stdlib/putenv.c

   1 /* Copyright (C) 1991, 94, 95, 96, 97, 98, 99 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #if defined _AIX && !defined __GNUC__
  20  #pragma alloca
  21 #endif
  22
  23 #if HAVE_CONFIG_H
  24 # include <config.h>
  25 #endif
  26
  27 #if _LIBC || HAVE_STDLIB_H
  28 # include <stdlib.h>
  29 #endif
  30 #if _LIBC || HAVE_STRING_H
  31 # include <string.h>
  32 #endif
  33
  34 #if !__GNU_LIBRARY__ && !HAVE_STRCHR
  35 # define strchr index
  36 #endif
  37
  38 #ifndef _LIBC
  39 # ifdef HAVE_ALLOCA_H
  40 #  include <alloca.h>
  41 # else
  42 #  ifdef __GNUC__
  43 #   define alloca __builtin_alloca
  44 #  else
  45 extern char *alloca ();
  46 #  endif /* __GNUC__ */
  47 # endif /* HAVE_ALLOCA_H */
  48 #endif /* _LIBC */
  49
  50
  51 /* Put STRING, which is of the form "NAME=VALUE", in the environment.  */
  52 int
  53 putenv (string)
  54      char *string;
  55 {
  56   const char *const name_end = strchr (string, '=');
  57
  58   if (name_end != NULL)
  59     {
  60 #ifdef _LIBC
  61       char *name = strndupa (string, name_end - string);
  62 #else
  63       char *name = alloca (name_end - string + 1);
  64       memcpy (name, string, name_end - string);
  65       name[name_end - string] = '\0';
  66 #endif
  67       return __add_to_environ (name, NULL, string, 1);
  68     }
  69
  70   __unsetenv (string);
  71   return 0;
  72 }