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73 lines
2.2 KiB
C++
73 lines
2.2 KiB
C++
/* Copyright (C) 2015
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* swift project Community / Contributors
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*
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* This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
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* directory of this distribution and at http://www.swift-project.org/license.html. No part of swift project,
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* including this file, may be copied, modified, propagated, or distributed except according to the terms
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* contained in the LICENSE file.
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*/
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//! \file
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#ifndef BLACKMISC_ATOMICFILE_H
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#define BLACKMISC_ATOMICFILE_H
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#include "blackmisc/blackmiscexport.h"
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#include <QFile>
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#include <QFileDevice>
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#include <QIODevice>
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#include <QString>
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#include <exception>
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namespace BlackMisc
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{
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/*!
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* A subclass of QFile which writes to a temporary file while it is open, then renames the file
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* when it is closed, so that it overwrites the target file as a single, atomic transaction.
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*
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* If the application crashes while data is still being written, the original file is unchanged.
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*
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* \fixme Consider using QSaveFile.
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*/
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class BLACKMISC_EXPORT CAtomicFile : public QFile
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{
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public:
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//! \copydoc QFile::QFile(const QString &)
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CAtomicFile(const QString &filename) : QFile(filename) {}
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//! \copydoc QFile::~QFile
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~CAtomicFile() { if (std::uncaught_exception()) { QFile::close(); } }
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//! \copydoc QFile::open
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//! Just before opening the file, the filename is changed so we actually write to a temporary file.
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virtual bool open(OpenMode mode) override;
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//! \copydoc QFileDevice::close
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//! After closing the file, it is renamed so that it overwrites the target file.
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virtual void close() override;
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//! Calls close() and returns false if there was an error at any stage.
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bool checkedClose();
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//! Closes the file without renaming it.
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void abandon();
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//! \copydoc QFileDevice::error
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FileError error() const;
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//! \copydoc QFileDevice::unsetError
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void unsetError();
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private:
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static QString randomSuffix();
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void replaceOriginal();
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QString m_originalFilename;
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bool m_renameError = false;
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bool m_permissionError = false;
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};
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}
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#endif
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