lib/libc/gen/confstr.c

   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 }