lib/putenv.c

   1 /* Copyright (C) 1991, 1994, 1997, 1998 Free Software Foundation, Inc.
   2
   3    NOTE: The canonical source of this file is maintained with the GNU C
   4    Library.  Bugs can be reported to bug-glibc@prep.ai.mit.edu.
   5
   6    This program is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by the
   8    Free Software Foundation; either version 2, or (at your option) any
   9    later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21
  22 #if HAVE_CONFIG_H
  23 # include <config.h>
  24 #endif
  25
  26 #include <sys/types.h>
  27
  28 /* Don't include stdlib.h because some (e.g., Solaris 2.7) declare putenv
  29    with a non-const argument.  That would conflict with the declaration of
  30    rpl_putenv below (due to the #define putenv rpl_putenv from config.h).  */
  31
  32 char *malloc ();
  33 void free ();
  34
  35 #if defined (__GNU_LIBRARY__) || defined (HAVE_STRING_H)
  36 # include <string.h>
  37 #endif
  38 #if defined (__GNU_LIBRARY__) || defined (HAVE_UNISTD_H)
  39 # include <unistd.h>
  40 #endif
  41
  42 #if !defined (__GNU_LIBRARY__) && !defined (HAVE_STRCHR)
  43 # define strchr index
  44 #endif
  45 #if !defined (__GNU_LIBRARY__) && !defined (HAVE_MEMCPY)
  46 # define memcpy(d,s,n) bcopy ((s), (d), (n))
  47 #endif
  48
  49 #if HAVE_GNU_LD
  50 # define environ __environ
  51 #else
  52 extern char **environ;
  53 #endif
  54
  55 #ifndef NULL
  56 # define NULL 0
  57 #endif
  58
  59
  60 /* Put STRING, which is of the form "NAME=VALUE", in the environment.  */
  61 int
  62 rpl_putenv (const char *string)
  63 {
  64   const char *const name_end = strchr (string, '=');
  65   register size_t size;
  66   register char **ep;
  67
  68   if (name_end == NULL)
  69     {
  70       /* Remove the variable from the environment.  */
  71       size = strlen (string);
  72       for (ep = environ; *ep != NULL; ++ep)
  73         if (!strncmp (*ep, string, size) && (*ep)[size] == '=')
  74           {
  75             while (ep[1] != NULL)
  76               {
  77                 ep[0] = ep[1];
  78                 ++ep;
  79               }
  80             *ep = NULL;
  81             return 0;
  82           }
  83     }
  84
  85   size = 0;
  86   for (ep = environ; *ep != NULL; ++ep)
  87     if (!strncmp (*ep, string, name_end - string) &&
  88         (*ep)[name_end - string] == '=')
  89       break;
  90     else
  91       ++size;
  92
  93   if (*ep == NULL)
  94     {
  95       static char **last_environ = NULL;
  96       char **new_environ = (char **) malloc ((size + 2) * sizeof (char *));
  97       if (new_environ == NULL)
  98         return -1;
  99       (void) memcpy ((void *) new_environ, (void *) environ,
 100                      size * sizeof (char *));
 101       new_environ[size] = (char *) string;
 102       new_environ[size + 1] = NULL;
 103       if (last_environ != NULL)
 104         free ((void *) last_environ);
 105       last_environ = new_environ;
 106       environ = new_environ;
 107     }
 108   else
 109     *ep = (char *) string;
 110
 111   return 0;
 112 }