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[tools/e2fsprogs.git] / lib / blkid / probe.c
1 /*
2  * probe.c - identify a block device by its contents, and return a dev
3  *           struct with the details
4  *
5  * Copyright (C) 1999 by Andries Brouwer
6  * Copyright (C) 1999, 2000, 2003 by Theodore Ts'o
7  * Copyright (C) 2001 by Andreas Dilger
8  *
9  * %Begin-Header%
10  * This file may be redistributed under the terms of the
11  * GNU Lesser General Public License.
12  * %End-Header%
13  */
14
15 #include <stdio.h>
16 #include <string.h>
17 #include <stdlib.h>
18 #include <unistd.h>
19 #include <fcntl.h>
20 #include <sys/types.h>
21 #ifdef HAVE_SYS_STAT_H
22 #include <sys/stat.h>
23 #endif
24 #ifdef HAVE_SYS_MKDEV_H
25 #include <sys/mkdev.h>
26 #endif
27 #ifdef HAVE_ERRNO_H
28 #include <errno.h>
29 #endif
30 #include "blkidP.h"
31 #include "uuid/uuid.h"
32 #include "probe.h"
33
34 /*
35  * This is a special case code to check for an MDRAID device.  We do
36  * this special since it requires checking for a superblock at the end
37  * of the device.
38  */
39 static int check_mdraid(int fd, unsigned char *ret_uuid)
40 {
41         struct mdp_superblock_s *md;
42         blkid_loff_t            offset;
43         char                    buf[4096];
44         
45         if (fd < 0)
46                 return -BLKID_ERR_PARAM;
47
48         offset = (blkid_get_dev_size(fd) & ~((blkid_loff_t)65535)) - 65536;
49
50         if (blkid_llseek(fd, offset, 0) < 0 ||
51             read(fd, buf, 4096) != 4096)
52                 return -BLKID_ERR_IO;
53
54         /* Check for magic number */
55         if (memcmp("\251+N\374", buf, 4))
56                 return -BLKID_ERR_PARAM;
57
58         if (!ret_uuid)
59                 return 0;
60         *ret_uuid = 0;
61
62         /* The MD UUID is not contiguous in the superblock, make it so */
63         md = (struct mdp_superblock_s *)buf;
64         if (md->set_uuid0 || md->set_uuid1 || md->set_uuid2 || md->set_uuid3) {
65                 memcpy(ret_uuid, &md->set_uuid0, 4);
66                 memcpy(ret_uuid, &md->set_uuid1, 12);
67         }
68         return 0;
69 }
70
71 static void set_uuid(blkid_dev dev, uuid_t uuid)
72 {
73         char    str[37];
74
75         if (!uuid_is_null(uuid)) {
76                 uuid_unparse(uuid, str);
77                 blkid_set_tag(dev, "UUID", str, sizeof(str));
78         }
79 }
80
81 static void get_ext2_info(blkid_dev dev, unsigned char *buf)
82 {
83         struct ext2_super_block *es = (struct ext2_super_block *) buf;
84         const char *label = 0;
85
86         DBG(DEBUG_PROBE, printf("ext2_sb.compat = %08X:%08X:%08X\n", 
87                    blkid_le32(es->s_feature_compat),
88                    blkid_le32(es->s_feature_incompat),
89                    blkid_le32(es->s_feature_ro_compat)));
90
91         if (strlen(es->s_volume_name))
92                 label = es->s_volume_name;
93         blkid_set_tag(dev, "LABEL", label, sizeof(es->s_volume_name));
94
95         set_uuid(dev, es->s_uuid);
96 }
97
98 static int probe_ext3(int fd __BLKID_ATTR((unused)), 
99                       blkid_cache cache __BLKID_ATTR((unused)), 
100                       blkid_dev dev,
101                       struct blkid_magic *id __BLKID_ATTR((unused)), 
102                       unsigned char *buf)
103 {
104         struct ext2_super_block *es;
105
106         es = (struct ext2_super_block *)buf;
107
108         /* Distinguish between jbd and ext2/3 fs */
109         if (blkid_le32(es->s_feature_incompat) & 
110             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
111                 return -BLKID_ERR_PARAM;
112
113         /* Distinguish between ext3 and ext2 */
114         if (!(blkid_le32(es->s_feature_compat) &
115               EXT3_FEATURE_COMPAT_HAS_JOURNAL))
116                 return -BLKID_ERR_PARAM;
117
118         get_ext2_info(dev, buf);
119
120         blkid_set_tag(dev, "SEC_TYPE", "ext2", sizeof("ext2"));
121
122         return 0;
123 }
124
125 static int probe_ext2(int fd __BLKID_ATTR((unused)), 
126                       blkid_cache cache __BLKID_ATTR((unused)), 
127                       blkid_dev dev,
128                       struct blkid_magic *id __BLKID_ATTR((unused)), 
129                       unsigned char *buf)
130 {
131         struct ext2_super_block *es;
132
133         es = (struct ext2_super_block *)buf;
134
135         /* Distinguish between jbd and ext2/3 fs */
136         if (blkid_le32(es->s_feature_incompat) & 
137             EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
138                 return -BLKID_ERR_PARAM;
139         
140         /* Distinguish between ext3 and ext2 */
141         if ((blkid_le32(es->s_feature_compat) &
142               EXT3_FEATURE_COMPAT_HAS_JOURNAL))
143                 return -BLKID_ERR_PARAM;
144
145         get_ext2_info(dev, buf);
146
147         return 0;
148 }
149
150 static int probe_jbd(int fd __BLKID_ATTR((unused)), 
151                      blkid_cache cache __BLKID_ATTR((unused)), 
152                      blkid_dev dev, 
153                      struct blkid_magic *id __BLKID_ATTR((unused)), 
154                      unsigned char *buf)
155 {
156         struct ext2_super_block *es = (struct ext2_super_block *) buf;
157
158         if (!(blkid_le32(es->s_feature_incompat) &
159               EXT3_FEATURE_INCOMPAT_JOURNAL_DEV))
160                 return -BLKID_ERR_PARAM;
161
162         get_ext2_info(dev, buf);
163
164         return 0;
165 }
166
167 static int probe_vfat(int fd __BLKID_ATTR((unused)), 
168                       blkid_cache cache __BLKID_ATTR((unused)), 
169                       blkid_dev dev,
170                       struct blkid_magic *id __BLKID_ATTR((unused)), 
171                       unsigned char *buf)
172 {
173         struct vfat_super_block *vs;
174         char serno[10];
175         const char *label = 0;
176         int label_len = 0;
177
178         vs = (struct vfat_super_block *)buf;
179
180         if (strncmp(vs->vs_label, "NO NAME", 7)) {
181                 char *end = vs->vs_label + sizeof(vs->vs_label) - 1;
182
183                 while (*end == ' ' && end >= vs->vs_label)
184                         --end;
185                 if (end >= vs->vs_label) {
186                         label = vs->vs_label;
187                         label_len = end - vs->vs_label + 1;
188                 }
189         }
190
191         /* We can't just print them as %04X, because they are unaligned */
192         sprintf(serno, "%02X%02X-%02X%02X", vs->vs_serno[3], vs->vs_serno[2],
193                 vs->vs_serno[1], vs->vs_serno[0]);
194         blkid_set_tag(dev, "LABEL", label, label_len);
195         blkid_set_tag(dev, "UUID", serno, sizeof(serno));
196
197         return 0;
198 }
199
200 static int probe_msdos(int fd __BLKID_ATTR((unused)), 
201                        blkid_cache cache __BLKID_ATTR((unused)), 
202                        blkid_dev dev,
203                        struct blkid_magic *id __BLKID_ATTR((unused)), 
204                        unsigned char *buf)
205 {
206         struct msdos_super_block *ms = (struct msdos_super_block *) buf;
207         char serno[10];
208         const char *label = 0;
209         int label_len = 0;
210
211         if (strncmp(ms->ms_label, "NO NAME", 7)) {
212                 char *end = ms->ms_label + sizeof(ms->ms_label) - 1;
213
214                 while (*end == ' ' && end >= ms->ms_label)
215                         --end;
216                 if (end >= ms->ms_label) {
217                         label = ms->ms_label;
218                         label_len = end - ms->ms_label + 1;
219                 }
220         }
221
222         /* We can't just print them as %04X, because they are unaligned */
223         sprintf(serno, "%02X%02X-%02X%02X", ms->ms_serno[3], ms->ms_serno[2],
224                 ms->ms_serno[1], ms->ms_serno[0]);
225         blkid_set_tag(dev, "UUID", serno, 0);
226         blkid_set_tag(dev, "LABEL", label, label_len);
227         blkid_set_tag(dev, "SEC_TYPE", "msdos", sizeof("msdos"));
228
229         return 0;
230 }
231
232 static int probe_xfs(int fd __BLKID_ATTR((unused)), 
233                      blkid_cache cache __BLKID_ATTR((unused)), 
234                      blkid_dev dev,
235                      struct blkid_magic *id __BLKID_ATTR((unused)), 
236                      unsigned char *buf)
237 {
238         struct xfs_super_block *xs;
239         const char *label = 0;
240
241         xs = (struct xfs_super_block *)buf;
242
243         if (strlen(xs->xs_fname))
244                 label = xs->xs_fname;
245         blkid_set_tag(dev, "LABEL", label, sizeof(xs->xs_fname));
246         set_uuid(dev, xs->xs_uuid);
247         return 0;
248 }
249
250 static int probe_reiserfs(int fd __BLKID_ATTR((unused)), 
251                           blkid_cache cache __BLKID_ATTR((unused)), 
252                           blkid_dev dev,
253                           struct blkid_magic *id, unsigned char *buf)
254 {
255         struct reiserfs_super_block *rs = (struct reiserfs_super_block *) buf;
256         unsigned int blocksize;
257         const char *label = 0;
258
259         blocksize = blkid_le16(rs->rs_blocksize);
260
261         /* If the superblock is inside the journal, we have the wrong one */
262         if (id->bim_kboff/(blocksize>>10) > blkid_le32(rs->rs_journal_block))
263                 return -BLKID_ERR_BIG;
264
265         /* LABEL/UUID are only valid for later versions of Reiserfs v3.6. */
266         if (!strcmp(id->bim_magic, "ReIsEr2Fs") ||
267             !strcmp(id->bim_magic, "ReIsEr3Fs")) {
268                 if (strlen(rs->rs_label))
269                         label = rs->rs_label;
270                 set_uuid(dev, rs->rs_uuid);
271         }
272         blkid_set_tag(dev, "LABEL", label, sizeof(rs->rs_label));
273
274         return 0;
275 }
276
277 static int probe_jfs(int fd __BLKID_ATTR((unused)), 
278                      blkid_cache cache __BLKID_ATTR((unused)), 
279                      blkid_dev dev,
280                      struct blkid_magic *id __BLKID_ATTR((unused)), 
281                      unsigned char *buf)
282 {
283         struct jfs_super_block *js;
284         const char *label = 0;
285
286         js = (struct jfs_super_block *)buf;
287
288         if (strlen((char *) js->js_label))
289                 label = (char *) js->js_label;
290         blkid_set_tag(dev, "LABEL", label, sizeof(js->js_label));
291         set_uuid(dev, js->js_uuid);
292         return 0;
293 }
294
295 static int probe_romfs(int fd __BLKID_ATTR((unused)), 
296                        blkid_cache cache __BLKID_ATTR((unused)), 
297                        blkid_dev dev,
298                        struct blkid_magic *id __BLKID_ATTR((unused)), 
299                        unsigned char *buf)
300 {
301         struct romfs_super_block *ros;
302         const char *label = 0;
