path: root/synchronization.cpp

#include "synchronization.h"
#include <wx/intl.h>
#include <wx/msgdlg.h>
#include <wx/log.h>
#include "library/resources.h"
#include "algorithm.h"
#include "library/globalFunctions.h"
#include "library/statusHandler.h"
#include "library/fileHandling.h"
#include <utility>

#ifdef FFS_WIN
#include <wx/msw/wrapwin.h> //includes "windows.h"
#endif

using namespace FreeFileSync;


inline
SyncConfiguration::Direction getSyncDirection(const CompareFilesResult cmpResult, const SyncConfiguration& config)
{
    switch (cmpResult)
    {
    case FILE_LEFT_SIDE_ONLY:
        return config.exLeftSideOnly;
        break;

    case FILE_RIGHT_SIDE_ONLY:
        return config.exRightSideOnly;
        break;

    case FILE_RIGHT_NEWER:
        return config.rightNewer;
        break;

    case FILE_LEFT_NEWER:
        return config.leftNewer;
        break;

    case FILE_DIFFERENT:
        return config.different;
        break;

    default:
        return SyncConfiguration::SYNC_DIR_NONE;
    }
}


inline
bool getBytesToTransfer(const FileCompareLine& fileCmpLine,
                        const SyncConfiguration& config,
                        int& objectsToCreate,
                        int& objectsToOverwrite,
                        int& objectsToDelete,
                        wxULongLong& dataToProcess)
{   //return false if nothing has to be done

    objectsToCreate    = 0;  //always initialize variables
    objectsToOverwrite = 0;
    objectsToDelete    = 0;
    dataToProcess      = 0;

    //do not add filtered entries
    if (!fileCmpLine.selectedForSynchronization)
        return false;


    switch (fileCmpLine.cmpResult)
    {
    case FILE_LEFT_SIDE_ONLY:
        //get data to process
        switch (getSyncDirection(fileCmpLine.cmpResult, config))
        {
        case SyncConfiguration::SYNC_DIR_LEFT:   //delete file on left
            dataToProcess   = 0;
            objectsToDelete = 1;
            break;
        case SyncConfiguration::SYNC_DIR_RIGHT:  //copy from left to right
            dataToProcess   = fileCmpLine.fileDescrLeft.fileSize;
            objectsToCreate = 1;
            break;
        case SyncConfiguration::SYNC_DIR_NONE:
            return false;
        }
        break;

    case FILE_RIGHT_SIDE_ONLY:
        switch (getSyncDirection(fileCmpLine.cmpResult, config))
        {
        case SyncConfiguration::SYNC_DIR_LEFT:   //copy from right to left
            dataToProcess   = fileCmpLine.fileDescrRight.fileSize;
            objectsToCreate = 1;
            break;
        case SyncConfiguration::SYNC_DIR_RIGHT:  //delete file on right
            dataToProcess   = 0;
            objectsToDelete = 1;
            break;
        case SyncConfiguration::SYNC_DIR_NONE:
            return false;
        }
        break;

    case FILE_LEFT_NEWER:
    case FILE_RIGHT_NEWER:
    case FILE_DIFFERENT:
        //get data to process
        switch (getSyncDirection(fileCmpLine.cmpResult, config))
        {
        case SyncConfiguration::SYNC_DIR_LEFT:   //copy from right to left
            dataToProcess      = fileCmpLine.fileDescrRight.fileSize;
            objectsToOverwrite = 1;
            break;
        case SyncConfiguration::SYNC_DIR_RIGHT:  //copy from left to right
            dataToProcess      = fileCmpLine.fileDescrLeft.fileSize;
            objectsToOverwrite = 1;
            break;
        case SyncConfiguration::SYNC_DIR_NONE:
            return false;
        }
        break;

    case FILE_EQUAL:
        return false;

    default:
        assert(false);
        return false;
    };

    return true;
}


//runs at folder pair level
void calcBytesToSync(const FileComparison& fileCmp,
                     const SyncConfiguration& config,
                     int& objectsToCreate,
                     int& objectsToOverwrite,
                     int& objectsToDelete,
                     wxULongLong& dataToProcess)
{
    objectsToCreate    = 0;
    objectsToOverwrite = 0;
    objectsToDelete    = 0;
    dataToProcess      = 0;

    int toCreate    = 0;
    int toOverwrite = 0;
    int toDelete    = 0;
    wxULongLong data;

    for (FileComparison::const_iterator i = fileCmp.begin(); i != fileCmp.end(); ++i)
    {   //only sum up sizes of files AND directories
        if (getBytesToTransfer(*i, config, toCreate, toOverwrite, toDelete, data))
        {
            objectsToCreate    += toCreate;
            objectsToOverwrite += toOverwrite;
            objectsToDelete    += toDelete;
            dataToProcess      += data;
        }
    }
}


