libiberty/setenv.c

   1 /* Copyright (C) 1992, 1995, 1996, 1997, 2002, 2011 Free Software Foundation,
   2    Inc.
   3    This file based on setenv.c in the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  18    Boston, MA 02110-1301, USA.  */
  19
  20
  21 /*
  22
  23 @deftypefn Supplemental int setenv (const char *@var{name}, @
  24   const char *@var{value}, int @var{overwrite})
  25 @deftypefnx Supplemental void unsetenv (const char *@var{name})
  26
  27 @code{setenv} adds @var{name} to the environment with value
  28 @var{value}.  If the name was already present in the environment,
  29 the new value will be stored only if @var{overwrite} is nonzero.
  30 The companion @code{unsetenv} function removes @var{name} from the
  31 environment.  This implementation is not safe for multithreaded code.
  32
  33 @end deftypefn
  34
  35 */
  36
  37 #if HAVE_CONFIG_H
  38 # include <config.h>
  39 #endif
  40
  41 #define setenv libiberty_setenv
  42 #define unsetenv libiberty_unsetenv
  43
  44 #include "ansidecl.h"
  45 #include <sys/types.h> /* For `size_t' */
  46 #include <stdio.h>     /* For `NULL' */
  47
  48 #include <errno.h>
  49 #if !defined(errno) && !defined(HAVE_ERRNO_DECL)
  50 extern int errno;
  51 #endif
  52 #define __set_errno(ev) ((errno) = (ev))
  53
  54 #if HAVE_STDLIB_H
  55 # include <stdlib.h>
  56 #endif
  57 #if HAVE_STRING_H
  58 # include <string.h>
  59 #endif
  60 #if HAVE_UNISTD_H
  61 # include <unistd.h>
  62 #endif
  63
  64 #define __environ       environ
  65 #ifndef HAVE_ENVIRON_DECL
  66 extern char **environ;
  67 #endif
  68
  69 #undef setenv
  70 #undef unsetenv
  71
  72 /* LOCK and UNLOCK are defined as no-ops.  This makes the libiberty
  73  * implementation MT-Unsafe. */
  74 #define LOCK
  75 #define UNLOCK
  76
  77 /* Below this point, it's verbatim code from the glibc-2.0 implementation */
  78
  79 /* If this variable is not a null pointer we allocated the current
  80    environment.  */
  81 static char **last_environ;
  82
  83
  84 int
  85 setenv (const char *name, const char *value, int replace)
  86 {
  87   register char **ep = 0;
  88   register size_t size;
  89   const size_t namelen = strlen (name);
  90   const size_t vallen = strlen (value) + 1;
  91
  92   LOCK;
  93
  94   size = 0;
  95   if (__environ != NULL)
  96     {
  97       for (ep = __environ; *ep != NULL; ++ep)
  98         if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
  99           break;
 100         else
 101           ++size;
 102     }
 103
 104   if (__environ == NULL || *ep == NULL)
 105     {
 106       char **new_environ;
 107       if (__environ == last_environ && __environ != NULL)
 108         /* We allocated this space; we can extend it.  */
 109         new_environ = (char **) realloc (last_environ,
 110                                          (size + 2) * sizeof (char *));
 111       else
 112         new_environ = (char **) malloc ((size + 2) * sizeof (char *));
 113
 114       if (new_environ == NULL)
 115         {
 116           UNLOCK;
 117           return -1;
 118         }
 119
 120       new_environ[size] = (char *) malloc (namelen + 1 + vallen);
 121       if (new_environ[size] == NULL)
 122         {
 123           free ((char *) new_environ);
 124           __set_errno (ENOMEM);
 125           UNLOCK;
 126           return -1;
 127         }
 128
 129       if (__environ != last_environ)
 130         memcpy ((char *) new_environ, (char *) __environ,
 131                 size * sizeof (char *));
 132
 133       memcpy (new_environ[size], name, namelen);
 134       new_environ[size][namelen] = '=';
 135       memcpy (&new_environ[size][namelen + 1], value, vallen);
 136
 137       new_environ[size + 1] = NULL;
 138
 139       last_environ = __environ = new_environ;
 140     }
 141   else if (replace)
 142     {
 143       size_t len = strlen (*ep);
 144       if (len + 1 < namelen + 1 + vallen)
 145         {
 146           /* The existing string is too short; malloc a new one.  */
 147           char *new_string = (char *) malloc (namelen + 1 + vallen);
 148           if (new_string == NULL)
 149             {
 150               UNLOCK;
 151               return -1;
 152             }
 153           *ep = new_string;
 154         }
 155       memcpy (*ep, name, namelen);
 156       (*ep)[namelen] = '=';
 157       memcpy (&(*ep)[namelen + 1], value, vallen);
 158     }
 159
 160   UNLOCK;
 161
 162   return 0;
 163 }
 164
 165 void
 166 unsetenv (const char *name)
 167 {
 168   const size_t len = strlen (name);
 169   char **ep;
 170
 171   LOCK;
 172
 173   for (ep = __environ; *ep; ++ep)
 174     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
 175       {
 176         /* Found it.  Remove this pointer by moving later ones back.  */
 177         char **dp = ep;
 178         do
 179           dp[0] = dp[1];
 180         while (*dp++);
 181         /* Continue the loop in case NAME appears again.  */
 182       }
 183
 184   UNLOCK;
 185 }