728 lines
18 KiB
C
728 lines
18 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (C) 1995, 1996, 1997 Wolfgang Solfrank
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* Copyright (c) 1995 Martin Husemann
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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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__RCSID("$NetBSD: fat.c,v 1.18 2006/06/05 16:51:18 christos Exp $");
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static const char rcsid[] =
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"$FreeBSD$";
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#endif /* not lint */
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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 <stdio.h>
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#include <unistd.h>
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#include "ext.h"
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#include "fsutil.h"
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static int checkclnum(struct bootblock *, u_int, cl_t, cl_t *);
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static int clustdiffer(cl_t, cl_t *, cl_t *, u_int);
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static int tryclear(struct bootblock *, struct fatEntry *, cl_t, cl_t *);
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static int _readfat(int, struct bootblock *, u_int, u_char **);
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/*-
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* The first 2 FAT entries contain pseudo-cluster numbers with the following
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* layout:
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*
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* 31...... ........ ........ .......0
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* rrrr1111 11111111 11111111 mmmmmmmm FAT32 entry 0
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* rrrrsh11 11111111 11111111 11111xxx FAT32 entry 1
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*
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* 11111111 mmmmmmmm FAT16 entry 0
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* sh111111 11111xxx FAT16 entry 1
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*
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* r = reserved
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* m = BPB media ID byte
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* s = clean flag (1 = dismounted; 0 = still mounted)
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* h = hard error flag (1 = ok; 0 = I/O error)
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* x = any value ok
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*/
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int
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checkdirty(int fs, struct bootblock *boot)
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{
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off_t off;
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u_char *buffer;
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int ret = 0;
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size_t len;
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if (boot->ClustMask != CLUST16_MASK && boot->ClustMask != CLUST32_MASK)
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return 0;
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off = boot->bpbResSectors;
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off *= boot->bpbBytesPerSec;
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buffer = malloc(len = boot->bpbBytesPerSec);
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if (buffer == NULL) {
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perr("No space for FAT sectors (%zu)", len);
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return 1;
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}
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if (lseek(fs, off, SEEK_SET) != off) {
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perr("Unable to read FAT");
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goto err;
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}
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if ((size_t)read(fs, buffer, boot->bpbBytesPerSec) !=
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boot->bpbBytesPerSec) {
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perr("Unable to read FAT");
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goto err;
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}
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/*
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* If we don't understand the FAT, then the file system must be
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* assumed to be unclean.
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*/
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if (buffer[0] != boot->bpbMedia || buffer[1] != 0xff)
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goto err;
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if (boot->ClustMask == CLUST16_MASK) {
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if ((buffer[2] & 0xf8) != 0xf8 || (buffer[3] & 0x3f) != 0x3f)
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goto err;
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} else {
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if (buffer[2] != 0xff || (buffer[3] & 0x0f) != 0x0f
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|| (buffer[4] & 0xf8) != 0xf8 || buffer[5] != 0xff
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|| buffer[6] != 0xff || (buffer[7] & 0x03) != 0x03)
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goto err;
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}
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/*
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* Now check the actual clean flag (and the no-error flag).
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*/
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if (boot->ClustMask == CLUST16_MASK) {
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if ((buffer[3] & 0xc0) == 0xc0)
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ret = 1;
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} else {
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if ((buffer[7] & 0x0c) == 0x0c)
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ret = 1;
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}
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err:
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free(buffer);
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return ret;
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}
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/*
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* Check a cluster number for valid value
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*/
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static int
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checkclnum(struct bootblock *boot, u_int fat, cl_t cl, cl_t *next)
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{
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if (*next >= (CLUST_RSRVD&boot->ClustMask))
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*next |= ~boot->ClustMask;
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if (*next == CLUST_FREE) {
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boot->NumFree++;
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return FSOK;
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}
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if (*next == CLUST_BAD) {
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boot->NumBad++;
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return FSOK;
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}
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if (*next < CLUST_FIRST
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|| (*next >= boot->NumClusters && *next < CLUST_EOFS)) {
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pwarn("Cluster %u in FAT %d continues with %s cluster number %u\n",
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cl, fat,
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*next < CLUST_RSRVD ? "out of range" : "reserved",
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*next&boot->ClustMask);
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if (ask(0, "Truncate")) {
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*next = CLUST_EOF;
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return FSFATMOD;
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}
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return FSERROR;
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}
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return FSOK;
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}
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/*
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* Read a FAT from disk. Returns 1 if successful, 0 otherwise.
