/****************************************************************************+
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**+
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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).+
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** All rights reserved.+
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** Contact: Nokia Corporation (qt-info@nokia.com)+
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**+
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** This file is part of the test suite of the Qt Toolkit.+
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**+
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** $QT_BEGIN_LICENSE:LGPL$+
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** No Commercial Usage+
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** This file contains pre-release code and may not be distributed.+
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** You may use this file in accordance with the terms and conditions+
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** contained in the Technology Preview License Agreement accompanying+
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** this package.+
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**+
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** GNU Lesser General Public License Usage+
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** Alternatively, this file may be used under the terms of the GNU Lesser+
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** General Public License version 2.1 as published by the Free Software+
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** Foundation and appearing in the file LICENSE.LGPL included in the+
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** packaging of this file.  Please review the following information to+
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** ensure the GNU Lesser General Public License version 2.1 requirements+
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.+
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**+
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** In addition, as a special exception, Nokia gives you certain additional+
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** rights.  These rights are described in the Nokia Qt LGPL Exception+
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.+
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**+
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** If you have questions regarding the use of this file, please contact+
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** Nokia at qt-info@nokia.com.+
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**+
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**+
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**+
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**+
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**+
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**+
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**+
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**+
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** $QT_END_LICENSE$+
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**+
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****************************************************************************/+
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+
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+
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#include "qsystemlock.h"+
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#include "qsystemlock_p.h"+
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#include <qdebug.h>+
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#include <QtCore>+
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QSystemLockPrivate::QSystemLockPrivate() :+
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        semaphore(0), semaphoreLock(0),+
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	lockCount(0), error(QSystemLock::NoError)+
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{+
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}+
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+
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void QSystemLockPrivate::setErrorString(const QString &function)+
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{+
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    BOOL windowsError = GetLastError();+
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    if (windowsError == 0)+
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        return;+
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    errorString = function + QLatin1String(": ")+
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                    + QLatin1String("Unknown error");+
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    error = QSystemLock::UnknownError;+
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    qWarning() << errorString << "key" << key << (int)windowsError << semaphore << semaphoreLock;+
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}+
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+
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/*!+
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    \internal+
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+
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    Setup the semaphore+
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 */+
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HANDLE QSystemLockPrivate::handle()+
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{+
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    // don't allow making handles on empty keys+
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    if (key.isEmpty())+
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        return 0;+
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+
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    // Create it if it doesn't already exists.+
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    if (semaphore == 0) {+
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        QString safeName = makeKeyFileName();+
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        semaphore = CreateSemaphore(0, MAX_LOCKS, MAX_LOCKS, (wchar_t*)safeName.utf16());+
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+
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        if (semaphore == 0) {+
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            setErrorString(QLatin1String("QSystemLockPrivate::handle"));+
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            return 0;+
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        }+
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    }+
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+
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    if (semaphoreLock == 0) {+
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        QString safeLockName = QSharedMemoryPrivate::makePlatformSafeKey(key + QLatin1String("lock"), QLatin1String("qipc_systemlock_"));+
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        semaphoreLock = CreateSemaphore(0, 1, 1, (wchar_t*)safeLockName.utf16());+
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+
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        if (semaphoreLock == 0) {+
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            setErrorString(QLatin1String("QSystemLockPrivate::handle"));+
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            return 0;+
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        }+
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    }+
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+
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    return semaphore;+
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}+
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+
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/*!+
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    \internal+
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+
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    Cleanup the semaphore+
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 */+
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void QSystemLockPrivate::cleanHandle()+
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{+
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    if (semaphore && !CloseHandle(semaphore))+
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        setErrorString(QLatin1String("QSystemLockPrivate::cleanHandle:"));+
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    if (semaphoreLock && !CloseHandle(semaphoreLock))+
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        setErrorString(QLatin1String("QSystemLockPrivate::cleanHandle:"));+
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    semaphore = 0;+
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    semaphoreLock = 0;+
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}+
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+
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bool QSystemLockPrivate::lock(HANDLE handle, int count)+
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{+
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    if (count == 1) {+
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	WaitForSingleObject(handle, INFINITE);+
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	return true;+
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    }+
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+
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    int i = count;+
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    while (i > 0) {+
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	if (WAIT_OBJECT_0 == WaitForSingleObject(handle, 0)) {+
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	    --i;+
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	} else {+
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	    // undo what we have done, sleep and then try again later+
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	    ReleaseSemaphore(handle, (count - i), 0);+
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	    i = count;+
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	    ReleaseSemaphore(semaphoreLock, 1, 0);+
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	    Sleep(1);+
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	    WaitForSingleObject(semaphoreLock, INFINITE);+
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	}+
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    }+
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    return true;+
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}+
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+
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bool QSystemLockPrivate::unlock(HANDLE handle, int count)+
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{+
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    if (0 == ReleaseSemaphore(handle, count, 0)) {+
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        setErrorString(QLatin1String("QSystemLockPrivate::unlock"));+
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        return false;+
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    }+
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    return true;+
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}+
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+
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/*!+
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    \internal+
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+
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    modifySemaphore handles recursive behavior and modifies the semaphore.+
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 */+
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bool QSystemLockPrivate::modifySemaphore(QSystemLockPrivate::Operation op,+
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        QSystemLock::LockMode mode)+
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{+
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    if (0 == handle())+
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        return false;+
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+
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    if ((lockCount == 0 && op == Lock) || (lockCount > 0 && op == Unlock)) {+
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        if (op == Unlock) {+
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            --lockCount;+
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            Q_ASSERT(lockCount >= 0);+
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            if (lockCount > 0)+
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                return true;+
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        }+
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+
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        int count = (mode == QSystemLock::ReadWrite) ? MAX_LOCKS : 1;+
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        if (op == Lock) {+
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            lock(semaphoreLock, 1);+
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            lock(semaphore, count);+
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            if (count != MAX_LOCKS) unlock(semaphoreLock, 1);+
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	    lockedMode = mode;+
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        } else {+
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            if (count == MAX_LOCKS) unlock(semaphoreLock, 1);+
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	    unlock(semaphore, count);+
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        }+
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+
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    }+
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    if (op == Lock)+
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        lockCount++;+
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+
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    return true;+
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}+
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+
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