source: MondoRescue/branches/3.3/mindi-busybox/util-linux/volume_id/fat.c@ 3621

Last change on this file since 3621 was 3621, checked in by Bruno Cornec, 7 years ago

New 3?3 banch for incorporation of latest busybox 1.25. Changing minor version to handle potential incompatibilities.
  • Property svn:eol-style set to native
File size: 9.3 KB
Line 
1/*
2 * volume_id - reads filesystem label and uuid
3 *
4 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
5 *
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.
10 *
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.
15 *
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
19 */
20
21//kbuild:lib-$(CONFIG_FEATURE_VOLUMEID_FAT) += fat.o
22
23//config:
24//config:config FEATURE_VOLUMEID_FAT
25//config: bool "fat filesystem"
26//config: default y
27//config: depends on VOLUMEID
28//config: help
29//config: TODO
30//config:
31
32#include "volume_id_internal.h"
33
34/* linux/msdos_fs.h says: */
35#define FAT12_MAX 0xff4
36#define FAT16_MAX 0xfff4
37#define FAT32_MAX 0x0ffffff6
38
39#define FAT_ATTR_VOLUME_ID 0x08
40#define FAT_ATTR_DIR 0x10
41#define FAT_ATTR_LONG_NAME 0x0f
42#define FAT_ATTR_MASK 0x3f
43#define FAT_ENTRY_FREE 0xe5
44
45struct vfat_super_block {
46 uint8_t boot_jump[3];
47 uint8_t sysid[8];
48 uint16_t sector_size_bytes;
49 uint8_t sectors_per_cluster;
50 uint16_t reserved_sct;
51 uint8_t fats;
52 uint16_t dir_entries;
53 uint16_t sectors;
54 uint8_t media;
55 uint16_t fat_length;
56 uint16_t secs_track;
57 uint16_t heads;
58 uint32_t hidden;
59 uint32_t total_sect;
60 union {
61 struct fat_super_block {
62 uint8_t unknown[3];
63 uint8_t serno[4];
64 uint8_t label[11];
65 uint8_t magic[8];
66 uint8_t dummy2[192];
67 uint8_t pmagic[2];
68 } PACKED fat;
69 struct fat32_super_block {
70 uint32_t fat32_length;
71 uint16_t flags;
72 uint8_t version[2];
73 uint32_t root_cluster;
74 uint16_t insfo_sector;
75 uint16_t backup_boot;
76 uint16_t reserved2[6];
77 uint8_t unknown[3];
78 uint8_t serno[4];
79 uint8_t label[11];
80 uint8_t magic[8];
81 uint8_t dummy2[164];
82 uint8_t pmagic[2];
83 } PACKED fat32;
84 } PACKED type;
85} PACKED;
86
87struct vfat_dir_entry {
88 uint8_t name[11];
89 uint8_t attr;
90 uint16_t time_creat;
91 uint16_t date_creat;
92 uint16_t time_acc;
93 uint16_t date_acc;
94 uint16_t cluster_high;
95 uint16_t time_write;
96 uint16_t date_write;
97 uint16_t cluster_low;
98 uint32_t size;
99} PACKED;
100
101static uint8_t *get_attr_volume_id(struct vfat_dir_entry *dir, int count)
102{
103 for (;--count >= 0; dir++) {
104 /* end marker */
105 if (dir->name[0] == 0x00) {
106 dbg("end of dir");
107 break;
108 }
109
110 /* empty entry */
111 if (dir->name[0] == FAT_ENTRY_FREE)
112 continue;
113
114 /* long name */
115 if ((dir->attr & FAT_ATTR_MASK) == FAT_ATTR_LONG_NAME)
116 continue;
117
118 if ((dir->attr & (FAT_ATTR_VOLUME_ID | FAT_ATTR_DIR)) == FAT_ATTR_VOLUME_ID) {
119 /* labels do not have file data */
120 if (dir->cluster_high != 0 || dir->cluster_low != 0)
121 continue;
122
123 dbg("found ATTR_VOLUME_ID id in root dir");
124 return dir->name;
125 }
126
127 dbg("skip dir entry");
128 }
129
130 return NULL;
131}
132
133int FAST_FUNC volume_id_probe_vfat(struct volume_id *id /*,uint64_t fat_partition_off*/)
134{
135#define fat_partition_off ((uint64_t)0)
136 struct vfat_super_block *vs;
137 struct vfat_dir_entry *dir;
