resolve.c revision 28595220024d4a5e8726d0288030341c809a5fbc 
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#include "probe.h"
24
25/*
26 * Find a tagname (e.g. LABEL or UUID) on a specific device.
27 */
28char *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 */
62char *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			return blkid_strdup(token);
85		blkid_parse_tag_string(token, &t, &v);
86		if (!t || !v)
87			goto errout;
88		token = t;
89		value = v;
90	}
91
92	dev = blkid_find_dev_with_tag(c, token, value);
93	if (!dev)
94		goto errout;
95
96	ret = blkid_strdup(blkid_dev_devname(dev));
97
98errout:
99	if (t)
100		free(t);
101	if (v)
102		free(v);
103	if (!cache) {
104		blkid_put_cache(c);
105	}
106	return (ret);
107}
108
109#ifdef TEST_PROGRAM
110int 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