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 /* 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 #include <sys/types.h>
  32
  33 #if defined (__GNU_LIBRARY__) || defined (HAVE_STDLIB_H)
  34 # include <stdlib.h>
  35 #endif
  36 #if defined (__GNU_LIBRARY__) || defined (HAVE_STRING_H)
  37 # include <string.h>
  38 #endif
  39 #if defined (__GNU_LIBRARY__) || defined (HAVE_UNISTD_H)
  40 # include <unistd.h>
  41 #endif
  42
  43 #if !defined (__GNU_LIBRARY__) && !defined (HAVE_STRCHR)
  44 # define strchr index
  45 #endif
  46 #if !defined (__GNU_LIBRARY__) && !defined (HAVE_MEMCPY)
  47 # define memcpy(d,s,n) bcopy ((s), (d), (n))
  48 #endif
  49
  50 #if HAVE_GNU_LD
  51 # define environ __environ
  52 #else
  53 extern char **environ;
  54 #endif
  55
  56 #ifndef NULL
  57 # define NULL 0
  58 #endif
  59
  60
  61 /* Put STRING, which is of the form "NAME=VALUE", in the environment.  */
  62 int
  63 rpl_putenv (string)
  64      const char *string;
  65 {
  66   const char *const name_end = strchr (string, '=');
  67   register size_t size;
  68   register char **ep;
  69
  70   if (name_end == NULL)
  71     {
  72       /* Remove the variable from the environment.  */
  73       size = strlen (string);
  74       for (ep = environ; *ep != NULL; ++ep)
  75         if (!strncmp (*ep, string, size) && (*ep)[size] == '=')
  76           {
  77             while (ep[1] != NULL)
  78               {
  79                 ep[0] = ep[1];
  80                 ++ep;
  81               }
  82             *ep = NULL;
  83             return 0;
  84           }
  85     }
  86
  87   size = 0;
  88   for (ep = environ; *ep != NULL; ++ep)
  89     if (!strncmp (*ep, string, name_end - string) &&
  90         (*ep)[name_end - string] == '=')
  91       break;
  92     else
  93       ++size;
  94
  95   if (*ep == NULL)
  96     {
  97       static char **last_environ = NULL;
  98       char **new_environ = (char **) malloc ((size + 2) * sizeof (char *));
  99       if (new_environ == NULL)
 100         return -1;
 101       (void) memcpy ((void *) new_environ, (void *) environ,
 102                      size * sizeof (char *));
 103       new_environ[size] = (char *) string;
 104       new_environ[size + 1] = NULL;
 105       if (last_environ != NULL)
 106         free ((void *) last_environ);
 107       last_environ = new_environ;
 108       environ = new_environ;
 109     }
 110   else
 111     *ep = (char *) string;
 112
 113   return 0;
 114 }