libiberty/setenv.c

   1 /* Copyright (C) 1992, 1995, 1996, 1997 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 #include "ansidecl.h"
  40 #include <sys/types.h> /* For `size_t' */
  41 #include <stdio.h>     /* For `NULL' */
  42
  43 #include <errno.h>
  44 #if !defined(errno) && !defined(HAVE_ERRNO_DECL)
  45 extern int errno;
  46 #endif
  47 #define __set_errno(ev) ((errno) = (ev))
  48
  49 #if HAVE_STDLIB_H
  50 # include <stdlib.h>
  51 #endif
  52 #if HAVE_STRING_H
  53 # include <string.h>
  54 #endif
  55 #if HAVE_UNISTD_H
  56 # include <unistd.h>
  57 #endif
  58
  59 #define __environ       environ
  60 #ifndef HAVE_ENVIRON_DECL
  61 extern char **environ;
  62 #endif
  63
  64 /* LOCK and UNLOCK are defined as no-ops.  This makes the libiberty
  65  * implementation MT-Unsafe. */
  66 #define LOCK
  67 #define UNLOCK
  68
  69 /* Below this point, it's verbatim code from the glibc-2.0 implementation */
  70
  71 /* If this variable is not a null pointer we allocated the current
  72    environment.  */
  73 static char **last_environ;
  74
  75
  76 int
  77 setenv (name, value, replace)
  78      const char *name;
  79      const char *value;
  80      int replace;
  81 {
  82   register char **ep = 0;
  83   register size_t size;
  84   const size_t namelen = strlen (name);
  85   const size_t vallen = strlen (value) + 1;
  86
  87   LOCK;
  88
  89   size = 0;
  90   if (__environ != NULL)
  91     {
  92       for (ep = __environ; *ep != NULL; ++ep)
  93         if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
  94           break;
  95         else
  96           ++size;
  97     }
  98
  99   if (__environ == NULL || *ep == NULL)
 100     {
 101       char **new_environ;
 102       if (__environ == last_environ && __environ != NULL)
 103         /* We allocated this space; we can extend it.  */
 104         new_environ = (char **) realloc (last_environ,
 105                                          (size + 2) * sizeof (char *));
 106       else
 107         new_environ = (char **) malloc ((size + 2) * sizeof (char *));
 108
 109       if (new_environ == NULL)
 110         {
 111           UNLOCK;
 112           return -1;
 113         }
 114
 115       new_environ[size] = malloc (namelen + 1 + vallen);
 116       if (new_environ[size] == NULL)
 117         {
 118           free ((char *) new_environ);
 119           __set_errno (ENOMEM);
 120           UNLOCK;
 121           return -1;
 122         }
 123
 124       if (__environ != last_environ)
 125         memcpy ((char *) new_environ, (char *) __environ,
 126                 size * sizeof (char *));
 127
 128       memcpy (new_environ[size], name, namelen);
 129       new_environ[size][namelen] = '=';
 130       memcpy (&new_environ[size][namelen + 1], value, vallen);
 131
 132       new_environ[size + 1] = NULL;
 133
 134       last_environ = __environ = new_environ;
 135     }
 136   else if (replace)
 137     {
 138       size_t len = strlen (*ep);
 139       if (len + 1 < namelen + 1 + vallen)
 140         {
 141           /* The existing string is too short; malloc a new one.  */
 142           char *new = malloc (namelen + 1 + vallen);
 143           if (new == NULL)
 144             {
 145               UNLOCK;
 146               return -1;
 147             }
 148           *ep = new;
 149         }
 150       memcpy (*ep, name, namelen);
 151       (*ep)[namelen] = '=';
 152       memcpy (&(*ep)[namelen + 1], value, vallen);
 153     }
 154
 155   UNLOCK;
 156
 157   return 0;
 158 }
 159
 160 void
 161 unsetenv (name)
 162      const char *name;
 163 {
 164   const size_t len = strlen (name);
 165   char **ep;
 166
 167   LOCK;
 168
 169   for (ep = __environ; *ep; ++ep)
 170     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
 171       {
 172         /* Found it.  Remove this pointer by moving later ones back.  */
 173         char **dp = ep;
 174         do
 175           dp[0] = dp[1];
 176         while (*dp++);
 177         /* Continue the loop in case NAME appears again.  */
 178       }
 179
 180   UNLOCK;
 181 }