libguile/putenv.c

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