//aggregate over all folder pairs
void FreeFileSync::calcTotalBytesToSync(const FolderComparison& folderCmp,
                                        const SyncConfiguration& config,
                                        int& objectsToCreate,
                                        int& objectsToOverwrite,
                                        int& objectsToDelete,
                                        wxULongLong& dataToProcess)
{
    objectsToCreate    = 0;
    objectsToOverwrite = 0;
    objectsToDelete    = 0;
    dataToProcess      = 0;

    for (FolderComparison::const_iterator j = folderCmp.begin(); j != folderCmp.end(); ++j)
    {
        const FileComparison& fileCmp = j->fileCmp;

        int toCreate    = 0;
        int toOverwrite = 0;
        int toDelete    = 0;
        wxULongLong data;

        calcBytesToSync(fileCmp, config, toCreate, toOverwrite, toDelete, data);

        objectsToCreate    += toCreate;
        objectsToOverwrite += toOverwrite;
        objectsToDelete    += toDelete;
        dataToProcess      += data;
    }
}


template <bool recyclerUsed>
std::pair<wxLongLong, wxLongLong> spaceNeededSub(const FileComparison& fileCmp, const SyncConfiguration& config)
{
    wxLongLong spaceNeededLeft;
    wxLongLong spaceNeededRight;

    for (FileComparison::const_iterator i = fileCmp.begin(); i != fileCmp.end(); ++i)
    {
        if (i->selectedForSynchronization) //do not add filtered entries
        {
            //get data to process
            switch (getSyncDirection(i->cmpResult, config))
            {
            case SyncConfiguration::SYNC_DIR_LEFT:   //copy from right to left
                if (!recyclerUsed)
                    spaceNeededLeft -= globalFunctions::convertToSigned(i->fileDescrLeft.fileSize);
                spaceNeededLeft += globalFunctions::convertToSigned(i->fileDescrRight.fileSize);
                break;

            case SyncConfiguration::SYNC_DIR_RIGHT:  //copy from left to right
                if (!recyclerUsed)
                    spaceNeededRight -= globalFunctions::convertToSigned(i->fileDescrRight.fileSize);
                spaceNeededRight += globalFunctions::convertToSigned(i->fileDescrLeft.fileSize);
                break;

            case SyncConfiguration::SYNC_DIR_NONE:
                break;
            }
        }
    }

    return std::pair<wxLongLong, wxLongLong>(spaceNeededLeft, spaceNeededRight);
}


std::pair<wxLongLong, wxLongLong> freeDiskSpaceNeeded(const FileComparison& fileCmp, const SyncConfiguration& config, const bool recyclerUsed)
{
    if (recyclerUsed)
        return spaceNeededSub<true>(fileCmp, config);
    else
        return spaceNeededSub<false>(fileCmp, config);
}


bool FreeFileSync::synchronizationNeeded(const FolderComparison& folderCmp, const SyncConfiguration& config)
{
    int objectsToCreate     = 0;
    int objectsToOverwrite  = 0;
    int objectsToDelete     = 0;
    wxULongLong dataToProcess;

    FreeFileSync::calcTotalBytesToSync(folderCmp,
                                       config,
                                       objectsToCreate,
                                       objectsToOverwrite,
                                       objectsToDelete,
                                       dataToProcess);

    return objectsToCreate + objectsToOverwrite + objectsToDelete != 0;
}


//test if more then 50% of files will be deleted/overwritten
bool significantDifferenceDetected(const FileComparison& fileCmp, const SyncConfiguration& config)
{
    int objectsToCreate     = 0;
    int objectsToOverwrite  = 0;
    int objectsToDelete     = 0;
    wxULongLong dataToProcess;

    calcBytesToSync(fileCmp,
                    config,
                    objectsToCreate,
                    objectsToOverwrite,
                    objectsToDelete,
                    dataToProcess);

    const int changedFiles = objectsToCreate + objectsToOverwrite + objectsToDelete; //include objectsToCreate also!

