134 lines
4.1 KiB
C
134 lines
4.1 KiB
C
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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is the Netscape Portable Runtime (NSPR).
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*
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* The Initial Developer of the Original Code is
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 1999-2000
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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/*
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* File: pripcsem.h
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*
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* Description: named semaphores for interprocess
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* synchronization
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*
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* Unrelated processes obtain access to a shared semaphore
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* by specifying its name.
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*
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* Our goal is to support named semaphores on at least
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* Unix and Win32 platforms. The implementation will use
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* one of the three native semaphore APIs: POSIX, System V,
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* and Win32.
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*
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* Because POSIX named semaphores have kernel persistence,
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* we are forced to have a delete function in this API.
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*/
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#ifndef pripcsem_h___
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#define pripcsem_h___
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#include "prtypes.h"
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#include "prio.h"
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PR_BEGIN_EXTERN_C
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/*
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* PRSem is an opaque structure that represents a named
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* semaphore.
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*/
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typedef struct PRSem PRSem;
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/*
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* PR_OpenSemaphore --
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*
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* Create or open a named semaphore with the specified name.
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* A handle to the semaphore is returned.
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*
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* If the named semaphore doesn't exist and the PR_SEM_CREATE
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* flag is specified, the named semaphore is created. The
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* created semaphore needs to be removed from the system with
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* a PR_DeleteSemaphore call.
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*
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* If PR_SEM_CREATE is specified, the third argument is the
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* access permission bits of the new semaphore (same
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* interpretation as the mode argument to PR_Open) and the
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* fourth argument is the initial value of the new semaphore.
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* If PR_SEM_CREATE is not specified, the third and fourth
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* arguments are ignored.
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*/
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#define PR_SEM_CREATE 0x1 /* create if not exist */
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#define PR_SEM_EXCL 0x2 /* fail if already exists */
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NSPR_API(PRSem *) PR_OpenSemaphore(
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const char *name, PRIntn flags, PRIntn mode, PRUintn value);
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/*
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* PR_WaitSemaphore --
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*
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* If the value of the semaphore is > 0, decrement the value and return.
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* If the value is 0, sleep until the value becomes > 0, then decrement
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* the value and return.
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*
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* The "test and decrement" operation is performed atomically.
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*/
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NSPR_API(PRStatus) PR_WaitSemaphore(PRSem *sem);
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/*
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* PR_PostSemaphore --
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*
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* Increment the value of the named semaphore by 1.
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*/
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NSPR_API(PRStatus) PR_PostSemaphore(PRSem *sem);
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/*
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* PR_CloseSemaphore --
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*
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* Close a named semaphore handle.
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*/
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NSPR_API(PRStatus) PR_CloseSemaphore(PRSem *sem);
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/*
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* PR_DeleteSemaphore --
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*
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* Remove a named semaphore from the system.
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*/
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NSPR_API(PRStatus) PR_DeleteSemaphore(const char *name);
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PR_END_EXTERN_C
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#endif /* pripcsem_h___ */
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