2001-07-09 10:35:18 +00:00
|
|
|
memcpy(cp, np, nl);
|
2019-09-04 04:44:03 +00:00
|
|
|
dir = dir->parent;
|
|
|
|
if (!dir)
|
|
|
|
break;
|
2001-07-09 10:35:18 +00:00
|
|
|
*--cp = '/';
|
2019-09-04 04:44:03 +00:00
|
|
|
}
|
|
|
|
|
2001-07-09 10:35:18 +00:00
|
|
|
return cp;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Calculate a checksum over an 8.3 alias name
|
|
|
|
*/
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
static inline u_char
|
2002-03-20 22:57:10 +00:00
|
|
|
calcShortSum(u_char *p)
|
2001-07-09 10:35:18 +00:00
|
|
|
{
|
|
|
|
u_char sum = 0;
|
|
|
|
int i;
|
|
|
|
|
|
|
|
for (i = 0; i < 11; i++) {
|
|
|
|
sum = (sum << 7)|(sum >> 1); /* rotate right */
|
|
|
|
sum += p[i];
|
|
|
|
}
|
|
|
|
|
|
|
|
return sum;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Global variables temporarily used during a directory scan
|
|
|
|
*/
|
|
|
|
static char longName[DOSLONGNAMELEN] = "";
|
|
|
|
static u_char *buffer = NULL;
|
|
|
|
static u_char *delbuf = NULL;
|
|
|
|
|
2014-07-14 19:16:49 +00:00
|
|
|
static struct dosDirEntry *rootDir;
|
2001-07-09 10:35:18 +00:00
|
|
|
static struct dosDirEntry *lostDir;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Init internal state for a new directory scan.
|
|
|
|
*/
|
|
|
|
int
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
resetDosDirSection(struct fat_descriptor *fat)
|
2001-07-09 10:35:18 +00:00
|
|
|
{
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
int rootdir_size, cluster_size;
|
2001-07-09 10:35:18 +00:00
|
|
|
int ret = FSOK;
|
2012-10-21 12:01:11 +00:00
|
|
|
size_t len;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
struct bootblock *boot;
|
|
|
|
|
|
|
|
boot = fat_get_boot(fat);
|
2001-07-09 10:35:18 +00:00
|
|
|
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
rootdir_size = boot->bpbRootDirEnts * 32;
|
|
|
|
cluster_size = boot->bpbSecPerClust * boot->bpbBytesPerSec;
|
2001-07-09 10:35:18 +00:00
|
|
|
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if ((buffer = malloc(len = MAX(rootdir_size, cluster_size))) == NULL) {
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("No space for directory buffer (%zu)", len);
|
2001-07-09 10:35:18 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
2010-02-14 12:30:30 +00:00
|
|
|
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if ((delbuf = malloc(len = cluster_size)) == NULL) {
|
2010-02-14 12:30:30 +00:00
|
|
|
free(buffer);
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("No space for directory delbuf (%zu)", len);
|
2010-02-14 12:30:30 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
if ((rootDir = newDosDirEntry()) == NULL) {
|
|
|
|
free(buffer);
|
|
|
|
free(delbuf);
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("No space for directory entry");
|
2010-02-14 12:30:30 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
|
2001-07-09 10:35:18 +00:00
|
|
|
memset(rootDir, 0, sizeof *rootDir);
|
|
|
|
if (boot->flags & FAT32) {
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (!fat_is_cl_head(fat, boot->bpbRootClust)) {
|
2019-08-19 04:28:12 +00:00
|
|
|
pfatal("Root directory doesn't start a cluster chain");
|
|
|
|
return FSFATAL;
|
2001-07-09 10:35:18 +00:00
|
|
|
}
|
2010-02-14 12:31:28 +00:00
|
|
|
rootDir->head = boot->bpbRootClust;
|
2001-07-09 10:35:18 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Cleanup after a directory scan
|
|
|
|
*/
|
|
|
|
void
|
2002-03-20 22:57:10 +00:00
|
|
|
finishDosDirSection(void)
|
2001-07-09 10:35:18 +00:00
|
|
|
{
|
|
|
|
struct dirTodoNode *p, *np;
|
|
|
|
struct dosDirEntry *d, *nd;
|
|
|
|
|
|
|
|
for (p = pendingDirectories; p; p = np) {
|
|
|
|
np = p->next;
|
|
|
|
freeDirTodo(p);
|
|
|
|
}
|
2016-04-19 19:08:37 +00:00
|
|
|
pendingDirectories = NULL;
|
2001-07-09 10:35:18 +00:00
|
|
|
for (d = rootDir; d; d = nd) {
|
|
|
|
if ((nd = d->child) != NULL) {
|
|
|
|
d->child = 0;
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
if (!(nd = d->next))
|
|
|
|
nd = d->parent;
|
|
|
|
freeDosDirEntry(d);
|
|
|
|
}
|
|
|
|
rootDir = lostDir = NULL;
|
|
|
|
free(buffer);
|
|
|
|
free(delbuf);
|
|
|
|
buffer = NULL;
|
|
|
|
delbuf = NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Delete directory entries between startcl, startoff and endcl, endoff.
