From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-wi0-f171.google.com ([209.85.212.171]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TEI9N-0007PX-CJ for barebox@lists.infradead.org; Wed, 19 Sep 2012 11:09:02 +0000 Received: by wibhq4 with SMTP id hq4so3892340wib.0 for ; Wed, 19 Sep 2012 04:08:58 -0700 (PDT) From: Franck Jullien Date: Wed, 19 Sep 2012 13:09:01 +0200 Message-Id: <1348052942-13853-1-git-send-email-franck.jullien@gmail.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 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: [PATCH 1/2] [v4] filetype: Improve FAT detection To: barebox@lists.infradead.org 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 | 60 +++++++++++++++++++++++++++++++++++++++++---------- include/filetype.h | 2 + 2 files changed, 50 insertions(+), 12 deletions(-) diff --git a/common/filetype.c b/common/filetype.c index e736d43..b139d78 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 +55,43 @@ 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(const unsigned char *sector, unsigned long *bootsec) { - if (get_unaligned_le16(&buf[510]) != 0xAA55) - return 0; + /* bootsec can be used to return index of the first sector in the first partition */ + 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 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 +119,10 @@ 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 +132,7 @@ 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 +146,19 @@ 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(buf, &bootsec); + ret = lseek(fd, (bootsec) * 512, SEEK_SET); + if (ret < 0) + goto err_out; + ret = read(fd, buf, 512); + if (ret < 0) + goto err_out; + type = is_fat_or_mbr((u8 *)buf, NULL); + } + err_out: close(fd); free(buf); diff --git a/include/filetype.h b/include/filetype.h index 179ec0f..37eb620 100644 --- a/include/filetype.h +++ b/include/filetype.h @@ -19,10 +19,12 @@ enum filetype { filetype_sh, filetype_mips_barebox, filetype_fat, + filetype_mbr, }; const char *file_type_to_string(enum filetype f); enum filetype file_detect_type(void *_buf); enum filetype file_name_detect_type(const char *filename); +enum filetype is_fat_or_mbr(const unsigned char *sector, unsigned long *bootsec); #endif /* __FILE_TYPE_H */ -- 1.7.1 _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox