/*
* This function is used by MBR partition table parser to avoid
* misinterpretation of FAT filesystem.
*/
int blkid_probe_is_vfat(blkid_probe pr)
{
struct vfat_super_block *vs;
struct msdos_super_block *ms;
const struct blkid_idmag *mag = NULL;
if (blkid_probe_get_idmag(pr, &vfat_idinfo, NULL, &mag) || !mag)
return 0;
ms = blkid_probe_get_sb(pr, mag, struct msdos_super_block);
if (!ms)
return 0;
vs = blkid_probe_get_sb(pr, mag, struct vfat_super_block);
if (!vs)
return 0;
return fat_valid_superblock(mag, ms, vs, NULL, NULL);
}
/*
* This function is used by MBR partition table parser to avoid
* misinterpretation of FAT filesystem.
*/
int blkid_probe_is_vfat(blkid_probe pr)
{
struct vfat_super_block *vs;
struct msdos_super_block *ms;
const struct blkid_idmag *mag = NULL;
int rc;
rc = blkid_probe_get_idmag(pr, &vfat_idinfo, NULL, &mag);
if (rc < 0)
return rc; /* error */
if (rc != BLKID_PROBE_OK || !mag)
return 0;
ms = blkid_probe_get_sb(pr, mag, struct msdos_super_block);
if (!ms)
return errno ? -errno : 0;
vs = blkid_probe_get_sb(pr, mag, struct vfat_super_block);
if (!vs)
return errno ? -errno : 0;
return fat_valid_superblock(pr, mag, ms, vs, NULL, NULL);
}
/* FAT label extraction from the root directory taken from Kay
* Sievers's volume_id library */
static int probe_vfat(blkid_probe pr, const struct blkid_idmag *mag)
{
struct vfat_super_block *vs;
struct msdos_super_block *ms;
const unsigned char *vol_label = 0;
unsigned char *vol_serno = NULL, vol_label_buf[11];
uint16_t sector_size = 0, reserved;
uint32_t cluster_count, fat_size;
const char *version = NULL;
ms = blkid_probe_get_sb(pr, mag, struct msdos_super_block);
if (!ms)
return errno ? -errno : 1;
vs = blkid_probe_get_sb(pr, mag, struct vfat_super_block);
if (!vs)
return errno ? -errno : 1;
if (!fat_valid_superblock(pr, mag, ms, vs, &cluster_count, &fat_size))
return 1;
sector_size = unaligned_le16(&ms->ms_sector_size);
reserved = le16_to_cpu(ms->ms_reserved);
if (ms->ms_fat_length) {
/* the label may be an attribute in the root directory */
uint32_t root_start = (reserved + fat_size) * sector_size;
uint32_t root_dir_entries = unaligned_le16(&vs->vs_dir_entries);
vol_label = search_fat_label(pr, root_start, root_dir_entries);
if (vol_label) {
memcpy(vol_label_buf, vol_label, 11);
vol_label = vol_label_buf;
}
if (!vol_label || !memcmp(vol_label, no_name, 11))
vol_label = ms->ms_label;
vol_serno = ms->ms_serno;
blkid_probe_set_value(pr, "SEC_TYPE", (unsigned char *) "msdos",
sizeof("msdos"));
if (cluster_count < FAT12_MAX)
version = "FAT12";
else if (cluster_count < FAT16_MAX)
version = "FAT16";
} else if (vs->vs_fat32_length) {
unsigned char *buf;
uint16_t fsinfo_sect;
int maxloop = 100;
/* Search the FAT32 root dir for the label attribute */
uint32_t buf_size = vs->vs_cluster_size * sector_size;
uint32_t start_data_sect = reserved + fat_size;
uint32_t entries = le32_to_cpu(vs->vs_fat32_length) *
sector_size / sizeof(uint32_t);
uint32_t next = le32_to_cpu(vs->vs_root_cluster);
while (next && next < entries && --maxloop) {
uint32_t next_sect_off;
uint64_t next_off, fat_entry_off;
int count;
next_sect_off = (next - 2) * vs->vs_cluster_size;
next_off = (uint64_t)(start_data_sect + next_sect_off) *
sector_size;
count = buf_size / sizeof(struct vfat_dir_entry);
vol_label = search_fat_label(pr, next_off, count);
if (vol_label) {
memcpy(vol_label_buf, vol_label, 11);
vol_label = vol_label_buf;
break;
}
/* get FAT entry */
fat_entry_off = ((uint64_t) reserved * sector_size) +
(next * sizeof(uint32_t));
buf = blkid_probe_get_buffer(pr, fat_entry_off, buf_size);
if (buf == NULL)
break;
/* set next cluster */
next = le32_to_cpu(*((uint32_t *) buf)) & 0x0fffffff;
}
version = "FAT32";
if (!vol_label || !memcmp(vol_label, no_name, 11))
vol_label = vs->vs_label;
vol_serno = vs->vs_serno;
/*
* 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->vs_fsinfo_sector);
if (fsinfo_sect) {
struct fat32_fsinfo *fsinfo;
buf = blkid_probe_get_buffer(pr,
(blkid_loff_t) fsinfo_sect * sector_size,
sizeof(struct fat32_fsinfo));
if (buf == NULL)
return errno ? -errno : 1;
fsinfo = (struct fat32_fsinfo *) buf;
if (memcmp(fsinfo->signature1, "\x52\x52\x61\x41", 4) != 0 &&
memcmp(fsinfo->signature1, "\x52\x52\x64\x41", 4) != 0 &&
memcmp(fsinfo->signature1, "\x00\x00\x00\x00", 4) != 0)
return 1;
if (memcmp(fsinfo->signature2, "\x72\x72\x41\x61", 4) != 0 &&
memcmp(fsinfo->signature2, "\x00\x00\x00\x00", 4) != 0)
return 1;
}
}
if (vol_label && memcmp(vol_label, no_name, 11))
blkid_probe_set_label(pr, (unsigned char *) vol_label, 11);
/* We can't just print them as %04X, because they are unaligned */
if (vol_serno)
blkid_probe_sprintf_uuid(pr, vol_serno, 4, "%02X%02X-%02X%02X",
vol_serno[3], vol_serno[2], vol_serno[1], vol_serno[0]);
if (version)
blkid_probe_set_version(pr, version);
return 0;
}
