devname.c revision 48882 
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
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#include <sys/stat.h>
48
49static char *
50xdevname(dev, type)
51	dev_t dev;
52	mode_t type;
53{
54	struct {
55		mode_t type;
56		dev_t dev;
57	} bkey;
58	static DB *db;
59	static int failure;
60	DBT data, key;
61
62	if (!db && !failure &&
63	    !(db = dbopen(_PATH_DEVDB, O_RDONLY, 0, DB_HASH, NULL))) {
64		warn("warning: %s", _PATH_DEVDB);
65		failure = 1;
66	}
67	if (failure)
68		return (NULL);
69
70	/*
71	 * Keys are a mode_t followed by a dev_t.  The former is the type of
72	 * the file (mode & S_IFMT), the latter is the st_rdev field.  Be
73	 * sure to clear any padding that may be found in bkey.
74	 */
75	memset(&bkey, 0, sizeof(bkey));
76	bkey.dev = dev;
77	bkey.type = type;
78	key.data = &bkey;
79	key.size = sizeof(bkey);
80	return ((db->get)(db, &key, &data, 0) ? NULL : (char *)data.data);
81}
82
83char *
84devname(dev, type)
85	dev_t dev;
86	mode_t type;
87{
88	static char buf[20];
89	char *r;
90
91	r = xdevname(dev, type);
92	if (!r) {
93		r = buf;
94		if (minor(dev) > 255) {
95			sprintf(buf, "#%c%d:0x%x",
96			    (type & S_IFMT) == S_IFCHR ? 'C' : 'B',
97			    major(dev), minor(dev));
98		} else {
99			sprintf(buf, "#%c%d:%d",
100			    (type & S_IFMT) == S_IFCHR ? 'C' : 'B',
101			    major(dev), minor(dev));
102		}
103	}
104	return (r);
105}
106