2 * volume_id - reads filesystem label and uuid
4 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 #include "volume_id_internal.h"
23 /* linux/msdos_fs.h says: */
24 #define FAT12_MAX 0xff4
25 #define FAT16_MAX 0xfff4
26 #define FAT32_MAX 0x0ffffff6
28 #define FAT_ATTR_VOLUME_ID 0x08
29 #define FAT_ATTR_DIR 0x10
30 #define FAT_ATTR_LONG_NAME 0x0f
31 #define FAT_ATTR_MASK 0x3f
32 #define FAT_ENTRY_FREE 0xe5
34 struct vfat_super_block
{
37 uint16_t sector_size_bytes
;
38 uint8_t sectors_per_cluster
;
39 uint16_t reserved_sct
;
50 struct fat_super_block
{
58 struct fat32_super_block
{
59 uint32_t fat32_length
;
62 uint32_t root_cluster
;
63 uint16_t insfo_sector
;
65 uint16_t reserved2
[6];
76 struct vfat_dir_entry
{
83 uint16_t cluster_high
;
90 static uint8_t *get_attr_volume_id(struct vfat_dir_entry
*dir
, int count
)
92 for (;--count
>= 0; dir
++) {
94 if (dir
->name
[0] == 0x00) {
100 if (dir
->name
[0] == FAT_ENTRY_FREE
)
104 if ((dir
->attr
& FAT_ATTR_MASK
) == FAT_ATTR_LONG_NAME
)
107 if ((dir
->attr
& (FAT_ATTR_VOLUME_ID
| FAT_ATTR_DIR
)) == FAT_ATTR_VOLUME_ID
) {
108 /* labels do not have file data */
109 if (dir
->cluster_high
!= 0 || dir
->cluster_low
!= 0)
112 dbg("found ATTR_VOLUME_ID id in root dir");
116 dbg("skip dir entry");
122 int FAST_FUNC
volume_id_probe_vfat(struct volume_id
*id
/*,uint64_t fat_partition_off*/)
124 #define fat_partition_off ((uint64_t)0)
125 struct vfat_super_block
*vs
;
126 struct vfat_dir_entry
*dir
;
127 uint16_t sector_size_bytes
;
128 uint16_t dir_entries
;
130 uint16_t reserved_sct
;
131 uint32_t fat_size_sct
;
132 uint32_t root_cluster
;
133 uint32_t dir_size_sct
;
134 uint32_t cluster_count
;
135 uint64_t root_start_off
;
136 uint32_t start_data_sct
;
139 uint8_t *label
= NULL
;
140 uint32_t next_cluster
;
143 dbg("probing at offset 0x%llx", (unsigned long long) fat_partition_off
);
145 vs
= volume_id_get_buffer(id
, fat_partition_off
, 0x200);
149 /* believe only that's fat, don't trust the version
150 * the cluster_count will tell us
152 if (memcmp(vs
->sysid
, "NTFS", 4) == 0)
155 if (memcmp(vs
->type
.fat32
.magic
, "MSWIN", 5) == 0)
158 if (memcmp(vs
->type
.fat32
.magic
, "FAT32 ", 8) == 0)
161 if (memcmp(vs
->type
.fat
.magic
, "FAT16 ", 8) == 0)
164 if (memcmp(vs
->type
.fat
.magic
, "MSDOS", 5) == 0)
167 if (memcmp(vs
->type
.fat
.magic
, "FAT12 ", 8) == 0)
171 * There are old floppies out there without a magic, so we check
172 * for well known values and guess if it's a fat volume
175 /* boot jump address check */
176 if ((vs
->boot_jump
[0] != 0xeb || vs
->boot_jump
[2] != 0x90)
177 && vs
->boot_jump
[0] != 0xe9
186 /* cluster size check */
187 if (vs
->sectors_per_cluster
== 0
188 || (vs
->sectors_per_cluster
& (vs
->sectors_per_cluster
-1))
194 if (vs
->media
< 0xf8 && vs
->media
!= 0xf0)
202 /* sector size check */
203 sector_size_bytes
= le16_to_cpu(vs
->sector_size_bytes
);
204 if (sector_size_bytes
!= 0x200 && sector_size_bytes
!= 0x400
205 && sector_size_bytes
!= 0x800 && sector_size_bytes
!= 0x1000
210 dbg("sector_size_bytes 0x%x", sector_size_bytes
);
211 dbg("sectors_per_cluster 0x%x", vs
->sectors_per_cluster
);
213 reserved_sct
= le16_to_cpu(vs
->reserved_sct
);
214 dbg("reserved_sct 0x%x", reserved_sct
);
216 sect_count
= le16_to_cpu(vs
->sectors
);
218 sect_count
= le32_to_cpu(vs
->total_sect
);
219 dbg("sect_count 0x%x", sect_count
);
221 fat_size_sct
= le16_to_cpu(vs
->fat_length
);
222 if (fat_size_sct
== 0)
223 fat_size_sct
= le32_to_cpu(vs
->type
.fat32
.fat32_length
);
224 fat_size_sct
*= vs
->fats
;
