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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"
+
+/*!
+ \class QtLockedFile
+
+ \brief The QtLockedFile class extends QFile with advisory locking
+ functions.
+
+ A file may be locked in read or write mode. Multiple instances of
+ \e QtLockedFile, created in multiple processes running on the same
+ machine, may have a file locked in read mode. Exactly one instance
+ may have it locked in write mode. A read and a write lock cannot
+ exist simultaneously on the same file.
+
+ The file locks are advisory. This means that nothing prevents
+ another process from manipulating a locked file using QFile or
+ file system functions offered by the OS. Serialization is only
+ guaranteed if all processes that access the file use
+ QLockedFile. Also, while holding a lock on a file, a process
+ must not open the same file again (through any API), or locks
+ can be unexpectedly lost.
+
+ The lock provided by an instance of \e QtLockedFile is released
+ whenever the program terminates. This is true even when the
+ program crashes and no destructors are called.
+*/
+
+/*! \enum QtLockedFile::LockMode
+
+ This enum describes the available lock modes.
+
+ \value ReadLock A read lock.
+ \value WriteLock A write lock.
+ \value NoLock Neither a read lock nor a write lock.
+*/
+
+/*!
+ Constructs an unlocked \e QtLockedFile object. This constructor
+ behaves in the same way as \e QFile::QFile().
+
+ \sa QFile::QFile()
+*/
+QtLockedFile::QtLockedFile()
+ : QFile()
+{
+#ifdef Q_OS_WIN
+ wmutex = 0;
+ rmutex = 0;
+#endif
+ m_lock_mode = NoLock;
+}
+
+/*!
+ Constructs an unlocked QtLockedFile object with file \a name. This
+ constructor behaves in the same way as \e QFile::QFile(const
+ QString&).
+
+ \sa QFile::QFile()
+*/
+QtLockedFile::QtLockedFile(const QString &name)
+ : QFile(name)
+{
+#ifdef Q_OS_WIN
+ wmutex = 0;
+ rmutex = 0;
+#endif
+ m_lock_mode = NoLock;
+}
+
+/*!
+ Opens the file in OpenMode \a mode.
+
+ This is identical to QFile::open(), with the one exception that the
+ Truncate mode flag is disallowed. Truncation would conflict with the
+ advisory file locking, since the file would be modified before the
+ write lock is obtained. If truncation is required, use resize(0)
+ after obtaining the write lock.
+
+ Returns true if successful; otherwise false.
+
+ \sa QFile::open(), QFile::resize()
+*/
+bool QtLockedFile::open(OpenMode mode)
+{
+ if (mode & QIODevice::Truncate) {
+ qWarning("QtLockedFile::open(): Truncate mode not allowed.");
+ return false;
+ }
+ return QFile::open(mode);
+}
+
+/*!
+ Returns \e true if this object has a in read or write lock;
+ otherwise returns \e false.
+
+ \sa lockMode()
+*/
+bool QtLockedFile::isLocked() const
+{
+ return m_lock_mode != NoLock;
+}
+
+/*!
+ Returns the type of lock currently held by this object, or \e
+ QtLockedFile::NoLock.
+
+ \sa isLocked()
+*/
+QtLockedFile::LockMode QtLockedFile::lockMode() const
+{
+ return m_lock_mode;
+}
+
+/*!
+ \fn bool QtLockedFile::lock(LockMode mode, bool block = true)
+
+ Obtains a lock of type \a mode. The file must be opened before it
+ can be locked.
+
+ If \a block is true, this function will block until the lock is
+ aquired. If \a block is false, this function returns \e false
+ immediately if the lock cannot be aquired.
+
+ If this object already has a lock of type \a mode, this function
+ returns \e true immediately. If this object has a lock of a
+ different type than \a mode, the lock is first released and then a
+ new lock is obtained.
+
+ This function returns \e true if, after it executes, the file is
+ locked by this object, and \e false otherwise.
+
+ \sa unlock(), isLocked(), lockMode()
+*/
+
+/*!
+ \fn bool QtLockedFile::unlock()
+
+ Releases a lock.
+
+ If the object has no lock, this function returns immediately.
+
+ This function returns \e true if, after it executes, the file is
+ not locked by this object, and \e false otherwise.
+
+ \sa lock(), isLocked(), lockMode()
+*/
+
+/*!
+ \fn QtLockedFile::~QtLockedFile()
+
+ Destroys the \e QtLockedFile object. If any locks were held, they
+ are released.
+*/