newlib/libc/sys/rdos/getenv.c

   1 /*#######################################################################
   2 # RDOS operating system
   3 # Copyright (C) 1988-2006, Leif Ekblad
   4 #
   5 # This library is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU Lesser General Public License as published
   7 # by the Free Software Foundation; either version 2.1 of the License, or
   8 # (at your option) any later version.
   9 #
  10 # This library is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13 # GNU Lesser General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU Lesser General Public
  16 # License along with this library; if not, write to the Free Software
  17 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  18 #
  19 # The author of this program may be contacted at leif@rdos.net
  20 #
  21 # getenv.c
  22 # getenv function implementation
  23 #
  24 ##########################################################################*/
  25
  26 /*
  27 FUNCTION
  28 <<getenv>>---look up environment variable
  29
  30 INDEX
  31         getenv
  32 INDEX
  33         environ
  34
  35 SYNOPSIS
  36         #include <stdlib.h>
  37         char *getenv(const char *<[name]>);
  38
  39 DESCRIPTION
  40 <<getenv>> searches the list of environment variable names and values
  41 (using the global pointer ``<<char **environ>>'') for a variable whose
  42 name matches the string at <[name]>.  If a variable name matches,
  43 <<getenv>> returns a pointer to the associated value.
  44
  45 RETURNS
  46 A pointer to the (string) value of the environment variable, or
  47 <<NULL>> if there is no such environment variable.
  48
  49 PORTABILITY
  50 <<getenv>> is ANSI, but the rules for properly forming names of environment
  51 variables vary from one system to another.
  52
  53 This function is not thread-safe, but does it need to be??
  54 There is an reentrant class that should be used if reentrance is required
  55
  56 */
  57
  58 #include <stdlib.h>
  59 #include <stddef.h>
  60 #include <string.h>
  61 #include <rdos.h>
  62
  63 static char envbuf[256];
  64
  65 char *getenv(const char *name)
  66 {
  67     int handle;
  68     char *ptr = 0;
  69
  70     handle = RdosOpenSysEnv();
  71     if (handle)
  72     {
  73         if (RdosFindEnvVar(handle, name, envbuf))
  74             ptr = envbuf;
  75     }
  76     RdosCloseEnv(handle);
  77     return ptr;
  78 }