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