/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#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(constchar *var);
/* ** PR_GetEnvSecure() -- get a security-sensitive environment variable ** ** Description: ** ** PR_GetEnvSecure() is similar to PR_GetEnv(), but it returns NULL if ** the program was run with elevated privilege (e.g., setuid or setgid ** on Unix). This can be used for cases like log file paths which ** could otherwise be used for privilege escalation. Note that some ** platforms may have platform-specific privilege elevation mechanisms ** not recognized by this function; see the implementation for details.
*/
NSPR_API(char*) PR_GetEnvSecure(constchar *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(constchar *string);
/* ** PR_DuplicateEnvironment() -- Obtain a copy of the environment. ** ** Description: ** PR_DuplicateEnvironment() copies the environment so that it can be ** modified without changing the current process's environment, and ** then passed to interfaces such as POSIX execve(). In particular, ** this avoids needing to allocate memory or take locks in the child ** after a fork(); neither of these is allowed by POSIX after a ** multithreaded process calls fork(), and PR_SetEnv does both. ** ** Inputs: ** none ** ** Returns: ** A pointer to a null-terminated array of null-terminated strings, ** like the traditional global variable "environ". The array and ** the strings are allocated with PR_Malloc(), and it is the ** caller's responsibility to free them. ** ** In case of memory allocation failure, or if the operating system ** doesn't support reading the entire environment through the global ** variable "environ" or similar, returns NULL instead. ** ** Restrictions: ** Similarly to PR_GetEnv(), this function may not interoperate as ** expected with the operating system's native environment accessors.
*/
NSPR_API(char **) PR_DuplicateEnvironment(void);
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