303
304         ros = (struct romfs_super_block *)buf;
305
306         if (strlen((char *) ros->ros_volume))
307                 label = (char *) ros->ros_volume;
308         blkid_set_tag(dev, "LABEL", label, 0);
309         return 0;
310 }
311
312 static int probe_cramfs(int fd __BLKID_ATTR((unused)), 
313                        blkid_cache cache __BLKID_ATTR((unused)), 
314                        blkid_dev dev,
315                        struct blkid_magic *id __BLKID_ATTR((unused)), 
316                        unsigned char *buf)
317 {
318         struct cramfs_super_block *csb;
319         const char *label = 0;
320
321         csb = (struct cramfs_super_block *)buf;
322
323         if (strlen((char *) csb->name))
324                 label = (char *) csb->name;
325         blkid_set_tag(dev, "LABEL", label, 0);
326         return 0;
327 }
328
329 static int probe_swap0(int fd __BLKID_ATTR((unused)),
330                        blkid_cache cache __BLKID_ATTR((unused)),
331                        blkid_dev dev,
332                        struct blkid_magic *id __BLKID_ATTR((unused)),
333                        unsigned char *buf __BLKID_ATTR((unused)))
334 {
335         blkid_set_tag(dev, "UUID", 0, 0);
336         blkid_set_tag(dev, "LABEL", 0, 0);
337         return 0;
338 }
339
340 static int probe_swap1(int fd,
341                        blkid_cache cache __BLKID_ATTR((unused)),
342                        blkid_dev dev,
343                        struct blkid_magic *id __BLKID_ATTR((unused)),
344                        unsigned char *buf __BLKID_ATTR((unused)))
345 {
346         struct swap_id_block *sws;
347
348         probe_swap0(fd, cache, dev, id, buf);
349         /*
350          * Version 1 swap headers are always located at offset of 1024
351          * bytes, although the swap signature itself is located at the
352          * end of the page (which may vary depending on hardware
353          * pagesize).
354          */
355         if (lseek(fd, 1024, SEEK_SET) < 0) return 1;
356         if (!(sws = (struct swap_id_block *)malloc(1024))) return 1;
357         if (read(fd, sws, 1024) != 1024) {
358                 free(sws);
359                 return 1;
360         }
361
362         /* arbitrary sanity check.. is there any garbage down there? */
363         if (sws->sws_pad[32] == 0 && sws->sws_pad[33] == 0)  {
364                 if (sws->sws_volume[0])
365                         blkid_set_tag(dev, "LABEL", sws->sws_volume, 
366                                       sizeof(sws->sws_volume));
367                 if (sws->sws_uuid[0])
368                         set_uuid(dev, sws->sws_uuid);
369         }
370         free(sws);
371
372         return 0;
373 }
374
375 static const char
376 *udf_magic[] = { "BEA01", "BOOT2", "CD001", "CDW02", "NSR02",
377                  "NSR03", "TEA01", 0 };
378
379 static int probe_udf(int fd, blkid_cache cache __BLKID_ATTR((unused)), 
380                      blkid_dev dev __BLKID_ATTR((unused)),
381                        struct blkid_magic *id __BLKID_ATTR((unused)), 
382                      unsigned char *buf __BLKID_ATTR((unused)))
383 {
384         int j, bs;
385         struct iso_volume_descriptor isosb;
386         const char ** m;
387
388         /* determine the block size by scanning in 2K increments
389            (block sizes larger than 2K will be null padded) */
390         for (bs = 1; bs < 16; bs++) {
391                 lseek(fd, bs*2048+32768, SEEK_SET);
392                 if (read(fd, (char *)&isosb, sizeof(isosb)) != sizeof(isosb))
393                         return 1;
394                 if (isosb.id[0])
