lib/putenv.c

   1 /* Copyright (C) 1991 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #ifdef HAVE_CONFIG_H
  20 #if defined (CONFIG_BROKETS)
  21 /* We use <config.h> instead of "config.h" so that a compilation
  22    using -I. -I$srcdir will use ./config.h rather than $srcdir/config.h
  23    (which it would do because it found this file in $srcdir).  */
  24 #include <config.h>
  25 #else
  26 #include "config.h"
  27 #endif
  28 #endif
  29
  30 #include <sys/types.h>
  31 #include <errno.h>
  32
  33 /* This needs to come after some library #include
  34    to get __GNU_LIBRARY__ defined.  */
  35 #ifdef  __GNU_LIBRARY__
  36 /* Don't include stdlib.h for non-GNU C libraries because some of them
  37    contain conflicting prototypes for getopt.  */
  38 #include <stdlib.h>
  39 #endif  /* GNU C library.  */
  40
  41 #ifndef STDC_HEADERS
  42 extern int errno;
  43 #endif
  44
  45 #if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
  46 #include <string.h>
  47 #ifndef index
  48 #define index strchr
  49 #endif
  50 #ifndef bcopy
  51 #define bcopy(s, d, n) memcpy((d), (s), (n))
  52 #endif
  53 #else
  54 #include <strings.h>
  55 #endif
  56
  57 #ifdef HAVE_UNISTD_H
  58 #include <unistd.h>
  59 #endif
  60
  61 #ifndef NULL
  62 #define NULL 0
  63 #endif
  64
  65 extern char **environ;
  66
  67 /* Put STRING, which is of the form "NAME=VALUE", in the environment.  */
  68 int
  69 putenv (string)
  70      const char *string;
  71 {
  72   char *name_end = index (string, '=');
  73   register size_t size;
  74   register char **ep;
  75
  76   if (name_end == NULL)
  77     {
  78       /* Remove the variable from the environment.  */
  79       size = strlen (string);
  80       for (ep = environ; *ep != NULL; ++ep)
  81         if (!strncmp (*ep, string, size) && (*ep)[size] == '=')
  82           {
  83             while (ep[1] != NULL)
  84               {
  85                 ep[0] = ep[1];
  86                 ++ep;
  87               }
  88             *ep = NULL;
  89             return 0;
  90           }
  91     }
  92
  93   size = 0;
  94   for (ep = environ; *ep != NULL; ++ep)
  95     if (!strncmp (*ep, string, name_end - string) &&
  96         (*ep)[name_end - string] == '=')
  97       break;
  98     else
  99       ++size;
 100
 101   if (*ep == NULL)
 102     {
 103       static char **last_environ = NULL;
 104       char **new_environ = (char **) malloc ((size + 2) * sizeof (char *));
 105       if (new_environ == NULL)
 106         return -1;
 107       (void) bcopy ((char *) environ, (char *) new_environ, size * sizeof (char *));
 108       new_environ[size] = (char *) string;
 109       new_environ[size + 1] = NULL;
 110       if (last_environ != NULL)
 111         free ((char *) last_environ);
 112       last_environ = new_environ;
 113       environ = new_environ;
 114     }
 115   else
 116     *ep = (char *) string;
 117
 118   return 0;
 119 }