resolve.c revision 50b380b4d4ab668bad45033e3a8aaf93c7f42844 
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#ifdef DEBUG_RESOLVE
26#define DBG(x)	x
27#else
28#define DBG(x)
29#endif
30
31
32/*
33 * Find a tagname (e.g. LABEL or UUID) on a specific device.
34 */
35char *blkid_get_tagname_devname(blkid_cache cache, const char *tagname,
36				const char *devname)
37{
38	blkid_tag found;
39	blkid_dev dev;
40	char *ret = NULL;
41
42	DBG(printf("looking for %s on %s\n", tagname, devname));
43
44	if (!devname)
45		return NULL;
46
47	if (!cache)
48		DBG(printf("no cache given, direct device probe\n"));
49
50	if ((dev = blkid_get_devname(cache, devname, BLKID_DEV_NORMAL)) &&
51	    (found = blkid_find_tag_dev(dev, tagname)))
52		ret = blkid_strdup(found->bit_val);
53
54	if (!cache)
55		blkid_free_dev(dev);
56
57	return ret;
58}
59
60/*
61 * Locate a device name from a token (NAME=value string), or (name, value)
62 * pair.  In the case of a token, value is ignored.  If the "token" is not
63 * of the form "NAME=value" and there is no value given, then it is assumed
64 * to be the actual devname and a copy is returned.
65 */
66char *blkid_get_token(blkid_cache cache, const char *token,
67		      const char *value)
68{
69	blkid_dev dev;
70	blkid_cache c = cache;
71	char *t = 0, *v = 0;
72	char *ret = NULL;
73
74	if (!token)
75		return NULL;
76
77	DBG(printf("looking for %s%c%s %s\n", token, value ? '=' : ' ',
78		   value ? value : "", cache ? "in cache" : "from disk"));
79
80	if (!cache) {
81		if (blkid_get_cache(&c, NULL) < 0)
82			c = blkid_new_cache();
83		if (!c)
84			return NULL;
85	}
86
87	if (!value) {
88		blkid_parse_tag_string(token, &t, &v);
89		if (!t || !v)
90			goto errout;
91		token = t;
92		value = v;
93	}
94
95	dev = blkid_find_dev_with_tag(c, token, value);
96	if (!dev)
97		goto errout;
98
99	ret = blkid_strdup(blkid_devname_name(dev));
100
101errout:
102	if (t)
103		free(t);
104	if (v)
105		free(v);
106	if (!cache) {
107		blkid_put_cache(c);
108	}
109	return (ret);
110}
111
112#ifdef TEST_PROGRAM
113int main(int argc, char **argv)
114{
115	char *value;
116
117	if (argc != 2 && argc != 3) {
118		fprintf(stderr, "Usage:\t%s tagname=value\n"
119			"\t%s tagname devname\n"
120			"Find which device holds a given token or\n"
121			"Find what the value of a tag is in a device\n",
122			argv[0], argv[0]);
123		exit(1);
124	}
125	if (argv[2]) {
126		value = blkid_get_tagname_devname(NULL, argv[1], argv[2]);
127		printf("%s has tag %s=%s\n", argv[2], argv[1],
128		       value ? value : "<missing>");
129	} else {
130		value = blkid_get_token(NULL, argv[1], NULL);
131		printf("%s has tag %s\n", value ? value : "<none>", argv[1]);
132	}
133	return value ? 0 : 1;
134}
135#endif
136