lib/libc/stdlib/setenv.c

   1 /*      $NetBSD: setenv.c,v 1.43 2010/11/14 18:11:43 tron 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 1.43 2010/11/14 18:11:43 tron 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
  48 #include "env.h"
  49 #include "reentrant.h"
  50 #include "local.h"
  51
  52 #ifdef __weak_alias
  53 __weak_alias(setenv,_setenv)
  54 #endif
  55
  56 /*
  57  * setenv --
  58  *      Set the value of the environmental variable "name" to be
  59  *      "value".  If rewrite is set, replace any current value.
  60  */
  61 int
  62 setenv(const char *name, const char *value, int rewrite)
  63 {
  64         size_t l_name, l_value, length;
  65         ssize_t offset;
  66         char *envvar;
  67
  68         _DIAGASSERT(name != NULL);
  69         _DIAGASSERT(value != NULL);
  70
  71         l_name = __envvarnamelen(name, false);
  72         if (l_name == 0 || value == NULL) {
  73                 errno = EINVAL;
  74                 return -1;
  75         }
  76
  77         if (!__writelockenv())
  78                 return -1;
  79
  80         /* Find slot in the enviroment. */
  81         offset = __getenvslot(name, l_name, true);
  82         if (offset == -1)
  83                 goto bad;
  84
  85         l_value = strlen(value);
  86         length = l_name + l_value + 2;
  87
  88         /* Handle overwriting a current environt variable. */
  89         envvar = environ[offset];
  90         if (envvar != NULL) {
  91                 if (!rewrite)
  92                         goto good;
  93                 /*
  94                  * Check whether the buffer was allocated via setenv(3) and
  95                  * whether there is enough space. If so simply overwrite the
  96                  * existing value.
  97                  */
  98                 if (__canoverwriteenvvar(envvar, length)) {
  99                         envvar += l_name + 1;
 100                         goto copy;
 101                 }
 102         }
 103
 104         /* Allocate memory for name + `=' + value + NUL. */
 105         if ((envvar = __allocenvvar(length)) == NULL)
 106                 goto bad;
 107
 108         if (environ[offset] != NULL)
 109                 __freeenvvar(environ[offset]);
 110
 111         environ[offset] = envvar;
 112
 113         (void)memcpy(envvar, name, l_name);
 114
 115         envvar += l_name;
 116         *envvar++ = '=';
 117
 118 copy:
 119         (void)memcpy(envvar, value, l_value + 1);
 120
 121 good:
 122         (void)__unlockenv();
 123         return 0;
 124
 125 bad:
 126         (void)__unlockenv();
 127         return -1;
 128 }