395                         break;
396         }
397
398         /* Scan up to another 64 blocks looking for additional VSD's */
399         for (j = 1; j < 64; j++) {
400                 if (j > 1) {
401                         lseek(fd, j*bs*2048+32768, SEEK_SET);
402                         if (read(fd, (char *)&isosb, sizeof(isosb))
403                             != sizeof(isosb))
404                                 return 1;
405                 }
406                 /* If we find NSR0x then call it udf:
407                    NSR01 for UDF 1.00
408                    NSR02 for UDF 1.50
409                    NSR03 for UDF 2.00 */
410                 if (!strncmp(isosb.id, "NSR0", 4))
411                         return 0;
412                 for (m = udf_magic; *m; m++)
413                         if (!strncmp(*m, isosb.id, 5))
414                                 break;
415                 if (*m == 0)
416                         return 1;
417         }
418         return 1;
419 }
420
421 static int probe_ocfs(int fd __BLKID_ATTR((unused)), 
422                       blkid_cache cache __BLKID_ATTR((unused)), 
423                       blkid_dev dev,
424                       struct blkid_magic *id __BLKID_ATTR((unused)), 
425                       unsigned char *buf)
426 {
427         struct ocfs_volume_header ovh;
428         struct ocfs_volume_label ovl;
429         __u32 major;
430
431         memcpy(&ovh, buf, sizeof(ovh));
432         memcpy(&ovl, buf+512, sizeof(ovl));
433
434         major = ocfsmajor(ovh);
435         if (major == 1)
436                 blkid_set_tag(dev,"SEC_TYPE","ocfs1",sizeof("ocfs1"));
437         else if (major >= 9)
438                 blkid_set_tag(dev,"SEC_TYPE","ntocfs",sizeof("ntocfs"));
439         
440         blkid_set_tag(dev, "LABEL", ovl.label, ocfslabellen(ovl));
441         blkid_set_tag(dev, "MOUNT", ovh.mount, ocfsmountlen(ovh));
442         set_uuid(dev, ovl.vol_id);
443         return 0;
444 }
445
446 static int probe_ocfs2(int fd __BLKID_ATTR((unused)), 
447                        blkid_cache cache __BLKID_ATTR((unused)), 
448                        blkid_dev dev,
449                        struct blkid_magic *id __BLKID_ATTR((unused)), 
450                        unsigned char *buf)
451 {
452         struct ocfs2_super_block *osb;
453
454         osb = (struct ocfs2_super_block *)buf;
455
456         blkid_set_tag(dev, "LABEL", osb->s_label, sizeof(osb->s_label));
457         set_uuid(dev, osb->s_uuid);
458         return 0;
459 }
460
461 static int probe_oracleasm(int fd __BLKID_ATTR((unused)), 
462                            blkid_cache cache __BLKID_ATTR((unused)), 
463                            blkid_dev dev,
464                            struct blkid_magic *id __BLKID_ATTR((unused)), 
465                            unsigned char *buf)
466 {
467         struct oracle_asm_disk_label *dl;
468
469         dl = (struct oracle_asm_disk_label *)buf;
470
471         blkid_set_tag(dev, "LABEL", dl->dl_id, sizeof(dl->dl_id));
472         return 0;
473 }
474
475 /*
476  * BLKID_BLK_OFFS is at least as large as the highest bim_kboff defined
477  * in the type_array table below + bim_kbalign.
478  *
479  * When probing for a lot of magics, we handle everything in 1kB buffers so
480  * that we don't have to worry about reading each combination of block sizes.
481  */
482 #define BLKID_BLK_OFFS  64      /* currently reiserfs */
483
484 /*
485  * Various filesystem magics that we can check for.  Note that kboff and
486  * sboff are in kilobytes and bytes respectively.  All magics are in
487  * byte strings so we don't worry about endian issues.
