1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ 2/* 3 * The contents of this file are subject to the Mozilla Public 4 * License Version 1.1 (the "License"); you may not use this file 5 * except in compliance with the License. You may obtain a copy of 6 * the License at http://www.mozilla.org/MPL/ 7 * 8 * Software distributed under the License is distributed on an "AS 9 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or 10 * implied. See the License for the specific language governing 11 * rights and limitations under the License. 12 * 13 * The Original Code is the Netscape Portable Runtime (NSPR). 14 * 15 * The Initial Developer of the Original Code is Netscape 16 * Communications Corporation. Portions created by Netscape are 17 * Copyright (C) 1998-2000 Netscape Communications Corporation. All 18 * Rights Reserved. 19 * 20 * Contributor(s): 21 * 22 * Alternatively, the contents of this file may be used under the 23 * terms of the GNU General Public License Version 2 or later (the 24 * "GPL"), in which case the provisions of the GPL are applicable 25 * instead of those above. If you wish to allow use of your 26 * version of this file only under the terms of the GPL and not to 27 * allow others to use your version of this file under the MPL, 28 * indicate your decision by deleting the provisions above and 29 * replace them with the notice and other provisions requiored by 30 * the GPL. If you do not delete the provisions above, a recipient 31 * may use your version of this file under either the MPL or the 32 * GPL. 33 */ 34 35#ifndef prenv_h___ 36#define prenv_h___ 37 38#include <security_asn1/prtypes.h> 39 40/*******************************************************************************/ 41/*******************************************************************************/ 42/****************** THESE FUNCTIONS MAY NOT BE THREAD SAFE *********************/ 43/*******************************************************************************/ 44/*******************************************************************************/ 45 46PR_BEGIN_EXTERN_C 47 48/* 49** PR_GetEnv() -- Retrieve value of environment variable 50** 51** Description: 52** PR_GetEnv() is modeled on Unix getenv(). 53** 54** 55** Inputs: 56** var -- The name of the environment variable 57** 58** Returns: 59** The value of the environment variable 'var' or NULL if 60** the variable is undefined. 61** 62** Restrictions: 63** You'd think that a POSIX getenv(), putenv() would be 64** consistently implemented everywhere. Surprise! It is not. On 65** some platforms, a putenv() where the argument is of 66** the form "name" causes the named environment variable to 67** be un-set; that is: a subsequent getenv() returns NULL. On 68** other platforms, the putenv() fails, on others, it is a 69** no-op. Similarly, a putenv() where the argument is of the 70** form "name=" causes the named environment variable to be 71** un-set; a subsequent call to getenv() returns NULL. On 72** other platforms, a subsequent call to getenv() returns a 73** pointer to a null-string (a byte of zero). 74** 75** PR_GetEnv(), PR_SetEnv() provide a consistent behavior 76** across all supported platforms. There are, however, some 77** restrictions and some practices you must use to achieve 78** consistent results everywhere. 79** 80** When manipulating the environment there is no way to un-set 81** an environment variable across all platforms. We suggest 82** you interpret the return of a pointer to null-string to 83** mean the same as a return of NULL from PR_GetEnv(). 84** 85** A call to PR_SetEnv() where the parameter is of the form 86** "name" will return PR_FAILURE; the environment remains 87** unchanged. A call to PR_SetEnv() where the parameter is 88** of the form "name=" may un-set the envrionment variable on 89** some platforms; on others it may set the value of the 90** environment variable to the null-string. 91** 92** For example, to test for NULL return or return of the 93** null-string from PR_GetEnv(), use the following code 94** fragment: 95** 96** char *val = PR_GetEnv("foo"); 97** if ((NULL == val) || ('\0' == *val)) { 98** ... interpret this as un-set ... 99** } 100** 101** The caller must ensure that the string passed 102** to PR_SetEnv() is persistent. That is: The string should 103** not be on the stack, where it can be overwritten 104** on return from the function calling PR_SetEnv(). 105** Similarly, the string passed to PR_SetEnv() must not be 106** overwritten by other actions of the process. ... Some 107** platforms use the string by reference rather than copying 108** it into the environment space. ... You have been warned! 109** 110** Use of platform-native functions that manipulate the 111** environment (getenv(), putenv(), 112** SetEnvironmentVariable(), etc.) must not be used with 113** NSPR's similar functions. The platform-native functions 114** may not be thread safe and/or may operate on different 115** conceptual environment space than that operated upon by 116** NSPR's functions or other environment manipulating 117** functions on the same platform. (!) 118** 119*/ 120NSPR_API(char*) PR_GetEnv(const char *var); 121 122/* 123** PR_SetEnv() -- set, unset or change an environment variable 124** 125** Description: 126** PR_SetEnv() is modeled on the Unix putenv() function. 127** 128** Inputs: 129** string -- pointer to a caller supplied 130** constant, persistent string of the form name=value. Where 131** name is the name of the environment variable to be set or 132** changed; value is the value assigned to the variable. 133** 134** Returns: 135** PRStatus. 136** 137** Restrictions: 138** See the Restrictions documented in the description of 139** PR_GetEnv() in this header file. 140** 141** 142*/ 143NSPR_API(PRStatus) PR_SetEnv(const char *string); 144 145/* 146** DEPRECATED. Use PR_SetEnv() instead. 147*/ 148#ifdef XP_MAC 149NSPR_API(PRIntn) PR_PutEnv(const char *string); 150#endif 151 152PR_END_EXTERN_C 153 154#endif /* prenv_h___ */ 155