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*/
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static int
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_readfat(int fs, struct bootblock *boot, u_int no, u_char **buffer)
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{
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off_t off;
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size_t len;
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*buffer = malloc(len = boot->FATsecs * boot->bpbBytesPerSec);
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if (*buffer == NULL) {
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perr("No space for FAT sectors (%zu)", len);
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return 0;
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}
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off = boot->bpbResSectors + no * boot->FATsecs;
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off *= boot->bpbBytesPerSec;
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if (lseek(fs, off, SEEK_SET) != off) {
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perr("Unable to read FAT");
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goto err;
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}
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if ((size_t)read(fs, *buffer, boot->FATsecs * boot->bpbBytesPerSec)
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!= boot->FATsecs * boot->bpbBytesPerSec) {
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perr("Unable to read FAT");
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goto err;
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}
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return 1;
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err:
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free(*buffer);
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return 0;
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}
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/*
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* Read a FAT and decode it into internal format
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*/
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int
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readfat(int fs, struct bootblock *boot, u_int no, struct fatEntry **fp)
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{
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struct fatEntry *fat;
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u_char *buffer, *p;
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cl_t cl;
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int ret = FSOK;
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size_t len;
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boot->NumFree = boot->NumBad = 0;
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if (!_readfat(fs, boot, no, &buffer))
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return FSFATAL;
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fat = malloc(len = boot->NumClusters * sizeof(struct fatEntry));
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if (fat == NULL) {
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perr("No space for FAT clusters (%zu)", len);
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free(buffer);
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return FSFATAL;
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}
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(void)memset(fat, 0, len);
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if (buffer[0] != boot->bpbMedia
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|| buffer[1] != 0xff || buffer[2] != 0xff
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|| (boot->ClustMask == CLUST16_MASK && buffer[3] != 0xff)
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|| (boot->ClustMask == CLUST32_MASK
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&& ((buffer[3]&0x0f) != 0x0f
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|| buffer[4] != 0xff || buffer[5] != 0xff
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|| buffer[6] != 0xff || (buffer[7]&0x0f) != 0x0f))) {
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/* Windows 95 OSR2 (and possibly any later) changes
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* the FAT signature to 0xXXffff7f for FAT16 and to
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* 0xXXffff0fffffff07 for FAT32 upon boot, to know that the
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* file system is dirty if it doesn't reboot cleanly.
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* Check this special condition before errorring out.
