resolve.c revision 45e338f5332a54295893dba2e32cc093d1316f60 
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#if 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 */
27char *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 = blkid_strdup(found->bit_val);
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 */
61char *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 = blkid_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 = blkid_strdup(blkid_dev_devname(dev));
98
99out:
100	free(t);
101	free(v);
102	if (!cache) {
103		blkid_put_cache(c);
104	}
105	return (ret);
106}
107
108#ifdef TEST_PROGRAM
109int main(int argc, char **argv)
110{
111	char *value;
112	blkid_cache cache;
113
114	blkid_debug_mask = DEBUG_ALL;
115	if (argc != 2 && argc != 3) {
116		fprintf(stderr, "Usage:\t%s tagname=value\n"
117			"\t%s tagname devname\n"
118			"Find which device holds a given token or\n"
119			"Find what the value of a tag is in a device\n",
120			argv[0], argv[0]);
121		exit(1);
122	}
123	if (blkid_get_cache(&cache, "/dev/null") < 0) {
124		fprintf(stderr, "Couldn't get blkid cache\n");
125		exit(1);
126	}
127
128	if (argv[2]) {
129		value = blkid_get_tag_value(cache, argv[1], argv[2]);
130		printf("%s has tag %s=%s\n", argv[2], argv[1],
131		       value ? value : "<missing>");
132	} else {
133		value = blkid_get_devname(cache, argv[1], NULL);
134		printf("%s has tag %s\n", value ? value : "<none>", argv[1]);
135	}
136	blkid_put_cache(cache);
137	return value ? 0 : 1;
138}
139#endif
140