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/*
* Copyright (c) 2008-2009 Jeff Mitchell <mitchell@kde.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "SafeFileSaver.h"
#include <QtDebug>
#include <QCryptographicHash>
#include <QFile>
#include <QFileInfo>
#include <QRandomGenerator>
#include <QString>
#ifdef Q_OS_WINDOWS
#include <process.h>
#else
#include <unistd.h>
#include <sys/types.h>
#endif
SafeFileSaver::SafeFileSaver( const QString &origPath )
: m_origPath( origPath )
, m_tempSavePath()
, m_origRenamedSavePath()
, m_cleanupNeeded( false )
, m_verbose( false )
, m_prefix( QStringLiteral("safefilesaver") )
{
}
SafeFileSaver::~SafeFileSaver()
{
if( m_cleanupNeeded )
cleanupSave();
}
QString
SafeFileSaver::prepareToSave()
{
if( m_verbose )
qDebug() << "prepareToSave start";
m_cleanupNeeded = true;
QCryptographicHash md5sum( QCryptographicHash::Md5 );
QString pid;
#ifdef Q_OS_WINDOWS
pid.setNum( _getpid() );
#else
pid.setNum( getpid() );
#endif
int length = 8;
//The following snippet of code is copied from kdelibs, and is copyright Matthias Kalle Dalheimer, Charles Samuels, Joseph Wenninger, and maybe more
QString str; str.resize( length );
int i = 0;
while( length-- )
{
int r = QRandomGenerator::global()->generate() % 62;
r+=48;
if( r > 57 ) r+=7;
if( r > 90 ) r+=6;
str[i++] = QLatin1Char( r );
}
QString randomString = str;
m_tempSavePath = m_origPath + QLatin1Char('.') + m_prefix + QStringLiteral("temp.pid-") + pid + QStringLiteral(".random-") + randomString + QLatin1Char('.') + QFileInfo( m_origPath ).suffix();
m_origRenamedSavePath = m_origPath + QLatin1Char('.') + m_prefix + QStringLiteral("original.pid-") + pid + QStringLiteral(".random-") + randomString + QLatin1Char('.') + QFileInfo( m_origPath ).suffix();
if( m_verbose )
qDebug() << "Copying original file " << m_origPath << " to copy at " << m_tempSavePath << " and caluclating MD5";
if( !QFile::copy( m_origPath, m_tempSavePath ) )
{
if( m_verbose )
qDebug() << "Could not copy the file. Check that you have sufficient permissions/disk space "
"and that the destination path does not already exist!";
return QString();
}
QFile tempFile( m_tempSavePath );
if( !tempFile.open( QIODevice::ReadOnly | QIODevice::Unbuffered ) )
{
if( m_verbose )
qDebug() << "Could not open temp file for MD5 calculation!";
return QString();
}
md5sum.addData( tempFile.readLine() );
m_tempSaveDigest = QLatin1String( md5sum.result().toHex() );
tempFile.close();
//By this point, we have the following:
//The original file is copied at path m_tempSavePath
//We have generated what will be the filename to rename the original to in m_origRenamedSavePath
//We have successfully copied the original file to the temp location
//We've calculated the md5sum of the original file
if( m_verbose )
qDebug() << "MD5 sum of temp file: " << m_tempSaveDigest;
//Now, we have a MD5 sum of the original file at the time of copying saved in m_tempSaveDigest
return m_tempSavePath;
}
bool
SafeFileSaver::doSave()
{
if( m_verbose )
qDebug() << "doSave start";
//TODO: much commenting needed. For now this pretty much follows algorithm laid out in bug 131353,
//but isn't useable since I need to find a good way to switch the file path with taglib, or a good way
//to get all the metadata copied over.
m_cleanupNeeded = true;
QCryptographicHash md5sum( QCryptographicHash::Md5 );
QString origRenamedDigest;
if( m_tempSavePath.isEmpty() || m_tempSaveDigest.isEmpty() || m_origRenamedSavePath.isEmpty() )
{
if( m_verbose)
qDebug() << "You must run prepareToSave() and it must return successfully before calling doSave()!";
return false;
}
if( m_verbose )
qDebug() << "Renaming original file to temporary name " << m_origRenamedSavePath;
if( !QFile::rename( m_origPath, m_origRenamedSavePath ) )
{
if( m_verbose )
qDebug() << "Could not move original!";
failRemoveCopy( false );
return false;
}
if( m_verbose )
qDebug() << "Calculating MD5 of " << m_origRenamedSavePath;
QFile origRenamedFile( m_origRenamedSavePath );
if( !origRenamedFile.open( QIODevice::ReadOnly | QIODevice::Unbuffered ) )
{
if( m_verbose )
qDebug() << "Could not open temporary file!";
failRemoveCopy( true );
return false;
}
md5sum.addData( origRenamedFile.readLine() );
origRenamedDigest = QLatin1String( md5sum.result().toHex() );
origRenamedFile.close();
if( m_verbose )
qDebug() << "md5sum of original renamed file: " << origRenamedDigest;
if( origRenamedDigest != m_tempSaveDigest )
{
if( m_verbose )
qDebug() << "Original checksum did not match current checksum!";
failRemoveCopy( true );
return false;
}
if( m_verbose )
qDebug() << "Renaming temp file to original's filename";
if( !QFile::rename( m_tempSavePath, m_origPath ) )
{
if( m_verbose )
qDebug() << "Could not rename new file to original!";
failRemoveCopy( true );
return false;
}
if( m_verbose )
qDebug() << "Deleting original";
if( !QFile::remove( m_origRenamedSavePath ) )
{
if( m_verbose )
qDebug() << "Could not delete the original file!";
return false;
}
if( m_verbose )
qDebug() << "Save done, returning true!";
return true;
}
void
SafeFileSaver::failRemoveCopy( bool revert )
{
if( m_verbose )
qDebug() << "failRemoveCopy start";
if( !QFile::remove( m_tempSavePath ) )
{
if( m_verbose )
qDebug() << "Could not delete the temporary file!";
}
if( !revert )
return;
if( m_verbose )
qDebug() << "Reverting original file to original filename!";
if( !QFile::rename( m_origRenamedSavePath, m_origPath ) )
{
if( m_verbose )
qDebug() << "Could not revert file to original filename!";
}
}
bool
SafeFileSaver::cleanupSave()
{
if( m_verbose )
qDebug() << "cleanupSave start";
bool dirty = false;
if( !m_tempSavePath.isEmpty() && QFile::exists( m_tempSavePath ) )
{
if( !QFile::remove( m_tempSavePath ) )
{
dirty = true;
if( m_verbose )
qDebug() << "Could not delete the temporary file!";
}
}
m_tempSavePath.clear();
m_origRenamedSavePath.clear();
m_tempSaveDigest.clear();
m_cleanupNeeded = false;
return !dirty;
}
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