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*/
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if (buffer[0] == boot->bpbMedia && buffer[1] == 0xff
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&& buffer[2] == 0xff
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&& ((boot->ClustMask == CLUST16_MASK && buffer[3] == 0x7f)
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|| (boot->ClustMask == CLUST32_MASK
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&& buffer[3] == 0x0f && buffer[4] == 0xff
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&& buffer[5] == 0xff && buffer[6] == 0xff
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&& buffer[7] == 0x07)))
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ret |= FSDIRTY;
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else {
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/* just some odd byte sequence in FAT */
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switch (boot->ClustMask) {
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case CLUST32_MASK:
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pwarn("%s (%02x%02x%02x%02x%02x%02x%02x%02x)\n",
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"FAT starts with odd byte sequence",
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buffer[0], buffer[1], buffer[2], buffer[3],
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buffer[4], buffer[5], buffer[6], buffer[7]);
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break;
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case CLUST16_MASK:
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pwarn("%s (%02x%02x%02x%02x)\n",
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"FAT starts with odd byte sequence",
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buffer[0], buffer[1], buffer[2], buffer[3]);
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break;
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default:
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pwarn("%s (%02x%02x%02x)\n",
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"FAT starts with odd byte sequence",
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buffer[0], buffer[1], buffer[2]);
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break;
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}
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if (ask(1, "Correct"))
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ret |= FSFIXFAT;
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}
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}
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switch (boot->ClustMask) {
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case CLUST32_MASK:
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p = buffer + 8;
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break;
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case CLUST16_MASK:
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p = buffer + 4;
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break;
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default:
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p = buffer + 3;
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break;
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}
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for (cl = CLUST_FIRST; cl < boot->NumClusters;) {
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switch (boot->ClustMask) {
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case CLUST32_MASK:
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fat[cl].next = p[0] + (p[1] << 8)
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+ (p[2] << 16) + (p[3] << 24);
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fat[cl].next &= boot->ClustMask;
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ret |= checkclnum(boot, no, cl, &fat[cl].next);
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cl++;
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p += 4;
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break;
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case CLUST16_MASK:
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fat[cl].next = p[0] + (p[1] << 8);
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ret |= checkclnum(boot, no, cl, &fat[cl].next);
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cl++;
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p += 2;
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break;
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default:
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fat[cl].next = (p[0] + (p[1] << 8)) & 0x0fff;
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ret |= checkclnum(boot, no, cl, &fat[cl].next);
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cl++;
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if (cl >= boot->NumClusters)
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break;
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fat[cl].next = ((p[1] >> 4) + (p[2] << 4)) & 0x0fff;
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ret |= checkclnum(boot, no, cl, &fat[cl].next);
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cl++;
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p += 3;
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break;
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}
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}
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free(buffer);
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if (ret & FSFATAL) {
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free(fat);
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*fp = NULL;
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} else
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*fp = fat;
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return ret;
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}
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/*
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* Get type of reserved cluster
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*/
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const char *
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rsrvdcltype(cl_t cl)
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{
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if (cl == CLUST_FREE)
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return "free";
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if (cl < CLUST_BAD)
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return "reserved";
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if (cl > CLUST_BAD)
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return "as EOF";
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return "bad";
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}
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static int
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clustdiffer(cl_t cl, cl_t *cp1, cl_t *cp2, u_int fatnum)
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{
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if (*cp1 == CLUST_FREE || *cp1 >= CLUST_RSRVD) {
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if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
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if ((*cp1 != CLUST_FREE && *cp1 < CLUST_BAD
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&& *cp2 != CLUST_FREE && *cp2 < CLUST_BAD)
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|| (*cp1 > CLUST_BAD && *cp2 > CLUST_BAD)) {
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pwarn("Cluster %u is marked %s with different indicators\n",
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cl, rsrvdcltype(*cp1));
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if (ask(1, "Fix")) {
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*cp2 = *cp1;
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return FSFATMOD;
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}
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return FSFATAL;
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}
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pwarn("Cluster %u is marked %s in FAT 0, %s in FAT %u\n",
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cl, rsrvdcltype(*cp1), rsrvdcltype(*cp2), fatnum);
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if (ask(0, "Use FAT 0's entry")) {
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*cp2 = *cp1;
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return FSFATMOD;
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}
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if (ask(0, "Use FAT %u's entry", fatnum)) {
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*cp1 = *cp2;
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return FSFATMOD;
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}
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return FSFATAL;
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}
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pwarn("Cluster %u is marked %s in FAT 0, but continues with cluster %u in FAT %d\n",
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cl, rsrvdcltype(*cp1), *cp2, fatnum);
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if (ask(0, "Use continuation from FAT %u", fatnum)) {
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*cp1 = *cp2;
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return FSFATMOD;
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}
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if (ask(0, "Use mark from FAT 0")) {
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*cp2 = *cp1;
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return FSFATMOD;
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}
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return FSFATAL;
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}
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if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
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pwarn("Cluster %u continues with cluster %u in FAT 0, but is marked %s in FAT %u\n",
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cl, *cp1, rsrvdcltype(*cp2), fatnum);
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if (ask(0, "Use continuation from FAT 0")) {
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*cp2 = *cp1;
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return FSFATMOD;
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}
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if (ask(0, "Use mark from FAT %d", fatnum)) {
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*cp1 = *cp2;
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return FSFATMOD;
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}
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return FSERROR;
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}
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pwarn("Cluster %u continues with cluster %u in FAT 0, but with cluster %u in FAT %u\n",
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cl, *cp1, *cp2, fatnum);
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if (ask(0, "Use continuation from FAT 0")) {
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*cp2 = *cp1;
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return FSFATMOD;
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}
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if (ask(0, "Use continuation from FAT %u", fatnum)) {
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*cp1 = *cp2;
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return FSFATMOD;
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}
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return FSERROR;
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}
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/*
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* Compare two FAT copies in memory. Resolve any conflicts and merge them
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* into the first one.
