diff options
Diffstat (limited to 'disk')
| -rw-r--r-- | disk/part_dos.c | 39 |
1 files changed, 25 insertions, 14 deletions
diff --git a/disk/part_dos.c b/disk/part_dos.c index 8ddc13b50c..83ff40d310 100644 --- a/disk/part_dos.c +++ b/disk/part_dos.c @@ -67,28 +67,39 @@ static int test_block_type(unsigned char *buffer) { int slot; struct dos_partition *p; + int part_count = 0; if((buffer[DOS_PART_MAGIC_OFFSET + 0] != 0x55) || (buffer[DOS_PART_MAGIC_OFFSET + 1] != 0xaa) ) { return (-1); } /* no DOS Signature at all */ p = (struct dos_partition *)&buffer[DOS_PART_TBL_OFFSET]; - for (slot = 0; slot < 3; slot++) { - if (p->boot_ind != 0 && p->boot_ind != 0x80) { - if (!slot && - (strncmp((char *)&buffer[DOS_PBR_FSTYPE_OFFSET], - "FAT", 3) == 0 || - strncmp((char *)&buffer[DOS_PBR32_FSTYPE_OFFSET], - "FAT32", 5) == 0)) { - return DOS_PBR; /* is PBR */ - } else { - return -1; - } - } + + /* Check that the boot indicators are valid and count the partitions. */ + for (slot = 0; slot < 4; ++slot, ++p) { + if (p->boot_ind != 0 && p->boot_ind != 0x80) + break; + if (p->sys_ind) + ++part_count; } - return DOS_MBR; /* Is MBR */ -} + /* + * If the partition table is invalid or empty, + * check if this is a DOS PBR + */ + if (slot != 4 || !part_count) { + if (!strncmp((char *)&buffer[DOS_PBR_FSTYPE_OFFSET], + "FAT", 3) || + !strncmp((char *)&buffer[DOS_PBR32_FSTYPE_OFFSET], + "FAT32", 5)) + return DOS_PBR; /* This is a DOS PBR and not an MBR */ + } + if (slot == 4) + return DOS_MBR; /* This is an DOS MBR */ + + /* This is neither a DOS MBR nor a DOS PBR */ + return -1; +} static int part_test_dos(struct blk_desc *dev_desc) { |