|
|
|
|
*/
|
|
|
|
static int
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
delete(struct fat_descriptor *fat, cl_t startcl,
|
2002-03-20 22:57:10 +00:00
|
|
|
int startoff, cl_t endcl, int endoff, int notlast)
|
2001-07-09 10:35:18 +00:00
|
|
|
{
|
|
|
|
u_char *s, *e;
|
|
|
|
off_t off;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
int clsz, fd;
|
|
|
|
struct bootblock *boot;
|
|
|
|
|
|
|
|
boot = fat_get_boot(fat);
|
|
|
|
fd = fat_get_fd(fat);
|
|
|
|
clsz = boot->bpbSecPerClust * boot->bpbBytesPerSec;
|
2001-07-09 10:35:18 +00:00
|
|
|
|
|
|
|
s = delbuf + startoff;
|
|
|
|
e = delbuf + clsz;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
while (fat_is_valid_cl(fat, startcl)) {
|
2001-07-09 10:35:18 +00:00
|
|
|
if (startcl == endcl) {
|
|
|
|
if (notlast)
|
|
|
|
break;
|
|
|
|
e = delbuf + endoff;
|
|
|
|
}
|
2019-09-15 19:41:54 +00:00
|
|
|
off = (startcl - CLUST_FIRST) * boot->bpbSecPerClust + boot->FirstCluster;
|
|
|
|
|
2010-02-14 12:31:28 +00:00
|
|
|
off *= boot->bpbBytesPerSec;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (lseek(fd, off, SEEK_SET) != off) {
|
2019-03-28 18:20:47 +00:00
|
|
|
perr("Unable to lseek to %" PRId64, off);
|
|
|
|
return FSFATAL;
|
|
|
|
}
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (read(fd, delbuf, clsz) != clsz) {
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("Unable to read directory");
|
2001-07-09 10:35:18 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
while (s < e) {
|
|
|
|
*s = SLOT_DELETED;
|
|
|
|
s += 32;
|
|
|
|
}
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (lseek(fd, off, SEEK_SET) != off) {
|
2019-03-28 18:20:47 +00:00
|
|
|
perr("Unable to lseek to %" PRId64, off);
|
|
|
|
return FSFATAL;
|
|
|
|
}
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (write(fd, delbuf, clsz) != clsz) {
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("Unable to write directory");
|
2001-07-09 10:35:18 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
if (startcl == endcl)
|
|
|
|
break;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
startcl = fat_get_cl_next(fat, startcl);
|
2001-07-09 10:35:18 +00:00
|
|
|
s = delbuf;
|
|
|
|
}
|
|
|
|
return FSOK;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
removede(struct fat_descriptor *fat, u_char *start,
|
|
|
|
u_char *end, cl_t startcl, cl_t endcl, cl_t curcl,
|
|
|
|
char *path, int type)
|
2001-07-09 10:35:18 +00:00
|
|
|
{
|
|
|
|
switch (type) {
|
|
|
|
case 0:
|
|
|
|
pwarn("Invalid long filename entry for %s\n", path);
|
|
|
|
break;
|
|
|
|
case 1:
|
2010-06-20 09:40:54 +00:00
|
|
|
pwarn("Invalid long filename entry at end of directory %s\n",
|
|
|
|
path);
|
2001-07-09 10:35:18 +00:00
|
|
|
break;
|
|
|
|
case 2:
|
|
|
|
pwarn("Invalid long filename entry for volume label\n");
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
if (ask(0, "Remove")) {
|
|
|
|
if (startcl != curcl) {
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (delete(fat,
|
2001-07-09 10:35:18 +00:00
|
|
|
startcl, start - buffer,
|
|
|
|
endcl, end - buffer,
|
|
|
|
endcl == curcl) == FSFATAL)
|
|
|
|
return FSFATAL;
|
|
|
|
start = buffer;
|
|
|
|
}
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
/* startcl is < CLUST_FIRST for !FAT32 root */
|
2010-02-14 12:30:30 +00:00
|
|
|
if ((endcl == curcl) || (startcl < CLUST_FIRST))
|
2001-07-09 10:35:18 +00:00
|
|
|
for (; start < end; start += 32)
|
|
|
|
*start = SLOT_DELETED;
|
|
|
|
return FSDIRMOD;
|
|
|
|
}
|
|
|
|
return FSERROR;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Check an in-memory file entry
|
|
|
|
*/
|
|
|
|
static int
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
checksize(struct fat_descriptor *fat, u_char *p, struct dosDirEntry *dir)
|
2001-07-09 10:35:18 +00:00
|
|
|
{
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
int ret = FSOK;
|
2020-09-23 06:52:22 +00:00
|
|
|
size_t chainsize;
|
|
|
|
u_int64_t physicalSize;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
struct bootblock *boot;
|
|
|
|
|
|
|
|
boot = fat_get_boot(fat);
|
|
|
|
|
2001-07-09 10:35:18 +00:00
|
|
|
/*
|
|
|
|
* Check size on ordinary files
|
|
|
|
*/
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (dir->head == CLUST_FREE) {
|
2001-07-09 10:35:18 +00:00
|
|
|
physicalSize = 0;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
} else {
|
2021-11-04 05:09:32 +00:00
|
|
|
if (!fat_is_valid_cl(fat, dir->head) || !fat_is_cl_head(fat, dir->head)) {
|
|
|
|
pwarn("Directory entry %s of size %u referencing invalid cluster %u\n",
|
|
|
|
fullpath(dir), dir->size, dir->head);
|
|
|
|
if (ask(1, "Truncate")) {
|
|
|
|
p[28] = p[29] = p[30] = p[31] = 0;
|
|
|
|
p[26] = p[27] = 0;
|
|
|
|
if (boot->ClustMask == CLUST32_MASK)
|
|
|
|
p[20] = p[21] = 0;
|
|
|
|
dir->size = 0;
|
|
|
|
dir->head = CLUST_FREE;
|
|
|
|
return FSDIRMOD;
|
|
|
|
} else {
|
|
|
|
return FSERROR;
|
|
|
|
}
|
|
|
|
}
|
2020-09-23 06:52:22 +00:00
|
|
|
ret = checkchain(fat, dir->head, &chainsize);
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
/*
|
2020-09-23 06:52:22 +00:00
|
|
|
* Upon return, chainsize would hold the chain length
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
* that checkchain() was able to validate, but if the user
|
|
|
|
* refused the proposed repair, it would be unsafe to
|
|
|
|
* proceed with directory entry fix, so bail out in that
|
|
|
|
* case.
|
|
|
|
*/
|
|
|
|
if (ret == FSERROR) {
|
|
|
|
return (FSERROR);
|
|
|
|
}
|
2020-09-23 06:52:22 +00:00
|
|
|
/*
|
|
|
|
* The maximum file size on FAT32 is 4GiB - 1, which
|
|
|
|
* will occupy a cluster chain of exactly 4GiB in
|
|
|
|
* size. On 32-bit platforms, since size_t is 32-bit,
|
|
|
|
* it would wrap back to 0.
|
|
|
|
*/
|
|
|
|
physicalSize = (u_int64_t)chainsize * boot->ClusterSize;
|
2001-07-09 10:35:18 +00:00
|
|
|
}
|
|
|
|
if (physicalSize < dir->size) {
|
2020-09-28 04:30:31 +00:00
|
|
|
pwarn("size of %s is %u, should at most be %ju\n",
|
|
|
|
fullpath(dir), dir->size, (uintmax_t)physicalSize);
|
2001-07-09 10:35:18 +00:00
|
|
|
if (ask(1, "Truncate")) {
|
|
|
|
dir->size = physicalSize;
|
|
|
|
p[28] = (u_char)physicalSize;
|
|
|
|
p[29] = (u_char)(physicalSize >> 8);
|
|
|
|
p[30] = (u_char)(physicalSize >> 16);
|
|
|
|
p[31] = (u_char)(physicalSize >> 24);
|
|
|
|
return FSDIRMOD;
|
|
|
|
} else
|
|
|
|
return FSERROR;
|
|
|
|
} else if (physicalSize - dir->size >= boot->ClusterSize) {
|
|
|
|
pwarn("%s has too many clusters allocated\n",
|
|
|
|
fullpath(dir));
|
|
|
|
if (ask(1, "Drop superfluous clusters")) {
|
|
|
|
cl_t cl;
|
2014-07-14 20:58:02 +00:00
|
|
|
u_int32_t sz, len;
|
2001-07-09 10:35:18 +00:00
|
|
|
|
2014-07-14 20:58:02 +00:00
|
|
|
for (cl = dir->head, len = sz = 0;
|
|
|
|
(sz += boot->ClusterSize) < dir->size; len++)
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
cl = fat_get_cl_next(fat, cl);
|
|
|
|
clearchain(fat, fat_get_cl_next(fat, cl));
|
|
|
|
ret = fat_set_cl_next(fat, cl, CLUST_EOF);
|
|
|
|
return (FSFATMOD | ret);
|
2001-07-09 10:35:18 +00:00
|
|
|
} else
|
|
|
|
return FSERROR;
|
|
|
|
}
|
|
|
|
return FSOK;
|
|
|
|
}
|
|
|
|
|
2019-04-06 03:42:15 +00:00
|
|
|
static const u_char dot_name[11] = ". ";
|
|
|
|
static const u_char dotdot_name[11] = ".. ";
|
2019-04-05 02:21:16 +00:00
|
|
|
|
|
|
|
/*
|
|
|
|
* Basic sanity check if the subdirectory have good '.' and '..' entries,
|
|
|
|
* and they are directory entries. Further sanity checks are performed
|
|
|
|
* when we traverse into it.
