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 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
  19    gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
  20
  21 #ifdef HAVE_CONFIG_H
  22 #include "libguile/scmconfig.h"
  23 #endif
  24
  25 #include <sys/types.h>
  26 #include <errno.h>
  27 #ifndef errno
  28 extern int errno;
  29 #endif
  30
  31 /* Don't include stdlib.h for non-GNU C libraries because some of them
  32    contain conflicting prototypes for getopt.
  33    This needs to come after some library #include
  34    to get __GNU_LIBRARY__ defined.  */
  35 #ifdef  __GNU_LIBRARY__
  36 #include <stdlib.h>
  37 #else
  38 char *malloc ();
  39 #endif  /* GNU C library.  */
  40
  41 #if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
  42 #include <string.h>
  43 #else
  44 #include <strings.h>
  45 #ifndef strchr
  46 #define strchr index
  47 #endif
  48 #ifndef memcpy
  49 #define memcpy(d, s, n) bcopy((s), (d), (n))
  50 #endif
  51 #endif
  52
  53 #ifdef HAVE_UNISTD_H
  54 #include <unistd.h>
  55 #endif
  56
  57 #ifndef NULL
  58 #define NULL 0
  59 #endif
  60
  61 extern char **environ;
  62
  63 /* Put STRING, which is of the form "NAME=VALUE", in the environment.  */
  64 int
  65 putenv (const char *string)
  66 {
  67   char *name_end = strchr (string, '=');
  68   register size_t size;
  69   register char **ep;
  70
  71   if (name_end == NULL)
  72     {
  73       /* Remove the variable from the environment.  */
  74       size = strlen (string);
  75       for (ep = environ; *ep != NULL; ++ep)
  76         if (!strncmp (*ep, string, size) && (*ep)[size] == '=')
  77           {
  78             while (ep[1] != NULL)
  79               {
  80                 ep[0] = ep[1];
  81                 ++ep;
  82               }
  83             *ep = NULL;
  84             return 0;
  85           }
  86     }
  87
  88   size = 0;
  89   for (ep = environ; *ep != NULL; ++ep)
  90     if (!strncmp (*ep, string, name_end - string) &&
  91         (*ep)[name_end - string] == '=')
  92       break;
  93     else
  94       ++size;
  95
  96   if (*ep == NULL)
  97     {
  98       static char **last_environ = NULL;
  99       char **new_environ = (char **) malloc ((size + 2) * sizeof (char *));
 100       if (new_environ == NULL)
 101         return -1;
 102       memcpy ((char *) new_environ, (char *) environ, size * sizeof (char *));
 103       new_environ[size] = (char *) string;
 104       new_environ[size + 1] = NULL;
 105       if (last_environ != NULL)
 106         free ((char *) last_environ);
 107       last_environ = new_environ;
 108       environ = new_environ;
 109     }
 110   else
 111     *ep = (char *) string;
 112
 113   return 0;
 114 }