mdw@git.distorted.org.uk Git - mLib/blob - env.h

   1 /* -*-c-*-
   2  *
   3  * $Id: env.h,v 1.1 1999/07/26 23:15:57 mdw Exp $
   4  *
   5  * Fiddling with environment variables
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the mLib utilities library.
  13  *
  14  * mLib is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * mLib is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with mLib; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: env.h,v $
  33  * Revision 1.1  1999/07/26 23:15:57  mdw
  34  * Fiddling with environment variables.
  35  *
  36  */
  37
  38 #ifndef ENV_H
  39 #define ENV_H
  40
  41 #ifdef __cplusplus
  42   extern "C" {
  43 #endif
  44
  45 /*----- Header files ------------------------------------------------------*/
  46
  47 #ifndef SYM_H
  48 #  include "sym.h"
  49 #endif
  50
  51 /*----- Functions provided ------------------------------------------------*/
  52
  53 /* --- @env_get@ --- *
  54  *
  55  * Arguments:   @sym_table *t@ = pointer to a symbol table
  56  *              @const char *name@ = pointer to variable name to look up
  57  *
  58  * Returns:     Pointer to corresponding value string, or null.
  59  *
  60  * Use:         Looks up an environment variable in the table and returns its
  61  *              value.  If the variable can't be found, a null pointer is
  62  *              returned.
  63  */
  64
  65 extern char *env_get(sym_table */*t*/, const char */*name*/);
  66
  67 /* --- @env_put@ --- *
  68  *
  69  * Arguments:   @sym_table *t@ = pointer to a symbol table
  70  *              @const char *name@ = pointer to variable name to set
  71  *              @const char *value@ = pointer to value string to assign
  72  *
  73  * Returns:     ---
  74  *
  75  * Use:         Assigns a value to a variable.  If the @name@ contains an
  76  *              equals character, then it's assumed to be of the form
  77  *              `VAR=VALUE' and @value@ argument is ignored.  Otherwise, if
  78  *              @value@ is null, the variable is deleted.  Finally, the
  79  *              normal case: @name@ is a plain name, and @value@ is a normal
  80  *              string causes the variable to be assigned the value in the
  81  *              way you'd expect.
  82  */
  83
  84 extern void env_put(sym_table */*t*/,
  85                     const char */*name*/, const char */*value*/);
  86
  87 /* --- @env_import@ --- *
  88  *
  89  * Arguments:   @sym_table *t@ = pointer to a symbol table
  90  *              @char **env@ = pointer to an environment list
  91  *
  92  * Returns:     ---
  93  *
  94  * Use:         Inserts all of the environment variables listed into a symbol
  95  *              table for rapid access.  Equivalent to a lot of calls to
  96  *              @env_put@.
  97  */
  98
  99 extern void env_import(sym_table */*t*/, char **/*env*/);
 100
 101 /* --- @env_export@ --- *
 102  *
 103  * Arguments:   @sym_table *t@ = pointer to a symbol table
 104  *
 105  * Returns:     A big environment list.
 106  *
 107  * Use:         Extracts an environment table from a symbol table
 108  *              representation of an environment.  The table and all of the
 109  *              strings are in one big block allocated from the heap.
 110  */
 111
 112 extern char **env_export(sym_table */*t*/);
 113
 114 /* --- @env_destroy@ --- *
 115  *
 116  * Arguments:   @sym_table *t@ = pointer to symbol table
 117  *
 118  * Returns:     ---
 119  *
 120  * Use:         Destroys all the variables in the symbol table.
 121  */
 122
 123 extern void env_destroy(sym_table */*t*/);
 124
 125 /*----- That's all, folks -------------------------------------------------*/
 126
 127 #ifdef __cplusplus
 128   }
 129 #endif
 130
 131 #endif