|
|
|
|
*/
|
|
|
|
static int
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
check_subdirectory(struct fat_descriptor *fat, struct dosDirEntry *dir)
|
2019-04-05 02:21:16 +00:00
|
|
|
{
|
|
|
|
u_char *buf, *cp;
|
|
|
|
off_t off;
|
|
|
|
cl_t cl;
|
|
|
|
int retval = FSOK;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
int fd;
|
|
|
|
struct bootblock *boot;
|
|
|
|
|
|
|
|
boot = fat_get_boot(fat);
|
|
|
|
fd = fat_get_fd(fat);
|
2019-04-05 02:21:16 +00:00
|
|
|
|
|
|
|
cl = dir->head;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (dir->parent && !fat_is_valid_cl(fat, cl)) {
|
2019-04-05 02:21:16 +00:00
|
|
|
return FSERROR;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (!(boot->flags & FAT32) && !dir->parent) {
|
|
|
|
off = boot->bpbResSectors + boot->bpbFATs *
|
|
|
|
boot->FATsecs;
|
|
|
|
} else {
|
2019-09-15 19:41:54 +00:00
|
|
|
off = (cl - CLUST_FIRST) * boot->bpbSecPerClust + boot->FirstCluster;
|
2019-04-05 02:21:16 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* We only need to check the first two entries of the directory,
|
|
|
|
* which is found in the first sector of the directory entry,
|
|
|
|
* so read in only the first sector.
|
|
|
|
*/
|
|
|
|
buf = malloc(boot->bpbBytesPerSec);
|
|
|
|
if (buf == NULL) {
|
|
|
|
perr("No space for directory buffer (%u)",
|
|
|
|
boot->bpbBytesPerSec);
|
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
off *= boot->bpbBytesPerSec;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (lseek(fd, off, SEEK_SET) != off ||
|
|
|
|
read(fd, buf, boot->bpbBytesPerSec) != (ssize_t)boot->bpbBytesPerSec) {
|
2019-04-05 02:21:16 +00:00
|
|
|
perr("Unable to read directory");
|
|
|
|
free(buf);
|
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Both `.' and `..' must be present and be the first two entries
|
|
|
|
* and be ATTR_DIRECTORY of a valid subdirectory.
|
|
|
|
*/
|
|
|
|
cp = buf;
|
|
|
|
if (memcmp(cp, dot_name, sizeof(dot_name)) != 0 ||
|
|
|
|
(cp[11] & ATTR_DIRECTORY) != ATTR_DIRECTORY) {
|
|
|
|
pwarn("%s: Incorrect `.' for %s.\n", __func__, dir->name);
|
|
|
|
retval |= FSERROR;
|
|
|
|
}
|
|
|
|
cp += 32;
|
|
|
|
if (memcmp(cp, dotdot_name, sizeof(dotdot_name)) != 0 ||
|
|
|
|
(cp[11] & ATTR_DIRECTORY) != ATTR_DIRECTORY) {
|
|
|
|
pwarn("%s: Incorrect `..' for %s. \n", __func__, dir->name);
|
|
|
|
retval |= FSERROR;
|
|
|
|
}
|
|
|
|
|
|
|
|
free(buf);
|
|
|
|
return retval;
|
|
|
|
}
|
|
|
|
|
2001-07-09 10:35:18 +00:00
|
|
|
/*
|
|
|
|
* Read a directory and
|
|
|
|
* - resolve long name records
|
|
|
|
* - enter file and directory records into the parent's list
|
|
|
|
* - push directories onto the todo-stack
|
|
|
|
*/
|
|
|
|
static int
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
readDosDirSection(struct fat_descriptor *fat, struct dosDirEntry *dir)
|
2001-07-09 10:35:18 +00:00
|
|
|
{
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
struct bootblock *boot;
|
2001-07-09 10:35:18 +00:00
|
|
|
struct dosDirEntry dirent, *d;
|
|
|
|
u_char *p, *vallfn, *invlfn, *empty;
|
|
|
|
off_t off;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
int fd, i, j, k, iosize, entries;
|
|
|
|
bool is_legacyroot;
|
2001-07-09 10:35:18 +00:00
|
|
|
cl_t cl, valcl = ~0, invcl = ~0, empcl = ~0;
|
|
|
|
char *t;
|
|
|
|
u_int lidx = 0;
|
|
|
|
int shortSum;
|
|
|
|
int mod = FSOK;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
size_t dirclusters;
|
2001-07-09 10:35:18 +00:00
|
|
|
#define THISMOD 0x8000 /* Only used within this routine */
|
|
|
|
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
boot = fat_get_boot(fat);
|
|
|
|
fd = fat_get_fd(fat);
|
|
|
|
|
2001-07-09 10:35:18 +00:00
|
|
|
cl = dir->head;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (dir->parent && (!fat_is_valid_cl(fat, cl))) {
|
2001-07-09 10:35:18 +00:00
|
|
|
/*
|
|
|
|
* Already handled somewhere else.
|
|
|
|
*/
|
|
|
|
return FSOK;
|
|
|
|
}
|
|
|
|
shortSum = -1;
|
|
|
|
vallfn = invlfn = empty = NULL;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
|
|
|
|
/*
|
|
|
|
* If we are checking the legacy root (for FAT12/FAT16),
|
|
|
|
* we will operate on the whole directory; otherwise, we
|
|
|
|
* will operate on one cluster at a time, and also take
|
|
|
|
* this opportunity to examine the chain.
|
|
|
|
*
|
|
|
|
* Derive how many entries we are going to encounter from
|
|
|
|
* the I/O size.
