197 lines
6.3 KiB
C++
197 lines
6.3 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
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** Contact: http://www.qt-project.org/legal
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**
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** This file is part of Qt Creator.
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**
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and Digia. For licensing terms and
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** conditions see http://qt.digia.com/licensing. For further information
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** use the contact form at http://qt.digia.com/contact-us.
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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, Digia gives you certain additional
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** rights. These rights are described in the Digia 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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****************************************************************************/
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#include "qtlockedfile.h"
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#include <qt_windows.h>
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#include <QFileInfo>
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namespace SharedTools {
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#define SEMAPHORE_PREFIX "QtLockedFile semaphore "
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#define MUTEX_PREFIX "QtLockedFile mutex "
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#define SEMAPHORE_MAX 100
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static QString errorCodeToString(DWORD errorCode)
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{
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QString result;
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char *data = 0;
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FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
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0, errorCode, 0,
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(char*)&data, 0, 0);
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result = QString::fromLocal8Bit(data);
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if (data != 0)
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LocalFree(data);
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if (result.endsWith(QLatin1Char('\n')))
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result.truncate(result.length() - 1);
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return result;
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}
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bool QtLockedFile::lock(LockMode mode, bool block)
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{
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if (!isOpen()) {
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qWarning("QtLockedFile::lock(): file is not opened");
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return false;
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}
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if (mode == m_lock_mode)
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return true;
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if (m_lock_mode != 0)
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unlock();
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if (m_semaphore_hnd == 0) {
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QFileInfo fi(*this);
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QString sem_name = QString::fromLatin1(SEMAPHORE_PREFIX)
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+ fi.absoluteFilePath().toLower();
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m_semaphore_hnd = CreateSemaphoreW(0, SEMAPHORE_MAX, SEMAPHORE_MAX,
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(TCHAR*)sem_name.utf16());
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if (m_semaphore_hnd == 0) {
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qWarning("QtLockedFile::lock(): CreateSemaphore: %s",
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errorCodeToString(GetLastError()).toLatin1().constData());
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return false;
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}
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}
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bool gotMutex = false;
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int decrement;
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if (mode == ReadLock) {
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decrement = 1;
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} else {
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decrement = SEMAPHORE_MAX;
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if (m_mutex_hnd == 0) {
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QFileInfo fi(*this);
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QString mut_name = QString::fromLatin1(MUTEX_PREFIX)
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+ fi.absoluteFilePath().toLower();
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m_mutex_hnd = CreateMutexW(nullptr, FALSE, (TCHAR*)mut_name.utf16());
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if (m_mutex_hnd == 0) {
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qWarning("QtLockedFile::lock(): CreateMutex: %s",
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errorCodeToString(GetLastError()).toLatin1().constData());
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return false;
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}
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}
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DWORD res = WaitForSingleObject(m_mutex_hnd, block ? INFINITE : 0);
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if (res == WAIT_TIMEOUT)
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return false;
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if (res == WAIT_FAILED) {
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qWarning("QtLockedFile::lock(): WaitForSingleObject (mutex): %s",
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errorCodeToString(GetLastError()).toLatin1().constData());
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return false;
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}
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gotMutex = true;
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}
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for (int i = 0; i < decrement; ++i) {
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DWORD res = WaitForSingleObject(m_semaphore_hnd, block ? INFINITE : 0);
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if (res == WAIT_TIMEOUT) {
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if (i) {
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// A failed nonblocking rw locking. Undo changes to semaphore.
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if (ReleaseSemaphore(m_semaphore_hnd, i, nullptr) == 0) {
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qWarning("QtLockedFile::unlock(): ReleaseSemaphore: %s",
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errorCodeToString(GetLastError()).toLatin1().constData());
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// Fall through
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}
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}
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if (gotMutex)
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ReleaseMutex(m_mutex_hnd);
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return false;
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}
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if (res != WAIT_OBJECT_0) {
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if (gotMutex)
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ReleaseMutex(m_mutex_hnd);
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qWarning("QtLockedFile::lock(): WaitForSingleObject (semaphore): %s",
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errorCodeToString(GetLastError()).toLatin1().constData());
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return false;
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}
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}
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m_lock_mode = mode;
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if (gotMutex)
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ReleaseMutex(m_mutex_hnd);
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return true;
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}
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bool QtLockedFile::unlock()
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{
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if (!isOpen()) {
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qWarning("QtLockedFile::unlock(): file is not opened");
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return false;
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}
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if (!isLocked())
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return true;
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int increment;
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if (m_lock_mode == ReadLock)
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increment = 1;
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else
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increment = SEMAPHORE_MAX;
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DWORD ret = ReleaseSemaphore(m_semaphore_hnd, increment, 0);
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if (ret == 0) {
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qWarning("QtLockedFile::unlock(): ReleaseSemaphore: %s",
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errorCodeToString(GetLastError()).toLatin1().constData());
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return false;
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}
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m_lock_mode = QtLockedFile::NoLock;
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remove();
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return true;
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}
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QtLockedFile::~QtLockedFile()
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{
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if (isOpen())
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unlock();
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if (m_mutex_hnd != 0) {
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DWORD ret = CloseHandle(m_mutex_hnd);
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if (ret == 0) {
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qWarning("QtLockedFile::~QtLockedFile(): CloseHandle (mutex): %s",
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errorCodeToString(GetLastError()).toLatin1().constData());
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}
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m_mutex_hnd = 0;
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}
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if (m_semaphore_hnd != 0) {
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DWORD ret = CloseHandle(m_semaphore_hnd);
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if (ret == 0) {
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qWarning("QtLockedFile::~QtLockedFile(): CloseHandle (semaphore): %s",
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errorCodeToString(GetLastError()).toLatin1().constData());
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}
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m_semaphore_hnd = 0;
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}
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}
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} // namespace SharedTools
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