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authorKyle Moffett <Kyle.D.Moffett@boeing.com>2011-12-21 07:08:10 +0000
committerWolfgang Denk <wd@denx.de>2012-01-05 20:10:06 +0100
commit9813b750f32c0056f0a35813b9a9ec0f68b664af (patch)
tree8e9f487ab2a7be1fd914dd98507521626e4e6a02 /fs/fat
parent26784f1ecb5002aa309f2aefcb1157a9282a2007 (diff)
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fs/fat: Fix FAT detection to support non-DOS partition tables
The FAT filesystem code currently ends up requiring that the partition table be a DOS MBR, as it checks for the DOS 0x55 0xAA signature on the partition table (which may be Mac, EFI, ISO9660, etc) before actually computing the partition offset. This fixes support for accessing a FAT filesystem in an ISO9660 boot volume (El-Torito format) by reordering the filesystem checks and reading the 0x55 0xAA "DOS boot signature" and FAT/FAT32 magic number from the first sector of the partition instead of from sector 0. Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com> Fix build warning: fat.c: In function 'fat_register_device': fat.c:66:15: warning: variable 'found_partition' set but not used [-Wunused-but-set-variable] Signed-off-by: Wolfgang Denk <wd@denx.de>
Diffstat (limited to 'fs/fat')
-rw-r--r--fs/fat/fat.c115
1 files changed, 52 insertions, 63 deletions
diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index 1542194a1a..2bb7adfcf1 100644
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -43,50 +43,30 @@ static void downcase (char *str)
}
}
-static block_dev_desc_t *cur_dev = NULL;
+static block_dev_desc_t *cur_dev;
+static unsigned int cur_part_nr;
+static disk_partition_t cur_part_info;
-static unsigned long part_offset = 0;
-
-static int cur_part = 1;
-
-#define DOS_PART_TBL_OFFSET 0x1be
-#define DOS_PART_MAGIC_OFFSET 0x1fe
+#define DOS_BOOT_MAGIC_OFFSET 0x1fe
#define DOS_FS_TYPE_OFFSET 0x36
#define DOS_FS32_TYPE_OFFSET 0x52
-static int disk_read (__u32 startblock, __u32 getsize, __u8 * bufptr)
+static int disk_read(__u32 block, __u32 nr_blocks, void *buf)
{
- if (cur_dev == NULL)
+ if (!cur_dev || !cur_dev->block_read)
return -1;
- startblock += part_offset;
-
- if (cur_dev->block_read) {
- return cur_dev->block_read(cur_dev->dev, startblock, getsize,
- (unsigned long *) bufptr);
- }
- return -1;
+ return cur_dev->block_read(cur_dev->dev,
+ cur_part_info.start + block, nr_blocks, buf);
}
int fat_register_device (block_dev_desc_t * dev_desc, int part_no)
{
unsigned char buffer[dev_desc->blksz];
- if (!dev_desc->block_read)
- return -1;
+ /* First close any currently found FAT filesystem */
+ cur_dev = NULL;
- cur_dev = dev_desc;
- /* check if we have a MBR (on floppies we have only a PBR) */
- if (dev_desc->block_read(dev_desc->dev, 0, 1, (ulong *)buffer) != 1) {
- printf("** Can't read from device %d **\n",
- dev_desc->dev);
- return -1;
- }
- if (buffer[DOS_PART_MAGIC_OFFSET] != 0x55 ||
- buffer[DOS_PART_MAGIC_OFFSET + 1] != 0xaa) {
- /* no signature found */
- return -1;
- }
#if (defined(CONFIG_CMD_IDE) || \
defined(CONFIG_CMD_MG_DISK) || \
defined(CONFIG_CMD_SATA) || \
@@ -94,45 +74,54 @@ int fat_register_device (block_dev_desc_t * dev_desc, int part_no)
defined(CONFIG_CMD_USB) || \
defined(CONFIG_MMC) || \
defined(CONFIG_SYSTEMACE) )
- {
- disk_partition_t info;
-
- /* First we assume there is a MBR */
- if (!get_partition_info(dev_desc, part_no, &info)) {
- part_offset = info.start;
- cur_part = part_no;
- } else if ((strncmp((char *)&buffer[DOS_FS_TYPE_OFFSET],
- "FAT", 3) == 0) ||
- (strncmp((char *)&buffer[DOS_FS32_TYPE_OFFSET],
- "FAT32", 5) == 0)) {
- /* ok, we assume we are on a PBR only */
- cur_part = 1;
- part_offset = 0;
- } else {
+
+ /* Read the partition table, if present */
+ if (!get_partition_info(dev_desc, part_no, &cur_part_info)) {
+ cur_dev = dev_desc;
+ cur_part_nr = part_no;
+ }
+#endif
+
+ /* Otherwise it might be a superfloppy (whole-disk FAT filesystem) */
+ if (!cur_dev) {
+ if (part_no != 1) {
printf("** Partition %d not valid on device %d **\n",
- part_no, dev_desc->dev);
+ part_no, dev_desc->dev);
return -1;
}
+
+ cur_dev = dev_desc;
+ cur_part_nr = 1;
+ cur_part_info.start = 0;
+ cur_part_info.size = dev_desc->lba;
+ cur_part_info.blksz = dev_desc->blksz;
+ memset(cur_part_info.name, 0, sizeof(cur_part_info.name));
+ memset(cur_part_info.type, 0, sizeof(cur_part_info.type));
}
-#else
- if ((strncmp((char *)&buffer[DOS_FS_TYPE_OFFSET], "FAT", 3) == 0) ||
- (strncmp((char *)&buffer[DOS_FS32_TYPE_OFFSET], "FAT32", 5) == 0)) {
- /* ok, we assume we are on a PBR only */
- cur_part = 1;
- part_offset = 0;
- } else {
- /* FIXME we need to determine the start block of the
- * partition where the DOS FS resides. This can be done
- * by using the get_partition_info routine. For this
- * purpose the libpart must be included.
- */
- part_offset = 32;
- cur_part = 1;
+
+ /* Make sure it has a valid FAT header */
+ if (disk_read(0, 1, buffer) != 1) {
+ cur_dev = NULL;
+ return -1;
}
-#endif
- return 0;
+
+ /* Check if it's actually a DOS volume */
+ if (memcmp(buffer + DOS_BOOT_MAGIC_OFFSET, "\x55\xAA", 2)) {
+ cur_dev = NULL;
+ return -1;
+ }
+
+ /* Check for FAT12/FAT16/FAT32 filesystem */
+ if (!memcmp(buffer + DOS_FS_TYPE_OFFSET, "FAT", 3))
+ return 0;
+ if (!memcmp(buffer + DOS_FS32_TYPE_OFFSET, "FAT32", 5))
+ return 0;
+
+ cur_dev = NULL;
+ return -1;
}
+
/*
* Get the first occurence of a directory delimiter ('/' or '\') in a string.
* Return index into string if found, -1 otherwise.
@@ -1172,7 +1161,7 @@ int file_fat_detectfs (void)
vol_label[11] = '\0';
volinfo.fs_type[5] = '\0';
- printf("Partition %d: Filesystem: %s \"%s\"\n", cur_part,
+ printf("Partition %d: Filesystem: %s \"%s\"\n", cur_part_nr,
volinfo.fs_type, vol_label);
return 0;
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