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fs/fat: Handle MBR on the first sector 

Use filetype to detect FAT boot sector.
Add support for disk with MBR on the first sector.

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
This commit is contained in:
Franck Jullien 2012-09-19 13:09:02 +02:00 committed by Sascha Hauer
parent 010ee209b7
commit 466e505fd9
1 changed files with 19 additions and 18 deletions
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37
fs/fat/ff.c
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@ -93,6 +93,7 @@
#include <errno.h>
#include <malloc.h>
#include <linux/ctype.h>
#include <filetype.h>
#include "ff.h" /* FatFs configurations and declarations */
#include "diskio.h" /* Declarations of low level disk I/O functions */
@ -1531,29 +1532,20 @@ int follow_path ( /* 0(0): successful, !=0: error code */
/*
* Load boot record and check if it is an FAT boot record
*/
static int check_fs ( /* 0:The FAT BR, 1:Valid BR but not an FAT, 2:Not a BR, 3:Disk error */
static enum filetype check_fs ( /* 0:The FAT BR, 1:Valid BR but not an FAT, 2:Not a BR, 3:Disk error */
FATFS *fs, /* File system object */
DWORD sect /* Sector# (lba) to check if it is an FAT boot record or not */
DWORD sect, /* Sector# (lba) to check if it is an FAT boot record or not */
DWORD *bootsec
)
{
int ret;
enum filetype ret;
/* Load boot record */
ret = disk_read(fs, fs->win, sect, 1);
if (ret)
return ret;
/* Check record signature (always placed at offset 510 even if the sector size is>512) */
if (LD_WORD(&fs->win[BS_55AA]) != 0xAA55)
return -ENODEV;
return filetype_unknown;
/* Check "FAT" string */
if ((LD_DWORD(&fs->win[BS_FilSysType]) & 0xFFFFFF) == 0x544146)
return 0;
if ((LD_DWORD(&fs->win[BS_FilSysType32]) & 0xFFFFFF) == 0x544146)
return 0;
return -ENODEV;
return is_fat_or_mbr(fs->win, bootsec);
}
/*
@ -1565,8 +1557,10 @@ static int chk_mounted ( /* 0(0): successful, !=0: any error occurred */
)
{
BYTE fmt, b;
DWORD first_boot_sect;
DWORD bsect, fasize, tsect, sysect, nclst, szbfat;
WORD nrsv;
enum filetype type;
INIT_LIST_HEAD(&fs->dirtylist);
@ -1579,9 +1573,16 @@ static int chk_mounted ( /* 0(0): successful, !=0: any error occurred */
return -EIO;
#endif
/* Search FAT partition on the drive. Supports only generic partitionings, FDISK and SFD. */
fmt = check_fs(fs, bsect = 0); /* Check sector 0 if it is a VBR */
if (fmt)
return fmt; /* No FAT volume is found */
type = check_fs(fs, bsect = 0, &first_boot_sect); /* Check sector 0 if it is a VBR */
if (type == filetype_mbr) {
/* Sector 0 is an MBR, now check for FAT in the first partition */
type = check_fs(fs, bsect = first_boot_sect, NULL);
if (type != filetype_fat)
return -ENODEV;
}
if (type == filetype_unknown)
return -ENODEV;
/* Following code initializes the file system object */