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*/
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int
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comparefat(struct bootblock *boot, struct fatEntry *first,
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struct fatEntry *second, u_int fatnum)
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{
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cl_t cl;
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int ret = FSOK;
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for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++)
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if (first[cl].next != second[cl].next)
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ret |= clustdiffer(cl, &first[cl].next, &second[cl].next, fatnum);
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return ret;
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}
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void
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clearchain(struct bootblock *boot, struct fatEntry *fat, cl_t head)
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{
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cl_t p, q;
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for (p = head; p >= CLUST_FIRST && p < boot->NumClusters; p = q) {
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if (fat[p].head != head)
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break;
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q = fat[p].next;
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fat[p].next = fat[p].head = CLUST_FREE;
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fat[p].length = 0;
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}
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}
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int
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tryclear(struct bootblock *boot, struct fatEntry *fat, cl_t head, cl_t *truncp)
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{
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if (ask(0, "Clear chain starting at %u", head)) {
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clearchain(boot, fat, head);
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return FSFATMOD;
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} else if (ask(0, "Truncate")) {
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uint32_t len;
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cl_t p;
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for (p = head, len = 0;
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p >= CLUST_FIRST && p < boot->NumClusters;
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p = fat[p].next, len++)
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continue;
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*truncp = CLUST_EOF;
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fat[head].length = len;
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return FSFATMOD;
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} else
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return FSERROR;
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}
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/*
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* Check a complete FAT in-memory for crosslinks
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*/
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int
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checkfat(struct bootblock *boot, struct fatEntry *fat)
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{
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cl_t head, p, h, n;
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u_int len;
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int ret = 0;
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int conf;
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/*
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* pass 1: figure out the cluster chains.
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*/
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for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
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/* find next untravelled chain */
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if (fat[head].head != 0 /* cluster already belongs to some chain */
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|| fat[head].next == CLUST_FREE
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|| fat[head].next == CLUST_BAD)
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continue; /* skip it. */
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/* follow the chain and mark all clusters on the way */
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for (len = 0, p = head;
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p >= CLUST_FIRST && p < boot->NumClusters &&
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fat[p].head != head;
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p = fat[p].next) {
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fat[p].head = head;
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len++;
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}
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/* the head record gets the length */
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fat[head].length = fat[head].next == CLUST_FREE ? 0 : len;
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}
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/*
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* pass 2: check for crosslinked chains (we couldn't do this in pass 1 because
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* we didn't know the real start of the chain then - would have treated partial
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* chains as interlinked with their main chain)
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*/
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for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
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/* find next untravelled chain */
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if (fat[head].head != head)
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continue;
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/* follow the chain to its end (hopefully) */
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for (len = fat[head].length, p = head;
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(n = fat[p].next) >= CLUST_FIRST && n < boot->NumClusters;
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p = n)
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if (fat[n].head != head || len-- < 2)
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break;
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if (n >= CLUST_EOFS)
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continue;
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if (n == CLUST_FREE || n >= CLUST_RSRVD) {
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pwarn("Cluster chain starting at %u ends with cluster marked %s\n",
|
|
head, rsrvdcltype(n));
|
|
clear:
|
|
ret |= tryclear(boot, fat, head, &fat[p].next);
|
|
continue;
|
|
}
|
|
if (n < CLUST_FIRST || n >= boot->NumClusters) {
|
|
pwarn("Cluster chain starting at %u ends with cluster out of range (%u)\n",
|
|
head, n);
|
|
goto clear;
|
|
}
|
|
if (head == fat[n].head) {
|
|
pwarn("Cluster chain starting at %u loops at cluster %u\n",
|
|
|
|
head, p);
|
|
goto clear;
|
|
}
|
|
pwarn("Cluster chains starting at %u and %u are linked at cluster %u\n",
|
|
head, fat[n].head, n);
|
|
conf = tryclear(boot, fat, head, &fat[p].next);
|
|
if (ask(0, "Clear chain starting at %u", h = fat[n].head)) {
|
|
if (conf == FSERROR) {
|
|
/*
|
|
* Transfer the common chain to the one not cleared above.
