libblkid/src/resolve.c

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