225 dbg("fat_size_sct 0x%x", fat_size_sct
);
227 dir_entries
= le16_to_cpu(vs
->dir_entries
);
228 dir_size_sct
= ((dir_entries
* sizeof(struct vfat_dir_entry
)) +
229 (sector_size_bytes
-1)) / sector_size_bytes
;
230 dbg("dir_size_sct 0x%x", dir_size_sct
);
232 cluster_count
= sect_count
- (reserved_sct
+ fat_size_sct
+ dir_size_sct
);
233 cluster_count
/= vs
->sectors_per_cluster
;
234 dbg("cluster_count 0x%x", cluster_count
);
236 // if (cluster_count < FAT12_MAX) {
237 // strcpy(id->type_version, "FAT12");
238 // } else if (cluster_count < FAT16_MAX) {
239 // strcpy(id->type_version, "FAT16");
241 // strcpy(id->type_version, "FAT32");
244 if (cluster_count
>= FAT16_MAX
)
247 /* the label may be an attribute in the root directory */
248 root_start_off
= (reserved_sct
+ fat_size_sct
) * sector_size_bytes
;
249 dbg("root dir start 0x%llx", (unsigned long long) root_start_off
);
250 dbg("expected entries 0x%x", dir_entries
);
252 buf_size
= dir_entries
* sizeof(struct vfat_dir_entry
);
253 buf
= volume_id_get_buffer(id
, fat_partition_off
+ root_start_off
, buf_size
);
257 label
= get_attr_volume_id((struct vfat_dir_entry
*) buf
, dir_entries
);
259 vs
= volume_id_get_buffer(id
, fat_partition_off
, 0x200);
263 if (label
!= NULL
&& memcmp(label
, "NO NAME ", 11) != 0) {
264 // volume_id_set_label_raw(id, label, 11);
265 volume_id_set_label_string(id
, label
, 11);
266 } else if (memcmp(vs
->type
.fat
.label
, "NO NAME ", 11) != 0) {
267 // volume_id_set_label_raw(id, vs->type.fat.label, 11);
268 volume_id_set_label_string(id
, vs
->type
.fat
.label
, 11);
270 volume_id_set_uuid(id
, vs
->type
.fat
.serno
, UUID_DOS
);
274 /* FAT32 root dir is a cluster chain like any other directory */
275 buf_size
= vs
->sectors_per_cluster
* sector_size_bytes
;
276 root_cluster
= le32_to_cpu(vs
->type
.fat32
.root_cluster
);
277 start_data_sct
= reserved_sct
+ fat_size_sct
;
279 next_cluster
= root_cluster
;
282 uint64_t next_off_sct
;
284 uint64_t fat_entry_off
;
287 dbg("next_cluster 0x%x", (unsigned)next_cluster
);
288 next_off_sct
= (uint64_t)(next_cluster
- 2) * vs
->sectors_per_cluster
;
289 next_off
= (start_data_sct
+ next_off_sct
) * sector_size_bytes
;
290 dbg("cluster offset 0x%llx", (unsigned long long) next_off
);
293 buf
= volume_id_get_buffer(id
, fat_partition_off
+ next_off
, buf_size
);
297 dir
= (struct vfat_dir_entry
*) buf
;
298 count
= buf_size
/ sizeof(struct vfat_dir_entry
);
299 dbg("expected entries 0x%x", count
);
301 label
= get_attr_volume_id(dir
, count
);
306 fat_entry_off
= (reserved_sct
* sector_size_bytes
) + (next_cluster
* sizeof(uint32_t));
307 dbg("fat_entry_off 0x%llx", (unsigned long long)fat_entry_off
);
308 buf
= volume_id_get_buffer(id
, fat_partition_off
+ fat_entry_off
, buf_size
);
312 /* set next cluster */
313 next_cluster
= le32_to_cpu(*(uint32_t*)buf
) & 0x0fffffff;
314 if (next_cluster
< 2 || next_cluster
> FAT32_MAX
)
318 dbg("reached maximum follow count of root cluster chain, give up");
320 vs
= volume_id_get_buffer(id
, fat_partition_off
, 0x200);
324 if (label
!= NULL
&& memcmp(label
, "NO NAME ", 11) != 0) {
325 // volume_id_set_label_raw(id, label, 11);
326 volume_id_set_label_string(id
, label
, 11);
327 } else if (memcmp(vs
->type
.fat32
.label
, "NO NAME ", 11) != 0) {
328 // volume_id_set_label_raw(id, vs->type.fat32.label, 11);
329 volume_id_set_label_string(id
, vs
->type
.fat32
.label
, 11);
331 volume_id_set_uuid(id
, vs
->type
.fat32
.serno
, UUID_DOS
);
334 // volume_id_set_usage(id, VOLUME_ID_FILESYSTEM);
335 IF_FEATURE_BLKID_TYPE(id
->type
= "vfat";)