|
|
|
|
*/
|
|
|
|
is_legacyroot = (dir->parent == NULL && !(boot->flags & FAT32));
|
|
|
|
if (is_legacyroot) {
|
|
|
|
iosize = boot->bpbRootDirEnts * 32;
|
|
|
|
entries = boot->bpbRootDirEnts;
|
|
|
|
} else {
|
|
|
|
iosize = boot->bpbSecPerClust * boot->bpbBytesPerSec;
|
|
|
|
entries = iosize / 32;
|
|
|
|
mod |= checkchain(fat, dir->head, &dirclusters);
|
|
|
|
}
|
|
|
|
|
2001-07-09 10:35:18 +00:00
|
|
|
do {
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (is_legacyroot) {
|
|
|
|
/*
|
|
|
|
* Special case for FAT12/FAT16 root -- read
|
|
|
|
* in the whole root directory.
|
|
|
|
*/
|
2010-06-20 09:40:54 +00:00
|
|
|
off = boot->bpbResSectors + boot->bpbFATs *
|
|
|
|
boot->FATsecs;
|
2001-07-09 10:35:18 +00:00
|
|
|
} else {
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
/*
|
|
|
|
* Otherwise, read in a cluster of the
|
|
|
|
* directory.
|
|
|
|
*/
|
2019-09-15 19:41:54 +00:00
|
|
|
off = (cl - CLUST_FIRST) * boot->bpbSecPerClust + boot->FirstCluster;
|
2001-07-09 10:35:18 +00:00
|
|
|
}
|
|
|
|
|
2010-02-14 12:31:28 +00:00
|
|
|
off *= boot->bpbBytesPerSec;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (lseek(fd, off, SEEK_SET) != off ||
|
|
|
|
read(fd, buffer, iosize) != iosize) {
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("Unable to read directory");
|
2001-07-09 10:35:18 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
|
|
|
|
for (p = buffer, i = 0; i < entries; i++, p += 32) {
|
2001-07-09 10:35:18 +00:00
|
|
|
if (dir->fsckflags & DIREMPWARN) {
|
|
|
|
*p = SLOT_EMPTY;
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (*p == SLOT_EMPTY || *p == SLOT_DELETED) {
|
|
|
|
if (*p == SLOT_EMPTY) {
|
|
|
|
dir->fsckflags |= DIREMPTY;
|
|
|
|
empty = p;
|
|
|
|
empcl = cl;
|
|
|
|
}
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (dir->fsckflags & DIREMPTY) {
|
|
|
|
if (!(dir->fsckflags & DIREMPWARN)) {
|
|
|
|
pwarn("%s has entries after end of directory\n",
|
|
|
|
fullpath(dir));
|
|
|
|
if (ask(1, "Extend")) {
|
|
|
|
u_char *q;
|
|
|
|
|
|
|
|
dir->fsckflags &= ~DIREMPTY;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (delete(fat,
|
2001-07-09 10:35:18 +00:00
|
|
|
empcl, empty - buffer,
|
|
|
|
cl, p - buffer, 1) == FSFATAL)
|
|
|
|
return FSFATAL;
|
2019-04-03 07:09:28 +00:00
|
|
|
q = ((empcl == cl) ? empty : buffer);
|
|
|
|
assert(q != NULL);
|
2001-07-09 10:35:18 +00:00
|
|
|
for (; q < p; q += 32)
|
|
|
|
*q = SLOT_DELETED;
|
|
|
|
mod |= THISMOD|FSDIRMOD;
|
|
|
|
} else if (ask(0, "Truncate"))
|
|
|
|
dir->fsckflags |= DIREMPWARN;
|
|
|
|
}
|
|
|
|
if (dir->fsckflags & DIREMPWARN) {
|
|
|
|
*p = SLOT_DELETED;
|
|
|
|
mod |= THISMOD|FSDIRMOD;
|
|
|
|
continue;
|
|
|
|
} else if (dir->fsckflags & DIREMPTY)
|
|
|
|
mod |= FSERROR;
|
|
|
|
empty = NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (p[11] == ATTR_WIN95) {
|
|
|
|
if (*p & LRFIRST) {
|
|
|
|
if (shortSum != -1) {
|
|
|
|
if (!invlfn) {
|
|
|
|
invlfn = vallfn;
|
|
|
|
invcl = valcl;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
memset(longName, 0, sizeof longName);
|
|
|
|
shortSum = p[13];
|
|
|
|
vallfn = p;
|
|
|
|
valcl = cl;
|
|
|
|
} else if (shortSum != p[13]
|
|
|
|
|| lidx != (*p & LRNOMASK)) {
|
|
|
|
if (!invlfn) {
|
|
|
|
invlfn = vallfn;
|
|
|
|
invcl = valcl;
|
|
|
|
}
|
|
|
|
if (!invlfn) {
|
|
|
|
invlfn = p;
|
|
|
|
invcl = cl;
|
|
|
|
}
|
|
|
|
vallfn = NULL;
|
|
|
|
}
|
|
|
|
lidx = *p & LRNOMASK;
|
2019-06-11 22:21:29 +00:00
|
|
|
if (lidx == 0) {
|
|
|
|
pwarn("invalid long name\n");
|
|
|
|
if (!invlfn) {
|
|
|
|
invlfn = vallfn;
|
|
|
|
invcl = valcl;
|
|
|
|
}
|
|
|
|
vallfn = NULL;
|
|
|
|
continue;
|
|
|
|
}
|
2001-07-09 10:35:18 +00:00
|
|
|
t = longName + --lidx * 13;
|
2010-06-20 09:40:54 +00:00
|
|
|
for (k = 1; k < 11 && t < longName +
|
|
|
|
sizeof(longName); k += 2) {
|
2001-07-09 10:35:18 +00:00
|
|
|
if (!p[k] && !p[k + 1])
|
|
|
|
break;
|
|
|
|
*t++ = p[k];
|
|
|
|
/*
|
|
|
|
* Warn about those unusable chars in msdosfs here? XXX
|
|
|
|
*/
|
|
|
|
if (p[k + 1])
|
|
|
|
t[-1] = '?';
|
|
|
|
}
|
|
|
|
if (k >= 11)
|
|
|
|
for (k = 14; k < 26 && t < longName + sizeof(longName); k += 2) {
|
|
|
|
if (!p[k] && !p[k + 1])
|
|
|
|
break;
|
|
|
|
*t++ = p[k];
|
|
|
|
if (p[k + 1])
|
|
|
|
t[-1] = '?';
|
|
|
|
}
|
|
|
|
if (k >= 26)
|
|
|
|
for (k = 28; k < 32 && t < longName + sizeof(longName); k += 2) {
|
|
|
|
if (!p[k] && !p[k + 1])
|
|
|
|
break;
|
|
|
|
*t++ = p[k];
|
|
|
|
if (p[k + 1])
|
|
|
|
t[-1] = '?';
|
|
|
|
}
|
|
|
|
if (t >= longName + sizeof(longName)) {
|
|
|
|
pwarn("long filename too long\n");
|
|
|
|
if (!invlfn) {
|
|
|
|
invlfn = vallfn;
|
|
|
|
invcl = valcl;
|
|
|
|
}
|
|
|
|
vallfn = NULL;
|
|
|
|
}
|
|
|
|
if (p[26] | (p[27] << 8)) {
|
|
|
|
pwarn("long filename record cluster start != 0\n");
|
|
|
|
if (!invlfn) {
|
|
|
|
invlfn = vallfn;
|
|
|
|
invcl = cl;
|
|
|
|
}
|
|
|
|
vallfn = NULL;
|
|
|
|
}
|
|
|
|
continue; /* long records don't carry further
|
|
|
|
* information */
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* This is a standard msdosfs directory entry.
