libiberty/setenv.c

   1 /* Copyright (C) 1992, 1995, 1996, 1997, 2002 Free Software Foundation, Inc.
   2    This file based on setenv.c in the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19
  20 /*
  21
  22 @deftypefn Supplemental int setenv (const char *@var{name}, const char *@var{value}, int @var{overwrite})
  23 @deftypefnx Supplemental void unsetenv (const char *@var{name})
  24
  25 @code{setenv} adds @var{name} to the environment with value
  26 @var{value}.  If the name was already present in the environment,
  27 the new value will be stored only if @var{overwrite} is nonzero.
  28 The companion @code{unsetenv} function removes @var{name} from the
  29 environment.  This implementation is not safe for multithreaded code.
  30
  31 @end deftypefn
  32
  33 */
  34
  35 #if HAVE_CONFIG_H
  36 # include <config.h>
  37 #endif
  38
  39 #define setenv libiberty_setenv
  40 #define unsetenv libiberty_unsetenv
  41
  42 #include "ansidecl.h"
  43 #include <sys/types.h> /* For `size_t' */
  44 #include <stdio.h>     /* For `NULL' */
  45
  46 #include <errno.h>
  47 #if !defined(errno) && !defined(HAVE_ERRNO_DECL)
  48 extern int errno;
  49 #endif
  50 #define __set_errno(ev) ((errno) = (ev))
  51
  52 #if HAVE_STDLIB_H
  53 # include <stdlib.h>
  54 #endif
  55 #if HAVE_STRING_H
  56 # include <string.h>
  57 #endif
  58 #if HAVE_UNISTD_H
  59 # include <unistd.h>
  60 #endif
  61
  62 #define __environ       environ
  63 #ifndef HAVE_ENVIRON_DECL
  64 extern char **environ;
  65 #endif
  66
  67 #undef setenv
  68 #undef unsetenv
  69
  70 /* LOCK and UNLOCK are defined as no-ops.  This makes the libiberty
  71  * implementation MT-Unsafe. */
  72 #define LOCK
  73 #define UNLOCK
  74
  75 /* Below this point, it's verbatim code from the glibc-2.0 implementation */
  76
  77 /* If this variable is not a null pointer we allocated the current
  78    environment.  */
  79 static char **last_environ;
  80
  81
  82 int
  83 setenv (name, value, replace)
  84      const char *name;
  85      const char *value;
  86      int replace;
  87 {
  88   register char **ep = 0;
  89   register size_t size;
  90   const size_t namelen = strlen (name);
  91   const size_t vallen = strlen (value) + 1;
  92
  93   LOCK;
  94
  95   size = 0;
  96   if (__environ != NULL)
  97     {
  98       for (ep = __environ; *ep != NULL; ++ep)
  99         if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
 100           break;
 101         else
 102           ++size;
 103     }
 104
 105   if (__environ == NULL || *ep == NULL)
 106     {
 107       char **new_environ;
 108       if (__environ == last_environ && __environ != NULL)
 109         /* We allocated this space; we can extend it.  */
 110         new_environ = (char **) realloc (last_environ,
 111                                          (size + 2) * sizeof (char *));
 112       else
 113         new_environ = (char **) malloc ((size + 2) * sizeof (char *));
 114
 115       if (new_environ == NULL)
 116         {
 117           UNLOCK;
 118           return -1;
 119         }
 120
 121       new_environ[size] = malloc (namelen + 1 + vallen);
 122       if (new_environ[size] == NULL)
 123         {
 124           free ((char *) new_environ);
 125           __set_errno (ENOMEM);
 126           UNLOCK;
 127           return -1;
 128         }
 129
 130       if (__environ != last_environ)
 131         memcpy ((char *) new_environ, (char *) __environ,
 132                 size * sizeof (char *));
 133
 134       memcpy (new_environ[size], name, namelen);
 135       new_environ[size][namelen] = '=';
 136       memcpy (&new_environ[size][namelen + 1], value, vallen);
 137
 138       new_environ[size + 1] = NULL;
 139
 140       last_environ = __environ = new_environ;
 141     }
 142   else if (replace)
 143     {
 144       size_t len = strlen (*ep);
 145       if (len + 1 < namelen + 1 + vallen)
 146         {
 147           /* The existing string is too short; malloc a new one.  */
 148           char *new = malloc (namelen + 1 + vallen);
 149           if (new == NULL)
 150             {
 151               UNLOCK;
 152               return -1;
 153             }
 154           *ep = new;
 155         }
 156       memcpy (*ep, name, namelen);
 157       (*ep)[namelen] = '=';
 158       memcpy (&(*ep)[namelen + 1], value, vallen);
 159     }
 160
 161   UNLOCK;
 162
 163   return 0;
 164 }
 165
 166 void
 167 unsetenv (name)
 168      const char *name;
 169 {
 170   const size_t len = strlen (name);
 171   char **ep;
 172
 173   LOCK;
 174
 175   for (ep = __environ; *ep; ++ep)
 176     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
 177       {
 178         /* Found it.  Remove this pointer by moving later ones back.  */
 179         char **dp = ep;
 180         do
 181           dp[0] = dp[1];
 182         while (*dp++);
 183         /* Continue the loop in case NAME appears again.  */
 184       }
 185
 186   UNLOCK;
 187 }