|
|
*/
|
|
for (p = n;
|
|
p >= CLUST_FIRST && p < boot->NumClusters;
|
|
p = fat[p].next) {
|
|
if (h != fat[p].head) {
|
|
/*
|
|
* Have to reexamine this chain.
|
|
*/
|
|
head--;
|
|
break;
|
|
}
|
|
fat[p].head = head;
|
|
}
|
|
}
|
|
clearchain(boot, fat, h);
|
|
conf |= FSFATMOD;
|
|
}
|
|
ret |= conf;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Write out FATs encoding them from the internal format
|
|
*/
|
|
int
|
|
writefat(int fs, struct bootblock *boot, struct fatEntry *fat, int correct_fat)
|
|
{
|
|
u_char *buffer, *p;
|
|
cl_t cl;
|
|
u_int i;
|
|
size_t fatsz;
|
|
off_t off;
|
|
int ret = FSOK;
|
|
|
|
buffer = malloc(fatsz = boot->FATsecs * boot->bpbBytesPerSec);
|
|
if (buffer == NULL) {
|
|
perr("No space for FAT sectors (%zu)", fatsz);
|
|
return FSFATAL;
|
|
}
|
|
memset(buffer, 0, fatsz);
|
|
boot->NumFree = 0;
|
|
p = buffer;
|
|
if (correct_fat) {
|
|
*p++ = (u_char)boot->bpbMedia;
|
|
*p++ = 0xff;
|
|
*p++ = 0xff;
|
|
switch (boot->ClustMask) {
|
|
case CLUST16_MASK:
|
|
*p++ = 0xff;
|
|
break;
|
|
case CLUST32_MASK:
|
|
*p++ = 0x0f;
|
|
*p++ = 0xff;
|
|
*p++ = 0xff;
|
|
*p++ = 0xff;
|
|
*p++ = 0x0f;
|
|
break;
|
|
}
|
|
} else {
|
|
/* use same FAT signature as the old FAT has */
|
|
int count;
|
|
u_char *old_fat;
|
|
|
|
switch (boot->ClustMask) {
|
|
case CLUST32_MASK:
|
|
count = 8;
|
|
break;
|
|
case CLUST16_MASK:
|
|
count = 4;
|
|
break;
|
|
default:
|
|
count = 3;
|
|
break;
|
|
}
|
|
|
|
if (!_readfat(fs, boot, boot->ValidFat >= 0 ? boot->ValidFat :0,
|
|
&old_fat)) {
|
|
free(buffer);
|
|
return FSFATAL;
|
|
}
|
|
|
|
memcpy(p, old_fat, count);
|
|
free(old_fat);
|
|
p += count;
|
|
}
|
|
|
|
for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++) {
|
|
switch (boot->ClustMask) {
|
|
case CLUST32_MASK:
|
|
if (fat[cl].next == CLUST_FREE)
|
|
boot->NumFree++;
|
|
*p++ = (u_char)fat[cl].next;
|
|
*p++ = (u_char)(fat[cl].next >> 8);
|
|
*p++ = (u_char)(fat[cl].next >> 16);
|
|
*p &= 0xf0;
|
|
*p++ |= (fat[cl].next >> 24)&0x0f;
|
|
break;
|
|
case CLUST16_MASK:
|
|
if (fat[cl].next == CLUST_FREE)
|
|
boot->NumFree++;
|
|
*p++ = (u_char)fat[cl].next;
|
|
*p++ = (u_char)(fat[cl].next >> 8);
|
|
break;
|
|
default:
|
|
if (fat[cl].next == CLUST_FREE)
|
|
boot->NumFree++;
|
|
*p++ = (u_char)fat[cl].next;
|
|
