OSGA_Archive.cpp

#include <osg/Notify>
#include <osg/Endian>

#include <osgDB/Registry>
#include <osgDB/FileNameUtils>

#include "OSGA_Archive.h"

using namespace osgDB;

/*
Functions to convert between
    std::streampos ( typedef'ed as iostream::pos_type
              used as seekp,seekg argument and tellp,tellg return value )
and
    OSGA_Archive::pos_type (64 bit file position index)

Purpose:
    To allow using OSGA files larger than 4GiB in Windows.

    std::streampos is used as argument to iostreams seekp and seekg methods
    and is returned as result from iostream tellp and tellg methods.

    std::streampos can be implicitly cast from/to std::streamoff as
    std::streampos class defines appropriate constructor and cast operator.

    Since std::streamoff is usually defined as simple int,
    it is possible to call seekp( ), seekg( ) with int argument and
    assign tellp(), tellg() result to int type.

    But this implicit methods fail when std::streamoff is 32 bit and
    std::streampos actually points past 32 bit addressable range (2 GiB).

    Even if std::streamoff is 32 bit and incapable of representing 64 bit file
    positions, original std::streampos may be perfectly able to handle them.

    But, when such situation occurs more elaborate conversion methods from/to
    std::streampos are needed. Functions below employ such methods.

    I made this fix for use with 32 bit Windows OSG. Actually this
    solution is not dependent on OS but standard C++ library.
    Microsoft SDKs always use some version of Dinkumware libs.

    Practically this tweak is made for Dinkumware C++ libs. I hope it can
    be easily extended to other 32bit systems supporting 64bit files, provided
    their std::streampos implementations are similar.

    I based my solution on a small portion of boost iostreams code.
    For additional reference look at:
        http://boost.org/boost/iostreams/positioning.hpp
*/

/*
    Recognize Dinkumware std C++ lib implementation. Its used by Microsoft,
    but method is more generic - should work in all Dinkumware environments.

    Complex condition below was taken from
        http://boost.org/boost/iostreams/positioning.hpp

    Great thanks to J.Tukanis and G. Sylvester-Bradley for figuring it out.
*/
#if ((defined(_YVALS) && !defined(__IBMCPP__)) || defined(_CPPLIB_VER)) && \
     !defined(__SGI_STL_PORT) && !defined(_STLPORT_VERSION) \
     && !defined(__QNX__)

inline std::streampos STREAM_POS( const OSGA_Archive::pos_type pos )
{
    return std::streampos( std::mbstate_t(), pos );
}

inline OSGA_Archive::pos_type ARCHIVE_POS( const std::streampos & pos )
{
#if (defined(_CPPLIB_VER) && defined(_MSC_VER) && _MSC_VER > 1914)   // VC++ 2017 version 15.8 or later
	fpos_t position = pos;
#elif (defined(_CPPLIB_VER) && defined(_MSC_VER)) // Dinkumware (eg: one included with VC++ 2003, 2005...)
	fpos_t position = pos.seekpos();
#else // older Dinkumware (eg: one included in Win Server 2003 Platform SDK )
	fpos_t position = pos.get_fpos_t();
#endif
    std::streamoff offset = pos.operator std::streamoff( ) - _FPOSOFF( position );

    return OSGA_Archive::pos_type( position + offset );
}
#else // non Dinkumware std C++ lib implementations
// do the old school streampos <-> streamoff casts
inline std::streampos STREAM_POS( const OSGA_Archive::pos_type pos )
{
    return std::streampos( pos );
}

inline OSGA_Archive::pos_type ARCHIVE_POS( const std::streampos & pos )
{
    return OSGA_Archive::pos_type( pos );
}
#endif // Dinkumware std C++ lib
////////////////////////////////////////////////////////////////////////////////
float OSGA_Archive::s_currentSupportedVersion = 0.0;
const unsigned int ENDIAN_TEST_NUMBER = 0x00000001;

OSGA_Archive::IndexBlock::IndexBlock(unsigned int blockSize):
    _requiresWrite(false),
    _filePosition(0),
    _blockSize(0),
    _filePositionNextIndexBlock(0),
    _offsetOfNextAvailableSpace(0),
    _data(0)
{
    allocateData(blockSize);
}

