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