devname.c revision 90039 
1/*
2 * Copyright (c) 1989, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#if defined(LIBC_SCCS) && !defined(lint)
35static char sccsid[] = "@(#)devname.c	8.2 (Berkeley) 4/29/95";
36#endif /* LIBC_SCCS and not lint */
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD: head/lib/libc/gen/devname.c 90039 2002-02-01 00:57:29Z obrien $");
39
40#include <sys/types.h>
41#include <sys/sysctl.h>
42
43#include <db.h>
44#include <err.h>
45#include <fcntl.h>
46#include <paths.h>
47#include <stdio.h>
48#include <string.h>
49#include <sys/param.h>
50#include <sys/stat.h>
51
52static char *
53xdevname(dev, type)
54	dev_t dev;
55	mode_t type;
56{
57	struct {
58		mode_t type;
59		dev_t dev;
60	} bkey;
61	static DB *db;
62	static int failure;
63	DBT data, key;
64
65	if (!db && !failure &&
66	    !(db = dbopen(_PATH_DEVDB, O_RDONLY, 0, DB_HASH, NULL)))
67		failure = 1;
68	if (failure)
69		return (NULL);
70
71	/*
72	 * Keys are a mode_t followed by a dev_t.  The former is the type of
73	 * the file (mode & S_IFMT), the latter is the st_rdev field.  Be
74	 * sure to clear any padding that may be found in bkey.
75	 */
76	memset(&bkey, 0, sizeof(bkey));
77	bkey.dev = dev;
78	bkey.type = type;
79	key.data = &bkey;
80	key.size = sizeof(bkey);
81	return ((db->get)(db, &key, &data, 0) ? NULL : (char *)data.data);
82}
83
84char *
85devname(dev, type)
86	dev_t dev;
87	mode_t type;
88{
89	static char buf[SPECNAMELEN + 1];
90	int i;
91	size_t j;
92	char *r;
93
94	/* First check the DB file. */
95	r = xdevname(dev, type);
96	if (r != NULL)
97		return (r);
98
99	/* Then ask the kernel. */
100	if ((type & S_IFMT) == S_IFCHR) {
101		j = sizeof(buf);
102		i = sysctlbyname("kern.devname", buf, &j, &dev, sizeof (dev));
103		if (i == 0)
104		    return (buf);
105	}
106
107	/* Finally just format it */
108	if (minor(dev) > 255)
109		r = "#%c:%d:0x%x";
110	else
111		r = "#%c:%d:0x%d";
112	snprintf(buf, SPECNAMELEN + 1, r,
113	    (type & S_IFMT) == S_IFCHR ? 'C' : 'B', major(dev), minor(dev));
114	return (buf);
115}
116