OSGA_Archive::IndexBlock::~IndexBlock()
{
    delete [] _data;
}

void OSGA_Archive::IndexBlock::allocateData(unsigned int blockSize)
{
    _data = (blockSize!=0) ? new char[blockSize]  : 0;
    if (_data)
    {
        _blockSize = blockSize;

        // initialize the array
        char* end = _data + _blockSize;
        for(char* ptr=_data; ptr < end; ++ptr) *ptr = 0;
    }
    else
    {
        _blockSize = 0;
    }
}

OSGA_Archive::IndexBlock* OSGA_Archive::IndexBlock::read(std::istream& in, bool doEndianSwap)
{
    if (!in) return 0;

    osg::ref_ptr<IndexBlock> indexBlock = new IndexBlock;
    indexBlock->_filePosition = ARCHIVE_POS( in.tellg() );
    in.read(reinterpret_cast<char*>(&indexBlock->_blockSize), sizeof(indexBlock->_blockSize));
    in.read(reinterpret_cast<char*>(&indexBlock->_filePositionNextIndexBlock), sizeof(indexBlock->_filePositionNextIndexBlock));
    in.read(reinterpret_cast<char*>(&indexBlock->_offsetOfNextAvailableSpace), sizeof(indexBlock-> _offsetOfNextAvailableSpace));

    if (doEndianSwap)
    {
        osg::swapBytes(reinterpret_cast<char*>(&indexBlock->_blockSize), sizeof(indexBlock->_blockSize));
        osg::swapBytes(reinterpret_cast<char*>(&indexBlock->_filePositionNextIndexBlock), sizeof(indexBlock->_filePositionNextIndexBlock));
        osg::swapBytes(reinterpret_cast<char*>(&indexBlock->_offsetOfNextAvailableSpace), sizeof(indexBlock-> _offsetOfNextAvailableSpace));
    }

//    OSG_INFO<<"indexBlock->_blockSize="<<indexBlock->_blockSize<<std::endl;
//    OSG_INFO<<"indexBlock->_filePositionNextIndexBlock="<<indexBlock->_filePositionNextIndexBlock<<std::endl;
//    OSG_INFO<<"indexBlock->_offsetOfNextAvailableSpace="<<indexBlock->_offsetOfNextAvailableSpace<<std::endl;

    indexBlock->allocateData(indexBlock->_blockSize);
    if (indexBlock->_data)
    {
        in.read(reinterpret_cast<char*>(indexBlock->_data),indexBlock->_blockSize);

        if (doEndianSwap)
        {
            char* ptr = indexBlock->_data;
            char* end_ptr = indexBlock->_data + indexBlock->_offsetOfNextAvailableSpace;
            while (ptr<end_ptr)
            {
                osg::swapBytes(ptr,sizeof(pos_type));
                ptr += sizeof(pos_type);

                osg::swapBytes(ptr,sizeof(size_type));
                ptr += sizeof(size_type);

                osg::swapBytes(ptr,sizeof(unsigned int));
                unsigned int filename_size; // = *(reinterpret_cast<unsigned int*>(ptr));
                _read(ptr, filename_size);
                ptr += sizeof(unsigned int);
                ptr += filename_size;

                OSG_INFO<<"filename size="<<filename_size<<std::endl;

            }
        }
    }
    else
    {
        OSG_INFO<<"Allocation Problem in OSGA_Archive::IndexBlock::read(std::istream& in)"<<std::endl;
        return 0;
    }

    OSG_INFO<<"Read index block"<<std::endl;

    return indexBlock.release();