138 uint16_t sector_size_bytes;
139 uint16_t dir_entries;
140 uint32_t sect_count;
141 uint16_t reserved_sct;
142 uint32_t fat_size_sct;
143 uint32_t root_cluster;
144 uint32_t dir_size_sct;
145 uint32_t cluster_count;
146 uint64_t root_start_off;
147 uint32_t start_data_sct;
148 uint8_t *buf;
149 uint32_t buf_size;
150 uint8_t *label = NULL;
151 uint32_t next_cluster;
152 int maxloop;
153
154 dbg("probing at offset 0x%llx", (unsigned long long) fat_partition_off);
155
156 vs = volume_id_get_buffer(id, fat_partition_off, 0x200);
157 if (vs == NULL)
158 return -1;
159
160 /* believe only that's fat, don't trust the version
161 * the cluster_count will tell us
162 */
163 if (memcmp(vs->sysid, "NTFS", 4) == 0)
164 return -1;
165
166 if (memcmp(vs->type.fat32.magic, "MSWIN", 5) == 0)
167 goto valid;
168
169 if (memcmp(vs->type.fat32.magic, "FAT32 ", 8) == 0)
170 goto valid;
171
172 if (memcmp(vs->type.fat.magic, "FAT16 ", 8) == 0)
173 goto valid;
174
175 if (memcmp(vs->type.fat.magic, "MSDOS", 5) == 0)
176 goto valid;
177
178 if (memcmp(vs->type.fat.magic, "FAT12 ", 8) == 0)
179 goto valid;
180
181 /*
182 * There are old floppies out there without a magic, so we check
183 * for well known values and guess if it's a fat volume
184 */
185
186 /* boot jump address check */
187 if ((vs->boot_jump[0] != 0xeb || vs->boot_jump[2] != 0x90)
188 && vs->boot_jump[0] != 0xe9
189 ) {
190 return -1;
191 }
192
193 /* heads check */
194 if (vs->heads == 0)
195 return -1;
196
197 /* cluster size check */
198 if (vs->sectors_per_cluster == 0
199 || (vs->sectors_per_cluster & (vs->sectors_per_cluster-1))
200 ) {
201 return -1;
202 }
203
204 /* media check */
205 if (vs->media < 0xf8 && vs->media != 0xf0)
206 return -1;
207
208 /* fat count*/
209 if (vs->fats != 2)
210 return -1;
211
212 valid:
213 /* sector size check */
214 sector_size_bytes = le16_to_cpu(vs->sector_size_bytes);
215 if (sector_size_bytes != 0x200 && sector_size_bytes != 0x400
216 && sector_size_bytes != 0x800 && sector_size_bytes != 0x1000
217 ) {
218 return -1;
219 }
220
221 dbg("sector_size_bytes 0x%x", sector_size_bytes);
222 dbg("sectors_per_cluster 0x%x", vs->sectors_per_cluster);
223
224 reserved_sct = le16_to_cpu(vs->reserved_sct);
225 dbg("reserved_sct 0x%x", reserved_sct);
226
227 sect_count = le16_to_cpu(vs->sectors);
228 if (sect_count == 0)
229 sect_count = le32_to_cpu(vs->total_sect);
230 dbg("sect_count 0x%x", sect_count);
231
232 fat_size_sct = le16_to_cpu(vs->fat_length);
233 if (fat_size_sct == 0)
234 fat_size_sct = le32_to_cpu(vs->type.fat32.fat32_length);
235 fat_size_sct *= vs->fats;
236 dbg("fat_size_sct 0x%x", fat_size_sct);
237
238 dir_entries = le16_to_cpu(vs->dir_entries);
239 dir_size_sct = ((dir_entries * sizeof(struct vfat_dir_entry)) +
240 (sector_size_bytes-1)) / sector_size_bytes;
241 dbg("dir_size_sct 0x%x", dir_size_sct);
242
243 cluster_count = sect_count - (reserved_sct + fat_size_sct + dir_size_sct);
244 cluster_count /= vs->sectors_per_cluster;
245 dbg("cluster_count 0x%x", cluster_count);
246
247// if (cluster_count < FAT12_MAX) {
248// strcpy(id->type_version, "FAT12");
249// } else if (cluster_count < FAT16_MAX) {
250// strcpy(id->type_version, "FAT16");
251// } else {
252// strcpy(id->type_version, "FAT32");
253// goto fat32;
254// }
255 if (cluster_count >= FAT16_MAX)
256 goto fat32;
257
