Hi Franck,
On Sun, Sep 16, 2012 at 10:33:32PM +0200, Franck Jullien wrote:
> 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 add to file_name_detect_type function the ability to find
> the FAT boot sector on the first sector of the first partition in case
> it is not on sector 0.
>
> It also introduce is_fat_boot_sector to check if a buffer is a FAT boot
> sector.
I think it would be cleaner to introduce a filetype MBR as a first
step...
> @@ -110,6 +128,7 @@ enum filetype file_name_detect_type(const char *filename)
> int fd, ret;
> void *buf;
> enum filetype type = filetype_unknown;
> + unsigned long bootsec;
>
> fd = open(filename, O_RDONLY);
> if (fd < 0)
> @@ -123,6 +142,25 @@ enum filetype file_name_detect_type(const char *filename)
>
> type = file_detect_type(buf);
>
> + /* Let's give FAT another chance */
> + if (type == filetype_unknown) {
... then you could check for type == filetype_mbr here instead and
return filetype_mbr when the check for fat below fails.
> + ret = is_fat_boot_sector((u8 *)buf, &bootsec);
> + if (ret && bootsec != 0) {
> + /* The first sector is an MBR, now check for
> + * FAT in the first partition */
> + lseek(fd, (bootsec) * 512, SEEK_SET);
Please check the return value of lseek here. lseek will fail when the file
is on a tftp filesystem or when the file is not large enough.
Sascha
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