libguile/putenv.c

   1 /* Copyright (C) 1991, 2000, 2001, 2004, 2005, 2006 Free Software Foundation, Inc.
   2
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library 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 GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18
  19 #if HAVE_CONFIG_H
  20 #  include <config.h>
  21 #endif
  22
  23 #include "libguile/scmconfig.h"
  24
  25 #include <sys/types.h>
  26 #include <errno.h>
  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 #if HAVE_CRT_EXTERNS_H
  55 #include <crt_externs.h>  /* for Darwin _NSGetEnviron */
  56 #endif
  57
  58 #ifndef NULL
  59 #define NULL 0
  60 #endif
  61
  62 extern char **environ;
  63
  64 /* On Apple Darwin in a shared library there's no "environ" to access
  65    directly, instead the address of that variable must be obtained with
  66    _NSGetEnviron().  */
  67 #if HAVE__NSGETENVIRON && defined (PIC)
  68 #define environ (*_NSGetEnviron())
  69 #endif
  70
  71 /* Put STRING, which is of the form "NAME=VALUE", in the environment.  */
  72 int
  73 putenv (const char *string)
  74 {
  75   char *name_end = strchr (string, '=');
  76   register size_t size;
  77   register char **ep;
  78
  79   if (name_end == NULL)
  80     {
  81       /* Remove the variable from the environment.  */
  82       size = strlen (string);
  83       for (ep = environ; *ep != NULL; ++ep)
  84         if (!strncmp (*ep, string, size) && (*ep)[size] == '=')
  85           {
  86             while (ep[1] != NULL)
  87               {
  88                 ep[0] = ep[1];
  89                 ++ep;
  90               }
  91             *ep = NULL;
  92             return 0;
  93           }
  94     }
  95
  96   size = 0;
  97   for (ep = environ; *ep != NULL; ++ep)
  98     if (!strncmp (*ep, string, name_end - string) &&
  99         (*ep)[name_end - string] == '=')
 100       break;
 101     else
 102       ++size;
 103
 104   if (*ep == NULL)
 105     {
 106       static char **last_environ = NULL;
 107       char **new_environ = (char **) scm_malloc ((size + 2) * sizeof (char *));
 108       memcpy ((char *) new_environ, (char *) environ, size * sizeof (char *));
 109       new_environ[size] = (char *) string;
 110       new_environ[size + 1] = NULL;
 111       if (last_environ != NULL)
 112         free ((char *) last_environ);
 113       last_environ = new_environ;
 114       environ = new_environ;
 115     }
 116   else
 117     *ep = (char *) string;
 118
 119   return 0;
 120 }
 121
 122 /*
 123   Local Variables:
 124   c-file-style: "gnu"
 125   End:
 126 */