488  */
489 static struct blkid_magic type_array[] = {
490 /*  type     kboff   sboff len  magic                   probe */
491   { "oracleasm", 0,     32,  8, "ORCLDISK",             probe_oracleasm },
492   { "ntfs",      0,      3,  8, "NTFS    ",             0 },
493   { "jbd",       1,   0x38,  2, "\123\357",             probe_jbd },
494   { "ext3",      1,   0x38,  2, "\123\357",             probe_ext3 },
495   { "ext2",      1,   0x38,  2, "\123\357",             probe_ext2 },
496   { "reiserfs",  8,   0x34,  8, "ReIsErFs",             probe_reiserfs },
497   { "reiserfs", 64,   0x34,  9, "ReIsEr2Fs",            probe_reiserfs },
498   { "reiserfs", 64,   0x34,  9, "ReIsEr3Fs",            probe_reiserfs },
499   { "reiserfs", 64,   0x34,  8, "ReIsErFs",             probe_reiserfs },
500   { "reiserfs",  8,     20,  8, "ReIsErFs",             probe_reiserfs },
501   { "vfat",      0,   0x52,  5, "MSWIN",                probe_vfat },
502   { "vfat",      0,   0x52,  8, "FAT32   ",             probe_vfat },
503   { "vfat",      0,   0x36,  5, "MSDOS",                probe_msdos },
504   { "vfat",      0,   0x36,  8, "FAT16   ",             probe_msdos },
505   { "vfat",      0,   0x36,  8, "FAT12   ",             probe_msdos },
506   { "minix",     1,   0x10,  2, "\177\023",             0 },
507   { "minix",     1,   0x10,  2, "\217\023",             0 },
508   { "minix",     1,   0x10,  2, "\150\044",             0 },
509   { "minix",     1,   0x10,  2, "\170\044",             0 },
510   { "vxfs",      1,      0,  4, "\365\374\001\245",     0 },
511   { "xfs",       0,      0,  4, "XFSB",                 probe_xfs },
512   { "romfs",     0,      0,  8, "-rom1fs-",             probe_romfs },
513   { "bfs",       0,      0,  4, "\316\372\173\033",     0 },
514   { "cramfs",    0,      0,  4, "E=\315\050",           probe_cramfs },
515   { "qnx4",      0,      4,  6, "QNX4FS",               0 },
516   { "udf",      32,      1,  5, "BEA01",                probe_udf },
517   { "udf",      32,      1,  5, "BOOT2",                probe_udf },
518   { "udf",      32,      1,  5, "CD001",                probe_udf },
519   { "udf",      32,      1,  5, "CDW02",                probe_udf },
520   { "udf",      32,      1,  5, "NSR02",                probe_udf },
521   { "udf",      32,      1,  5, "NSR03",                probe_udf },
522   { "udf",      32,      1,  5, "TEA01",                probe_udf },
523   { "iso9660",  32,      1,  5, "CD001",                0 },
524   { "iso9660",  32,      9,  5, "CDROM",                0 },
525   { "jfs",      32,      0,  4, "JFS1",                 probe_jfs },
526   { "hfs",       1,      0,  2, "BD",                   0 },
527   { "ufs",       8,  0x55c,  4, "T\031\001\000",        0 },
528   { "hpfs",      8,      0,  4, "I\350\225\371",        0 },
529   { "sysv",      0,  0x3f8,  4, "\020~\030\375",        0 },
530   { "swap",      0,  0xff6, 10, "SWAP-SPACE",           probe_swap0 },
531   { "swap",      0,  0xff6, 10, "SWAPSPACE2",           probe_swap1 },
532   { "swsuspend", 0,  0xff6,  9, "S1SUSPEND",            probe_swap1 },
533   { "swsuspend", 0,  0xff6,  9, "S2SUSPEND",            probe_swap1 },
534   { "swap",      0, 0x1ff6, 10, "SWAP-SPACE",           probe_swap0 },
535   { "swap",      0, 0x1ff6, 10, "SWAPSPACE2",           probe_swap1 },
536   { "swsuspend", 0, 0x1ff6,  9, "S1SUSPEND",            probe_swap1 },
537   { "swsuspend", 0, 0x1ff6,  9, "S2SUSPEND",            probe_swap1 },
