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
{
57 } __attribute__((__packed__
)) fat
;
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];
72 } __attribute__((__packed__
)) fat32
;
73 } __attribute__((__packed__
)) type
;
74 } __attribute__((__packed__
));
76 struct vfat_dir_entry
{
83 uint16_t cluster_high
;
88 } __attribute__((__packed__
));
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 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)
184 /* cluster size check */
185 if (vs
->sectors_per_cluster
== 0 ||
186 (vs
->sectors_per_cluster
& (vs
->sectors_per_cluster
-1)))
190 if (vs
->media
< 0xf8 && vs
->media
!= 0xf0)
198 /* sector size check */
199 sector_size_bytes
= le16_to_cpu(vs
->sector_size_bytes
);
200 if (sector_size_bytes
!= 0x200 && sector_size_bytes
!= 0x400 &&
201 sector_size_bytes
!= 0x800 && sector_size_bytes
!= 0x1000)
204 dbg("sector_size_bytes 0x%x", sector_size_bytes
);
205 dbg("sectors_per_cluster 0x%x", vs
->sectors_per_cluster
);
207 reserved_sct
= le16_to_cpu(vs
->reserved_sct
);
208 dbg("reserved_sct 0x%x", reserved_sct
);
210 sect_count
= le16_to_cpu(vs
->sectors
);
212 sect_count
= le32_to_cpu(vs
->total_sect
);
213 dbg("sect_count 0x%x", sect_count
);
215 fat_size_sct
= le16_to_cpu(vs
->fat_length
);
216 if (fat_size_sct
== 0)
217 fat_size_sct
= le32_to_cpu(vs
->type
.fat32
.fat32_length
);
218 fat_size_sct
*= vs
->fats
;
219 dbg("fat_size_sct 0x%x", fat_size_sct
);
221 dir_entries
= le16_to_cpu(vs
->dir_entries
);
222 dir_size_sct
= ((dir_entries
* sizeof(struct vfat_dir_entry
)) +
223 (sector_size_bytes
-1)) / sector_size_bytes
;
224 dbg("dir_size_sct 0x%x", dir_size_sct
);
226 cluster_count
= sect_count
- (reserved_sct
+ fat_size_sct
+ dir_size_sct
);
227 cluster_count
/= vs
->sectors_per_cluster
;
228 dbg("cluster_count 0x%x", cluster_count
);
230 // if (cluster_count < FAT12_MAX) {
231 // strcpy(id->type_version, "FAT12");
232 // } else if (cluster_count < FAT16_MAX) {
233 // strcpy(id->type_version, "FAT16");
235 // strcpy(id->type_version, "FAT32");
238 if (cluster_count
>= FAT16_MAX
)
241 /* the label may be an attribute in the root directory */
242 root_start_off
= (reserved_sct
+ fat_size_sct
) * sector_size_bytes
;
243 dbg("root dir start 0x%llx", (unsigned long long) root_start_off
);
244 dbg("expected entries 0x%x", dir_entries
);
246 buf_size
= dir_entries
* sizeof(struct vfat_dir_entry
);
247 buf
= volume_id_get_buffer(id
, fat_partition_off
+ root_start_off
, buf_size
);
251 label
= get_attr_volume_id((struct vfat_dir_entry
*) buf
, dir_entries
);
253 vs
= volume_id_get_buffer(id
, fat_partition_off
, 0x200);
257 if (label
!= NULL
&& memcmp(label
, "NO NAME ", 11) != 0) {
258 // volume_id_set_label_raw(id, label, 11);
259 volume_id_set_label_string(id
, label
, 11);
260 } else if (memcmp(vs
->type
.fat
.label
, "NO NAME ", 11) != 0) {
261 // volume_id_set_label_raw(id, vs->type.fat.label, 11);
262 volume_id_set_label_string(id
, vs
->type
.fat
.label
, 11);
264 volume_id_set_uuid(id
, vs
->type
.fat
.serno
, UUID_DOS
);
268 /* FAT32 root dir is a cluster chain like any other directory */
269 buf_size
= vs
->sectors_per_cluster
* sector_size_bytes
;
270 root_cluster
= le32_to_cpu(vs
->type
.fat32
.root_cluster
);
271 start_data_sct
= reserved_sct
+ fat_size_sct
;
273 next_cluster
= root_cluster
;
276 uint64_t next_off_sct
;
278 uint64_t fat_entry_off
;
281 dbg("next_cluster 0x%x", (unsigned)next_cluster
);
282 next_off_sct
= (uint64_t)(next_cluster
- 2) * vs
->sectors_per_cluster
;
283 next_off
= (start_data_sct
+ next_off_sct
) * sector_size_bytes
;
284 dbg("cluster offset 0x%llx", (unsigned long long) next_off
);
287 buf
= volume_id_get_buffer(id
, fat_partition_off
+ next_off
, buf_size
);
291 dir
= (struct vfat_dir_entry
*) buf
;
292 count
= buf_size
/ sizeof(struct vfat_dir_entry
);
293 dbg("expected entries 0x%x", count
);
295 label
= get_attr_volume_id(dir
, count
);
300 fat_entry_off
= (reserved_sct
* sector_size_bytes
) + (next_cluster
* sizeof(uint32_t));
301 dbg("fat_entry_off 0x%llx", (unsigned long long)fat_entry_off
);
302 buf
= volume_id_get_buffer(id
, fat_partition_off
+ fat_entry_off
, buf_size
);
306 /* set next cluster */
307 next_cluster
= le32_to_cpu(*(uint32_t*)buf
) & 0x0fffffff;
308 if (next_cluster
< 2 || next_cluster
> FAT32_MAX
)
312 dbg("reached maximum follow count of root cluster chain, give up");
314 vs
= volume_id_get_buffer(id
, fat_partition_off
, 0x200);
318 if (label
!= NULL
&& memcmp(label
, "NO NAME ", 11) != 0) {
319 // volume_id_set_label_raw(id, label, 11);
320 volume_id_set_label_string(id
, label
, 11);
321 } else if (memcmp(vs
->type
.fat32
.label
, "NO NAME ", 11) != 0) {
322 // volume_id_set_label_raw(id, vs->type.fat32.label, 11);
323 volume_id_set_label_string(id
, vs
->type
.fat32
.label
, 11);
325 volume_id_set_uuid(id
, vs
->type
.fat32
.serno
, UUID_DOS
);
328 // volume_id_set_usage(id, VOLUME_ID_FILESYSTEM);
329 // id->type = "vfat";