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git.ipfire.org Git - thirdparty/util-linux.git/blob - libblkid/src/read.c
d31d024bc5c02fd8103138e5b9ba7c22f850ba4c
2 * read.c - read the blkid cache from disk, to avoid scanning all devices
4 * Copyright (C) 2001, 2003 Theodore Y. Ts'o
5 * Copyright (C) 2001 Andreas Dilger
8 * This file may be redistributed under the terms of the
9 * GNU Lesser General Public License.
18 #include <sys/types.h>
29 # ifndef _XOPEN_SOURCE
30 # define _XOPEN_SOURCE 600 /* for inclusion of strtoull */
36 #define STRTOULL strtoull /* defined in stdlib.h if you try hard enough */
38 /* FIXME: need to support real strtoull here */
39 #define STRTOULL strtoul
43 #define blkid_debug_dump_dev(dev) (debug_dump_dev(dev))
44 static void debug_dump_dev(blkid_dev dev
);
50 * <device [<NAME="value"> ...]>device_name</device>
52 * The following tags are required for each entry:
53 * <ID="id"> unique (within this file) ID number of this device
54 * <TIME="sec.usec"> (time_t and suseconds_t) time this entry was last
56 * <TYPE="type"> (detected) type of filesystem/data for this partition
58 * The following tags may be present, depending on the device contents
59 * <LABEL="label"> (user supplied) label (volume name, etc)
60 * <UUID="uuid"> (generated) universally unique identifier (serial no)
63 static char *skip_over_blank(char *cp
)
65 while (*cp
&& isspace(*cp
))
70 static char *skip_over_word(char *cp
)
75 /* If we see a backslash, skip the next character */
83 if (isspace(ch
) || ch
== '<' || ch
== '>')
90 static char *strip_line(char *line
)
94 line
= skip_over_blank(line
);
96 p
= line
+ strlen(line
) - 1;
109 static char *parse_word(char **buf
)
117 word
= skip_over_blank(word
);
118 next
= skip_over_word(word
);
120 char *end
= next
- 1;
121 if (*end
== '"' || *end
== '\'')
127 if (*word
== '"' || *word
== '\'')
134 * Start parsing a new line from the cache.
136 * line starts with "<device" return 1 -> continue parsing line
137 * line starts with "<foo", empty, or # return 0 -> skip line
138 * line starts with other, return -BLKID_ERR_CACHE -> error
140 static int parse_start(char **cp
)
146 /* Skip comment or blank lines. We can't just NUL the first '#' char,
147 * in case it is inside quotes, or escaped.
149 if (*p
== '\0' || *p
== '#')
152 if (!strncmp(p
, "<device", 7)) {
153 DBG(DEBUG_READ
, printf("found device header: %8s\n", p
));
163 return -BLKID_ERR_CACHE
;
166 /* Consume the remaining XML on the line (cosmetic only) */
167 static int parse_end(char **cp
)
169 *cp
= skip_over_blank(*cp
);
171 if (!strncmp(*cp
, "</device>", 9)) {
172 DBG(DEBUG_READ
, printf("found device trailer %9s\n", *cp
));
177 return -BLKID_ERR_CACHE
;
181 * Allocate a new device struct with device name filled in. Will handle
182 * finding the device on lines of the form:
183 * <device foo=bar>devname</device>
184 * <device>devname<foo>bar</foo></device>
186 static int parse_dev(blkid_cache cache
, blkid_dev
*dev
, char **cp
)
188 char *start
, *tmp
, *end
, *name
;
191 if ((ret
= parse_start(cp
)) <= 0)
194 start
= tmp
= strchr(*cp
, '>');
197 printf("blkid: short line parsing dev: %s\n", *cp
));
198 return -BLKID_ERR_CACHE
;
200 start
= skip_over_blank(start
+ 1);
201 end
= skip_over_word(start
);
203 DBG(DEBUG_READ
, printf("device should be %*s\n",
204 (int)(end
- start
), start
));
213 if (!(tmp
= strrchr(end
, '<')) || parse_end(&tmp
) < 0) {
215 printf("blkid: missing </device> ending: %s\n", end
));
219 if (end
- start
<= 1) {
220 DBG(DEBUG_READ
, printf("blkid: empty device name: %s\n", *cp
));
221 return -BLKID_ERR_CACHE
;
224 name
= blkid_strndup(start
, end
-start
);
226 return -BLKID_ERR_MEM
;
228 DBG(DEBUG_READ
, printf("found dev %s\n", name
));
230 if (!(*dev
= blkid_get_dev(cache
, name
, BLKID_DEV_CREATE
))) {
232 return -BLKID_ERR_MEM
;
240 * Extract a tag of the form NAME="value" from the line.
242 static int parse_token(char **name
, char **value
, char **cp
)
246 if (!name
|| !value
|| !cp
)
247 return -BLKID_ERR_PARAM
;
249 if (!(*value
= strchr(*cp
, '=')))
253 *name
= strip_line(*cp
);
254 *value
= skip_over_blank(*value
+ 1);
256 if (**value
== '"') {
257 end
= strchr(*value
+ 1, '"');
260 printf("unbalanced quotes at: %s\n", *value
));
262 return -BLKID_ERR_CACHE
;
268 end
= skip_over_word(*value
);
280 * Extract a tag of the form <NAME>value</NAME> from the line.
283 static int parse_xml(char **name, char **value, char **cp)
287 if (!name || !value || !cp)
288 return -BLKID_ERR_PARAM;
290 *name = strip_line(*cp);
292 if ((*name)[0] != '<' || (*name)[1] == '/')
300 * Extract a tag from the line.
