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Diffstat (limited to '3rdparty/qtsingleapplication/qtlockedfile.cpp')
-rw-r--r-- | 3rdparty/qtsingleapplication/qtlockedfile.cpp | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/3rdparty/qtsingleapplication/qtlockedfile.cpp b/3rdparty/qtsingleapplication/qtlockedfile.cpp new file mode 100644 index 0000000..2cf0805 --- /dev/null +++ b/3rdparty/qtsingleapplication/qtlockedfile.cpp @@ -0,0 +1,199 @@ +/**************************************************************************** +** +** 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. +*/ |