xref: /openbsd/lib/libc/gen/confstr.c (revision 404b540a)
1 /*	$OpenBSD: confstr.c,v 1.8 2006/12/04 15:02:25 otto Exp $ */
2 /*-
3  * Copyright (c) 1993
4  *	The Regents of the University of California.  All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. Neither the name of the University nor the names of its contributors
15  *    may be used to endorse or promote products derived from this software
16  *    without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  */
30 
31 #include <sys/param.h>
32 #include <sys/sysctl.h>
33 
34 #include <errno.h>
35 #include <paths.h>
36 #include <stdlib.h>
37 #include <string.h>
38 #include <unistd.h>
39 
40 size_t
41 confstr(int name, char *buf, size_t len)
42 {
43 	size_t tlen;
44 	int mib[2], sverrno;
45 	char *p;
46 
47 	switch (name) {
48 	case _CS_PATH:
49 		mib[0] = CTL_USER;
50 		mib[1] = USER_CS_PATH;
51 		if (sysctl(mib, 2, NULL, &tlen, NULL, 0) == -1)
52 			return (0);
53 		if (len != 0 && buf != NULL) {
54 			if ((p = malloc(tlen)) == NULL)
55 				return (0);
56 			if (sysctl(mib, 2, p, &tlen, NULL, 0) == -1) {
57 				sverrno = errno;
58 				free(p);
59 				errno = sverrno;
60 				return (0);
61 			}
62 			/*
63 			 * POSIX 1003.2 requires partial return of
64 			 * the string -- that should be *real* useful.
65 			 */
66 			strlcpy(buf, p, len);
67 			free(p);
68 		}
69 		return (tlen + 1);
70 	default:
71 		errno = EINVAL;
72 		return (0);
73 	}
74 	/* NOTREACHED */
75 }
76