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/****************************************************************************
**
** Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of a Qt Solutions component.
**
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Solutions Commercial License Agreement provided
** with the Software or, alternatively, in accordance with the terms
** contained in a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.1, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** Please note Third Party Software included with Qt Solutions may impose
** additional restrictions and it is the user's responsibility to ensure
** that they have met the licensing requirements of the GPL, LGPL, or Qt
** Solutions Commercial license and the relevant license of the Third
** Party Software they are using.
**
** If you are unsure which license is appropriate for your use, please
** contact Nokia at qt-info@nokia.com.
**
****************************************************************************/
#include "qtlockedfile.h"
#include <qt_windows.h>
#include <QtCore/QFileInfo>
#define MUTEX_PREFIX "QtLockedFile mutex "
// Maximum number of concurrent read locks. Must not be greater than MAXIMUM_WAIT_OBJECTS
#define MAX_READERS MAXIMUM_WAIT_OBJECTS
Qt::HANDLE QtLockedFile::getMutexHandle(int idx, bool doCreate)
{
if (mutexname.isEmpty()) {
QFileInfo fi(*this);
mutexname = QString::fromLatin1(MUTEX_PREFIX)
+ fi.absoluteFilePath().toLower();
}
QString mname(mutexname);
if (idx >= 0)
mname += QString::number(idx);
Qt::HANDLE mutex;
if (doCreate) {
QT_WA( { mutex = CreateMutexW(NULL, FALSE, (TCHAR*)mname.utf16()); },
{ mutex = CreateMutexA(NULL, FALSE, mname.toLocal8Bit().constData()); } );
if (!mutex) {
qErrnoWarning("QtLockedFile::lock(): CreateMutex failed");
return 0;
}
}
else {
QT_WA( { mutex = OpenMutexW(SYNCHRONIZE | MUTEX_MODIFY_STATE, FALSE, (TCHAR*)mname.utf16()); },
{ mutex = OpenMutexA(SYNCHRONIZE | MUTEX_MODIFY_STATE, FALSE, mname.toLocal8Bit().constData()); } );
if (!mutex) {
if (GetLastError() != ERROR_FILE_NOT_FOUND)
qErrnoWarning("QtLockedFile::lock(): OpenMutex failed");
return 0;
}
}
return mutex;
}
bool QtLockedFile::waitMutex(Qt::HANDLE mutex, bool doBlock)
{
Q_ASSERT(mutex);
DWORD res = WaitForSingleObject(mutex, doBlock ? INFINITE : 0);
switch (res) {
case WAIT_OBJECT_0:
case WAIT_ABANDONED:
return true;
break;
case WAIT_TIMEOUT:
break;
default:
qErrnoWarning("QtLockedFile::lock(): WaitForSingleObject failed");
}
return false;
}
bool QtLockedFile::lock(LockMode mode, bool block)
{
if (!isOpen()) {
qWarning("QtLockedFile::lock(): file is not opened");
return false;
}
if (mode == NoLock)
return unlock();
if (mode == m_lock_mode)
return true;
if (m_lock_mode != NoLock)
unlock();
if (!wmutex && !(wmutex = getMutexHandle(-1, true)))
return false;
if (!waitMutex(wmutex, block))
return false;
if (mode == ReadLock) {
int idx = 0;
for (; idx < MAX_READERS; idx++) {
rmutex = getMutexHandle(idx, false);
if (!rmutex || waitMutex(rmutex, false))
break;
CloseHandle(rmutex);
}
bool ok = true;
if (idx >= MAX_READERS) {
qWarning("QtLockedFile::lock(): too many readers");
rmutex = 0;
ok = false;
}
else if (!rmutex) {
rmutex = getMutexHandle(idx, true);
if (!rmutex || !waitMutex(rmutex, false))
ok = false;
}
if (!ok && rmutex) {
CloseHandle(rmutex);
rmutex = 0;
}
ReleaseMutex(wmutex);
if (!ok)
return false;
}
else {
Q_ASSERT(rmutexes.isEmpty());
for (int i = 0; i < MAX_READERS; i++) {
Qt::HANDLE mutex = getMutexHandle(i, false);
if (mutex)
rmutexes.append(mutex);
}
if (rmutexes.size()) {
DWORD res = WaitForMultipleObjects(rmutexes.size(), rmutexes.constData(),
TRUE, block ? INFINITE : 0);
if (res != WAIT_OBJECT_0 && res != WAIT_ABANDONED) {
if (res != WAIT_TIMEOUT)
qErrnoWarning("QtLockedFile::lock(): WaitForMultipleObjects failed");
m_lock_mode = WriteLock; // trick unlock() to clean up - semiyucky
unlock();
return false;
}
}
}
m_lock_mode = mode;
return true;
}
bool QtLockedFile::unlock()
{
if (!isOpen()) {
qWarning("QtLockedFile::unlock(): file is not opened");
return false;
}
if (!isLocked())
return true;
if (m_lock_mode == ReadLock) {
ReleaseMutex(rmutex);
CloseHandle(rmutex);
rmutex = 0;
}
else {
foreach(Qt::HANDLE mutex, rmutexes) {
ReleaseMutex(mutex);
CloseHandle(mutex);
}
rmutexes.clear();
ReleaseMutex(wmutex);
}
m_lock_mode = QtLockedFile::NoLock;
return true;
}
QtLockedFile::~QtLockedFile()
{
if (isOpen())
unlock();
if (wmutex)
CloseHandle(wmutex);
}
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