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+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt Solutions component.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+** * Redistributions of source code must retain the above copyright
+** notice, this list of conditions and the following disclaimer.
+** * Redistributions in binary form must reproduce the above copyright
+** notice, this list of conditions and the following disclaimer in
+** the documentation and/or other materials provided with the
+** distribution.
+** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
+** of its contributors may be used to endorse or promote products derived
+** from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "LockedFile.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()
+*/
+LockedFile::LockedFile()
+ : 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()
+*/
+LockedFile::LockedFile(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 LockedFile::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 LockedFile::isLocked() const
+{
+ return m_lock_mode != NoLock;
+}
+
+/*!
+ Returns the type of lock currently held by this object, or \e
+ QtLockedFile::NoLock.
+
+ \sa isLocked()
+*/
+LockedFile::LockMode LockedFile::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.
+*/