devname.c revision 65632 
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 * $FreeBSD: head/lib/libc/gen/devname.c 65632 2000-09-09 11:39:59Z phk $
34 */
35
36#if defined(LIBC_SCCS) && !defined(lint)
37static char sccsid[] = "@(#)devname.c	8.2 (Berkeley) 4/29/95";
38#endif /* LIBC_SCCS and not lint */
39
40#include <sys/types.h>
41#include <sys/sysctl.h>
42
43#include <db.h>
44#include <err.h>
45#include <errno.h>
46#include <fcntl.h>
47#include <paths.h>
48#include <stdio.h>
49#include <string.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		warn("warning: %s", _PATH_DEVDB);
68		failure = 1;
69	}
70	if (failure)
71		return (NULL);
72
73	/*
74	 * Keys are a mode_t followed by a dev_t.  The former is the type of
75	 * the file (mode & S_IFMT), the latter is the st_rdev field.  Be
76	 * sure to clear any padding that may be found in bkey.
77	 */
78	memset(&bkey, 0, sizeof(bkey));
79	bkey.dev = dev;
80	bkey.type = type;
81	key.data = &bkey;
82	key.size = sizeof(bkey);
83	return ((db->get)(db, &key, &data, 0) ? NULL : (char *)data.data);
84}
85
86char *
87devname(dev, type)
88	dev_t dev;
89	mode_t type;
90{
91	static char buf[30];	 /* XXX: pick up from <sys/conf.h> */
92	int i, j;
93	char *r;
94
95	/* First check the DB file. */
96	r = xdevname(dev, type);
97	if (r != NULL)
98		return (r);
99
100	/* Then ask the kernel. */
101	if ((type & S_IFMT) == S_IFCHR) {
102		j = sizeof(buf);
103		i = sysctlbyname("kern.devname", buf, &j, &dev, sizeof (dev));
104		if (i == 0)
105		    return (buf);
106	}
107
108	/* Finally just format it */
109	r = buf;
110	if (minor(dev) > 255) {
111		sprintf(buf, "#%c%d:0x%x",
112		    (type & S_IFMT) == S_IFCHR ? 'C' : 'B',
113		    major(dev), minor(dev));
114	} else {
115		sprintf(buf, "#%c%d:%d",
116		    (type & S_IFMT) == S_IFCHR ? 'C' : 'B',
117		    major(dev), minor(dev));
118	}
119	return (r);
120}
121