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

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