|
|
|
|
*/
|
|
|
|
memset(&dirent, 0, sizeof dirent);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* it's a short name record, but we need to know
|
|
|
|
* more, so get the flags first.
|
|
|
|
*/
|
|
|
|
dirent.flags = p[11];
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Translate from 850 to ISO here XXX
|
|
|
|
*/
|
|
|
|
for (j = 0; j < 8; j++)
|
|
|
|
dirent.name[j] = p[j];
|
|
|
|
dirent.name[8] = '\0';
|
|
|
|
for (k = 7; k >= 0 && dirent.name[k] == ' '; k--)
|
|
|
|
dirent.name[k] = '\0';
|
2017-11-30 08:28:17 +00:00
|
|
|
if (k < 0 || dirent.name[k] != '\0')
|
2001-07-09 10:35:18 +00:00
|
|
|
k++;
|
|
|
|
if (dirent.name[0] == SLOT_E5)
|
|
|
|
dirent.name[0] = 0xe5;
|
|
|
|
|
|
|
|
if (dirent.flags & ATTR_VOLUME) {
|
|
|
|
if (vallfn || invlfn) {
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
mod |= removede(fat,
|
2001-07-09 10:35:18 +00:00
|
|
|
invlfn ? invlfn : vallfn, p,
|
|
|
|
invlfn ? invcl : valcl, -1, 0,
|
|
|
|
fullpath(dir), 2);
|
|
|
|
vallfn = NULL;
|
|
|
|
invlfn = NULL;
|
|
|
|
}
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (p[8] != ' ')
|
|
|
|
dirent.name[k++] = '.';
|
|
|
|
for (j = 0; j < 3; j++)
|
|
|
|
dirent.name[k++] = p[j+8];
|
|
|
|
dirent.name[k] = '\0';
|
|
|
|
for (k--; k >= 0 && dirent.name[k] == ' '; k--)
|
|
|
|
dirent.name[k] = '\0';
|
|
|
|
|
|
|
|
if (vallfn && shortSum != calcShortSum(p)) {
|
|
|
|
if (!invlfn) {
|
|
|
|
invlfn = vallfn;
|
|
|
|
invcl = valcl;
|
|
|
|
}
|
|
|
|
vallfn = NULL;
|
|
|
|
}
|
|
|
|
dirent.head = p[26] | (p[27] << 8);
|
|
|
|
if (boot->ClustMask == CLUST32_MASK)
|
|
|
|
dirent.head |= (p[20] << 16) | (p[21] << 24);
|
|
|
|
dirent.size = p[28] | (p[29] << 8) | (p[30] << 16) | (p[31] << 24);
|
|
|
|
if (vallfn) {
|
2010-02-14 12:30:30 +00:00
|
|
|
strlcpy(dirent.lname, longName,
|
|
|
|
sizeof(dirent.lname));
|
2001-07-09 10:35:18 +00:00
|
|
|
longName[0] = '\0';
|
|
|
|
shortSum = -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
dirent.parent = dir;
|
|
|
|
dirent.next = dir->child;
|
|
|
|
|
|
|
|
if (invlfn) {
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
mod |= k = removede(fat,
|
2001-07-09 10:35:18 +00:00
|
|
|
invlfn, vallfn ? vallfn : p,
|
|
|
|
invcl, vallfn ? valcl : cl, cl,
|
|
|
|
fullpath(&dirent), 0);
|
|
|
|
if (mod & FSFATAL)
|
|
|
|
return FSFATAL;
|
|
|
|
if (vallfn
|
|
|
|
? (valcl == cl && vallfn != buffer)
|
|
|
|
: p != buffer)
|
|
|
|
if (k & FSDIRMOD)
|
|
|
|
mod |= THISMOD;
|
|
|
|
}
|
|
|
|
|
|
|
|
vallfn = NULL; /* not used any longer */
|
|
|
|
invlfn = NULL;
|
|
|
|
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
/*
|
|
|
|
* Check if the directory entry is sane.
|
|
|
|
*
|
|
|
|
* '.' and '..' are skipped, their sanity is
|
|
|
|
* checked somewhere else.
|
|
|
|
*
|
|
|
|
* For everything else, check if we have a new,
|
|
|
|
* valid cluster chain (beginning of a file or
|
|
|
|
* directory that was never previously claimed
|
|
|
|
* by another file) when it's a non-empty file
|
|
|
|
* or a directory. The sanity of the cluster
|
|
|
|
* chain is checked at a later time when we
|
|
|
|
* traverse into the directory, or examine the
|
|
|
|
* file's directory entry.
|
|
|
|
*
|
|
|
|
* The only possible fix is to delete the entry
|
|
|
|
* if it's a directory; for file, we have to
|
|
|
|
* truncate the size to 0.