    return changedFiles >= 10 && changedFiles > 0.5 * fileCmp.size();
}


SyncProcess::SyncProcess(const bool useRecycler,
                         const bool copyFileSymLinks,
                         const bool traverseDirSymLinks,
                         bool& warningSignificantDifference,
                         bool& warningNotEnoughDiskSpace,
                         StatusHandler* handler) :
        m_useRecycleBin(useRecycler),
        m_copyFileSymLinks(copyFileSymLinks),
        m_traverseDirSymLinks(traverseDirSymLinks),
        m_warningSignificantDifference(warningSignificantDifference),
        m_warningNotEnoughDiskSpace(warningNotEnoughDiskSpace),
        statusUpdater(handler),
        txtCopyingFile(Zstring(_("Copying file %x to %y")).Replace(wxT("%x"), wxT("\"%x\""), false).Replace(wxT("%y"), wxT("\n\"%y\""), false)),
        txtOverwritingFile(Zstring(_("Copying file %x to %y overwriting target")).Replace(wxT("%x"), wxT("\"%x\""), false).Replace(wxT("%y"), wxT("\n\"%y\""), false)),
        txtCreatingFolder(Zstring(_("Creating folder %x")).Replace( wxT("%x"), wxT("\n\"%x\""), false)),
        txtDeletingFile(Zstring(_("Deleting file %x")).Replace(wxT("%x"), wxT("\n\"%x\""), false)),
        txtDeletingFolder(Zstring(_("Deleting folder %x")).Replace( wxT("%x"), wxT("\n\"%x\""), false)) {}


inline
bool SyncProcess::synchronizeFile(const FileCompareLine& cmpLine, const SyncConfiguration& config, const FolderPair& folderPair)
{   //return false if nothing had to be done

    if (!cmpLine.selectedForSynchronization) return false;

    Zstring statusText;
    Zstring target;

    //synchronize file:
    switch (cmpLine.cmpResult)
    {
    case FILE_LEFT_SIDE_ONLY:
        switch (config.exLeftSideOnly)
        {
        case SyncConfiguration::SYNC_DIR_LEFT:   //delete files on left
            statusText = txtDeletingFile;
            statusText.Replace(wxT("%x"), cmpLine.fileDescrLeft.fullName, false);
            statusUpdater->updateStatusText(statusText);

            removeFile(cmpLine.fileDescrLeft.fullName, m_useRecycleBin);
            break;
        case SyncConfiguration::SYNC_DIR_RIGHT:  //copy files to right
            target = folderPair.rightDirectory + cmpLine.fileDescrLeft.relativeName.c_str();

            statusText = txtCopyingFile;
            statusText.Replace(wxT("%x"), cmpLine.fileDescrLeft.fullName.AfterLast(GlobalResources::FILE_NAME_SEPARATOR), false);
            statusText.Replace(wxT("%y"), target.BeforeLast(GlobalResources::FILE_NAME_SEPARATOR), false);
            statusUpdater->updateStatusText(statusText);

            copyFileUpdating(cmpLine.fileDescrLeft.fullName, target, cmpLine.fileDescrLeft.fileSize);
            break;
        case SyncConfiguration::SYNC_DIR_NONE:
            return false;
        }
        break;

    case FILE_RIGHT_SIDE_ONLY:
        switch (config.exRightSideOnly)
        {
        case SyncConfiguration::SYNC_DIR_LEFT:   //copy files to left
            target = folderPair.leftDirectory + cmpLine.fileDescrRight.relativeName.c_str();

            statusText = txtCopyingFile;
            statusText.Replace(wxT("%x"), cmpLine.fileDescrRight.fullName.AfterLast(GlobalResources::FILE_NAME_SEPARATOR), false);
            statusText.Replace(wxT("%y"), target.BeforeLast(GlobalResources::FILE_NAME_SEPARATOR), false);
            statusUpdater->updateStatusText(statusText);

            copyFileUpdating(cmpLine.fileDescrRight.fullName, target, cmpLine.fileDescrRight.fileSize);
            break;
        case SyncConfiguration::SYNC_DIR_RIGHT:  //delete files on right
            statusText = txtDeletingFile;
            statusText.Replace(wxT("%x"), cmpLine.fileDescrRight.fullName, false);
            statusUpdater->updateStatusText(statusText);

            removeFile(cmpLine.fileDescrRight.fullName, m_useRecycleBin);
            break;
        case SyncConfiguration::SYNC_DIR_NONE:
            return false;
        }
        break;

    case FILE_LEFT_NEWER:
    case FILE_RIGHT_NEWER:
    case FILE_DIFFERENT:
        switch (getSyncDirection(cmpLine.cmpResult, config))
        {
        case SyncConfiguration::SYNC_DIR_LEFT:   //copy from right to left
            statusText = txtOverwritingFile;
            statusText.Replace(wxT("%x"), cmpLine.fileDescrRight.fullName.AfterLast(GlobalResources::FILE_NAME_SEPARATOR), false);
            statusText.Replace(wxT("%y"), cmpLine.fileDescrLeft.fullName.BeforeLast(GlobalResources::FILE_NAME_SEPARATOR), false);
            statusUpdater->updateStatusText(statusText);

            removeFile(cmpLine.fileDescrLeft.fullName, m_useRecycleBin);  //only used if switch activated by user, else file is simply deleted
            copyFileUpdating(cmpLine.fileDescrRight.fullName, cmpLine.fileDescrLeft.fullName, cmpLine.fileDescrRight.fileSize);
            break;
        case SyncConfiguration::SYNC_DIR_RIGHT:  //copy from left to right
            statusText = txtOverwritingFile;
            statusText.Replace(wxT("%x"), cmpLine.fileDescrLeft.fullName.AfterLast(GlobalResources::FILE_NAME_SEPARATOR), false);
            statusText.Replace(wxT("%y"), cmpLine.fileDescrRight.fullName.BeforeLast(GlobalResources::FILE_NAME_SEPARATOR), false);
            statusUpdater->updateStatusText(statusText);

            removeFile(cmpLine.fileDescrRight.fullName, m_useRecycleBin);  //only used if switch activated by user, else file is simply deleted
            copyFileUpdating(cmpLine.fileDescrLeft.fullName, cmpLine.fileDescrRight.fullName, cmpLine.fileDescrLeft.fileSize);
            break;
        case SyncConfiguration::SYNC_DIR_NONE:
            return false;
        }
        break;

    case FILE_EQUAL:
        return false;

    default:
        assert (false);
    }
    return true;
}


inline
bool SyncProcess::synchronizeFolder(const FileCompareLine& cmpLine, const SyncConfiguration& config, const FolderPair& folderPair)
{   //return false if nothing had to be done

    if (!cmpLine.selectedForSynchronization) return false;

    Zstring statusText;
    Zstring target;

    //synchronize folders:
    switch (cmpLine.cmpResult)
    {
    case FILE_LEFT_SIDE_ONLY:
        switch (config.exLeftSideOnly)
        {
        case SyncConfiguration::SYNC_DIR_LEFT:   //delete folders on left
            statusText = txtDeletingFolder;
            statusText.Replace(wxT("%x"), cmpLine.fileDescrLeft.fullName, false);
            statusUpdater->updateStatusText(statusText);

            removeDirectory(cmpLine.fileDescrLeft.fullName, m_useRecycleBin);
            break;
        case SyncConfiguration::SYNC_DIR_RIGHT:  //create folders on right
            target = folderPair.rightDirectory + cmpLine.fileDescrLeft.relativeName.c_str();

            statusText = txtCreatingFolder;
            statusText.Replace(wxT("%x"), target, false);
            statusUpdater->updateStatusText(statusText);

            //some check to catch the error that directory on source has been deleted externally after "compare"...
            if (!wxDirExists(cmpLine.fileDescrLeft.fullName))
                throw FileError(Zstring(_("Error: Source directory does not exist anymore:")) + wxT("\n\"") + cmpLine.fileDescrLeft.fullName + wxT("\""));
            createDirectory(target, cmpLine.fileDescrLeft.fullName, !m_traverseDirSymLinks); //traverse symlinks <=> !copy symlinks
            break;
        case SyncConfiguration::SYNC_DIR_NONE:
            return false;
        }
        break;

    case FILE_RIGHT_SIDE_ONLY:
        switch (config.exRightSideOnly)
        {
        case SyncConfiguration::SYNC_DIR_LEFT:   //create folders on left
            target = folderPair.leftDirectory + cmpLine.fileDescrRight.relativeName.c_str();

            statusText = txtCreatingFolder;
            statusText.Replace(wxT("%x"), target, false);
            statusUpdater->updateStatusText(statusText);

            //some check to catch the error that directory on source has been deleted externally after "compare"...
            if (!wxDirExists(cmpLine.fileDescrRight.fullName))
                throw FileError(Zstring(_("Error: Source directory does not exist anymore:")) + wxT("\n\"") + cmpLine.fileDescrRight.fullName + wxT("\""));
            createDirectory(target, cmpLine.fileDescrRight.fullName, !m_traverseDirSymLinks); //traverse symlinks <=> !copy symlinks
            break;
        case SyncConfiguration::SYNC_DIR_RIGHT:  //delete folders on right
            statusText = txtDeletingFolder;
            statusText.Replace(wxT("%x"), cmpLine.fileDescrRight.fullName, false);
            statusUpdater->updateStatusText(statusText);

            removeDirectory(cmpLine.fileDescrRight.fullName, m_useRecycleBin);
            break;
        case SyncConfiguration::SYNC_DIR_NONE:
            return false;
        }
        break;

    case FILE_EQUAL:
        return false;

    case FILE_RIGHT_NEWER:
    case FILE_LEFT_NEWER:
    case FILE_DIFFERENT:
    default:
        assert (false);
    }
    return true;
}


inline
bool deletionImminent(const FileCompareLine& line, const SyncConfiguration& config)
{   //test if current sync-line will result in deletion of files    -> used to avoid disc space bottlenecks
    if (    (line.cmpResult == FILE_LEFT_SIDE_ONLY && config.exLeftSideOnly == SyncConfiguration::SYNC_DIR_LEFT) ||
            (line.cmpResult == FILE_RIGHT_SIDE_ONLY && config.exRightSideOnly == SyncConfiguration::SYNC_DIR_RIGHT))
        return true;
    else
        return false;
}


class RemoveAtExit //this class ensures, that the result of the method below is ALWAYS written on exit, even if exceptions are thrown!
{
public:
    RemoveAtExit(FileComparison& fileCmp) :
            gridToWrite(fileCmp) {}

    ~RemoveAtExit()
    {
        removeRowsFromVector(gridToWrite, rowsToDelete);
    }

    void markRow(int nr)
    {
        rowsToDelete.insert(nr);
    }

private:
    FileComparison& gridToWrite;
    std::set<int> rowsToDelete;
};


//synchronize and returns all rows that have not been synced
void SyncProcess::startSynchronizationProcess(FolderComparison& folderCmp, const SyncConfiguration& config)
{
#ifndef __WXDEBUG__
    wxLogNull noWxLogs; //prevent wxWidgets logging
#endif

    //-------------------some basic checks:------------------------------------------

    //test existence of Recycle Bin
    if (m_useRecycleBin && !FreeFileSync::recycleBinExists())
    {
        statusUpdater->reportFatalError(_("Unable to initialize Recycle Bin!"));
        return; //should be obsolete!
    }

    for (FolderComparison::const_iterator j = folderCmp.begin(); j != folderCmp.end(); ++j)
    {
        const FileComparison& fileCmp = j->fileCmp;

        //check if more than 50% of total number of files/dirs are to be created/overwritten/deleted
        if (m_warningSignificantDifference) //test if check should be executed
        {
            if (significantDifferenceDetected(fileCmp, config))
            {
                bool dontShowAgain = false;
                statusUpdater->reportWarning(Zstring(_("Significant difference detected:")) + wxT("\n") +
                                             j->syncPair.leftDirectory + wxT(" <-> ") + j->syncPair.rightDirectory + wxT("\n\n") +
                                             _("More than 50% of the total number of files will be copied or deleted!"),
                                             dontShowAgain);
                m_warningSignificantDifference = !dontShowAgain;
            }
        }

        //check for sufficient free diskspace in left directory
        if (m_warningNotEnoughDiskSpace)
        {
            const std::pair<wxLongLong, wxLongLong> spaceNeeded = freeDiskSpaceNeeded(fileCmp, config, m_useRecycleBin);

            wxLongLong freeDiskSpaceLeft;
            if (wxGetDiskSpace(j->syncPair.leftDirectory.c_str(), NULL, &freeDiskSpaceLeft))
            {
                if (freeDiskSpaceLeft < spaceNeeded.first)
                {
                    bool dontShowAgain = false;
                    statusUpdater->reportWarning(Zstring(_("Not enough free disk space available in:")) + wxT("\n") +
                                                 j->syncPair.leftDirectory + wxT("\n\n") +
                                                 _("Total required free disk space:") + wxT(" ") + formatFilesizeToShortString(spaceNeeded.first).c_str(),
                                                 dontShowAgain);
                    m_warningNotEnoughDiskSpace = !dontShowAgain;
                }
            }

