lib/sh/getenv.c

   1 /* getenv.c - get environment variable value from the shell's variable
   2               list. */
   3
   4 /* Copyright (C) 1997 Free Software Foundation, Inc.
   5
   6    This file is part of GNU Bash, the Bourne Again SHell.
   7
   8    Bash is free software; you can redistribute it and/or modify it under
   9    the terms of the GNU General Public License as published by the Free
  10    Software Foundation; either version 2, or (at your option) any later
  11    version.
  12
  13    Bash is distributed in the hope that it will be useful, but WITHOUT ANY
  14    WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16    for more details.
  17
  18    You should have received a copy of the GNU General Public License along
  19    with Bash; see the file COPYING.  If not, write to the Free Software
  20    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA */
  21
  22 #include <config.h>
  23
  24 #if defined (CAN_REDEFINE_GETENV)
  25
  26 #if defined (HAVE_UNISTD_H)
  27 #  include <unistd.h>
  28 #endif
  29
  30 #include <bashansi.h>
  31 #include <shell.h>
  32
  33 extern char **environ;
  34
  35 /* We supply our own version of getenv () because we want library
  36    routines to get the changed values of exported variables. */
  37
  38 /* The NeXT C library has getenv () defined and used in the same file.
  39    This screws our scheme.  However, Bash will run on the NeXT using
  40    the C library getenv (), since right now the only environment variable
  41    that we care about is HOME, and that is already defined.  */
  42 static char *last_tempenv_value = (char *)NULL;
  43
  44 char *
  45 getenv (name)
  46 #if defined (__linux__) || defined (__bsdi__) || defined (convex)
  47      const char *name;
  48 #else
  49      char const *name;
  50 #endif /* !__linux__ && !__bsdi__ && !convex */
  51 {
  52   SHELL_VAR *var;
  53
  54   var = find_tempenv_variable ((char *)name);
  55   if (var)
  56     {
  57       FREE (last_tempenv_value);
  58
  59       last_tempenv_value = value_cell (var) ? savestring (value_cell (var)) : (char *)NULL;
  60       dispose_variable (var);
  61       return (last_tempenv_value);
  62     }
  63   else if (shell_variables)
  64     {
  65       var = find_variable ((char *)name);
  66       if (var && exported_p (var))
  67         return (value_cell (var));
  68     }
  69   else
  70     {
  71       register int i, len;
  72
  73       /* In some cases, s5r3 invokes getenv() before main(); BSD systems
  74          using gprof also exhibit this behavior.  This means that
  75          shell_variables will be 0 when this is invoked.  We look up the
  76          variable in the real environment in that case. */
  77
  78       for (i = 0, len = strlen (name); environ[i]; i++)
  79         {
  80           if ((STREQN (environ[i], name, len)) && (environ[i][len] == '='))
  81             return (environ[i] + len + 1);
  82         }
  83     }
  84
  85   return ((char *)NULL);
  86 }
  87
  88 /* Some versions of Unix use _getenv instead. */
  89 char *
  90 _getenv (name)
  91 #if defined (__linux__) || defined (__bsdi__) || defined (convex)
  92      const char *name;
  93 #else
  94      char const *name;
  95 #endif /* !__linux__ && !__bsdi__ && !convex */
  96 {
  97   return (getenv (name));
  98 }
  99 #endif /* CAN_REDEFINE_GETENV */