From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-qc0-f177.google.com ([209.85.216.177]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TEEcz-0005KW-OL for barebox@lists.infradead.org; Wed, 19 Sep 2012 07:23:22 +0000 Received: by qcsu28 with SMTP id u28so602618qcs.36 for ; Wed, 19 Sep 2012 00:23:19 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20120919071225.GV6180@pengutronix.de> References: <1348005096-3419-1-git-send-email-franck.jullien@gmail.com> <20120919071225.GV6180@pengutronix.de> Date: Wed, 19 Sep 2012 09:23:19 +0200 Message-ID: From: Franck Jullien 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: Sascha Hauer Cc: barebox 2012/9/19 Sascha Hauer : > 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 | I shouldn't write code late at night. Hopefully you are reading my code with attention :) _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox