File indexing completed on 2024-05-12 16:20:57

 /*
  *  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_WS_WIN
 #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_WS_WIN
     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++] = char( r );
     }
 
     QString randomString = str;
 
     m_tempSavePath = m_origPath + QLatin1Char('.') + m_prefix + "temp.pid-" + pid + ".random-" + randomString + QLatin1Char('.') + QFileInfo( m_origPath ).suffix();
     m_origRenamedSavePath = m_origPath + QLatin1Char('.') + m_prefix + "original.pid-" + pid + ".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 = 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 = 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;
 }