lib/libc/stdlib/setenv.c

   1 /*      $NetBSD: setenv.c,v 1.44 2015/01/20 18:31:25 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 1.44 2015/01/20 18:31:25 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
  48 #include "env.h"
  49 #include "local.h"
  50
  51 #ifdef __weak_alias
  52 __weak_alias(setenv,_setenv)
  53 #endif
  54
  55 /*
  56  * setenv --
  57  *      Set the value of the environmental variable "name" to be
  58  *      "value".  If rewrite is set, replace any current value.
  59  */
  60 int
  61 setenv(const char *name, const char *value, int rewrite)
  62 {
  63         size_t l_name, l_value, length;
  64         ssize_t offset;
  65         char *envvar;
  66
  67         _DIAGASSERT(name != NULL);
  68         _DIAGASSERT(value != NULL);
  69
  70         l_name = __envvarnamelen(name, false);
  71         if (l_name == 0 || value == NULL) {
  72                 errno = EINVAL;
  73                 return -1;
  74         }
  75
  76         if (!__writelockenv())
  77                 return -1;
  78
  79         /* Find slot in the enviroment. */
  80         offset = __getenvslot(name, l_name, true);
  81         if (offset == -1)
  82                 goto bad;
  83
  84         l_value = strlen(value);
  85         length = l_name + l_value + 2;
  86
  87         /* Handle overwriting a current environt variable. */
  88         envvar = environ[offset];
  89         if (envvar != NULL) {
  90                 if (!rewrite)
  91                         goto good;
  92                 /*
  93                  * Check whether the buffer was allocated via setenv(3) and
  94                  * whether there is enough space. If so simply overwrite the
  95                  * existing value.
  96                  */
  97                 if (__canoverwriteenvvar(envvar, length)) {
  98                         envvar += l_name + 1;
  99                         goto copy;
 100                 }
 101         }
 102
 103         /* Allocate memory for name + `=' + value + NUL. */
 104         if ((envvar = __allocenvvar(length)) == NULL)
 105                 goto bad;
 106
 107         if (environ[offset] != NULL)
 108                 __freeenvvar(environ[offset]);
 109
 110         environ[offset] = envvar;
 111
 112         (void)memcpy(envvar, name, l_name);
 113
 114         envvar += l_name;
 115         *envvar++ = '=';
 116
 117 copy:
 118         (void)memcpy(envvar, value, l_value + 1);
 119
 120 good:
 121         (void)__unlockenv();
 122         return 0;
 123
 124 bad:
 125         (void)__unlockenv();
 126         return -1;
 127 }