*p = (u_char)((fat[cl].next >> 8) & 0xf);
|
|
cl++;
|
|
if (cl >= boot->NumClusters)
|
|
break;
|
|
if (fat[cl].next == CLUST_FREE)
|
|
boot->NumFree++;
|
|
*p++ |= (u_char)(fat[cl].next << 4);
|
|
*p++ = (u_char)(fat[cl].next >> 4);
|
|
break;
|
|
}
|
|
}
|
|
for (i = 0; i < boot->bpbFATs; i++) {
|
|
off = boot->bpbResSectors + i * boot->FATsecs;
|
|
off *= boot->bpbBytesPerSec;
|
|
if (lseek(fs, off, SEEK_SET) != off
|
|
|| (size_t)write(fs, buffer, fatsz) != fatsz) {
|
|
perr("Unable to write FAT");
|
|
ret = FSFATAL; /* Return immediately? XXX */
|
|
}
|
|
}
|
|
free(buffer);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Check a complete in-memory FAT for lost cluster chains
|
|
*/
|
|
int
|
|
checklost(int dosfs, struct bootblock *boot, struct fatEntry *fat)
|
|
{
|
|
cl_t head;
|
|
int mod = FSOK;
|
|
int ret;
|
|
|
|
for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
|
|
/* find next untravelled chain */
|
|
if (fat[head].head != head
|
|
|| fat[head].next == CLUST_FREE
|
|
|| (fat[head].next >= CLUST_RSRVD
|
|
&& fat[head].next < CLUST_EOFS)
|
|
|| (fat[head].flags & FAT_USED))
|
|
continue;
|
|
|
|
pwarn("Lost cluster chain at cluster %u\n%d Cluster(s) lost\n",
|
|
head, fat[head].length);
|
|
mod |= ret = reconnect(dosfs, boot, fat, head);
|
|
if (mod & FSFATAL)
|
|
break;
|
|
if (ret == FSERROR && ask(0, "Clear")) {
|
|
clearchain(boot, fat, head);
|
|
mod |= FSFATMOD;
|
|
}
|
|
}
|
|
finishlf();
|
|
|
|
if (boot->bpbFSInfo) {
|
|
ret = 0;
|
|
if (boot->FSFree != 0xffffffffU &&
|
|
boot->FSFree != boot->NumFree) {
|
|
pwarn("Free space in FSInfo block (%u) not correct (%u)\n",
|
|
boot->FSFree, boot->NumFree);
|
|
if (ask(1, "Fix")) {
|
|
boot->FSFree = boot->NumFree;
|
|
ret = 1;
|
|
}
|
|
}
|
|
if (boot->FSNext != 0xffffffffU &&
|
|
(boot->FSNext >= boot->NumClusters ||
|
|
(boot->NumFree && fat[boot->FSNext].next != CLUST_FREE))) {
|
|
pwarn("Next free cluster in FSInfo block (%u) %s\n",
|
|
boot->FSNext,
|
|
(boot->FSNext >= boot->NumClusters) ? "invalid" : "not free");
|
|
if (ask(1, "fix"))
|
|
for (head = CLUST_FIRST; head < boot->NumClusters; head++)
|
|
if (fat[head].next == CLUST_FREE) {
|
|
boot->FSNext = head;
|
|
ret = 1;
|
|
break;
|
|
}
|
|
}
|
|
if (ret)
|
|
mod |= writefsinfo(dosfs, boot);
|
|
}
|
|
|
|
return mod;
|
|
}
|