lib/libc/stdlib/unsetenv.c

   1 /*      $NetBSD: __unsetenv13.c,v 1.3 2003/08/07 16:43:37 agc Exp $     */
   2
   3 /*
   4  * Copyright (c) 1987, 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[] = "from: @(#)setenv.c      8.1 (Berkeley) 6/4/93";
  36 #else
  37 __RCSID("$NetBSD: __unsetenv13.c,v 1.3 2003/08/07 16:43:37 agc Exp $");
  38 #endif
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 #include "namespace.h"
  42
  43 #include <assert.h>
  44 #include <errno.h>
  45 #include <stdlib.h>
  46 #include <string.h>
  47 #include "local.h"
  48 #include "reentrant.h"
  49
  50 #ifdef _REENTRANT
  51 extern rwlock_t __environ_lock;
  52 #endif
  53
  54 extern char **environ;
  55
  56 /*
  57  * unsetenv(name) --
  58  *      Delete environmental variable "name".
  59  */
  60 int
  61 unsetenv(name)
  62         const char *name;
  63 {
  64         char **p;
  65         int offset;
  66
  67         _DIAGASSERT(name != NULL);
  68
  69         if (name == NULL || *name == '\0' || strchr(name, '=') != NULL) {
  70                 errno = EINVAL;
  71                 return -1;
  72         }
  73
  74         rwlock_wrlock(&__environ_lock);
  75         while (__findenv(name, &offset))        /* if set multiple times */
  76                 for (p = &environ[offset];; ++p)
  77                         if (!(*p = *(p + 1)))
  78                                 break;
  79         rwlock_unlock(&__environ_lock);
  80
  81         return 0;
  82 }