From e254127aa3fd76819fd97b90be958dff4c1c460c Mon Sep 17 00:00:00 2001 From: Dave Murphy Date: Mon, 25 Sep 2017 15:04:46 +0100 Subject: [PATCH] consolidate MBR check --- source/partition.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) diff --git a/source/partition.c b/source/partition.c index 1584e0e..4a29261 100644 --- a/source/partition.c +++ b/source/partition.c @@ -102,6 +102,14 @@ enum FSIB static const char FAT_SIG[3] = {'F', 'A', 'T'}; static const char FS_INFO_SIG1[4] = {'R', 'R', 'a', 'A'}; static const char FS_INFO_SIG2[4] = {'r', 'r', 'A', 'a'}; +static const char FS_TWL_SIG[8] = { 0xe9, 0x00, 0x00, 0x54, 0x57, 0x4c, 0x20, 0x20 }; + +static bool isValidMBR(uint8_t *sectorBuffer) { + return (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) || + !memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG)) || + !memcmp(sectorBuffer, FS_TWL_SIG, sizeof(FS_TWL_SIG))); + +} sec_t FindFirstValidPartition_buf(const DISC_INTERFACE* disc, uint8_t *sectorBuffer) { @@ -120,8 +128,8 @@ sec_t FindFirstValidPartition_buf(const DISC_INTERFACE* disc, uint8_t *sectorBuf for(i=0;i<4;i++,ptr+=16) { sec_t part_lba = u8array_to_u32(ptr, 0x8); - if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) || - !memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG))) { + if (isValidMBR(sectorBuffer)) + { return part_lba; } @@ -141,8 +149,7 @@ sec_t FindFirstValidPartition_buf(const DISC_INTERFACE* disc, uint8_t *sectorBuf if(!_FAT_disc_readSectors (disc, part_lba2, 1, sectorBuffer)) return 0; - if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) || - !memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG))) + if (isValidMBR(sectorBuffer)) { return part_lba2; } @@ -151,8 +158,10 @@ sec_t FindFirstValidPartition_buf(const DISC_INTERFACE* disc, uint8_t *sectorBuf } } else { if(!_FAT_disc_readSectors (disc, part_lba, 1, sectorBuffer)) return 0; - if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) || - !memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG))) { + + + if (isValidMBR(sectorBuffer)) + { return part_lba; } } @@ -199,9 +208,7 @@ PARTITION* _FAT_partition_constructor_buf (const DISC_INTERFACE* disc, uint32_t } } - // Now verify that this is indeed a FAT partition - if (memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) && - memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG))) + if (!isValidMBR(sectorBuffer)) { return NULL; }