538   { "swap",      0, 0x3ff6, 10, "SWAP-SPACE",           probe_swap0 },
539   { "swap",      0, 0x3ff6, 10, "SWAPSPACE2",           probe_swap1 },
540   { "swsuspend", 0, 0x3ff6,  9, "S1SUSPEND",            probe_swap1 },
541   { "swsuspend", 0, 0x3ff6,  9, "S2SUSPEND",            probe_swap1 },
542   { "swap",      0, 0x7ff6, 10, "SWAP-SPACE",           probe_swap0 },
543   { "swap",      0, 0x7ff6, 10, "SWAPSPACE2",           probe_swap1 },
544   { "swsuspend", 0, 0x7ff6,  9, "S1SUSPEND",            probe_swap1 },
545   { "swsuspend", 0, 0x7ff6,  9, "S2SUSPEND",            probe_swap1 },
546   { "swap",      0, 0xfff6, 10, "SWAP-SPACE",           probe_swap0 },
547   { "swap",      0, 0xfff6, 10, "SWAPSPACE2",           probe_swap1 },
548   { "swsuspend", 0, 0xfff6,  9, "S1SUSPEND",            probe_swap1 },
549   { "swsuspend", 0, 0xfff6,  9, "S2SUSPEND",            probe_swap1 },
550   { "ocfs",      0,      8,  9, "OracleCFS",            probe_ocfs },
551   { "ocfs2",     1,      0,  6, "OCFSV2",               probe_ocfs2 },
552   { "ocfs2",     2,      0,  6, "OCFSV2",               probe_ocfs2 },
553   { "ocfs2",     4,      0,  6, "OCFSV2",               probe_ocfs2 },
554   { "ocfs2",     8,      0,  6, "OCFSV2",               probe_ocfs2 },
555   {   NULL,      0,      0,  0, NULL,                   NULL }
556 };
557
558 /*
559  * Verify that the data in dev is consistent with what is on the actual
560  * block device (using the devname field only).  Normally this will be
561  * called when finding items in the cache, but for long running processes
562  * is also desirable to revalidate an item before use.
563  *
564  * If we are unable to revalidate the data, we return the old data and
565  * do not set the BLKID_BID_FL_VERIFIED flag on it.
566  */
567 blkid_dev blkid_verify(blkid_cache cache, blkid_dev dev)
568 {
569         struct blkid_magic *id;
570         unsigned char *bufs[BLKID_BLK_OFFS + 1], *buf;
571         const char *type;
572         struct stat st;
573         time_t diff, now;
574         int fd, idx;
575
576         if (!dev)
577                 return NULL;
578
579         now = time(0);
580         diff = now - dev->bid_time;
581
582         if ((now < dev->bid_time) ||
583             (diff < BLKID_PROBE_MIN) || 
584             (dev->bid_flags & BLKID_BID_FL_VERIFIED &&
585              diff < BLKID_PROBE_INTERVAL))
586                 return dev;
587
588         DBG(DEBUG_PROBE,
589             printf("need to revalidate %s (time since last check %lu)\n", 
590                    dev->bid_name, diff));
591
592         if (((fd = open(dev->bid_name, O_RDONLY)) < 0) ||
593             (fstat(fd, &st) < 0)) {
594                 if (errno == ENXIO || errno == ENODEV || errno == ENOENT) {
595                         blkid_free_dev(dev);
596                         return NULL;
597                 }
598                 /* We don't have read permission, just return cache data. */
599                 DBG(DEBUG_PROBE,
600                     printf("returning unverified data for %s\n",
601                            dev->bid_name));
602                 return dev;
603         }
604
605         memset(bufs, 0, sizeof(bufs));
606         
607         /*
608          * Iterate over the type array.  If we already know the type,
609          * then try that first.  If it doesn't work, then blow away
610          * the type information, and try again.