            //check for sufficient free diskspace in right directory
            if (m_warningNotEnoughDiskSpace)
            {
                wxLongLong freeDiskSpaceRight;
                if (wxGetDiskSpace(j->syncPair.rightDirectory.c_str(), NULL, &freeDiskSpaceRight))
                {
                    if (freeDiskSpaceRight < spaceNeeded.second)
                    {
                        bool dontShowAgain = false;
                        statusUpdater->reportWarning(Zstring(_("Not enough free disk space available in:")) + wxT("\n") +
                                                     j->syncPair.rightDirectory + wxT("\n\n") +
                                                     _("Total required free disk space:") + wxT(" ") + formatFilesizeToShortString(spaceNeeded.second).c_str(),
                                                     dontShowAgain);
                        m_warningNotEnoughDiskSpace = !dontShowAgain;
                    }
                }
            }
        }
    }
    //-------------------end of basic checks------------------------------------------


    //inform about the total amount of data that will be processed from now on
    int objectsToCreate      = 0;
    int objectsToOverwrite   = 0;
    int objectsToDelete      = 0;
    wxULongLong dataToProcess;

    FreeFileSync::calcTotalBytesToSync(folderCmp,
                                       config,
                                       objectsToCreate,
                                       objectsToOverwrite,
                                       objectsToDelete,
                                       dataToProcess);

    statusUpdater->initNewProcess(objectsToCreate + objectsToOverwrite + objectsToDelete,
                                  globalFunctions::convertToSigned(dataToProcess),
                                  StatusHandler::PROCESS_SYNCHRONIZING);

    try
    {
        //loop over folder pairs
        for (FolderComparison::iterator j = folderCmp.begin(); j != folderCmp.end(); ++j)
        {
            FileComparison& fileCmp = j->fileCmp;

            //ensure that folderCmp is always written to, even if method is left via exceptions
            RemoveAtExit removeRowsAtExit(fileCmp); //note: running at individual folder pair level!

            const FolderPair& currentPair = j->syncPair;

            // it should never happen, that a directory on left side has same name as file on right side. startCompareProcess() should take care of this
            // and split into two "exists on one side only" cases
            // Note: this case is not handled by this tool as this is considered to be a bug and must be solved by the user

            //synchronize folders first; advantage: in case of deletions the whole folder is moved to recycle bin instead of single files
            for (FileComparison::const_iterator i = fileCmp.begin(); i != fileCmp.end(); ++i)
            {
                if (    i->fileDescrLeft.objType == FileDescrLine::TYPE_DIRECTORY ||
                        i->fileDescrRight.objType == FileDescrLine::TYPE_DIRECTORY)
                {
                    while (true)
                    {   //trigger display refresh
                        statusUpdater->requestUiRefresh();

                        try
                        {
                            if (synchronizeFolder(*i, config, currentPair))
                                //progress indicator update
                                //indicator is updated only if directory is sync'ed correctly (and if some work was done)!
                                statusUpdater->updateProcessedData(1, 0);  //each call represents one processed file/directory

                            removeRowsAtExit.markRow(i - fileCmp.begin());
                            break;
                        }
                        catch (FileError& error)
                        {
                            ErrorHandler::Response rv = statusUpdater->reportError(error.show());

                            if ( rv == ErrorHandler::IGNORE_ERROR)
                                break;
                            else if (rv == ErrorHandler::RETRY)
                                ;  //continue with loop
                            else
                                assert (false);
                        }
                    }
                }
            }

            //PERF_START;

            //synchronize files:
            for (int k = 0; k < 2; ++k) //loop over all files twice; reason: first delete, then copy (no sorting necessary: performance)
            {
                bool deleteLoop = true;
                deleteLoop = k == 0;   //-> first loop: delete files, second loop: copy files

                for (FileComparison::const_iterator i = fileCmp.begin(); i != fileCmp.end(); ++i)
                {
                    if (    i->fileDescrLeft.objType == FileDescrLine::TYPE_FILE ||
                            i->fileDescrRight.objType == FileDescrLine::TYPE_FILE)
                    {
                        if (    (deleteLoop && deletionImminent(*i, config)) ||
                                (!deleteLoop && !deletionImminent(*i, config)))
                        {
                            while (true)
                            {    //trigger display refresh
                                statusUpdater->requestUiRefresh();

                                try
                                {
                                    if (synchronizeFile(*i, config, currentPair))
                                    {
                                        //progress indicator update
                                        //indicator is updated only if file is sync'ed correctly (and if some sync was done)!
                                        int objectsToCreate    = 0;
                                        int objectsToOverwrite = 0;
                                        int objectsToDelete    = 0;
                                        wxULongLong dataToProcess;

                                        if (getBytesToTransfer(*i,
                                                               config,
                                                               objectsToCreate,
                                                               objectsToOverwrite,
                                                               objectsToDelete,
                                                               dataToProcess))  //update status if some work was done (answer is always "yes" in this context)
                                            statusUpdater->updateProcessedData(objectsToCreate + objectsToOverwrite + objectsToDelete, 0); //processed data is communicated in subfunctions!
                                    }

                                    removeRowsAtExit.markRow(i - fileCmp.begin());
                                    break;
                                }
                                catch (FileError& error)
                                {
                                    ErrorHandler::Response rv = statusUpdater->reportError(error.show());

                                    if ( rv == ErrorHandler::IGNORE_ERROR)
                                        break;
                                    else if (rv == ErrorHandler::RETRY)
                                        ;   //continue with loop
                                    else
                                        assert (false);
                                }
                            }
                        }
                    }
                }
            }
        }
    }
    catch (const RuntimeException& theException)
    {
        statusUpdater->reportFatalError(theException.show().c_str());
        return; //should be obsolete!
    }
}


//###########################################################################################
//callback functionality for smooth progress indicators

struct CallBackData
{
    StatusHandler* handler;
    wxLongLong bytesTransferredLast;
};

#ifdef FFS_WIN
const DWORD COPY_FILE_COPY_SYMLINK = 0x00000800;

DWORD CALLBACK copyProcessCallback(
    LARGE_INTEGER totalFileSize,
    LARGE_INTEGER totalBytesTransferred,
    LARGE_INTEGER streamSize,
    LARGE_INTEGER streamBytesTransferred,
    DWORD dwStreamNumber,
    DWORD dwCallbackReason,
    HANDLE hSourceFile,
    HANDLE hDestinationFile,
    LPVOID lpData)
{
    //small performance optimization: it seems this callback function is called for every 64 kB (depending on cluster size).
    static unsigned callNr = 0;
    if (++callNr % 50 == 0) //reduce by factor of 50 =^ 10-20 calls/sec
    {
        CallBackData* sharedData = static_cast<CallBackData*>(lpData);

        assert(totalBytesTransferred.HighPart >= 0);

        if (totalBytesTransferred.HighPart < 0) //let's see if someone answers the call...
            wxMessageBox(wxT("You've just discovered a bug in WIN32 API function \"CopyFileEx\"! \n\n\
            Please write a mail to the author of FreeFileSync at zhnmju123@gmx.de and simply state that\n\
            \"totalBytesTransferred.HighPart can be below zero\"!\n\n\
            This will then be handled in future versions of FreeFileSync.\n\nThanks -ZenJu"), wxT("Warning"));

        //inform about the (differential) processed amount of data
        const wxLongLong currentBytesTransferred(totalBytesTransferred.HighPart, totalBytesTransferred.LowPart);
        sharedData->handler->updateProcessedData(0, currentBytesTransferred - sharedData->bytesTransferredLast);
        sharedData->bytesTransferredLast = currentBytesTransferred;

        sharedData->handler->requestUiRefresh(false); //don't allow throwing exception within this call

        if (sharedData->handler->abortIsRequested())
            return PROGRESS_CANCEL;
    }

    return PROGRESS_CONTINUE;
}

#elif defined FFS_LINUX
void copyProcessCallback(const wxULongLong& totalBytesTransferred, void* data)
{   //called every 512 kB

    CallBackData* sharedData = static_cast<CallBackData*>(data);

    //convert to unsigned
    const wxLongLong totalBytes = globalFunctions::convertToSigned(totalBytesTransferred);

    //inform about the (differential) processed amount of data
    sharedData->handler->updateProcessedData(0, totalBytes - sharedData->bytesTransferredLast);
    sharedData->bytesTransferredLast = totalBytes;

    sharedData->handler->requestUiRefresh(); //exceptions may be thrown here!
}
#endif


//copy file while executing statusUpdater->requestUiRefresh() calls
void SyncProcess::copyFileUpdating(const Zstring& source, const Zstring& target, const wxULongLong& totalBytesToCpy)
{
    //create folders first (see http://sourceforge.net/tracker/index.php?func=detail&aid=2628943&group_id=234430&atid=1093080)
    const Zstring targetDir = target.BeforeLast(GlobalResources::FILE_NAME_SEPARATOR);
    if (!wxDirExists(targetDir.c_str()))
    {
        const Zstring templateDir = source.BeforeLast(GlobalResources::FILE_NAME_SEPARATOR);
        FreeFileSync::createDirectory(targetDir, templateDir, !m_traverseDirSymLinks); //might throw FileError() exception
    }

