lib/putenv.c

   1 /* Copyright (C) 1991, 1994, 1997 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 /* Disable the definition of putenv to rpl_putenv (from config.h) in this
  27    file.  Otherwise, we'd get conflicting prototypes for rpl_putenv on
  28    systems like Irix 5.3.  */
  29 #undef putenv
  30
  31 #if defined (__GNU_LIBRARY__) || defined (HAVE_STDLIB_H)
  32 # include <stdlib.h>
  33 #endif
  34 #if defined (__GNU_LIBRARY__) || defined (HAVE_STRING_H)
  35 # include <string.h>
  36 #endif
  37 #if defined (__GNU_LIBRARY__) || defined (HAVE_UNISTD_H)
  38 # include <unistd.h>
  39 #endif
  40
  41 #if !defined (__GNU_LIBRARY__) && !defined (HAVE_STRCHR)
  42 # define strchr index
  43 #endif
  44 #if !defined (__GNU_LIBRARY__) && !defined (HAVE_MEMCPY)
  45 # define memcpy(d,s,n) bcopy ((s), (d), (n))
  46 #endif
  47
  48 #if HAVE_GNU_LD
  49 # define environ __environ
  50 #else
  51 extern char **environ;
  52 #endif
  53
  54
  55 /* Put STRING, which is of the form "NAME=VALUE", in the environment.  */
  56 int
  57 rpl_putenv (string)
  58      const char *string;
  59 {
  60   const char *const name_end = strchr (string, '=');
  61   register size_t size;
  62   register char **ep;
  63
  64   if (name_end == NULL)
  65     {
  66       /* Remove the variable from the environment.  */
  67       size = strlen (string);
  68       for (ep = environ; *ep != NULL; ++ep)
  69         if (!strncmp (*ep, string, size) && (*ep)[size] == '=')
  70           {
  71             while (ep[1] != NULL)
  72               {
  73                 ep[0] = ep[1];
  74                 ++ep;
  75               }
  76             *ep = NULL;
  77             return 0;
  78           }
  79     }
  80
  81   size = 0;
  82   for (ep = environ; *ep != NULL; ++ep)
  83     if (!strncmp (*ep, string, name_end - string) &&
  84         (*ep)[name_end - string] == '=')
  85       break;
  86     else
  87       ++size;
  88
  89   if (*ep == NULL)
  90     {
  91       static char **last_environ = NULL;
  92       char **new_environ = (char **) malloc ((size + 2) * sizeof (char *));
  93       if (new_environ == NULL)
  94         return -1;
  95       (void) memcpy ((void *) new_environ, (void *) environ,
  96                      size * sizeof (char *));
  97       new_environ[size] = (char *) string;
  98       new_environ[size + 1] = NULL;
  99       if (last_environ != NULL)
 100         free ((void *) last_environ);
 101       last_environ = new_environ;
 102       environ = new_environ;
 103     }
 104   else
 105     *ep = (char *) string;
 106
 107   return 0;
 108 }