/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is the Netscape Portable Runtime (NSPR).
*
* The Initial Developer of the Original Code is Netscape
* Communications Corporation. Portions created by Netscape are
* Copyright (C) 1998-2000 Netscape Communications Corporation. All
* Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the
* terms of the GNU General Public License Version 2 or later (the
* "GPL"), in which case the provisions of the GPL are applicable
* instead of those above. If you wish to allow use of your
* version of this file only under the terms of the GPL and not to
* allow others to use your version of this file under the MPL,
* indicate your decision by deleting the provisions above and
* replace them with the notice and other provisions requiored by
* the GPL. If you do not delete the provisions above, a recipient
* may use your version of this file under either the MPL or the
* GPL.
*/
#ifndef prenv_h___
#define prenv_h___
#include "prtypes.h"
/*******************************************************************************/
/*******************************************************************************/
/****************** THESE FUNCTIONS MAY NOT BE THREAD SAFE *********************/
/*******************************************************************************/
/*******************************************************************************/
PR_BEGIN_EXTERN_C
/*
** PR_GetEnv() -- Retrieve value of environment variable
**
** Description:
** PR_GetEnv() is modeled on Unix getenv().
**
**
** Inputs:
** var -- The name of the environment variable
**
** Returns:
** The value of the environment variable 'var' or NULL if
** the variable is undefined.
**
** Restrictions:
** You'd think that a POSIX getenv(), putenv() would be
** consistently implemented everywhere. Surprise! It is not. On
** some platforms, a putenv() where the argument is of
** the form "name" causes the named environment variable to
** be un-set; that is: a subsequent getenv() returns NULL. On
** other platforms, the putenv() fails, on others, it is a
** no-op. Similarly, a putenv() where the argument is of the
** form "name=" causes the named environment variable to be
** un-set; a subsequent call to getenv() returns NULL. On
** other platforms, a subsequent call to getenv() returns a
** pointer to a null-string (a byte of zero).
**
** PR_GetEnv(), PR_SetEnv() provide a consistent behavior
** across all supported platforms. There are, however, some
** restrictions and some practices you must use to achieve
** consistent results everywhere.
**
** When manipulating the environment there is no way to un-set
** an environment variable across all platforms. We suggest
** you interpret the return of a pointer to null-string to
** mean the same as a return of NULL from PR_GetEnv().
**
** A call to PR_SetEnv() where the parameter is of the form
** "name" will return PR_FAILURE; the environment remains
** unchanged. A call to PR_SetEnv() where the parameter is
** of the form "name=" may un-set the envrionment variable on
** some platforms; on others it may set the value of the
** environment variable to the null-string.
**
** For example, to test for NULL return or return of the
** null-string from PR_GetEnv(), use the following code
** fragment:
**
** char *val = PR_GetEnv("foo");
** if ((NULL == val) || ('\0' == *val)) {
** ... interpret this as un-set ...
** }
**
** The caller must ensure that the string passed
** to PR_SetEnv() is persistent. That is: The string should
** not be on the stack, where it can be overwritten
** on return from the function calling PR_SetEnv().
** Similarly, the string passed to PR_SetEnv() must not be
** overwritten by other actions of the process. ... Some
** platforms use the string by reference rather than copying
** it into the environment space. ... You have been warned!
**
** Use of platform-native functions that manipulate the
** environment (getenv(), putenv(),
** SetEnvironmentVariable(), etc.) must not be used with
** NSPR's similar functions. The platform-native functions
** may not be thread safe and/or may operate on different
** conceptual environment space than that operated upon by
** NSPR's functions or other environment manipulating
** functions on the same platform. (!)
**
*/
NSPR_API(char*) PR_GetEnv(const char *var);
/*
** PR_SetEnv() -- set, unset or change an environment variable
**
** Description:
** PR_SetEnv() is modeled on the Unix putenv() function.
**
** Inputs:
** string -- pointer to a caller supplied
** constant, persistent string of the form name=value. Where
** name is the name of the environment variable to be set or
** changed; value is the value assigned to the variable.
**
** Returns:
** PRStatus.
**
** Restrictions:
** See the Restrictions documented in the description of
** PR_GetEnv() in this header file.
**
**
*/
NSPR_API(PRStatus) PR_SetEnv(const char *string);
/*
** DEPRECATED. Use PR_SetEnv() instead.
*/
#ifdef XP_MAC
NSPR_API(PRIntn) PR_PutEnv(const char *string);
#endif
PR_END_EXTERN_C
#endif /* prenv_h___ */