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| 1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ |
| 2 /* ***** BEGIN LICENSE BLOCK ***** |
| 3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1 |
| 4 * |
| 5 * The contents of this file are subject to the Mozilla Public License Version |
| 6 * 1.1 (the "License"); you may not use this file except in compliance with |
| 7 * the License. You may obtain a copy of the License at |
| 8 * http://www.mozilla.org/MPL/ |
| 9 * |
| 10 * Software distributed under the License is distributed on an "AS IS" basis, |
| 11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License |
| 12 * for the specific language governing rights and limitations under the |
| 13 * License. |
| 14 * |
| 15 * The Original Code is the Netscape Portable Runtime (NSPR). |
| 16 * |
| 17 * The Initial Developer of the Original Code is |
| 18 * Netscape Communications Corporation. |
| 19 * Portions created by the Initial Developer are Copyright (C) 1998-2000 |
| 20 * the Initial Developer. All Rights Reserved. |
| 21 * |
| 22 * Contributor(s): |
| 23 * |
| 24 * Alternatively, the contents of this file may be used under the terms of |
| 25 * either the GNU General Public License Version 2 or later (the "GPL"), or |
| 26 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), |
| 27 * in which case the provisions of the GPL or the LGPL are applicable instead |
| 28 * of those above. If you wish to allow use of your version of this file only |
| 29 * under the terms of either the GPL or the LGPL, and not to allow others to |
| 30 * use your version of this file under the terms of the MPL, indicate your |
| 31 * decision by deleting the provisions above and replace them with the notice |
| 32 * and other provisions required by the GPL or the LGPL. If you do not delete |
| 33 * the provisions above, a recipient may use your version of this file under |
| 34 * the terms of any one of the MPL, the GPL or the LGPL. |
| 35 * |
| 36 * ***** END LICENSE BLOCK ***** */ |
| 37 |
| 38 #ifndef prenv_h___ |
| 39 #define prenv_h___ |
| 40 |
| 41 #include "prtypes.h" |
| 42 |
| 43 /*******************************************************************************
/ |
| 44 /*******************************************************************************
/ |
| 45 /****************** THESE FUNCTIONS MAY NOT BE THREAD SAFE *********************
/ |
| 46 /*******************************************************************************
/ |
| 47 /*******************************************************************************
/ |
| 48 |
| 49 PR_BEGIN_EXTERN_C |
| 50 |
| 51 /* |
| 52 ** PR_GetEnv() -- Retrieve value of environment variable |
| 53 ** |
| 54 ** Description: |
| 55 ** PR_GetEnv() is modeled on Unix getenv(). |
| 56 ** |
| 57 ** |
| 58 ** Inputs: |
| 59 ** var -- The name of the environment variable |
| 60 ** |
| 61 ** Returns: |
| 62 ** The value of the environment variable 'var' or NULL if |
| 63 ** the variable is undefined. |
| 64 ** |
| 65 ** Restrictions: |
| 66 ** You'd think that a POSIX getenv(), putenv() would be |
| 67 ** consistently implemented everywhere. Surprise! It is not. On |
| 68 ** some platforms, a putenv() where the argument is of |
| 69 ** the form "name" causes the named environment variable to |
| 70 ** be un-set; that is: a subsequent getenv() returns NULL. On |
| 71 ** other platforms, the putenv() fails, on others, it is a |
| 72 ** no-op. Similarly, a putenv() where the argument is of the |
| 73 ** form "name=" causes the named environment variable to be |
| 74 ** un-set; a subsequent call to getenv() returns NULL. On |
| 75 ** other platforms, a subsequent call to getenv() returns a |
| 76 ** pointer to a null-string (a byte of zero). |
| 77 ** |
| 78 ** PR_GetEnv(), PR_SetEnv() provide a consistent behavior |
| 79 ** across all supported platforms. There are, however, some |
| 80 ** restrictions and some practices you must use to achieve |
| 81 ** consistent results everywhere. |
| 82 ** |
| 83 ** When manipulating the environment there is no way to un-set |
| 84 ** an environment variable across all platforms. We suggest |
| 85 ** you interpret the return of a pointer to null-string to |
| 86 ** mean the same as a return of NULL from PR_GetEnv(). |
| 87 ** |
| 88 ** A call to PR_SetEnv() where the parameter is of the form |
| 89 ** "name" will return PR_FAILURE; the environment remains |
| 90 ** unchanged. A call to PR_SetEnv() where the parameter is |
| 91 ** of the form "name=" may un-set the envrionment variable on |
| 92 ** some platforms; on others it may set the value of the |
| 93 ** environment variable to the null-string. |
| 94 ** |
| 95 ** For example, to test for NULL return or return of the |
| 96 ** null-string from PR_GetEnv(), use the following code |
| 97 ** fragment: |
| 98 ** |
| 99 ** char *val = PR_GetEnv("foo"); |
| 100 ** if ((NULL == val) || ('\0' == *val)) { |
| 101 ** ... interpret this as un-set ... |
| 102 ** } |
| 103 ** |
| 104 ** The caller must ensure that the string passed |
| 105 ** to PR_SetEnv() is persistent. That is: The string should |
| 106 ** not be on the stack, where it can be overwritten |
| 107 ** on return from the function calling PR_SetEnv(). |
| 108 ** Similarly, the string passed to PR_SetEnv() must not be |
| 109 ** overwritten by other actions of the process. ... Some |
| 110 ** platforms use the string by reference rather than copying |
| 111 ** it into the environment space. ... You have been warned! |
| 112 ** |
| 113 ** Use of platform-native functions that manipulate the |
| 114 ** environment (getenv(), putenv(), |
| 115 ** SetEnvironmentVariable(), etc.) must not be used with |
| 116 ** NSPR's similar functions. The platform-native functions |
| 117 ** may not be thread safe and/or may operate on different |
| 118 ** conceptual environment space than that operated upon by |
| 119 ** NSPR's functions or other environment manipulating |
| 120 ** functions on the same platform. (!) |
| 121 ** |
| 122 */ |
| 123 NSPR_API(char*) PR_GetEnv(const char *var); |
| 124 |
| 125 /* |
| 126 ** PR_SetEnv() -- set, unset or change an environment variable |
| 127 ** |
| 128 ** Description: |
| 129 ** PR_SetEnv() is modeled on the Unix putenv() function. |
| 130 ** |
| 131 ** Inputs: |
| 132 ** string -- pointer to a caller supplied |
| 133 ** constant, persistent string of the form name=value. Where |
| 134 ** name is the name of the environment variable to be set or |
| 135 ** changed; value is the value assigned to the variable. |
| 136 ** |
| 137 ** Returns: |
| 138 ** PRStatus. |
| 139 ** |
| 140 ** Restrictions: |
| 141 ** See the Restrictions documented in the description of |
| 142 ** PR_GetEnv() in this header file. |
| 143 ** |
| 144 ** |
| 145 */ |
| 146 NSPR_API(PRStatus) PR_SetEnv(const char *string); |
| 147 |
| 148 /* |
| 149 ** DEPRECATED. Use PR_SetEnv() instead. |
| 150 */ |
| 151 #ifdef XP_MAC |
| 152 NSPR_API(PRIntn) PR_PutEnv(const char *string); |
| 153 #endif |
| 154 |
| 155 PR_END_EXTERN_C |
| 156 |
| 157 #endif /* prenv_h___ */ |
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