}

std::string OSGA_Archive::IndexBlock::getFirstFileName() const
{
    char* ptr = _data;
    char* end_ptr = _data + _offsetOfNextAvailableSpace;
    if (ptr<end_ptr)
    {
        ptr += sizeof(pos_type);
        ptr += sizeof(size_type);

        unsigned int filename_size; // = *(reinterpret_cast<unsigned int*>(ptr));
        _read(ptr, filename_size);
        ptr += sizeof(unsigned int);

        return std::string(ptr, ptr+filename_size);
    }
    else
    {
        return std::string();
    }
}

bool OSGA_Archive::IndexBlock::getFileReferences(FileNamePositionMap& indexMap) const
{
    if (!_data || _offsetOfNextAvailableSpace==0) return false;

    bool valuesAdded = false;

    char* ptr = _data;
    char* end_ptr = _data + _offsetOfNextAvailableSpace;
    while (ptr<end_ptr)
    {
        pos_type position; // = *(reinterpret_cast<pos_type*>(ptr));
        _read(ptr, position);
        ptr += sizeof(pos_type);

        size_type size; // = *(reinterpret_cast<size_type*>(ptr));
        _read(ptr, size);
        ptr += sizeof(size_type);

        unsigned int filename_size; // = *(reinterpret_cast<unsigned int*>(ptr));
        _read(ptr, filename_size);
        ptr += sizeof(unsigned int);

        std::string filename(ptr, ptr+filename_size);

        // record this entry into the FileNamePositionMap.
        // Requests for files will be in unix style even on Win32 so need unix style keys in map.
        indexMap[osgDB::convertFileNameToUnixStyle(filename)] = PositionSizePair(position,size);

        ptr += filename_size;

        valuesAdded = true;
    }
    return valuesAdded;
}

void OSGA_Archive::IndexBlock::write(std::ostream& out)
{
    pos_type currentPos = ARCHIVE_POS( out.tellp() );

    if (_filePosition==pos_type(0))
    {
        OSG_INFO<<"OSGA_Archive::IndexBlock::write() setting _filePosition"<<std::endl;
        _filePosition = currentPos;
    }
    else
    {
         out.seekp( STREAM_POS( _filePosition ) );
    }
    OSG_INFO<<"OSGA_Archive::IndexBlock::write() to _filePosition"<< ARCHIVE_POS( out.tellp() )<<std::endl;

    out.write(reinterpret_cast<char*>(&_blockSize), sizeof(_blockSize));
    out.write(reinterpret_cast<char*>(&_filePositionNextIndexBlock), sizeof(_filePositionNextIndexBlock));
    out.write(reinterpret_cast<char*>(&_offsetOfNextAvailableSpace), sizeof(_offsetOfNextAvailableSpace));

    out.write(reinterpret_cast<char*>(_data),_blockSize);

    if( _filePosition < currentPos ) // move file ptr to the end of file
        out.seekp( STREAM_POS( currentPos ) );

    OSG_INFO<<"OSGA_Archive::IndexBlock::write() end"<<std::endl;
}


bool OSGA_Archive::IndexBlock::addFileReference(pos_type position, size_type size, const std::string& filename)
{
    if (spaceAvailable(position, size, filename))
    {
        char* ptr = _data+_offsetOfNextAvailableSpace;

        //*(reinterpret_cast<pos_type*>(ptr)) = position;
        _write(ptr, position);
        ptr += sizeof(pos_type);

        //*(reinterpret_cast<size_type*>(ptr)) = size;
        _write(ptr, size);
        ptr += sizeof(size_type);

        //*(reinterpret_cast<unsigned int*>(ptr)) = filename.size();
        _write(ptr, static_cast<unsigned int>(filename.size()));
        ptr += sizeof(unsigned int);

        for(unsigned int i=0;i<filename.size();++i, ++ptr)
        {
            *ptr = filename[i];
        }

        _offsetOfNextAvailableSpace = ptr-_data;

        _requiresWrite = true;

        OSG_INFO<<"OSGA_Archive::IndexBlock::addFileReference("<<(unsigned int)position<<", "<<filename<<")"<<std::endl;

        return true;
    }
    else
    {
        return false;
    }
}

void OSGA_Archive::IndexBlock::setPositionNextIndexBlock(pos_type position)
{
    _filePositionNextIndexBlock = position;
    _requiresWrite = true;
}

OSGA_Archive::OSGA_Archive():
    _version(0.0f),
    _status(READ)
{
}

OSGA_Archive::~OSGA_Archive()
{
    close();
}


bool OSGA_Archive::open(const std::string& filename, ArchiveStatus status, unsigned int indexBlockSize)
{
    SERIALIZER();

    _archiveFileName = filename;

    if (status==READ)
    {
        _status = status;
        _input.open(filename.c_str(), std::ios_base::binary | std::ios_base::in);

        return _open(_input);
    }
    else
    {
        if (status==WRITE && open(filename,READ))
        {
            pos_type file_size( 0 );
            _input.seekg( 0, std::ios_base::end );
            file_size = ARCHIVE_POS( _input.tellg() );
            if( _input.is_open() && file_size <= 0 )
            {   // compute end of file position manually ...
                // seekp( 0, ios::end ), tellp( ) fails in 32 bit windows with files > 4 GiB
                size_t BlockHeaderSize =
                    sizeof( unsigned int /*_blockSize*/ ) +
                    sizeof( pos_type /*_filePositionNextIndexBlock*/ ) +
                    sizeof( unsigned int /*_offsetOfNextAvailableSpace*/ );

                for(IndexBlockList::iterator itr=_indexBlockList.begin();
                    itr!=_indexBlockList.end();
                    ++itr)
                {
                    pos_type end = (*itr)->getPosition() + BlockHeaderSize + (*itr)->getBlockSize();
                    if( file_size < end ) file_size = end;
                }

                for(FileNamePositionMap::iterator mitr=_indexMap.begin();
                    mitr!=_indexMap.end();
                    ++mitr)
                {
                    pos_type end = mitr->second.first + mitr->second.second;
                    if( file_size < end ) file_size = end;
                }
            }
            _input.close();
            _status = WRITE;

            osgDB::open(_output, filename.c_str(), std::ios_base::binary | std::ios_base::in | std::ios_base::out);

            OSG_INFO<<"File position after open = "<<ARCHIVE_POS( _output.tellp() )<<" is_open "<<_output.is_open()<<std::endl;

            // place write position at end of file.
            _output.seekp( STREAM_POS( file_size ) );

            OSG_INFO<<"File position after seekp = "<<ARCHIVE_POS( _output.tellp() )<<std::endl;

            OSG_INFO<<"OSGA_Archive::open("<<filename<<") open for writing"<<std::endl;

            return true;
        }
        else // no file opened or using create so resort to creating the archive.
        {
            OSG_INFO<<"OSGA_Archive::open("<<filename<<"), archive being created."<<std::endl;

            _status = WRITE;
            osgDB::open(_output, filename.c_str(), std::ios_base::out | std::ios_base::binary | std::ios_base::trunc);
            _output<<"osga";
            _output.write(reinterpret_cast<const char*>(&ENDIAN_TEST_NUMBER),4);
            _output.write(reinterpret_cast<char*>(&s_currentSupportedVersion),sizeof(float));

            IndexBlock *indexBlock = new IndexBlock(indexBlockSize);
            if (indexBlock)
            {
                indexBlock->write(_output);
                _indexBlockList.push_back(indexBlock);
            }

            OSG_INFO<<"File position after write = "<<ARCHIVE_POS( _output.tellp() )<<std::endl;

            return true;
        }

    }
}

bool OSGA_Archive::open(std::istream& fin)
{
    SERIALIZER();

    _archiveFileName = "";

    OSG_NOTICE<<"OSGA_Archive::open"<<std::endl;
    static_cast<std::istream&>(_input).rdbuf(fin.rdbuf());
    return _open(_input);
}

bool OSGA_Archive::_open(std::istream& input)
{
    if (input)
    {
        char identifier[4];
        input.read(identifier,4);

        bool validArchive = (identifier[0]=='o' && identifier[1]=='s' && identifier[2]=='g' && identifier[3]=='a');
        if (validArchive)
        {

            unsigned int endianTestWord=0;
            input.read(reinterpret_cast<char*>(&endianTestWord),4);
            bool doEndianSwap = (endianTestWord!=ENDIAN_TEST_NUMBER);

            input.read(reinterpret_cast<char*>(&_version),sizeof(_version));
            if (doEndianSwap)
            {
                osg::swapBytes(reinterpret_cast<char*>(&_version),sizeof(_version));
            }

