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      1 /*	$NetBSD: confstr.c,v 1.13 2012/06/25 22:32:43 abs Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)confstr.c	8.1 (Berkeley) 6/4/93";
     36 #else
     37 __RCSID("$NetBSD: confstr.c,v 1.13 2012/06/25 22:32:43 abs Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 #include <sys/param.h>
     43 #include <sys/sysctl.h>
     44 
     45 #include <errno.h>
     46 #include <paths.h>
     47 #include <stdlib.h>
     48 #include <string.h>
     49 #include <unistd.h>
     50 
     51 #ifdef __weak_alias
     52 __weak_alias(confstr,_confstr)
     53 #endif
     54 
     55 size_t
     56 confstr(int name, char *buf, size_t len)
     57 {
     58 	size_t tlen;
     59 	int mib[2], sverrno;
     60 	char *p;
     61 
     62 	/*
     63 	 * POSIX 1003.2 requires errors to return 0 --
     64 	 * that is *really* useful.
     65 	 */
     66 	switch (name) {
     67 	case _CS_PATH:
     68 		mib[0] = CTL_USER;
     69 		mib[1] = USER_CS_PATH;
     70 		if (sysctl(mib, 2, NULL, &tlen, NULL, 0) == -1)
     71 			return 0;
     72 		if (len != 0 && buf != NULL) {
     73 			if ((p = malloc(tlen)) == NULL)
     74 				return 0;
     75 			if (sysctl(mib, 2, p, &tlen, NULL, 0) == -1) {
     76 				sverrno = errno;
     77 				free(p);
     78 				errno = sverrno;
     79 				return 0;
     80 			}
     81 			/*
     82 			 * POSIX 1003.2 requires partial return of
     83 			 * the string -- that is even more useful.
     84 			 */
     85 			(void)strncpy(buf, p, len - 1);
     86 			buf[len - 1] = '\0';
     87 			free(p);
     88 		}
     89 		return tlen + 1;
     90 	default:
     91 		errno = EINVAL;
     92 		return 0;
     93 	}
     94 	/* NOTREACHED */
     95 }
     96