258 /* the label may be an attribute in the root directory */
259 root_start_off = (reserved_sct + fat_size_sct) * sector_size_bytes;
260 dbg("root dir start 0x%llx", (unsigned long long) root_start_off);
261 dbg("expected entries 0x%x", dir_entries);
262
263 buf_size = dir_entries * sizeof(struct vfat_dir_entry);
264 buf = volume_id_get_buffer(id, fat_partition_off + root_start_off, buf_size);
265 if (buf == NULL)
266 goto ret;
267
268 label = get_attr_volume_id((struct vfat_dir_entry*) buf, dir_entries);
269
270 vs = volume_id_get_buffer(id, fat_partition_off, 0x200);
271 if (vs == NULL)
272 return -1;
273
274 if (label != NULL && memcmp(label, "NO NAME ", 11) != 0) {
275// volume_id_set_label_raw(id, label, 11);
276 volume_id_set_label_string(id, label, 11);
277 } else if (memcmp(vs->type.fat.label, "NO NAME ", 11) != 0) {
278// volume_id_set_label_raw(id, vs->type.fat.label, 11);
279 volume_id_set_label_string(id, vs->type.fat.label, 11);
280 }
281 volume_id_set_uuid(id, vs->type.fat.serno, UUID_DOS);
282 goto ret;
283
284 fat32:
285 /* FAT32 root dir is a cluster chain like any other directory */
286 buf_size = vs->sectors_per_cluster * sector_size_bytes;
287 root_cluster = le32_to_cpu(vs->type.fat32.root_cluster);
288 start_data_sct = reserved_sct + fat_size_sct;
289
290 next_cluster = root_cluster;
291 maxloop = 100;
292 while (--maxloop) {
293 uint64_t next_off_sct;
294 uint64_t next_off;
295 uint64_t fat_entry_off;
296 int count;
297
298 dbg("next_cluster 0x%x", (unsigned)next_cluster);
299 next_off_sct = (uint64_t)(next_cluster - 2) * vs->sectors_per_cluster;
300 next_off = (start_data_sct + next_off_sct) * sector_size_bytes;
301 dbg("cluster offset 0x%llx", (unsigned long long) next_off);
302
303 /* get cluster */
304 buf = volume_id_get_buffer(id, fat_partition_off + next_off, buf_size);
305 if (buf == NULL)
306 goto ret;
307
308 dir = (struct vfat_dir_entry*) buf;
309 count = buf_size / sizeof(struct vfat_dir_entry);
310 dbg("expected entries 0x%x", count);
311
312 label = get_attr_volume_id(dir, count);
313 if (label)
314 break;
315
316 /* get FAT entry */
317 fat_entry_off = (reserved_sct * sector_size_bytes) + (next_cluster * sizeof(uint32_t));
318 dbg("fat_entry_off 0x%llx", (unsigned long long)fat_entry_off);
319 buf = volume_id_get_buffer(id, fat_partition_off + fat_entry_off, buf_size);
320 if (buf == NULL)
321 goto ret;
322
323 /* set next cluster */
324 next_cluster = le32_to_cpu(*(uint32_t*)buf) & 0x0fffffff;
325 if (next_cluster < 2 || next_cluster > FAT32_MAX)
326 break;
327 }
328 if (maxloop == 0)
329 dbg("reached maximum follow count of root cluster chain, give up");
330
331 vs = volume_id_get_buffer(id, fat_partition_off, 0x200);
332 if (vs == NULL)
333 return -1;
334
335 if (label != NULL && memcmp(label, "NO NAME ", 11) != 0) {
336// volume_id_set_label_raw(id, label, 11);
337 volume_id_set_label_string(id, label, 11);
338 } else if (memcmp(vs->type.fat32.label, "NO NAME ", 11) != 0) {
339// volume_id_set_label_raw(id, vs->type.fat32.label, 11);
340 volume_id_set_label_string(id, vs->type.fat32.label, 11);
341 }
342 volume_id_set_uuid(id, vs->type.fat32.serno, UUID_DOS);
343
344 ret:
345// volume_id_set_usage(id, VOLUME_ID_FILESYSTEM);
346 IF_FEATURE_BLKID_TYPE(id->type = "vfat";)
347
348 return 0;
349}
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