freebsd-dev/sys/geom/label/g_label_msdosfs.c
Pawel Jakub Dawidek 1894472106 Handle MSDOS file systems properly. Before the change file systems
created on Windows XP (and others maybe) were not detected.
We detected only those created with newfs_msdos(8).

Submitted by:		Tobias Reifenberger <treif@mayn.de>
style(9)ified by:	pjd
2006-08-12 15:34:15 +00:00

223 lines
6.4 KiB
C

/*-
* Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
* Copyright (c) 2006 Tobias Reifenberger
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <geom/geom.h>
#include <geom/label/g_label.h>
#include <geom/label/g_label_msdosfs.h>
#define G_LABEL_MSDOSFS_DIR "msdosfs"
#define LABEL_NO_NAME "NO NAME "
static void
g_label_msdosfs_taste(struct g_consumer *cp, char *label, size_t size)
{
struct g_provider *pp;
FAT_BSBPB *pfat_bsbpb;
FAT32_BSBPB *pfat32_bsbpb;
FAT_DES *pfat_entry;
uint8_t *sector0, *sector;
uint32_t i;
g_topology_assert_not();
pp = cp->provider;
sector0 = NULL;
sector = NULL;
bzero(label, size);
/* Check if the sector size of the medium is a valid FAT sector size. */
switch(pp->sectorsize) {
case 512:
case 1024:
case 2048:
case 4096:
break;
default:
G_LABEL_DEBUG(1, "MSDOSFS: %s: sector size %d not compatible.",
pp->name, pp->sectorsize);
return;
}
/* Load 1st sector with boot sector and boot parameter block. */
sector0 = (uint8_t *)g_read_data(cp, 0, pp->sectorsize, NULL);
if (sector0 == NULL)
return;
/* Check for the FAT boot sector signature. */
if (sector0[510] != 0x55 || sector0[511] != 0xaa) {
G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT signature found.",
pp->name);
goto error;
}
/*
* Test if this is really a FAT volume and determine the FAT type.
*/
pfat_bsbpb = (FAT_BSBPB *)sector0;
pfat32_bsbpb = (FAT32_BSBPB *)sector0;
if (UINT16BYTES(pfat_bsbpb->BPB_FATSz16) != 0) {
/*
* If the BPB_FATSz16 field is not zero and the string "FAT" is
* at the right place, this should be a FAT12 or FAT16 volume.
*/
if (strncmp(pfat_bsbpb->BS_FilSysType, "FAT", 3) != 0) {
G_LABEL_DEBUG(1,
"MSDOSFS: %s: FAT12/16 volume not valid.",
pp->name);
goto error;
}
G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT12/FAT16 volume detected.",
pp->name);
/* A volume with no name should have "NO NAME " as label. */
if (strncmp(pfat_bsbpb->BS_VolLab, LABEL_NO_NAME,
sizeof(pfat_bsbpb->BS_VolLab)) == 0) {
G_LABEL_DEBUG(1,
"MSDOSFS: %s: FAT12/16 volume has no name.",
pp->name);
goto error;
}
strlcpy(label, pfat_bsbpb->BS_VolLab,
MIN(size, sizeof(pfat_bsbpb->BS_VolLab) + 1));
} else if (UINT32BYTES(pfat32_bsbpb->BPB_FATSz32) != 0) {
uint32_t fat_FirstDataSector, fat_BytesPerSector, offset;
/*
* If the BPB_FATSz32 field is not zero and the string "FAT" is
* at the right place, this should be a FAT32 volume.
*/
if (strncmp(pfat32_bsbpb->BS_FilSysType, "FAT", 3) != 0) {
G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume not valid.",
pp->name);
goto error;
}
G_LABEL_DEBUG(1, "MSDOSFS: %s: FAT32 volume detected.",
pp->name);
/*
* If the volume label is not "NO NAME " we're done.
*/
if (strncmp(pfat32_bsbpb->BS_VolLab, LABEL_NO_NAME,
sizeof(pfat32_bsbpb->BS_VolLab)) != 0) {
strlcpy(label, pfat32_bsbpb->BS_VolLab,
MIN(size, sizeof(pfat32_bsbpb->BS_VolLab) + 1));
goto endofchecks;
}
/*
* If the volume label "NO NAME " is in the boot sector, the
* label of FAT32 volumes may be stored as a special entry in
* the root directory.
*/
fat_FirstDataSector =
UINT16BYTES(pfat32_bsbpb->BPB_RsvdSecCnt) +
(pfat32_bsbpb->BPB_NumFATs *
UINT32BYTES(pfat32_bsbpb->BPB_FATSz32));
fat_BytesPerSector = UINT16BYTES(pfat32_bsbpb->BPB_BytsPerSec);
G_LABEL_DEBUG(2,
"MSDOSFS: FAT_FirstDataSector=0x%x, FAT_BytesPerSector=%d",
fat_FirstDataSector, fat_BytesPerSector);
for (offset = fat_BytesPerSector * fat_FirstDataSector;;
offset += fat_BytesPerSector) {
sector = (uint8_t *)g_read_data(cp, offset,
fat_BytesPerSector, NULL);
if (sector == NULL)
goto error;
pfat_entry = (FAT_DES *)sector;
do {
/* No more entries available. */
if (pfat_entry->DIR_Name[0] == 0) {
G_LABEL_DEBUG(1, "MSDOSFS: %s: "
"FAT32 volume has no name.",
pp->name);
goto error;
}
/* Skip empty or long name entries. */
if (pfat_entry->DIR_Name[0] == 0xe5 ||
(pfat_entry->DIR_Attr &
FAT_DES_ATTR_LONG_NAME) ==
FAT_DES_ATTR_LONG_NAME) {
continue;
}
/*
* The name of the entry is the volume label if
* ATTR_VOLUME_ID is set.
*/
if (pfat_entry->DIR_Attr &
FAT_DES_ATTR_VOLUME_ID) {
strlcpy(label, pfat_entry->DIR_Name,
MIN(size,
sizeof(pfat_bsbpb->BS_VolLab) + 1));
goto endofchecks;
}
} while((uint8_t *)(++pfat_entry) <
(uint8_t *)(sector + fat_BytesPerSector));
g_free(sector);
}
} else {
G_LABEL_DEBUG(1, "MSDOSFS: %s: no FAT volume detected.",
pp->name);
goto error;
}
endofchecks:
for (i = size - 1; i > 0; i--) {
if (label[i] == '\0')
continue;
else if (label[i] == ' ')
label[i] = '\0';
else
break;
}
error:
if (sector0 != NULL)
g_free(sector0);
if (sector != NULL)
g_free(sector);
}
const struct g_label_desc g_label_msdosfs = {
.ld_taste = g_label_msdosfs_taste,
.ld_dir = G_LABEL_MSDOSFS_DIR
};