lib/libc/stdlib/setenv.c

   1 /*      $NetBSD: setenv.c,v 1.31 2008/11/01 00:54:47 christos 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[] = "@(#)setenv.c    8.1 (Berkeley) 6/4/93";
  36 #else
  37 __RCSID("$NetBSD: setenv.c,v 1.31 2008/11/01 00:54:47 christos 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 __weak_alias
  51 __weak_alias(setenv,_setenv)
  52 #endif
  53
  54 #ifdef _REENTRANT
  55 extern rwlock_t __environ_lock;
  56 #endif
  57
  58 extern char **environ;
  59
  60 /*
  61  * setenv --
  62  *      Set the value of the environmental variable "name" to be
  63  *      "value".  If rewrite is set, replace any current value.
  64  */
  65 int
  66 setenv(const char *name, const char *value, int rewrite)
  67 {
  68         static char **saveenv;  /* copy of previously allocated space */
  69         char *c, **newenv;
  70         const char *cc;
  71         size_t l_value, size;
  72         int offset;
  73
  74         _DIAGASSERT(name != NULL);
  75         _DIAGASSERT(value != NULL);
  76
  77         if (*value == '=')                      /* no `=' in value */
  78                 ++value;
  79         l_value = strlen(value);
  80         rwlock_wrlock(&__environ_lock);
  81         /* find if already exists */
  82         if ((c = __findenv(name, &offset)) != NULL) {
  83                 if (!rewrite)
  84                         goto good;
  85                 if (strlen(c) >= l_value)       /* old larger; copy over */
  86                         goto copy;
  87         } else {                                        /* create new slot */
  88                 size = (size_t)(sizeof(char *) * (offset + 2));
  89                 if (saveenv == environ) {               /* just increase size */
  90                         if ((newenv = realloc(saveenv, size)) == NULL)
  91                                 goto bad;
  92                         saveenv = newenv;
  93                 } else {                                /* get new space */
  94                         free(saveenv);
  95                         if ((saveenv = malloc(size)) == NULL)
  96                                 goto bad;
  97                         (void)memcpy(saveenv, environ, size - sizeof(char *));
  98                 }
  99                 environ = saveenv;
 100                 environ[offset + 1] = NULL;
 101         }
 102         for (cc = name; *cc && *cc != '='; ++cc)        /* no `=' in name */
 103                 continue;
 104         size = cc - name;
 105         /* name + `=' + value */
 106         if ((c = malloc(size + l_value + 2)) == NULL)
 107                 goto bad;
 108         environ[offset] = c;
 109         (void)memcpy(c, name, size);
 110         c += size;
 111         *c++ = '=';
 112 copy:
 113         (void)memcpy(c, value, l_value + 1);
 114 good:
 115         rwlock_unlock(&__environ_lock);
 116         return 0;
 117 bad:
 118         rwlock_unlock(&__environ_lock);
 119         return -1;
 120 }