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consolidate MBR check

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This commit is contained in:
Dave Murphy 2017-09-25 15:04:46 +01:00
parent 66a9b27dc0
commit e254127aa3
1 changed files with 16 additions and 9 deletions
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25
source/partition.c
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@ -102,6 +102,14 @@ enum FSIB
static const char FAT_SIG[3] = {'F', 'A', 'T'}; 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_SIG1[4] = {'R', 'R', 'a', 'A'};
static const char FS_INFO_SIG2[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) 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) { for(i=0;i<4;i++,ptr+=16) {
sec_t part_lba = u8array_to_u32(ptr, 0x8); sec_t part_lba = u8array_to_u32(ptr, 0x8);
if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) || if (isValidMBR(sectorBuffer))
!memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG))) { {
return part_lba; 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(!_FAT_disc_readSectors (disc, part_lba2, 1, sectorBuffer)) return 0;
if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) || if (isValidMBR(sectorBuffer))
!memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG)))
{ {
return part_lba2; return part_lba2;
} }
@ -151,8 +158,10 @@ sec_t FindFirstValidPartition_buf(const DISC_INTERFACE* disc, uint8_t *sectorBuf
} }
} else { } else {
if(!_FAT_disc_readSectors (disc, part_lba, 1, sectorBuffer)) return 0; 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; 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 (!isValidMBR(sectorBuffer))
if (memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) &&
memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG)))
{ {
return NULL; return NULL;
} }