            OSG_INFO<<"OSGA_Archive::open() doEndianSwap="<<doEndianSwap<<std::endl;
            OSG_INFO<<"OSGA_Archive::open() Version="<<_version<<std::endl;

            IndexBlock *indexBlock = 0;

            while ( (indexBlock=OSGA_Archive::IndexBlock::read(input, doEndianSwap)) != 0)
            {
                _indexBlockList.push_back(indexBlock);
                if (indexBlock->getPositionNextIndexBlock()==pos_type(0)) break;

                input.seekg( STREAM_POS( indexBlock->getPositionNextIndexBlock() ) );
            }

            // now need to build the filename map.
            _indexMap.clear();

            if (!_indexBlockList.empty())
            {
                _masterFileName = _indexBlockList.front()->getFirstFileName();
            }

            for(IndexBlockList::iterator itr=_indexBlockList.begin();
                itr!=_indexBlockList.end();
                ++itr)
            {
                (*itr)->getFileReferences(_indexMap);
            }

            for(FileNamePositionMap::iterator mitr=_indexMap.begin();
                mitr!=_indexMap.end();
                ++mitr)
            {
                OSG_INFO<<"    filename "<<(mitr->first)<<" pos="<<(int)((mitr->second).first)<<" size="<<(int)((mitr->second).second)<<std::endl;
            }


            return true;
        }
    }
    return false;
}

void OSGA_Archive::close()
{
    SERIALIZER();

    _input.close();

    if (_status==WRITE)
    {
        writeIndexBlocks();
        _output.close();
    }
}

std::string OSGA_Archive::getMasterFileName() const
{
    return _masterFileName;
}

osgDB::FileType OSGA_Archive::getFileType(const std::string& filename) const
{
    if (_indexMap.count(filename)!=0) return osgDB::REGULAR_FILE;
    return osgDB::FILE_NOT_FOUND;
}

bool OSGA_Archive::getFileNames(FileNameList& fileNameList) const
{
    SERIALIZER();

    fileNameList.clear();
    fileNameList.reserve(_indexMap.size());
    for(FileNamePositionMap::const_iterator itr=_indexMap.begin();
        itr!=_indexMap.end();
        ++itr)
    {
        fileNameList.push_back(itr->first);
    }
    return !fileNameList.empty();
}

void OSGA_Archive::writeIndexBlocks()
{
    SERIALIZER();

    if (_status==WRITE)
    {
        for(IndexBlockList::iterator itr=_indexBlockList.begin();
            itr!=_indexBlockList.end();
            ++itr)
        {
            if ((*itr)->requiresWrite())
            {
                (*itr)->write(_output);
            }
        }
    }
}

bool OSGA_Archive::fileExists(const std::string& filename) const
{
    return (_indexMap.count(filename)!=0);
}

bool OSGA_Archive::addFileReference(pos_type position, size_type size, const std::string& fileName)
{
    SERIALIZER();

    if (_status==READ)
    {
        OSG_INFO<<"OSGA_Archive::getPositionForNewEntry("<<fileName<<") failed, archive opened as read only."<<std::endl;
        return false;
    }

    if (!_output)
    {
        OSG_INFO<<"OSGA_Archive::getPositionForNewEntry("<<fileName<<") failed, _output set up."<<std::endl;
        return false;
    }


    // if the masterFileName isn't set yet use this fileName
    if (_masterFileName.empty()) _masterFileName = fileName;


    // get an IndexBlock with space available if possible
    unsigned int blockSize = 4096;
    osg::ref_ptr<IndexBlock> indexBlock = _indexBlockList.empty() ? 0 : _indexBlockList.back().get();
    osg::ref_ptr<IndexBlock> previousBlock = indexBlock;
    if (indexBlock.valid())
    {
        blockSize = indexBlock->getBlockSize();
        if (!(indexBlock->spaceAvailable(position, size, fileName)))
        {
            previousBlock = indexBlock;
            indexBlock = 0;
        }
    }

