From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:6f8:1178:4:290:27ff:fe1d:cc33]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TEESR-0004cl-6i for barebox@lists.infradead.org; Wed, 19 Sep 2012 07:12:29 +0000 Date: Wed, 19 Sep 2012 09:12:25 +0200 From: Sascha Hauer Message-ID: <20120919071225.GV6180@pengutronix.de> References: <1348005096-3419-1-git-send-email-franck.jullien@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1348005096-3419-1-git-send-email-franck.jullien@gmail.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: barebox-bounces@lists.infradead.org Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH 1/2] [v3] filetype: Improve FAT detection To: Franck Jullien Cc: barebox@lists.infradead.org On Tue, Sep 18, 2012 at 11:51:35PM +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_or_mbr to check if a buffer is a FAT boot > or MBR sector > > Signed-off-by: Franck Jullien > --- > common/filetype.c | 63 ++++++++++++++++++++++++++++++++++++++++++---------- > include/filetype.h | 2 + > 2 files changed, 53 insertions(+), 12 deletions(-) > > diff --git a/common/filetype.c b/common/filetype.c > index e736d43..cb4db5c 100644 > --- a/common/filetype.c > +++ b/common/filetype.c > @@ -26,6 +26,8 @@ > #include > #include > #include > +#include > +#include > > static const char *filetype_str[] = { > [filetype_unknown] = "unknown", > @@ -42,6 +44,7 @@ static const char *filetype_str[] = { > [filetype_sh] = "Bourne Shell", > [filetype_mips_barebox] = "MIPS barebox image", > [filetype_fat] = "FAT filesytem", > + [filetype_mbr] = "MBR sector", > }; > > const char *file_type_to_string(enum filetype f) > @@ -52,26 +55,42 @@ const char *file_type_to_string(enum filetype f) > return NULL; > } > > -static int is_fat(u8 *buf) > +#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) */ > + > +enum filetype is_fat_or_mbr(unsigned char *sector, unsigned long *bootsec) Could you add a comment describing the meaning of the bootsec argument? Also, please make the sector argument 'const'. (I'll send a patch making the other functions take a const argument where appropriate) > { > - if (get_unaligned_le16(&buf[510]) != 0xAA55) > - return 0; > + if(bootsec) whitespace after 'if' please. > + *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 filetype_unknown; > + > + /* Check "FAT" string */ > + if ((get_unaligned_le32(§or[BS_FilSysType]) & 0xFFFFFF) == 0x544146) > + return filetype_fat; > > - /* FAT */ > - if ((get_unaligned_le32(&buf[54]) & 0xFFFFFF) == 0x544146) > - return 1; > + if ((get_unaligned_le32(§or[BS_FilSysType32]) & 0xFFFFFF) == 0x544146) > + return filetype_fat; > > - /* 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 filetype_mbr; > } > > enum filetype file_detect_type(void *_buf) > { > u32 *buf = _buf; > u8 *buf8 = _buf; > + enum filetype type; > > if (strncmp(buf8, "#!/bin/sh", 9) == 0) > return filetype_sh; > @@ -99,8 +118,10 @@ enum filetype file_detect_type(void *_buf) > return filetype_aimage; > if (strncmp(buf8 + 0x10, "barebox", 7) == 0) > return filetype_mips_barebox; > - if (is_fat(buf8)) > - return filetype_fat; > + > + type = is_fat_or_mbr(buf8, NULL); > + if (type != filetype_unknown) > + return type; > > return filetype_unknown; > } > @@ -110,6 +131,7 @@ 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 +145,23 @@ enum filetype file_name_detect_type(const char *filename) > > type = file_detect_type(buf); > > + if (type == filetype_mbr) { > + /* Get the first partition start sector > + * and check for FAT in it */ > + is_fat_or_mbr((u8 *)buf, &bootsec); Unnecessary cast. > + ret = lseek(fd, (bootsec) * 512, SEEK_SET); > + if (ret < 0) { > + type = filetype_unknown; It's still an mbr in this case. > + goto err_out; > + } > + ret = read(fd, buf, 512); > + if (ret < 0) { > + type = filetype_unknown; ditto. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox