162 lines
5.2 KiB
C++
162 lines
5.2 KiB
C++
#include "qxtfilelock.h"
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/****************************************************************************
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** Copyright (c) 2006 - 2011, the LibQxt project.
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** See the Qxt AUTHORS file for a list of authors and copyright holders.
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** All rights reserved.
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**
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** Redistribution and use in source and binary forms, with or without
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** modification, are permitted provided that the following conditions are met:
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** * Redistributions of source code must retain the above copyright
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** notice, this list of conditions and the following disclaimer.
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** * Redistributions in binary form must reproduce the above copyright
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** notice, this list of conditions and the following disclaimer in the
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** documentation and/or other materials provided with the distribution.
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** * Neither the name of the LibQxt project nor the
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** names of its contributors may be used to endorse or promote products
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** derived from this software without specific prior written permission.
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**
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** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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** ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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** DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
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** DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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** (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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** SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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**
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** <http://libqxt.org> <foundation@libqxt.org>
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*****************************************************************************/
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#include "qxtfilelock_p.h"
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/*!
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\class QxtFileLock
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\inmodule QxtCore
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\brief The QxtFileLock class provides a crossplattform way to lock a QFile.
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QxtFileLock supports range locking of a file. The File will take parentship of the lock.
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The lock gets cleaned up with the QFile, and it is released when the QFile is closed.
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Example usage:
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\code
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off_t lockstart = 0x10;
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off_t locklength = 30
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QFile file("test.lock");
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//the lock gets deleted when file is cleaned up
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QxtFileLock * writeLock = new QxtFileLock(&file,lockstart,locklength,QxtFileLock::WriteLock);
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if(file.open(QIODevice::ReadWrite))
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{
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if(writeLock->lock())
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{
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// some write operations
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writeLock->unlock();
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}
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else
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//lock failed
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}
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\endcode
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\bold {Note:} QxtFileLock behaves different than normal unix locks on *nix. A thread can writelock the region of a file only ONCE if it uses two different handles.
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A different thread can not writelock a region that is owned by a other thread even if it is the SAME process.
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\bold {Note:} On *nix this class uses fctnl to lock the file. This may not be compatible to other locking functions like flock and lockf
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\bold {Note:} Please do not mix QxtFileLock and native file lock calls on the same QFile. The behaviour is undefined
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\bold {Note:} QxtFileLock lives in the same thread as the passed QFile
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\warning due to a refactoring issues of QFile this class will not work with Qt from version 4.3.0 to 4.3.2
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*/
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/*!
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\fn bool QxtFileLock::lock()
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\brief Locks the file
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Returns \c true if succeeds, \c false otherwise.
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*/
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/*!
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\fn bool QxtFileLock::unlock()
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\brief Unlocks the file.
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Returns \c true if succeeds, \c false otherwise.
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*/
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/*!
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\enum QxtFileLock::Mode
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\brief The mode of the lock
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\value ReadLock A non blocking read lock
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\value WriteLock A non blocking write lock
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\value ReadLockWait A blocking read lock. The lock() function will block until the lock is created.
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\value WriteLockWait A blocking write lock. The lock() function will block until the lock is created.
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*/
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QxtFileLockPrivate::QxtFileLockPrivate() : offset(0), length(0), mode(QxtFileLock::WriteLockWait), isLocked(false)
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{
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}
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/*!
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Contructs a new QxtFileLock. The lock is not activated.
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\a file the file that should be locked
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\a offset the offset where the lock starts
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\a length the length of the lock
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\a mode the lockmode
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*/
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QxtFileLock::QxtFileLock(QFile *file, const off_t offset, const off_t length, const QxtFileLock::Mode mode) : QObject(file)
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{
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QXT_INIT_PRIVATE(QxtFileLock);
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connect(file, SIGNAL(aboutToClose()), this, SLOT(unlock()));
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qxt_d().offset = offset;
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qxt_d().length = length;
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qxt_d().mode = mode;
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}
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/*!
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Destructs the file lock.
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*/
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QxtFileLock::~QxtFileLock()
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{
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unlock();
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}
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/*!
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Returns the offset of the lock
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*/
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off_t QxtFileLock::offset() const
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{
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return qxt_d().offset;
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}
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/*!
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Returns \c true if the lock is active otherwise it returns \c false
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*/
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bool QxtFileLock::isActive() const
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{
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return qxt_d().isLocked;
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}
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/*!
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Returns the length of the lock
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*/
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off_t QxtFileLock::length() const
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{
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return qxt_d().length;
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}
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/*!
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Returns the file the lock is created on.
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*/
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QFile * QxtFileLock::file() const
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{
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return qobject_cast<QFile *>(parent());
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}
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/*!
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Returns the mode of the lock
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*/
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QxtFileLock::Mode QxtFileLock::mode() const
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{
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return qxt_d().mode;
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}
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