devname.c revision 1573 
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	8.1 (Berkeley) 6/4/93";
36#endif /* LIBC_SCCS and not lint */
37
38#include <sys/types.h>
39
40#include <db.h>
41#include <err.h>
42#include <errno.h>
43#include <fcntl.h>
44#include <paths.h>
45#include <stdio.h>
46#include <string.h>
47
48char *
49devname(dev, type)
50	dev_t dev;
51	mode_t type;
52{
53	struct {
54		mode_t type;
55		dev_t dev;
56	} bkey;
57	static DB *db;
58	static int failure;
59	DBT data, key;
60
61	if (!db && !failure &&
62	    !(db = dbopen(_PATH_DEVDB, O_RDONLY, 0, DB_HASH, NULL))) {
63		warn("warning: %s", _PATH_DEVDB);
64		failure = 1;
65	}
66	if (failure)
67		return ("??");
68
69	/*
70	 * Keys are a mode_t followed by a dev_t.  The former is the type of
71	 * the file (mode & S_IFMT), the latter is the st_rdev field.  Be
72	 * sure to clear any padding that may be found in bkey.
73	 */
74	memset(&bkey, 0, sizeof(bkey));
75	bkey.dev = dev;
76	bkey.type = type;
77	key.data = &bkey;
78	key.size = sizeof(bkey);
79	return ((db->get)(db, &key, &data, 0) ? "??" : (char *)data.data);
80}
81