From: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
To: Franck Jullien <franck.jullien@gmail.com>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH 1/2] filetype: Improve FAT detection
Date: Sun, 16 Sep 2012 15:26:11 +0200 [thread overview]
Message-ID: <20120916132611.GL25990@game.jcrosoft.org> (raw)
In-Reply-To: <1347798733-22342-1-git-send-email-franck.jullien@gmail.com>
On 14:32 Sun 16 Sep , 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 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.
>
> Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
> ---
> common/filetype.c | 55 +++++++++++++++++++++++++++++++++++++++++----------
> include/filetype.h | 1 +
> 2 files changed, 45 insertions(+), 11 deletions(-)
>
> diff --git a/common/filetype.c b/common/filetype.c
> index e736d43..d07505b 100644
> --- a/common/filetype.c
> +++ b/common/filetype.c
> @@ -26,6 +26,8 @@
> #include <fcntl.h>
> #include <fs.h>
> #include <malloc.h>
> +#include <fat.h>
> +#include <errno.h>
>
> static const char *filetype_str[] = {
> [filetype_unknown] = "unknown",
> @@ -52,26 +54,45 @@ const char *file_type_to_string(enum filetype f)
> return NULL;
> }
>
> -static int is_fat(u8 *buf)
> +int fd;
> +
> +#define MBR_StartSector 8 /* MBR: Offset of Starting Sector in Partition Table Entry */
> +#define BS_55AA 510 /* Boot sector signature (2) */
> +#define MBR_Table 446 /* MBR: Partition table offset (2) */
> +#define BS_FilSysType32 82 /* File system type (1) */
> +#define BS_FilSysType 54 /* File system type (1) */
> +
> +int is_fat_boot_sector(unsigned char *sector, unsigned long *bootsec)
> {
> - if (get_unaligned_le16(&buf[510]) != 0xAA55)
> + if(bootsec)
> + *bootsec = 0;
> +
> + /* Check record signature (always placed at offset 510 even if the sector size is>512) */
> + if (get_unaligned_le16(§or[BS_55AA]) != 0xAA55)
> + return -ENODEV;
> +
> + /* Check "FAT" string */
> + if ((get_unaligned_le32(§or[BS_FilSysType]) & 0xFFFFFF) == 0x544146)
> return 0;
>
> - /* FAT */
> - if ((get_unaligned_le32(&buf[54]) & 0xFFFFFF) == 0x544146)
> - return 1;
> + if ((get_unaligned_le32(§or[BS_FilSysType32]) & 0xFFFFFF) == 0x544146)
> + return 0;
>
> - /* FAT32 */
> - if ((get_unaligned_le32(&buf[82]) & 0xFFFFFF) == 0x544146)
> - return 1;
> + 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 = get_unaligned_le16(§or[MBR_Table + MBR_StartSector]);
>
> - return 0;
> + return -ENODEV;
> }
>
> enum filetype file_detect_type(void *_buf)
you work on buf already read you do not knwon where or how
so you can not use fd
this is broken
Best Regards,
J.
> {
_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox
prev parent reply other threads:[~2012-09-16 13:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-16 12:32 Franck Jullien
2012-09-16 12:32 ` [PATCH 2/2] fs/fat: Handle MBR on the first sector Franck Jullien
2012-09-16 13:26 ` Jean-Christophe PLAGNIOL-VILLARD [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120916132611.GL25990@game.jcrosoft.org \
--to=plagnioj@jcrosoft.com \
--cc=barebox@lists.infradead.org \
--cc=franck.jullien@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox