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