302 * Return 1 if a valid tag was found.
303 * Return 0 if no tag found.
304 * Return -ve error code.
306 static int parse_tag(blkid_cache cache
, blkid_dev dev
, char **cp
)
313 return -BLKID_ERR_PARAM
;
315 if ((ret
= parse_token(&name
, &value
, cp
)) <= 0 /* &&
316 (ret = parse_xml(&name, &value, cp)) <= 0 */)
319 /* Some tags are stored directly in the device struct */
320 if (!strcmp(name
, "DEVNO"))
321 dev
->bid_devno
= STRTOULL(value
, 0, 0);
322 else if (!strcmp(name
, "PRI"))
323 dev
->bid_pri
= strtol(value
, 0, 0);
324 else if (!strcmp(name
, "TIME")) {
326 dev
->bid_time
= STRTOULL(value
, &end
, 0);
327 if (end
&& *end
== '.')
328 dev
->bid_utime
= STRTOULL(end
+ 1, 0, 0);
330 ret
= blkid_set_tag(dev
, name
, value
, strlen(value
));
332 DBG(DEBUG_READ
, printf(" tag: %s=\"%s\"\n", name
, value
));
334 return ret
< 0 ? ret
: 1;
338 * Parse a single line of data, and return a newly allocated dev struct.
339 * Add the new device to the cache struct, if one was read.
341 * Lines are of the form <device [TAG="value" ...]>/dev/foo</device>
343 * Returns -ve value on error.
344 * Returns 0 otherwise.
345 * If a valid device was read, *dev_p is non-NULL, otherwise it is NULL
346 * (e.g. comment lines, unknown XML content, etc).
348 static int blkid_parse_line(blkid_cache cache
, blkid_dev
*dev_p
, char *cp
)
353 if (!cache
|| !dev_p
)
354 return -BLKID_ERR_PARAM
;
358 DBG(DEBUG_READ
, printf("line: %s\n", cp
));
360 if ((ret
= parse_dev(cache
, dev_p
, &cp
)) <= 0)
365 while ((ret
= parse_tag(cache
, dev
, &cp
)) > 0) {
369 if (dev
->bid_type
== NULL
) {
371 printf("blkid: device %s has no TYPE\n",dev
->bid_name
));
376 DBG(DEBUG_READ
, blkid_debug_dump_dev(dev
));
383 * Parse the specified filename, and return the data in the supplied or
384 * a newly allocated cache struct. If the file doesn't exist, return a
385 * new empty cache struct.
387 void blkid_read_cache(blkid_cache cache
)
398 * If the file doesn't exist, then we just return an empty
399 * struct so that the cache can be populated.
401 if ((fd
= open(cache
->bic_filename
, O_RDONLY
|O_CLOEXEC
)) < 0)
403 if (fstat(fd
, &st
) < 0)
405 if ((st
.st_mtime
== cache
->bic_ftime
) ||
406 (cache
->bic_flags
& BLKID_BIC_FL_CHANGED
)) {
407 DBG(DEBUG_CACHE
, printf("skipping re-read of %s\n",
408 cache
->bic_filename
));
412 DBG(DEBUG_CACHE
, printf("reading cache file %s\n",
413 cache
->bic_filename
));
415 file
= fdopen(fd
, "r");
419 while (fgets(buf
, sizeof(buf
), file
)) {
426 end
= strlen(buf
) - 1;
427 /* Continue reading next line if it ends with a backslash */
428 while (end
< (sizeof(buf
) - 2) && buf
[end
] == '\\' &&
429 fgets(buf
+ end
, sizeof(buf
) - end
, file
)) {
430 end
= strlen(buf
) - 1;
434 if (blkid_parse_line(cache
, &dev
, buf
) < 0) {
436 printf("blkid: bad format on line %d\n", lineno
));
443 * Initially we do not need to write out the cache file.
445 cache
->bic_flags
&= ~BLKID_BIC_FL_CHANGED
;
446 cache
->bic_ftime
= st
.st_mtime
;
455 static void debug_dump_dev(blkid_dev dev
)
460 printf(" dev: NULL\n");
464 printf(" dev: name = %s\n", dev
->bid_name
);
465 printf(" dev: DEVNO=\"0x%0llx\"\n", (long long)dev
->bid_devno
);
466 printf(" dev: TIME=\"%ld.%ld\"\n", (long)dev
->bid_time
, (long)dev
->bid_utime
);
467 printf(" dev: PRI=\"%d\"\n", dev
->bid_pri
);
468 printf(" dev: flags = 0x%08X\n", dev
->bid_flags
);
470 list_for_each(p
, &dev
->bid_tags
) {
471 blkid_tag tag
= list_entry(p
, struct blkid_struct_tag
, bit_tags
);
473 printf(" tag: %s=\"%s\"\n", tag
->bit_name
,
476 printf(" tag: NULL\n");
481 int main(int argc
, char**argv
)
483 blkid_cache cache
= NULL
;
486 blkid_init_debug(DEBUG_ALL
);
488 fprintf(stderr
, "Usage: %s [filename]\n"
489 "Test parsing of the cache (filename)\n", argv
[0]);
492 if ((ret
= blkid_get_cache(&cache
, argv
[1])) < 0)
493 fprintf(stderr
, "error %d reading cache file %s\n", ret
,
494 argv
[1] ? argv
[1] : blkid_get_cache_filename(NULL
));
496 blkid_put_cache(cache
);