1 /* 2 * read.c - read the blkid cache from disk, to avoid scanning all devices 3 * 4 * Copyright (C) 2001, 2003 Theodore Y. Ts'o 5 * Copyright (C) 2001 Andreas Dilger 6 * 7 * %Begin-Header% 8 * This file may be redistributed under the terms of the 9 * GNU Lesser General Public License. 10 * %End-Header% 11 */ 12 13 #include <stdio.h> 14 #include <ctype.h> 15 #include <string.h> 16 #include <time.h> 17 #include <sys/types.h> 18 #include <sys/stat.h> 19 #include <fcntl.h> 20 #include <unistd.h> 21 #if HAVE_ERRNO_H 22 #include <errno.h> 23 #endif 24 25 #include "blkidP.h" 26 #include "uuid/uuid.h" 27 28 #ifdef HAVE_STRTOULL 29 #define __USE_ISOC9X 30 #define STRTOULL strtoull /* defined in stdlib.h if you try hard enough */ 31 #else 32 /* FIXME: need to support real strtoull here */ 33 #define STRTOULL strtoul 34 #endif 35 36 #if HAVE_STDLIB_H 37 #include <stdlib.h> 38 #endif 39 40 #ifdef TEST_PROGRAM 41 #define blkid_debug_dump_dev(dev) (debug_dump_dev(dev)) 42 static void debug_dump_dev(blkid_dev dev); 43 #endif 44 45 /* 46 * File format: 47 * 48 * <device [<NAME="value"> ...]>device_name</device> 49 * 50 * The following tags are required for each entry: 51 * <ID="id"> unique (within this file) ID number of this device 52 * <TIME="time"> (ascii time_t) time this entry was last read from disk 53 * <TYPE="type"> (detected) type of filesystem/data for this partition 54 * 55 * The following tags may be present, depending on the device contents 56 * <LABEL="label"> (user supplied) label (volume name, etc) 57 * <UUID="uuid"> (generated) universally unique identifier (serial no) 58 */ 59 60 static char *skip_over_blank(char *cp) 61 { 62 while (*cp && isspace(*cp)) 63 cp++; 64 return cp; 65 } 66 67 static char *skip_over_word(char *cp) 68 { 69 char ch; 70 71 while ((ch = *cp)) { 72 /* If we see a backslash, skip the next character */ 73 if (ch == '\\') { 74 cp++; 75 if (*cp == '\0') 76 break; 77 cp++; 78 continue; 79 } 80 if (isspace(ch) || ch == '<' || ch == '>') 81 break; 82 cp++; 83 } 84 return cp; 85 } 86 87 static char *strip_line(char *line) 88 { 89 char *p; 90 91 line = skip_over_blank(line); 92 93 p = line + strlen(line) - 1; 94 95 while (*line) { 96 if (isspace(*p)) 97 *p-- = '\0'; 98 else 99 break; 100 } 101 102 return line; 103 } 104 105 #if 0 106 static char *parse_word(char **buf) 107 { 108 char *word, *next; 109 110 word = *buf; 111 if (*word == '\0') 112 return NULL; 113 114 word = skip_over_blank(word); 115 next = skip_over_word(word); 116 if (*next) { 117 char *end = next - 1; 118 if (*end == '"' || *end == '\'') 119 *end = '\0'; 120 *next++ = '\0'; 121 } 122 *buf = next; 123 124 if (*word == '"' || *word == '\'') 125 word++; 126 return word; 127 } 128 #endif 129 130 /* 131 * Start parsing a new line from the cache. 132 * 133 * line starts with "<device" return 1 -> continue parsing line 134 * line starts with "<foo", empty, or # return 0 -> skip line 135 * line starts with other, return -BLKID_ERR_CACHE -> error 136 */ 137 static int parse_start(char **cp) 138 { 139 char *p; 140 141 p = strip_line(*cp); 142 143 /* Skip comment or blank lines. We can't just NUL the first '#' char, 144 * in case it is inside quotes, or escaped. 145 */ 146 if (*p == '\0' || *p == '#') 147 return 0; 148 149 if (!strncmp(p, "<device", 7)) { 150 DBG(DEBUG_READ, printf("found device header: %8s\n", p)); 151 p += 7; 152 153 *cp = p; 154 return 1; 155 } 156 157 if (*p == '<') 158 return 0; 159 160 return -BLKID_ERR_CACHE; 161 } 162 163 /* Consume the remaining XML on the line (cosmetic only) */ 164 static int parse_end(char **cp) 165 { 166 *cp = skip_over_blank(*cp); 167 168 if (!strncmp(*cp, "</device>", 9)) { 169 DBG(DEBUG_READ, printf("found device trailer %9s\n", *cp)); 170 *cp += 9; 171 return 0; 172 } 173 174 return -BLKID_ERR_CACHE; 175 } 176 177 /* 178 * Allocate a new device struct with device name filled in. Will handle 179 * finding the device on lines of the form: 180 * <device foo=bar>devname</device> 181 * <device>devname<foo>bar</foo></device> 182 */ 183 static int parse_dev(blkid_cache cache, blkid_dev *dev, char **cp) 184 { 185 char *start, *tmp, *end, *name; 186 int ret; 187 188 if ((ret = parse_start(cp)) <= 0) 189 return ret; 190 191 start = tmp = strchr(*cp, '>'); 192 if (!start) { 193 DBG(DEBUG_READ, 194 printf("blkid: short line parsing dev: %s\n", *cp)); 195 return -BLKID_ERR_CACHE; 196 } 197 start = skip_over_blank(start + 1); 198 end = skip_over_word(start); 199 200 DBG(DEBUG_READ, printf("device should be %*s\n", 201 (int)(end - start), start)); 202 203 if (**cp == '>') 204 *cp = end; 205 else 206 (*cp)++; 207 208 *tmp = '\0'; 209 210 if (!(tmp = strrchr(end, '<')) || parse_end(&tmp) < 0) { 211 DBG(DEBUG_READ, 212 printf("blkid: missing </device> ending: %s\n", end)); 213 } else if (tmp) 214 *tmp = '\0'; 215 216 if (end - start <= 1) { 217 DBG(DEBUG_READ, printf("blkid: empty device name: %s\n", *cp)); 218 return -BLKID_ERR_CACHE; 219 } 220 221 name = blkid_strndup(start, end-start); 222 if (name == NULL) 223 return -BLKID_ERR_MEM; 224 225 DBG(DEBUG_READ, printf("found dev %s\n", name)); 226 227 if (!(*dev = blkid_get_dev(cache, name, BLKID_DEV_CREATE))) { 228 free(name); 229 return -BLKID_ERR_MEM; 230 } 231 232 free(name); 233 return 1; 234 } 235 236 /* 237 * Extract a tag of the form NAME="value" from the line. 238 */ 239 static int parse_token(char **name, char **value, char **cp) 240 { 241 char *end; 242 243 if (!name || !value || !cp) 244 return -BLKID_ERR_PARAM; 245 246 if (!(*value = strchr(*cp, '='))) 247 return 0; 248 249 **value = '\0'; 250 *name = strip_line(*cp); 251 *value = skip_over_blank(*value + 1); 252 253 if (**value == '"') { 254 end = strchr(*value + 1, '"'); 255 if (!end) { 256 DBG(DEBUG_READ, 257 printf("unbalanced quotes at: %s\n", *value)); 258 *cp = *value; 259 return -BLKID_ERR_CACHE; 260 } 261 (*value)++; 262 *end = '\0'; 263 end++; 264 } else { 265 end = skip_over_word(*value); 266 if (*end) { 267 *end = '\0'; 268 end++; 269 } 270 } 271 *cp = end; 272 273 return 1; 274 } 275 276 /* 277 * Extract a tag of the form <NAME>value</NAME> from the line. 278 */ 279 /* 280 static int parse_xml(char **name, char **value, char **cp) 281 { 282 char *end; 283 284 if (!name || !value || !cp) 285 return -BLKID_ERR_PARAM; 286 287 *name = strip_line(*cp); 288 289 if ((*name)[0] != '<' || (*name)[1] == '/') 290 return 0; 291 292 FIXME: finish this. 293 } 294 */ 295 296 /* 297 * Extract a tag from the line. 298 * 299 * Return 1 if a valid tag was found. 300 * Return 0 if no tag found. 301 * Return -ve error code. 302 */ 303 static int parse_tag(blkid_cache cache, blkid_dev dev, char **cp) 304 { 305 char *name; 306 char *value; 307 int ret; 308 309 if (!cache || !dev) 310 return -BLKID_ERR_PARAM; 311 312 if ((ret = parse_token(&name, &value, cp)) <= 0 /* && 313 (ret = parse_xml(&name, &value, cp)) <= 0 */) 314 return ret; 315 316 /* Some tags are stored directly in the device struct */ 317 if (!strcmp(name, "DEVNO")) 318 dev->bid_devno = STRTOULL(value, 0, 0); 319 else if (!strcmp(name, "PRI")) 320 dev->bid_pri = strtol(value, 0, 0); 321 else if (!strcmp(name, "TIME")) 322 /* FIXME: need to parse a long long eventually */ 323 dev->bid_time = strtol(value, 0, 0); 324 else 325 ret = blkid_set_tag(dev, name, value, strlen(value)); 326 327 DBG(DEBUG_READ, printf(" tag: %s=\"%s\"\n", name, value)); 328 329 return ret < 0 ? ret : 1; 330 } 331 332 /* 333 * Parse a single line of data, and return a newly allocated dev struct. 334 * Add the new device to the cache struct, if one was read. 335 * 336 * Lines are of the form <device [TAG="value" ...]>/dev/foo</device> 337 * 338 * Returns -ve value on error. 339 * Returns 0 otherwise. 340 * If a valid device was read, *dev_p is non-NULL, otherwise it is NULL 341 * (e.g. comment lines, unknown XML content, etc). 342 */ 343 static int blkid_parse_line(blkid_cache cache, blkid_dev *dev_p, char *cp) 344 { 345 blkid_dev dev; 346 int ret; 347 348 if (!cache || !dev_p) 349 return -BLKID_ERR_PARAM; 350 351 *dev_p = NULL; 352 353 DBG(DEBUG_READ, printf("line: %s\n", cp)); 354 355 if ((ret = parse_dev(cache, dev_p, &cp)) <= 0) 356 return ret; 357 358 dev = *dev_p; 359 360 while ((ret = parse_tag(cache, dev, &cp)) > 0) { 361 ; 362 } 363 364 if (dev->bid_type == NULL) { 365 DBG(DEBUG_READ, 366 printf("blkid: device %s has no TYPE\n",dev->bid_name)); 367 blkid_free_dev(dev); 368 } 369 370 DBG(DEBUG_READ, blkid_debug_dump_dev(dev)); 371 372 return ret; 373 } 374 375 /* 376 * Parse the specified filename, and return the data in the supplied or 377 * a newly allocated cache struct. If the file doesn't exist, return a 378 * new empty cache struct. 379 */ 380 void blkid_read_cache(blkid_cache cache) 381 { 382 FILE *file; 383 char buf[4096]; 384 int fd, lineno = 0; 385 struct stat st; 386 387 if (!cache) 388 return; 389 390 /* 391 * If the file doesn't exist, then we just return an empty 392 * struct so that the cache can be populated. 393 */ 394 if ((fd = open(cache->bic_filename, O_RDONLY)) < 0) 395 return; 396 if (fstat(fd, &st) < 0) 397 goto errout; 398 if ((st.st_mtime == cache->bic_ftime) || 399 (cache->bic_flags & BLKID_BIC_FL_CHANGED)) { 400 DBG(DEBUG_CACHE, printf("skipping re-read of %s\n", 401 cache->bic_filename)); 402 goto errout; 403 } 404 405 DBG(DEBUG_CACHE, printf("reading cache file %s\n", 406 cache->bic_filename)); 407 408 file = fdopen(fd, "r"); 409 if (!file) 410 goto errout; 411 412 while (fgets(buf, sizeof(buf), file)) { 413 blkid_dev dev; 414 unsigned int end; 415 416 lineno++; 417 if (buf[0] == 0) 418 continue; 419 end = strlen(buf) - 1; 420 /* Continue reading next line if it ends with a backslash */ 421 while (buf[end] == '\\' && end < sizeof(buf) - 2 && 422 fgets(buf + end, sizeof(buf) - end, file)) { 423 end = strlen(buf) - 1; 424 lineno++; 425 } 426 427 if (blkid_parse_line(cache, &dev, buf) < 0) { 428 DBG(DEBUG_READ, 429 printf("blkid: bad format on line %d\n", lineno)); 430 continue; 431 } 432 } 433 fclose(file); 434 435 /* 436 * Initially we do not need to write out the cache file. 437 */ 438 cache->bic_flags &= ~BLKID_BIC_FL_CHANGED; 439 cache->bic_ftime = st.st_mtime; 440 441 return; 442 errout: 443 close(fd); 444 return; 445 } 446 447 #ifdef TEST_PROGRAM 448 static void debug_dump_dev(blkid_dev dev) 449 { 450 struct list_head *p; 451 452 if (!dev) { 453 printf(" dev: NULL\n"); 454 return; 455 } 456 457 printf(" dev: name = %s\n", dev->bid_name); 458 printf(" dev: DEVNO=\"0x%0llx\"\n", (long long)dev->bid_devno); 459 printf(" dev: TIME=\"%lld\"\n", (long long)dev->bid_time); 460 printf(" dev: PRI=\"%d\"\n", dev->bid_pri); 461 printf(" dev: flags = 0x%08X\n", dev->bid_flags); 462 463 list_for_each(p, &dev->bid_tags) { 464 blkid_tag tag = list_entry(p, struct blkid_struct_tag, bit_tags); 465 if (tag) 466 printf(" tag: %s=\"%s\"\n", tag->bit_name, 467 tag->bit_val); 468 else 469 printf(" tag: NULL\n"); 470 } 471 printf("\n"); 472 } 473 474 int main(int argc, char**argv) 475 { 476 blkid_cache cache = NULL; 477 int ret; 478 479 blkid_debug_mask = DEBUG_ALL; 480 if (argc > 2) { 481 fprintf(stderr, "Usage: %s [filename]\n" 482 "Test parsing of the cache (filename)\n", argv[0]); 483 exit(1); 484 } 485 if ((ret = blkid_get_cache(&cache, argv[1])) < 0) 486 fprintf(stderr, "error %d reading cache file %s\n", ret, 487 argv[1] ? argv[1] : BLKID_CACHE_FILE); 488 489 blkid_put_cache(cache); 490 491 return ret; 492 } 493 #endif 494