|
|
|
|
*/
|
|
|
|
if (!(dirent.flags & ATTR_DIRECTORY) ||
|
|
|
|
(strcmp(dirent.name, ".") != 0 &&
|
|
|
|
strcmp(dirent.name, "..") != 0)) {
|
|
|
|
if ((dirent.size != 0 || (dirent.flags & ATTR_DIRECTORY)) &&
|
|
|
|
((!fat_is_valid_cl(fat, dirent.head) ||
|
|
|
|
!fat_is_cl_head(fat, dirent.head)))) {
|
|
|
|
if (!fat_is_valid_cl(fat, dirent.head)) {
|
|
|
|
pwarn("%s starts with cluster out of range(%u)\n",
|
|
|
|
fullpath(&dirent),
|
|
|
|
dirent.head);
|
|
|
|
} else {
|
|
|
|
pwarn("%s doesn't start a new cluster chain\n",
|
|
|
|
fullpath(&dirent));
|
|
|
|
}
|
|
|
|
|
|
|
|
if (dirent.flags & ATTR_DIRECTORY) {
|
|
|
|
if (ask(0, "Remove")) {
|
|
|
|
*p = SLOT_DELETED;
|
|
|
|
mod |= THISMOD|FSDIRMOD;
|
|
|
|
} else
|
|
|
|
mod |= FSERROR;
|
|
|
|
continue;
|
|
|
|
} else {
|
|
|
|
if (ask(1, "Truncate")) {
|
|
|
|
p[28] = p[29] = p[30] = p[31] = 0;
|
|
|
|
p[26] = p[27] = 0;
|
|
|
|
if (boot->ClustMask == CLUST32_MASK)
|
|
|
|
p[20] = p[21] = 0;
|
|
|
|
dirent.size = 0;
|
|
|
|
dirent.head = 0;
|
|
|
|
mod |= THISMOD|FSDIRMOD;
|
|
|
|
} else
|
|
|
|
mod |= FSERROR;
|
|
|
|
}
|
2001-07-09 10:35:18 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
if (dirent.flags & ATTR_DIRECTORY) {
|
|
|
|
/*
|
|
|
|
* gather more info for directories
|
|
|
|
*/
|
|
|
|
struct dirTodoNode *n;
|
|
|
|
|
|
|
|
if (dirent.size) {
|
|
|
|
pwarn("Directory %s has size != 0\n",
|
|
|
|
fullpath(&dirent));
|
|
|
|
if (ask(1, "Correct")) {
|
|
|
|
p[28] = p[29] = p[30] = p[31] = 0;
|
|
|
|
dirent.size = 0;
|
|
|
|
mod |= THISMOD|FSDIRMOD;
|
|
|
|
} else
|
|
|
|
mod |= FSERROR;
|
|
|
|
}
|
|
|
|
/*
|
|
|
|
* handle `.' and `..' specially
|
|
|
|
*/
|
|
|
|
if (strcmp(dirent.name, ".") == 0) {
|
|
|
|
if (dirent.head != dir->head) {
|
|
|
|
pwarn("`.' entry in %s has incorrect start cluster\n",
|
|
|
|
fullpath(dir));
|
|
|
|
if (ask(1, "Correct")) {
|
|
|
|
dirent.head = dir->head;
|
|
|
|
p[26] = (u_char)dirent.head;
|
|
|
|
p[27] = (u_char)(dirent.head >> 8);
|
|
|
|
if (boot->ClustMask == CLUST32_MASK) {
|
|
|
|
p[20] = (u_char)(dirent.head >> 16);
|
|
|
|
p[21] = (u_char)(dirent.head >> 24);
|
|
|
|
}
|
|
|
|
mod |= THISMOD|FSDIRMOD;
|
|
|
|
} else
|
|
|
|
mod |= FSERROR;
|
|
|
|
}
|
|
|
|
continue;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
} else if (strcmp(dirent.name, "..") == 0) {
|
2001-07-09 10:35:18 +00:00
|
|
|
if (dir->parent) { /* XXX */
|
|
|
|
if (!dir->parent->parent) {
|
|
|
|
if (dirent.head) {
|
|
|
|
pwarn("`..' entry in %s has non-zero start cluster\n",
|
|
|
|
fullpath(dir));
|
|
|
|
if (ask(1, "Correct")) {
|
|
|
|
dirent.head = 0;
|
|
|
|
p[26] = p[27] = 0;
|
|
|
|
if (boot->ClustMask == CLUST32_MASK)
|
|
|
|
p[20] = p[21] = 0;
|
|
|
|
mod |= THISMOD|FSDIRMOD;
|
|
|
|
} else
|
|
|
|
mod |= FSERROR;
|
|
|
|
}
|
|
|
|
} else if (dirent.head != dir->parent->head) {
|
|
|
|
pwarn("`..' entry in %s has incorrect start cluster\n",
|
|
|
|
fullpath(dir));
|
|
|
|
if (ask(1, "Correct")) {
|
|
|
|
dirent.head = dir->parent->head;
|
|
|
|
p[26] = (u_char)dirent.head;
|
|
|
|
p[27] = (u_char)(dirent.head >> 8);
|
|
|
|
if (boot->ClustMask == CLUST32_MASK) {
|
|
|
|
p[20] = (u_char)(dirent.head >> 16);
|
|
|
|
p[21] = (u_char)(dirent.head >> 24);
|
|
|
|
}
|
|
|
|
mod |= THISMOD|FSDIRMOD;
|
|
|
|
} else
|
|
|
|
mod |= FSERROR;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
continue;
|
2019-04-05 02:21:16 +00:00
|
|
|
} else {
|
|
|
|
/*
|
|
|
|
* Only one directory entry can point
|
|
|
|
* to dir->head, it's '.'.
|
|
|
|
*/
|
|
|
|
if (dirent.head == dir->head) {
|
|
|
|
pwarn("%s entry in %s has incorrect start cluster\n",
|
|
|
|
dirent.name, fullpath(dir));
|
|
|
|
if (ask(1, "Remove")) {
|
|
|
|
*p = SLOT_DELETED;
|
|
|
|
mod |= THISMOD|FSDIRMOD;
|
|
|
|
} else
|
|
|
|
mod |= FSERROR;
|
|
|
|
continue;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
} else if ((check_subdirectory(fat,
|
2019-04-05 02:21:16 +00:00
|
|
|
&dirent) & FSERROR) == FSERROR) {
|
|
|
|
/*
|
|
|
|
* A subdirectory should have
|
|
|
|
* a dot (.) entry and a dot-dot
|
|
|
|
* (..) entry of ATTR_DIRECTORY,
|
|
|
|
* we will inspect further when
|
|
|
|
* traversing into it.
|
|
|
|
*/
|
|
|
|
if (ask(1, "Remove")) {
|
|
|
|
*p = SLOT_DELETED;
|
|
|
|
mod |= THISMOD|FSDIRMOD;
|
|
|
|
} else
|
|
|
|
mod |= FSERROR;
|
|
|
|
continue;
|
|
|
|
}
|
2001-07-09 10:35:18 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
/* create directory tree node */
|
|
|
|
if (!(d = newDosDirEntry())) {
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("No space for directory");
|
2001-07-09 10:35:18 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
memcpy(d, &dirent, sizeof(struct dosDirEntry));
|
|
|
|
/* link it into the tree */
|
|
|
|
dir->child = d;
|
|
|
|
|
|
|
|
/* Enter this directory into the todo list */
|
|
|
|
if (!(n = newDirTodo())) {
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("No space for todo list");
|
2001-07-09 10:35:18 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
n->next = pendingDirectories;
|
|
|
|
n->dir = d;
|
|
|
|
pendingDirectories = n;
|
|
|
|
} else {
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
mod |= k = checksize(fat, p, &dirent);
|
2001-07-09 10:35:18 +00:00
|
|
|
if (k & FSDIRMOD)
|
|
|
|
mod |= THISMOD;
|
|
|
|
}
|
|
|
|
boot->NumFiles++;
|
|
|
|
}
|
2010-02-14 12:30:30 +00:00
|
|
|
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if (is_legacyroot) {
|
|
|
|
/*
|
|
|
|
* Don't bother to write back right now because
|
|
|
|
* we may continue to make modification to the
|
|
|
|
* non-FAT32 root directory below.
