if (buf == NULL)
return -1;
- /* check signature */
- if (buf[510] != 0x55 || buf[511] != 0xaa)
- return -1;
-
vs = (struct vfat_super_block *) buf;
if (memcmp(vs->sysid, "NTFS", 4) == 0)
return -1;
if (memcmp(vs->type.fat.magic, "FAT12 ", 8) == 0)
goto magic;
+ /* check signature */
+ if (buf[510] != 0x55 || buf[511] != 0xaa)
+ return -1;
+
/* some old floppies don't have a magic, expect the boot jump address to match */
if ((vs->boot_jump[0] != 0xeb || vs->boot_jump[2] != 0x90) &&
vs->boot_jump[0] != 0xe9)
return -1;
magic:
+ info("magic found\n");
/* reserverd sector count */
if (!vs->reserved)
return -1;
if (sector_size == 0 || ((sector_size & (sector_size-1)) != 0))
return -1;
+ info("checks passed\n");
dbg("sector_size 0x%x\n", sector_size);
dbg("sectors_per_cluster 0x%x\n", vs->sectors_per_cluster);
dbg("sect_count 0x%x\n", sect_count);
fat_length = le16_to_cpu(vs->fat_length);
- dbg("fat_length 0x%x\n", fat_length);
+ info("fat_length 0x%x\n", fat_length);
fat32_length = le32_to_cpu(vs->type.fat32.fat32_length);
- dbg("fat32_length 0x%x\n", fat32_length);
+ info("fat32_length 0x%x\n", fat32_length);
if (fat_length)
fat_size = fat_length * vs->fats;
fat_size = fat32_length * vs->fats;
else
return -1;
- dbg("fat_size 0x%x\n", fat_size);
+ info("fat_size 0x%x\n", fat_size);
dir_size = ((dir_entries * sizeof(struct vfat_dir_entry)) +
(sector_size-1)) / sector_size;
- dbg("dir_size 0x%x\n", dir_size);
+ info("dir_size 0x%x\n", dir_size);
cluster_count = sect_count - (reserved + fat_size + dir_size);
cluster_count /= vs->sectors_per_cluster;
- dbg("cluster_count 0x%x\n", cluster_count);
+ info("cluster_count 0x%x\n", cluster_count);
/* must be FAT32 */
if (!fat_length && fat32_length)
goto found;
fat32:
- /* FAT32 should have a valid signature in the fsinfo block */
+ info("looking for FAT32\n");
+ /*
+ * FAT32 should have a valid signature in the fsinfo block,
+ * but also allow all bytes set to '\0', because some volumes
+ * do not set the signature at all.
+ */
fsinfo_sect = le16_to_cpu(vs->type.fat32.fsinfo_sector);
buf = volume_id_get_buffer(id, off + (fsinfo_sect * sector_size), 0x200);
if (buf == NULL)
return -1;
fsinfo = (struct fat32_fsinfo *) buf;
- if (memcmp(fsinfo->signature1, "\x52\x52\x61\x41", 4) != 0)
+ info("signature1: 0x%02x%02x%02x%02x\n",
+ fsinfo->signature1[0], fsinfo->signature1[1],
+ fsinfo->signature1[2], fsinfo->signature1[3]);
+ info("signature2: 0x%02x%02x%02x%02x\n",
+ fsinfo->signature2[0], fsinfo->signature2[1],
+ fsinfo->signature2[2], fsinfo->signature2[3]);
+ if (memcmp(fsinfo->signature1, "\x52\x52\x61\x41", 4) != 0 &&
+ memcmp(fsinfo->signature1, "\x00\x00\x00\x00", 4) != 0)
return -1;
- if (memcmp(fsinfo->signature2, "\x72\x72\x41\x61", 4) != 0)
+ if (memcmp(fsinfo->signature2, "\x72\x72\x41\x61", 4) != 0 &&
+ memcmp(fsinfo->signature2, "\x00\x00\x00\x00", 4) != 0)
return -1 ;
+ info("FAT32 signatures ok\n");
vs = (struct vfat_super_block *) volume_id_get_buffer(id, off, 0x200);
if (vs == NULL)
found:
volume_id_set_usage(id, VOLUME_ID_FILESYSTEM);
id->type = "vfat";
-
+ /* we think this is fat, but we make sure no other signatures are found */
+ id->force_unique_result = 1;
return 0;
}