    //start of (possibly) long-running copy process: ensure status updates are performed regularly
#ifdef FFS_WIN //update via call-back function

    CallBackData sharedData;
    sharedData.handler = statusUpdater;
//data.bytesTransferredLast =


    DWORD copyFlags = COPY_FILE_FAIL_IF_EXISTS;

    if (m_copyFileSymLinks) //copy symbolic links instead of the files pointed at
        copyFlags |= COPY_FILE_COPY_SYMLINK;

    if (!CopyFileEx( //same performance as CopyFile()
                source.c_str(),
                target.c_str(),
                copyProcessCallback,
                &sharedData,
                NULL,
                copyFlags))
    {
        //error situation: undo communication of processed amount of data
        statusUpdater->updateProcessedData(0, sharedData.bytesTransferredLast * -1 );

        statusUpdater->requestUiRefresh(); //abort if requested, don't show error message if cancelled by user!

        Zstring errorMessage = Zstring(_("Error copying file:")) + wxT("\n\"") + source +  wxT("\" -> \"") + target + wxT("\"");
        errorMessage += Zstring(wxT("\n\n"));
        errorMessage += FreeFileSync::getLastErrorFormatted(); //some additional windows error information
        throw FileError(errorMessage);
    }

    //inform about the (remaining) processed amount of data
    statusUpdater->updateProcessedData(0, globalFunctions::convertToSigned(totalBytesToCpy) - sharedData.bytesTransferredLast);


#elif defined FFS_LINUX //update via call-back function

    CallBackData sharedData;
    sharedData.handler = statusUpdater;
//data.bytesTransferredLast =

    try
    {
        FreeFileSync::copyFile(source,
                               target,
                               m_copyFileSymLinks,
                               copyProcessCallback,
                               &sharedData);
    }
    catch (...)
    {
        //error situation: undo communication of processed amount of data
        statusUpdater->updateProcessedData(0, sharedData.bytesTransferredLast * -1 );

        throw;
    }

    //inform about the (remaining) processed amount of data
    statusUpdater->updateProcessedData(0, globalFunctions::convertToSigned(totalBytesToCpy) - sharedData.bytesTransferredLast);
#endif
}

/*
//##### OLD IMPLEMENTATION WITHOUT SMOOTH PROGRESS INDICATOR ################

#ifdef FFS_LINUX
//handle execution of a method while updating the UI
class UpdateWhileCopying : public UpdateWhileExecuting
{
public:
    UpdateWhileCopying() {}
    ~UpdateWhileCopying() {}

    Zstring source;
    Zstring target;
    bool success;
    Zstring errorMessage;

private:
    virtual void longRunner()
    {
        try
        {
            FreeFileSync::copyFile(source, target);
        }
        catch (const FileError& e)
        {
            success = false;
            errorMessage = e.show();
            return;
        }

        success = true;
    }
};

void copyFileUpdating(const Zstring& source, const Zstring& target, const wxULongLong& totalBytesToCpy, StatusHandler* updateClass)
{
    //create folders first (see http://sourceforge.net/tracker/index.php?func=detail&aid=2628943&group_id=234430&atid=1093080)
    const Zstring targetDir = target.BeforeLast(GlobalResources::FILE_NAME_SEPARATOR);
    if (!wxDirExists(targetDir.c_str()))
    {
        const Zstring templateDir = source.BeforeLast(GlobalResources::FILE_NAME_SEPARATOR);
        FreeFileSync::createDirectory(targetDir, templateDir); //might throw FileError() exception
    }

//update while copying via additional worker thread
    static UpdateWhileCopying copyAndUpdate; //single instantiation: thread enters wait phase after each execution

    copyAndUpdate.waitUntilReady();

    //longRunner is called from thread, but no mutex needed here, since thread is in waiting state!
    copyAndUpdate.source = source;
    copyAndUpdate.target = target;

    copyAndUpdate.execute(updateClass);

    //no mutex needed here since longRunner is finished
    if (!copyAndUpdate.success)
        throw FileError(copyAndUpdate.errorMessage);

    //inform about the processed amount of data
    updateClass->updateProcessedData(0, totalBytesToCpy.ToDouble());
#endif
}
*/