probe.c revision f0a22d0fd3ec3f45b562af5afba8811f72b94a28
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 */ 39static 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 71static 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), 1); 78 } 79} 80 81static int probe_ext2(int fd, blkid_cache cache, blkid_dev dev, 82 struct blkid_magic *id, unsigned char *buf, 83 const char **ret_sectype) 84{ 85 struct ext2_super_block *es; 86 87 es = (struct ext2_super_block *)buf; 88 89 DBG(DEBUG_PROBE, printf("ext2_sb.compat = %08X:%08X:%08X\n", 90 blkid_le32(es->s_feature_compat), 91 blkid_le32(es->s_feature_incompat), 92 blkid_le32(es->s_feature_ro_compat))); 93 94 /* Make sure we don't keep re-probing as ext2 for a journaled fs */ 95 if (!strcmp(id->bim_type, "ext2") && 96 ((blkid_le32(es->s_feature_compat) & 97 EXT3_FEATURE_COMPAT_HAS_JOURNAL) || 98 (blkid_le32(es->s_feature_incompat) & 99 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV))) 100 return -BLKID_ERR_PARAM; 101 102 if (strlen(es->s_volume_name)) 103 blkid_set_tag(dev, "LABEL", es->s_volume_name, 104 sizeof(es->s_volume_name), 1); 105 106 set_uuid(dev, es->s_uuid); 107 108 return 0; 109} 110 111static int probe_jbd(int fd, blkid_cache cache, blkid_dev dev, 112 struct blkid_magic *id, unsigned char *buf, 113 const char **ret_sectype) 114{ 115 struct ext2_super_block *es = (struct ext2_super_block *) buf; 116 117 if (!(blkid_le32(es->s_feature_incompat) & 118 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) 119 return -BLKID_ERR_PARAM; 120 121 return (probe_ext2(fd, cache, dev, id, buf, ret_sectype)); 122} 123 124static int probe_ext3(int fd, blkid_cache cache, blkid_dev dev, 125 struct blkid_magic *id, unsigned char *buf, 126 const char **ret_sectype) 127{ 128 struct ext2_super_block *es = (struct ext2_super_block *) buf; 129 int ret; 130 131 if (!(blkid_le32(es->s_feature_compat) & 132 EXT3_FEATURE_COMPAT_HAS_JOURNAL)) 133 return -BLKID_ERR_PARAM; 134 135 if ((ret = probe_ext2(fd, cache, dev, id, buf, ret_sectype)) < 0) 136 return ret; 137 138 if (!(blkid_le32(es->s_feature_incompat) & 139 EXT3_FEATURE_INCOMPAT_RECOVER)) 140 *ret_sectype = "ext2"; 141 142 return 0; 143} 144 145static int probe_vfat(int fd, blkid_cache cache, blkid_dev dev, 146 struct blkid_magic *id, unsigned char *buf, 147 const char **ret_sectype) 148{ 149 struct vfat_super_block *vs; 150 char serno[10]; 151 152 vs = (struct vfat_super_block *)buf; 153 154 if (strncmp(vs->vs_label, "NO NAME", 7)) { 155 char *end = vs->vs_label + sizeof(vs->vs_label) - 1; 156 157 while (*end == ' ' && end >= vs->vs_label) 158 --end; 159 if (end >= vs->vs_label) 160 blkid_set_tag(dev, "LABEL", vs->vs_label, 161 end - vs->vs_label + 1, 1); 162 } 163 164 /* We can't just print them as %04X, because they are unaligned */ 165 sprintf(serno, "%02X%02X-%02X%02X", vs->vs_serno[3], vs->vs_serno[2], 166 vs->vs_serno[1], vs->vs_serno[0]); 167 blkid_set_tag(dev, "UUID", serno, sizeof(serno), 1); 168 169 return 0; 170} 171 172static int probe_msdos(int fd, blkid_cache cache, blkid_dev dev, 173 struct blkid_magic *id, unsigned char *buf, 174 const char **ret_sectype) 175{ 176 struct msdos_super_block *ms = (struct msdos_super_block *) buf; 177 char serno[10]; 178 179 if (strncmp(ms->ms_label, "NO NAME", 7)) { 180 char *end = ms->ms_label + sizeof(ms->ms_label) - 1; 181 182 while (*end == ' ' && end >= ms->ms_label) 183 --end; 184 if (end >= ms->ms_label) 185 blkid_set_tag(dev, "LABEL", ms->ms_label, 186 end - ms->ms_label + 1, 1); 187 } 188 189 /* We can't just print them as %04X, because they are unaligned */ 190 sprintf(serno, "%02X%02X-%02X%02X", ms->ms_serno[3], ms->ms_serno[2], 191 ms->ms_serno[1], ms->ms_serno[0]); 192 blkid_set_tag(dev, "UUID", serno, 0, 1); 193 194 return 0; 195} 196 197static int probe_xfs(int fd, blkid_cache cache, blkid_dev dev, 198 struct blkid_magic *id, unsigned char *buf, 199 const char **ret_sectype) 200{ 201 struct xfs_super_block *xs; 202 203 xs = (struct xfs_super_block *)buf; 204 205 if (strlen(xs->xs_fname)) 206 blkid_set_tag(dev, "LABEL", xs->xs_fname, 207 sizeof(xs->xs_fname), 1); 208 set_uuid(dev, xs->xs_uuid); 209 return 0; 210} 211 212static int probe_reiserfs(int fd, blkid_cache cache, blkid_dev dev, 213 struct blkid_magic *id, unsigned char *buf, 214 const char **ret_sectype) 215{ 216 struct reiserfs_super_block *rs = (struct reiserfs_super_block *) buf; 217 unsigned int blocksize; 218 219 blocksize = blkid_le16(rs->rs_blocksize); 220 221 /* If the superblock is inside the journal, we have the wrong one */ 222 if (id->bim_kboff/(blocksize>>10) > blkid_le32(rs->rs_journal_block)) 223 return -BLKID_ERR_BIG; 224 225 /* LABEL/UUID are only valid for later versions of Reiserfs v3.6. */ 226 if (!strcmp(id->bim_magic, "ReIsEr2Fs") || 227 !strcmp(id->bim_magic, "ReIsEr3Fs")) { 228 if (strlen(rs->rs_label)) { 229 blkid_set_tag(dev, "LABEL", rs->rs_label, 230 sizeof(rs->rs_label), 1); 231 } 232 233 set_uuid(dev, rs->rs_uuid); 234 } 235 236 return 0; 237} 238 239/* 240 * BLKID_BLK_OFFS is at least as large as the highest bim_kboff defined 241 * in the type_array table below + bim_kbalign. 242 * 243 * When probing for a lot of magics, we handle everything in 1kB buffers so 244 * that we don't have to worry about reading each combination of block sizes. 245 */ 246#define BLKID_BLK_OFFS 64 /* currently reiserfs */ 247 248/* 249 * Various filesystem magics that we can check for. Note that kboff and 250 * sboff are in kilobytes and bytes respectively. All magics are in 251 * byte strings so we don't worry about endian issues. 252 */ 253static struct blkid_magic type_array[] = { 254/* type kboff sboff len magic probe */ 255 { "jbd", 1, 0x38, 2, "\123\357", probe_jbd }, 256 { "ext3", 1, 0x38, 2, "\123\357", probe_ext3 }, 257 { "ext2", 1, 0x38, 2, "\123\357", probe_ext2 }, 258 { "reiserfs", 8, 0x34, 8, "ReIsErFs", probe_reiserfs }, 259 { "reiserfs", 64, 0x34, 9, "ReIsEr2Fs", probe_reiserfs }, 260 { "reiserfs", 64, 0x34, 9, "ReIsEr3Fs", probe_reiserfs }, 261 { "reiserfs", 64, 0x34, 8, "ReIsErFs", probe_reiserfs }, 262 { "reiserfs", 8, 20, 8, "ReIsErFs", probe_reiserfs }, 263 { "ntfs", 0, 3, 8, "NTFS ", 0 }, 264 { "vfat", 0, 0x52, 5, "MSWIN", probe_vfat }, 265 { "vfat", 0, 0x52, 8, "FAT32 ", probe_vfat }, 266 { "msdos", 0, 0x36, 5, "MSDOS", probe_msdos }, 267 { "msdos", 0, 0x36, 8, "FAT16 ", probe_msdos }, 268 { "msdos", 0, 0x36, 8, "FAT12 ", probe_msdos }, 269 { "minix", 1, 0x10, 2, "\177\023", 0 }, 270 { "minix", 1, 0x10, 2, "\217\023", 0 }, 271 { "minix", 1, 0x10, 2, "\150\044", 0 }, 272 { "minix", 1, 0x10, 2, "\170\044", 0 }, 273 { "vxfs", 1, 0, 4, "\365\374\001\245", 0 }, 274 { "xfs", 0, 0, 4, "XFSB", probe_xfs }, 275 { "romfs", 0, 0, 8, "-rom1fs-", 0 }, 276 { "bfs", 0, 0, 4, "\316\372\173\033", 0 }, 277 { "cramfs", 0, 0, 4, "E=\315\034", 0 }, 278 { "qnx4", 0, 4, 6, "QNX4FS", 0 }, 279 { "iso9660", 32, 1, 5, "CD001", 0 }, 280 { "iso9660", 32, 9, 5, "CDROM", 0 }, 281 { "udf", 32, 1, 5, "BEA01", 0 }, 282 { "udf", 32, 1, 5, "BOOT2", 0 }, 283 { "udf", 32, 1, 5, "CD001", 0 }, 284 { "udf", 32, 1, 5, "CDW02", 0 }, 285 { "udf", 32, 1, 5, "NSR02", 0 }, 286 { "udf", 32, 1, 5, "NSR03", 0 }, 287 { "udf", 32, 1, 5, "TEA01", 0 }, 288 { "jfs", 32, 0, 4, "JFS1", 0 }, 289 { "hfs", 1, 0, 2, "BD", 0 }, 290 { "ufs", 8, 0x55c, 4, "T\031\001\000", 0 }, 291 { "hpfs", 8, 0, 4, "I\350\225\371", 0 }, 292 { "sysv", 0, 0x3f8, 4, "\020~\030\375", 0 }, 293 { "swap", 0, 0xff6, 10, "SWAP-SPACE", 0 }, 294 { "swap", 0, 0xff6, 10, "SWAPSPACE2", 0 }, 295 { "swap", 0, 0x1ff6, 10, "SWAP-SPACE", 0 }, 296 { "swap", 0, 0x1ff6, 10, "SWAPSPACE2", 0 }, 297 { "swap", 0, 0x3ff6, 10, "SWAP-SPACE", 0 }, 298 { "swap", 0, 0x3ff6, 10, "SWAPSPACE2", 0 }, 299 { NULL, 0, 0, 0, NULL, NULL } 300}; 301 302/* 303 * If a device's filesystem no longer checks out, we need to nuke 304 * information about it from the entry. 305 */ 306static void blkid_invalidate_fs(blkid_dev dev) 307{ 308 blkid_set_tag(dev, "TYPE", 0, 0, 0); 309 blkid_set_tag(dev, "LABEL", 0, 0, 0); 310 blkid_set_tag(dev, "UUID", 0, 0, 0); 311} 312 313/* 314 * Verify that the data in dev is consistent with what is on the actual 315 * block device (using the devname field only). Normally this will be 316 * called when finding items in the cache, but for long running processes 317 * is also desirable to revalidate an item before use. 318 * 319 * If we are unable to revalidate the data, we return the old data and 320 * do not set the BLKID_BID_FL_VERIFIED flag on it. 321 */ 322blkid_dev blkid_verify_devname(blkid_cache cache, blkid_dev dev) 323{ 324 struct blkid_magic *id; 325 unsigned char *bufs[BLKID_BLK_OFFS + 1], *buf; 326 const char *sec_type, *type; 327 struct stat st; 328 time_t diff; 329 int fd, idx; 330 331 if (!dev) 332 return NULL; 333 334 diff = time(0) - dev->bid_time; 335 336 if (diff < BLKID_PROBE_MIN || (dev->bid_flags & BLKID_BID_FL_VERIFIED && 337 diff < BLKID_PROBE_INTERVAL)) 338 return dev; 339 340 DBG(DEBUG_PROBE, 341 printf("need to revalidate %s (time since last check %lu)\n", 342 dev->bid_name, diff)); 343 344 if (((fd = open(dev->bid_name, O_RDONLY)) < 0) || 345 (fstat(fd, &st) < 0) || !S_ISBLK(st.st_mode)) { 346 if (errno == ENXIO || errno == ENODEV || errno == ENOENT) { 347 blkid_free_dev(dev); 348 return NULL; 349 } 350 /* We don't have read permission, just return cache data. */ 351 DBG(DEBUG_PROBE, 352 printf("returning unverified data for %s\n", 353 dev->bid_name)); 354 return dev; 355 } 356 357 memset(bufs, 0, sizeof(bufs)); 358 359 /* 360 * Iterate over the type array. If we already know the type, 361 * then try that first. If it doesn't work, then blow away 362 * the type information, and try again. 363 * 364 */ 365try_again: 366 type = 0; 367 sec_type = 0; 368 if (!dev->bid_type || !strcmp(dev->bid_type, "mdraid")) { 369 uuid_t uuid; 370 371 if (check_mdraid(fd, uuid) == 0) { 372 set_uuid(dev, uuid); 373 type = "mdraid"; 374 goto found_type; 375 } 376 } 377 for (id = type_array; id->bim_type; id++) { 378 if (dev->bid_type && 379 strcmp(id->bim_type, dev->bid_type)) 380 continue; 381 382 idx = id->bim_kboff + (id->bim_sboff >> 10); 383 if (idx > BLKID_BLK_OFFS || idx < 0) 384 continue; 385 buf = bufs[idx]; 386 if (!buf) { 387 if (lseek(fd, idx << 10, SEEK_SET) < 0) 388 continue; 389 390 if (!(buf = (unsigned char *)malloc(1024))) 391 continue; 392 393 if (read(fd, buf, 1024) != 1024) { 394 free(buf); 395 continue; 396 } 397 bufs[idx] = buf; 398 } 399 400 if (memcmp(id->bim_magic, buf + (id->bim_sboff&0x3ff), 401 id->bim_len)) 402 continue; 403 404 if ((id->bim_probe == NULL) || 405 (id->bim_probe(fd, cache, dev, id, buf, &sec_type) == 0)) { 406 type = id->bim_type; 407 goto found_type; 408 } 409 } 410 411 if (!id->bim_type && dev->bid_type) { 412 /* 413 * Zap the device filesystem type and try again 414 */ 415 blkid_invalidate_fs(dev); 416 goto try_again; 417 } 418 419 if (!dev->bid_type) { 420 blkid_free_dev(dev); 421 return NULL; 422 } 423 424found_type: 425 if (dev && type) { 426 dev->bid_devno = st.st_rdev; 427 dev->bid_time = time(0); 428 dev->bid_flags |= BLKID_BID_FL_VERIFIED; 429 cache->bic_flags |= BLKID_BIC_FL_CHANGED; 430 431 blkid_set_tag(dev, "TYPE", type, 0, 1); 432 if (sec_type) 433 blkid_set_tag(dev, "TYPE", sec_type, 0, 0); 434 435 DBG(DEBUG_PROBE, printf("%s: devno 0x%04Lx, type %s\n", 436 dev->bid_name, st.st_rdev, type)); 437 } 438 439 close(fd); 440 441 return dev; 442} 443 444#ifdef TEST_PROGRAM 445int main(int argc, char **argv) 446{ 447 blkid_dev dev; 448 blkid_cache cache; 449 450 blkid_debug_mask = DEBUG_ALL; 451 if (argc != 2) { 452 fprintf(stderr, "Usage: %s device\n" 453 "Probe a single device to determine type\n", argv[0]); 454 exit(1); 455 } 456 cache = blkid_new_cache(); 457 dev = blkid_get_dev(cache, argv[1], BLKID_DEV_NORMAL); 458 if (!dev) { 459 printf("%s: %s has an unsupported type\n", argv[0], argv[1]); 460 return (1); 461 } 462 printf("%s is type %s\n", argv[1], dev->bid_type ? 463 dev->bid_type : "(null)"); 464 if (dev->bid_label) 465 printf("\tlabel is '%s'\n", dev->bid_label); 466 if (dev->bid_uuid) 467 printf("\tuuid is %s\n", dev->bid_uuid); 468 469 blkid_free_dev(dev); 470 return (0); 471} 472#endif 473