|
|
|
|
*/
|
2010-02-14 12:30:30 +00:00
|
|
|
break;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
} else if (mod & THISMOD) {
|
|
|
|
if (lseek(fd, off, SEEK_SET) != off
|
|
|
|
|| write(fd, buffer, iosize) != iosize) {
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("Unable to write directory");
|
2001-07-09 10:35:18 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
mod &= ~THISMOD;
|
|
|
|
}
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
} while (fat_is_valid_cl(fat, (cl = fat_get_cl_next(fat, cl))));
|
2001-07-09 10:35:18 +00:00
|
|
|
if (invlfn || vallfn)
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
mod |= removede(fat,
|
2001-07-09 10:35:18 +00:00
|
|
|
invlfn ? invlfn : vallfn, p,
|
|
|
|
invlfn ? invcl : valcl, -1, 0,
|
|
|
|
fullpath(dir), 1);
|
2010-02-14 12:30:30 +00:00
|
|
|
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
/*
|
|
|
|
* The root directory of non-FAT32 filesystems is in a special
|
|
|
|
* area and may have been modified above removede() without
|
|
|
|
* being written out.
|
2010-02-14 12:30:30 +00:00
|
|
|
*/
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
if ((mod & FSDIRMOD) && is_legacyroot) {
|
|
|
|
if (lseek(fd, off, SEEK_SET) != off
|
|
|
|
|| write(fd, buffer, iosize) != iosize) {
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("Unable to write directory");
|
2010-02-14 12:30:30 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
mod &= ~THISMOD;
|
|
|
|
}
|
2001-07-09 10:35:18 +00:00
|
|
|
return mod & ~THISMOD;
|
|
|
|
}
|
|
|
|
|
|
|
|
int
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
handleDirTree(struct fat_descriptor *fat)
|
2001-07-09 10:35:18 +00:00
|
|
|
{
|
|
|
|
int mod;
|
|
|
|
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
mod = readDosDirSection(fat, rootDir);
|
2001-07-09 10:35:18 +00:00
|
|
|
if (mod & FSFATAL)
|
|
|
|
return FSFATAL;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* process the directory todo list
|
|
|
|
*/
|
|
|
|
while (pendingDirectories) {
|
|
|
|
struct dosDirEntry *dir = pendingDirectories->dir;
|
|
|
|
struct dirTodoNode *n = pendingDirectories->next;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* remove TODO entry now, the list might change during
|
|
|
|
* directory reads
|
|
|
|
*/
|
|
|
|
freeDirTodo(pendingDirectories);
|
|
|
|
pendingDirectories = n;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* handle subdirectory
|
|
|
|
*/
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
mod |= readDosDirSection(fat, dir);
|
2001-07-09 10:35:18 +00:00
|
|
|
if (mod & FSFATAL)
|
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
|
|
|
|
return mod;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Try to reconnect a FAT chain into dir
|
|
|
|
*/
|
|
|
|
static u_char *lfbuf;
|
|
|
|
static cl_t lfcl;
|
|
|
|
static off_t lfoff;
|
|
|
|
|
|
|
|
int
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
reconnect(struct fat_descriptor *fat, cl_t head, size_t length)
|
2001-07-09 10:35:18 +00:00
|
|
|
{
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
struct bootblock *boot = fat_get_boot(fat);
|
2001-07-09 10:35:18 +00:00
|
|
|
struct dosDirEntry d;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
int len, dosfs;
|
2001-07-09 10:35:18 +00:00
|
|
|
u_char *p;
|
|
|
|
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
dosfs = fat_get_fd(fat);
|
|
|
|
|
2001-07-09 10:35:18 +00:00
|
|
|
if (!ask(1, "Reconnect"))
|
|
|
|
return FSERROR;
|
|
|
|
|
|
|
|
if (!lostDir) {
|
|
|
|
for (lostDir = rootDir->child; lostDir; lostDir = lostDir->next) {
|
|
|
|
if (!strcmp(lostDir->name, LOSTDIR))
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
if (!lostDir) { /* Create LOSTDIR? XXX */
|
|
|
|
pwarn("No %s directory\n", LOSTDIR);
|
|
|
|
return FSERROR;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
if (!lfbuf) {
|
|
|
|
lfbuf = malloc(boot->ClusterSize);
|
|
|
|
if (!lfbuf) {
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("No space for buffer");
|
2001-07-09 10:35:18 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
p = NULL;
|
|
|
|
} else
|
|
|
|
p = lfbuf;
|
|
|
|
while (1) {
|
|
|
|
if (p)
|
|
|
|
for (; p < lfbuf + boot->ClusterSize; p += 32)
|
|
|
|
if (*p == SLOT_EMPTY
|
|
|
|
|| *p == SLOT_DELETED)
|
|
|
|
break;
|
|
|
|
if (p && p < lfbuf + boot->ClusterSize)
|
|
|
|
break;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
lfcl = p ? fat_get_cl_next(fat, lfcl) : lostDir->head;
|
2001-07-09 10:35:18 +00:00
|
|
|
if (lfcl < CLUST_FIRST || lfcl >= boot->NumClusters) {
|
|
|
|
/* Extend LOSTDIR? XXX */
|
|
|
|
pwarn("No space in %s\n", LOSTDIR);
|
2019-04-04 23:34:03 +00:00
|
|
|
lfcl = (lostDir->head < boot->NumClusters) ? lostDir->head : 0;
|
2001-07-09 10:35:18 +00:00
|
|
|
return FSERROR;
|
|
|
|
}
|
2019-09-15 19:41:54 +00:00
|
|
|
lfoff = (lfcl - CLUST_FIRST) * boot->ClusterSize
|
|
|
|
+ boot->FirstCluster * boot->bpbBytesPerSec;
|
|
|
|
|
2001-07-09 10:35:18 +00:00
|
|
|
if (lseek(dosfs, lfoff, SEEK_SET) != lfoff
|
2010-02-14 12:30:30 +00:00
|
|
|
|| (size_t)read(dosfs, lfbuf, boot->ClusterSize) != boot->ClusterSize) {
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("could not read LOST.DIR");
|
2001-07-09 10:35:18 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
p = lfbuf;
|
|
|
|
}
|
|
|
|
|
|
|
|
boot->NumFiles++;
|
|
|
|
/* Ensure uniqueness of entry here! XXX */
|
|
|
|
memset(&d, 0, sizeof d);
|
2016-04-06 15:28:26 +00:00
|
|
|
/* worst case -1 = 4294967295, 10 digits */
|
|
|
|
len = snprintf(d.name, sizeof(d.name), "%u", head);
|
2001-07-09 10:35:18 +00:00
|
|
|
d.flags = 0;
|
|
|
|
d.head = head;
|
Reduce memory footprint of fsck_msdosfs.
