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 License
   5  * as published by the Free Software Foundation; either version 3 of
   6  * the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * 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
  16  * 02110-1301 USA
  17  */
  18
  19
  20 #ifdef HAVE_CONFIG_H
  21 #  include <config.h>
  22 #endif
  23
  24 #include "libguile/scmconfig.h"
  25
  26 #include <sys/types.h>
  27 #include <errno.h>
  28
  29 /* Don't include stdlib.h for non-GNU C libraries because some of them
  30    contain conflicting prototypes for getopt.
  31    This needs to come after some library #include
  32    to get __GNU_LIBRARY__ defined.  */
  33 #ifdef  __GNU_LIBRARY__
  34 #include <stdlib.h>
  35 #else
  36 char *malloc ();
  37 #endif  /* GNU C library.  */
  38
  39 #if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
  40 #include <string.h>
  41 #else
  42 #include <strings.h>
  43 #ifndef strchr
  44 #define strchr index
  45 #endif
  46 #ifndef memcpy
  47 #define memcpy(d, s, n) bcopy((s), (d), (n))
  48 #endif
  49 #endif
  50
  51 #ifdef HAVE_UNISTD_H
  52 #include <unistd.h>
  53 #endif
  54
  55 #if HAVE_CRT_EXTERNS_H
  56 #include <crt_externs.h>  /* for Darwin _NSGetEnviron */
  57 #endif
  58
  59 #ifndef NULL
  60 #define NULL 0
  61 #endif
  62
  63 extern char **environ;
  64
  65 /* On Apple Darwin in a shared library there's no "environ" to access
  66    directly, instead the address of that variable must be obtained with
  67    _NSGetEnviron().  */
  68 #if HAVE__NSGETENVIRON && defined (PIC)
  69 #define environ (*_NSGetEnviron())
  70 #endif
  71
  72 /* Put STRING, which is of the form "NAME=VALUE", in the environment.  */
  73 int
  74 putenv (const char *string)
  75 {
  76   char *name_end = strchr (string, '=');
  77   register size_t size;
  78   register char **ep;
  79
  80   if (name_end == NULL)
  81     {
  82       /* Remove the variable from the environment.  */
  83       size = strlen (string);
  84       for (ep = environ; *ep != NULL; ++ep)
  85         if (!strncmp (*ep, string, size) && (*ep)[size] == '=')
  86           {
  87             while (ep[1] != NULL)
  88               {
  89                 ep[0] = ep[1];
  90                 ++ep;
  91               }
  92             *ep = NULL;
  93             return 0;
  94           }
  95     }
  96
  97   size = 0;
  98   for (ep = environ; *ep != NULL; ++ep)
  99     if (!strncmp (*ep, string, name_end - string) &&
 100         (*ep)[name_end - string] == '=')
 101       break;
 102     else
 103       ++size;
 104
 105   if (*ep == NULL)
 106     {
 107       static char **last_environ = NULL;
 108       char **new_environ = (char **) scm_malloc ((size + 2) * sizeof (char *));
 109       memcpy ((char *) new_environ, (char *) environ, size * sizeof (char *));
 110       new_environ[size] = (char *) string;
 111       new_environ[size + 1] = NULL;
 112       if (last_environ != NULL)
 113         free ((char *) last_environ);
 114       last_environ = new_environ;
 115       environ = new_environ;
 116     }
 117   else
 118     *ep = (char *) string;
 119
 120   return 0;
 121 }
 122
 123 /*
 124   Local Variables:
 125   c-file-style: "gnu"
 126   End:
 127 */