    // if not one available create a new block.
    if (!indexBlock)
    {
        if (previousBlock.valid()) previousBlock->setPositionNextIndexBlock( ARCHIVE_POS( _output.tellp() ) );

        indexBlock = new IndexBlock(blockSize);
        indexBlock->write(_output);
        _indexBlockList.push_back(indexBlock.get());
    }

    if (indexBlock.valid())
    {
        return indexBlock->addFileReference(position, size, fileName);
    }
    return false;
}


// streambuffer class to give access to a portion of the archive stream, for numChars onwards
// from the current position in the archive.

class proxy_streambuf : public std::streambuf
{
public:

    proxy_streambuf(std::streambuf* streambuf, std::streamoff numChars):
        _streambuf(streambuf),_oneChar(0), _curPos(0),_numChars(numChars)
    {
        _startPos = ARCHIVE_POS(_streambuf->pubseekoff(0, std::ios_base::cur, std::ios_base::in));
        setg(&_oneChar, (&_oneChar)+1, (&_oneChar)+1);
    }

    // Destructor deallocates no buffer space.
    virtual ~proxy_streambuf()  {}

    std::streambuf* _streambuf; // Underlying archive stream

protected:

    char_type _oneChar;         // Single character buffer
    std::streamoff _curPos, _numChars;
    OSGA_Archive::pos_type _startPos;

    // Set internal position pointer to relative position.  Virtual function called by the public
    // member function pubseekoff to alter the stream position.

    virtual std::streampos seekoff (std::streamoff off, std::ios_base::seekdir way,
                   std::ios_base::openmode which = std::ios_base::in)
    {
        std::streamoff newpos;
        if ( way == std::ios_base::beg )
        {
            newpos = off;
        }
        else if ( way == std::ios_base::cur )
        {
            newpos = _curPos + off;
        }
        else if ( way == std::ios_base::end )
        {
            newpos = _numChars + off;
        }
        else
        {
            return -1;
        }

        if ( newpos<0 || newpos>_numChars ) return -1;
        if ( ARCHIVE_POS(_streambuf->pubseekpos( STREAM_POS(_startPos+newpos), which)) < 0 ) return -1;
        _curPos = newpos;
        return _curPos;
    }

    // Set internal position pointer to absolute position.  Virtual function called by the public
    // member function pubseekpos to alter the stream positions

    virtual std::streampos seekpos (std::streampos sp, std::ios_base::openmode which = std::ios_base::in)
    {
        return seekoff(sp, std::ios_base::beg, which);
    }

    // Virtual function called by other member functions to get the current character.  It is called
    // by streambuf public member functions such as sgetc to request a new character when there are
    // no read positions available at the get pointer (gptr).

    virtual int_type underflow()
    {
        // Return current character.

        if ( gptr() == &_oneChar ) return traits_type::to_int_type(_oneChar);

        // Get another character from the archive stream, if available.

        if ( _curPos==_numChars ) return traits_type::eof();
         _curPos += 1;

        int_type next_value = _streambuf->sbumpc();

        if ( !traits_type::eq_int_type(next_value,traits_type::eof()) )
        {
            setg(&_oneChar, &_oneChar, (&_oneChar)+1);
            _oneChar = traits_type::to_char_type(next_value);
        }

        return next_value;
    }
};

struct OSGA_Archive::ReadObjectFunctor : public OSGA_Archive::ReadFunctor
{
    ReadObjectFunctor(const std::string& filename, const ReaderWriter::Options* options):ReadFunctor(filename,options) {}
    virtual ReaderWriter::ReadResult doRead(ReaderWriter& rw, std::istream& input) const { return rw.readObject(input, _options); }
};

struct OSGA_Archive::ReadImageFunctor : public OSGA_Archive::ReadFunctor
{
   ReadImageFunctor(const std::string& filename, const ReaderWriter::Options* options):ReadFunctor(filename,options) {}
    virtual ReaderWriter::ReadResult doRead(ReaderWriter& rw, std::istream& input)const  { return rw.readImage(input, _options); }
};

struct OSGA_Archive::ReadHeightFieldFunctor : public OSGA_Archive::ReadFunctor
{
    ReadHeightFieldFunctor(const std::string& filename, const ReaderWriter::Options* options):ReadFunctor(filename,options) {}
    virtual ReaderWriter::ReadResult doRead(ReaderWriter& rw, std::istream& input) const { return rw.readHeightField(input, _options); }
};

