Hi Franck,
On Thu, Sep 13, 2012 at 02:13:29PM +0200, Franck Jullien wrote:
> *** Did not send this email with git because it's no working where I am **
>
> We may have some disk with MBR as a first sector. In this case, the
> current FAT check returns an error. However, the FAT sector exist and
> the MBR can tell us where it is.
>
> This patch make the FAT fs try to find the FAT boot sector on the first
> sector of the first partition in case it is not on sector 0.
The patch looks good. Not applying it because it's RFC, but I would if
you give your ok.
Sascha
>
> Signed-off-by: Franck Jullien <franck.jullien@xxxxxxxxx>
> ---
> fs/fat/ff.c | 24 ++++++++++++++++++++----
> 1 files changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/fs/fat/ff.c b/fs/fat/ff.c
> index 66db1d6..6a4ae32 100644
> --- a/fs/fat/ff.c
> +++ b/fs/fat/ff.c
> @@ -191,6 +191,7 @@
> #define FSI_Nxt_Free 492 /* FSI: Last allocated cluster (4) */
> #define MBR_Table 446 /* MBR: Partition table offset (2) */
> #define SZ_PTE 16 /* MBR: Size of a partition table entry */
> +#define MBR_StartSector 8 /* MBR: Offset of Starting Sector in
> Partition Table Entry */
> #define BS_55AA 510 /* Boot sector signature (2) */
>
> #define DIR_Name 0 /* Short file name (11) */
> @@ -1533,11 +1534,15 @@ int follow_path ( /* 0(0): successful, !=0:
> error code */
> */
> static int 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;
>
> + if(bootsec)
> + *bootsec = 0;
> +
> /* Load boot record */
> ret = disk_read(fs, fs->win, sect, 1);
> if (ret)
> @@ -1553,6 +1558,12 @@ static int check_fs ( /* 0:The FAT BR, 1:Valid
> BR but not an FAT, 2:Not a BR, 3:
> if ((LD_DWORD(&fs->win[BS_FilSysType32]) & 0xFFFFFF) == 0x544146)
> return 0;
>
> + if(bootsec)
> + /* This must be an MBR, so return the starting sector of the
> + * first partition so we could check if there is a FAT boot
> + * sector there */
> + *bootsec = LD_WORD(&fs->win[MBR_Table + MBR_StartSector]);
> +
> return -ENODEV;
> }
>
> @@ -1565,6 +1576,7 @@ 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;
>
> @@ -1579,9 +1591,13 @@ 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 */
> + fmt = check_fs(fs, bsect = 0, &first_boot_sect); /* Check sector 0
> if it is a VBR */
> + if (fmt && first_boot_sect != 0) {
> + /* Sector 0 is an MBR, now check for FAT in the first partition */
> + fmt = check_fs(fs, bsect = first_boot_sect, NULL);
> + if(fmt)
> + return fmt; /* No FAT volume is found */
> + }
>
> /* Following code initializes the file system object */
>
> --
> 1.7.1
>
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