Home | History | Annotate | Download | only in blkid 
      1 /*
      2  * resolve.c - resolve names and tags into specific devices
      3  *
      4  * Copyright (C) 2001, 2003 Theodore 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 "config.h"
     14 #include <stdio.h>
     15 #if HAVE_UNISTD_H
     16 #include <unistd.h>
     17 #endif
     18 #include <stdlib.h>
     19 #include <fcntl.h>
     20 #include <string.h>
     21 #include <sys/types.h>
     22 #include <sys/stat.h>
     23 #include "blkidP.h"
     24 
     25 /*
     26  * Find a tagname (e.g. LABEL or UUID) on a specific device.
     27  */
     28 char *blkid_get_tag_value(blkid_cache cache, const char *tagname,
     29 			  const char *devname)
     30 {
     31 	blkid_tag found;
     32 	blkid_dev dev;
     33 	blkid_cache c = cache;
     34 	char *ret = NULL;
     35 
     36 	DBG(DEBUG_RESOLVE, printf("looking for %s on %s\n", tagname, devname));
     37 
     38 	if (!devname)
     39 		return NULL;
     40 
     41 	if (!cache) {
     42 		if (blkid_get_cache(&c, NULL) < 0)
     43 			return NULL;
     44 	}
     45 
     46 	if ((dev = blkid_get_dev(c, devname, BLKID_DEV_NORMAL)) &&
     47 	    (found = blkid_find_tag_dev(dev, tagname)))
     48 		ret = blkid_strdup(found->bit_val);
     49 
     50 	if (!cache)
     51 		blkid_put_cache(c);
     52 
     53 	return ret;
     54 }
     55 
     56 /*
     57  * Locate a device name from a token (NAME=value string), or (name, value)
     58  * pair.  In the case of a token, value is ignored.  If the "token" is not
     59  * of the form "NAME=value" and there is no value given, then it is assumed
     60  * to be the actual devname and a copy is returned.
     61  */
     62 char *blkid_get_devname(blkid_cache cache, const char *token,
     63 			const char *value)
     64 {
     65 	blkid_dev dev;
     66 	blkid_cache c = cache;
     67 	char *t = 0, *v = 0;
     68 	char *ret = NULL;
     69 
     70 	if (!token)
     71 		return NULL;
     72 
     73 	if (!cache) {
     74 		if (blkid_get_cache(&c, NULL) < 0)
     75 			return NULL;
     76 	}
     77 
     78 	DBG(DEBUG_RESOLVE,
     79 	    printf("looking for %s%s%s %s\n", token, value ? "=" : "",
     80 		   value ? value : "", cache ? "in cache" : "from disk"));
     81 
     82 	if (!value) {
     83 		if (!strchr(token, '=')) {
     84 			ret = blkid_strdup(token);
     85 			goto out;
     86 		}
     87 		blkid_parse_tag_string(token, &t, &v);
     88 		if (!t || !v)
     89 			goto out;
     90 		token = t;
     91 		value = v;
     92 	}
     93 
     94 	dev = blkid_find_dev_with_tag(c, token, value);
     95 	if (!dev)
     96 		goto out;
     97 
     98 	ret = blkid_strdup(blkid_dev_devname(dev));
     99 
    100 out:
    101 	free(t);
    102 	free(v);
    103 	if (!cache) {
    104 		blkid_put_cache(c);
    105 	}
    106 	return (ret);
    107 }
    108 
    109 #ifdef TEST_PROGRAM
    110 int main(int argc, char **argv)
    111 {
    112 	char *value;
    113 	blkid_cache cache;
    114 
    115 	blkid_debug_mask = DEBUG_ALL;
    116 	if (argc != 2 && argc != 3) {
    117 		fprintf(stderr, "Usage:\t%s tagname=value\n"
    118 			"\t%s tagname devname\n"
    119 			"Find which device holds a given token or\n"
    120 			"Find what the value of a tag is in a device\n",
    121 			argv[0], argv[0]);
    122 		exit(1);
    123 	}
    124 	if (blkid_get_cache(&cache, "/dev/null") < 0) {
    125 		fprintf(stderr, "Couldn't get blkid cache\n");
    126 		exit(1);
    127 	}
    128 
    129 	if (argv[2]) {
    130 		value = blkid_get_tag_value(cache, argv[1], argv[2]);
    131 		printf("%s has tag %s=%s\n", argv[2], argv[1],
    132 		       value ? value : "<missing>");
    133 	} else {
    134 		value = blkid_get_devname(cache, argv[1], NULL);
    135 		printf("%s has tag %s\n", value ? value : "<none>", argv[1]);
    136 	}
    137 	blkid_put_cache(cache);
    138 	return value ? 0 : 1;
    139 }
    140 #endif
    141