611          * 
612          */
613 try_again:
614         type = 0;
615         if (!dev->bid_type || !strcmp(dev->bid_type, "mdraid")) {
616                 uuid_t  uuid;
617
618                 if (check_mdraid(fd, uuid) == 0) {
619                         set_uuid(dev, uuid);
620                         type = "mdraid";
621                         goto found_type;
622                 }
623         }
624         for (id = type_array; id->bim_type; id++) {
625                 if (dev->bid_type &&
626                     strcmp(id->bim_type, dev->bid_type))
627                         continue;
628
629                 idx = id->bim_kboff + (id->bim_sboff >> 10);
630                 if (idx > BLKID_BLK_OFFS || idx < 0)
631                         continue;
632                 buf = bufs[idx];
633                 if (!buf) {
634                         if (lseek(fd, idx << 10, SEEK_SET) < 0)
635                                 continue;
636
637                         if (!(buf = (unsigned char *)malloc(1024)))
638                                 continue;
639                         
640                         if (read(fd, buf, 1024) != 1024) {
641                                 free(buf);
642                                 continue;
643                         }
644                         bufs[idx] = buf;
645                 }
646
647                 if (memcmp(id->bim_magic, buf + (id->bim_sboff&0x3ff),
648                            id->bim_len))
649                         continue;
650
651                 if ((id->bim_probe == NULL) ||
652                     (id->bim_probe(fd, cache, dev, id, buf) == 0)) {
653                         type = id->bim_type;
654                         goto found_type;
655                 }
656         }
657
658         if (!id->bim_type && dev->bid_type) {
659                 /*
660                  * Zap the device filesystem type and try again
661                  */
662                 blkid_set_tag(dev, "TYPE", 0, 0);
663                 blkid_set_tag(dev, "SEC_TYPE", 0, 0);
664                 blkid_set_tag(dev, "LABEL", 0, 0);
665                 blkid_set_tag(dev, "UUID", 0, 0);
666                 goto try_again;
667         }
668
669         if (!dev->bid_type) {
670                 blkid_free_dev(dev);
671                 return NULL;
672         }
673                 
674 found_type:
675         if (dev && type) {
676                 dev->bid_devno = st.st_rdev;
677                 dev->bid_time = time(0);
678                 dev->bid_flags |= BLKID_BID_FL_VERIFIED;
679                 cache->bic_flags |= BLKID_BIC_FL_CHANGED;
680
681                 blkid_set_tag(dev, "TYPE", type, 0);
682                                 
683                 DBG(DEBUG_PROBE, printf("%s: devno 0x%04llx, type %s\n",
684                            dev->bid_name, st.st_rdev, type));
685         }
686
687         close(fd);
688
689         return dev;
690 }
691
692 int blkid_known_fstype(const char *fstype)
693 {
694         struct blkid_magic *id;
695
696         for (id = type_array; id->bim_type; id++) {
697                 if (strcmp(fstype, id->bim_type) == 0)
698                         return 1;
699         }
700         return 0;
701 }
702
703 #ifdef TEST_PROGRAM
704 int main(int argc, char **argv)
705 {
706         blkid_dev dev;
707         blkid_cache cache;
708         int ret;
709
710         blkid_debug_mask = DEBUG_ALL;
711         if (argc != 2) {
712                 fprintf(stderr, "Usage: %s device\n"
713                         "Probe a single device to determine type\n", argv[0]);
714                 exit(1);
715         }
716         if ((ret = blkid_get_cache(&cache, "/dev/null")) != 0) {
717                 fprintf(stderr, "%s: error creating cache (%d)\n",
718                         argv[0], ret);
719                 exit(1);
720         }
721         dev = blkid_get_dev(cache, argv[1], BLKID_DEV_NORMAL);
722         if (!dev) {
723                 printf("%s: %s has an unsupported type\n", argv[0], argv[1]);
724                 return (1);
725         }
726         printf("%s is type %s\n", argv[1], dev->bid_type ?
727                 dev->bid_type : "(null)");
728         if (dev->bid_label)
729                 printf("\tlabel is '%s'\n", dev->bid_label);
730         if (dev->bid_uuid)
731                 printf("\tuuid is %s\n", dev->bid_uuid);
732         
733         blkid_free_dev(dev);
734         return (0);
735 }
736 #endif