This is a re-apply r356249 with changes to make GCC happy.
This utility was initially written for FAT12/16, which were inherently
small. When FAT32 support was added, the old data structure and
algorithms remain used with minimal changes.
With growing size of FAT32 media, the current data structure that
requires 4 32-bit variables per each FAT32 table entry would consume up
to 4 GiB of RAM, which can be too big for systems with limited RAM
available.
Address this by taking a different approach of validating the FAT.
The FAT is essentially a set of linked lists of chains that was
referenced by directory entries, and the checker needs to make sure that
the linked chains of clusters do not have cross-linked chains, and every
chain were referenced by one and only one directory entry. Instead of
keeping track of the chain's 'head' cluster number, the size of the
chain, the used status of the chain and the "next" pointer which is
content of the FAT table, we create accessors for the FAT table data
for the "next" pointer, and keep only one bit to indicate if the
current cluster is a 'head' node of a cluster chain, in a bitmap.
We further overhaul the FAT checker to find out the possible head nodes
by excluding ones that are not (in other words, nodes that have some
other nodes claiming them as the next node) instead of marking the head
nodes for each node on the chain. This approach greatly reduced the
complexiety of computation from O(N^2) worst case, to an O(N) scan for
worst case. The file (cluster chain) length is not useful for the FAT
checker, so don't bother to calculate them in the FAT checker and
instead leave the task to the directory structure check, at which point
we would have non-crossed cluster chains, and we are guaranteed that
each cluster will be visited for at most one time.
When checking the directory structures, we use the head node indicator
to as the visited (used) flag: every cluster chain can only be
referenced by one directory entry, so we clear them when calculating
the length of the chain, and we can immediately tell if there are
anomalies in the directory entry.
As a result, the required RAM size is now 1 bit per each entry of
the FAT table, plus memory needed to hold the FAT table in memory,
instead of 16 bytes (=128 bits) per each entry. For FAT12 and FAT16,
we will load the whole FAT table into memory as they are smaller than
128KiB, and for FAT32, we first attempt to mmap() it into memory, and
when that fails, we would fall back to a simple LRU cache of 4 MiB of
RAM.
sbin/fsck_msdosfs/boot.c:
- Added additional sanity checks for valid FAT32/FAT16/FAT12 cluster
number.
- FAT32: check if root directory starts with a valid cluster number,
moved from dir.c. There is no point to proceed if the filesystem
is already damaged beyond repair.
sbin/fsck_msdosfs/check.c:
- Combine phase 1 and phase 2, now that the readfat() is able to
detect cross chains.
sbin/fsck_msdosfs/dir.c:
- Refactor code to use FAT accessor instead of accessing the internal
representation of FAT table.
- Make use of the cluster chain head bitmap.
- Clarify and simplify directory entry check, remove unnecessary
checks that are would be done at a later time (for example, whether
the directory's second cluster is a valid one, which is examined
more throughly in a later checkchain() and does not prevent us
from proceeding further).
sbin/fsck_msdosfs/dosfs.h:
- Remove internal representation of FAT table, which is replaced by
the head bitmap that is opaque to other code.
- Added a special CLUST_DEAD cluster type to indicate errors.
sbin/fsck_msdosfs/ext.h:
- Added a flag that overrides mmap(2) setting. The corresponding
command line option, -M is intentionally undocumented as we do not
expect users to need it.
- Added accessors for FAT table and convert existing interface to use
it.
sbin/fsck_msdosfs/fat.c:
- Added head bitmap to represent whether a cluster is a head cluster.
- Converted FAT internal representation to accessors.
- Implemented a LRU cache for FAT32 when mmap(2) should not or can not
be used.
- _readfat: Attempt a mmap(2) and fall back to regular read for
non-FAT32 file systems; use the LRU cache for FAT32 and prepopulate
the cache with the first 4MiB of the entries.
- readfat: Added support of head bitmap and use the population scan to
detect bogus chains.
- clusterdiff: removed, FATs are copied from the checked copy via
writefat()/copyfat().
- checkchain: calculates the length of a cluster chain and make sure
that it ends with a valid EOF marker.
- clearchain: follow and clear a chain and maintain the free cluster
count.
- checklost: convert to use head bitmap. At the end of all other scans,
the remaining 'head' nodes are leaders of lost cluster chains.
sbin/fsck_msdosfs/fat.c:
- Added a new -M option which is intentionally undocumented, to disable
the use of mmap().
Reviewed by: kevlo
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D22965
2020-01-03 00:31:48 +00:00
|
|
|
d.size = length * boot->ClusterSize;
|
2001-07-09 10:35:18 +00:00
|
|
|
|
2016-04-06 15:28:26 +00:00
|
|
|
memcpy(p, d.name, len);
|
|
|
|
memset(p + len, ' ', 11 - len);
|
|
|
|
memset(p + 11, 0, 32 - 11);
|
2001-07-09 10:35:18 +00:00
|
|
|
p[26] = (u_char)d.head;
|
|
|
|
p[27] = (u_char)(d.head >> 8);
|
|
|
|
if (boot->ClustMask == CLUST32_MASK) {
|
|
|
|
p[20] = (u_char)(d.head >> 16);
|
|
|
|
p[21] = (u_char)(d.head >> 24);
|
|
|
|
}
|
|
|
|
p[28] = (u_char)d.size;
|
|
|
|
p[29] = (u_char)(d.size >> 8);
|
|
|
|
p[30] = (u_char)(d.size >> 16);
|
|
|
|
p[31] = (u_char)(d.size >> 24);
|
|
|
|
if (lseek(dosfs, lfoff, SEEK_SET) != lfoff
|
2010-02-14 12:30:30 +00:00
|
|
|
|| (size_t)write(dosfs, lfbuf, boot->ClusterSize) != boot->ClusterSize) {
|
2012-10-21 12:01:11 +00:00
|
|
|
perr("could not write LOST.DIR");
|
2001-07-09 10:35:18 +00:00
|
|
|
return FSFATAL;
|
|
|
|
}
|
|
|
|
return FSDIRMOD;
|
|
|
|
}
|
|
|
|
|
|
|
|
void
|
2002-03-20 22:57:10 +00:00
|
|
|
finishlf(void)
|
2001-07-09 10:35:18 +00:00
|
|
|
{
|
|
|
|
if (lfbuf)
|
|
|
|
free(lfbuf);
|
|
|
|
lfbuf = NULL;
|
|
|
|
}
|