struct OSGA_Archive::ReadNodeFunctor : public OSGA_Archive::ReadFunctor
{
    ReadNodeFunctor(const std::string& filename, const ReaderWriter::Options* options):ReadFunctor(filename,options) {}
    virtual ReaderWriter::ReadResult doRead(ReaderWriter& rw, std::istream& input) const { return rw.readNode(input, _options); }
};

struct OSGA_Archive::ReadShaderFunctor : public OSGA_Archive::ReadFunctor
{
    ReadShaderFunctor(const std::string& filename, const ReaderWriter::Options* options):ReadFunctor(filename,options) {}
    virtual ReaderWriter::ReadResult doRead(ReaderWriter& rw, std::istream& input) const { return rw.readShader(input, _options); }
};

ReaderWriter::ReadResult OSGA_Archive::read(const ReadFunctor& readFunctor)
{
    SERIALIZER();

    if (_status!=READ)
    {
        OSG_INFO<<"OSGA_Archive::readObject(obj, "<<readFunctor._filename<<") failed, archive opened as write only."<<std::endl;
        return ReadResult(ReadResult::FILE_NOT_HANDLED);
    }

    FileNamePositionMap::const_iterator itr = _indexMap.find(readFunctor._filename);
    if (itr==_indexMap.end())
    {
        OSG_INFO<<"OSGA_Archive::readObject(obj, "<<readFunctor._filename<<") failed, file not found in archive"<<std::endl;
        return ReadResult(ReadResult::FILE_NOT_FOUND);
    }

    ReaderWriter* rw = osgDB::Registry::instance()->getReaderWriterForExtension(getLowerCaseFileExtension(readFunctor._filename));
    if (!rw)
    {
        OSG_INFO<<"OSGA_Archive::readObject(obj, "<<readFunctor._filename<<") failed to find appropriate plugin to read file."<<std::endl;
        return ReadResult(ReadResult::FILE_NOT_HANDLED);
    }

    OSG_INFO<<"OSGA_Archive::readObject(obj, "<<readFunctor._filename<<")"<<std::endl;

    _input.seekg( STREAM_POS( itr->second.first ) );

    // set up proxy stream buffer to provide the faked ending.
    std::istream& ins = _input;
    proxy_streambuf mystreambuf(ins.rdbuf(),itr->second.second);
    ins.rdbuf(&mystreambuf);

    ReaderWriter::ReadResult result = readFunctor.doRead(*rw, _input);

    ins.rdbuf(mystreambuf._streambuf);

    return result;
}

ReaderWriter::ReadResult OSGA_Archive::readObject(const std::string& fileName,const Options* options) const
{
    return const_cast<OSGA_Archive*>(this)->read(ReadObjectFunctor(fileName, options));
}

ReaderWriter::ReadResult OSGA_Archive::readImage(const std::string& fileName,const Options* options) const
{
    return const_cast<OSGA_Archive*>(this)->read(ReadImageFunctor(fileName, options));
}

ReaderWriter::ReadResult OSGA_Archive::readHeightField(const std::string& fileName,const Options* options) const
{
    return const_cast<OSGA_Archive*>(this)->read(ReadHeightFieldFunctor(fileName, options));
}

ReaderWriter::ReadResult OSGA_Archive::readNode(const std::string& fileName,const Options* options) const
{
    return const_cast<OSGA_Archive*>(this)->read(ReadNodeFunctor(fileName, options));
}

ReaderWriter::ReadResult OSGA_Archive::readShader(const std::string& fileName,const Options* options) const
{
    return const_cast<OSGA_Archive*>(this)->read(ReadShaderFunctor(fileName, options));
}


struct OSGA_Archive::WriteObjectFunctor : public OSGA_Archive::WriteFunctor
{
    WriteObjectFunctor(const osg::Object& object, const std::string& filename, const ReaderWriter::Options* options):
        WriteFunctor(filename,options),
        _object(object) {}
    const osg::Object& _object;

    virtual ReaderWriter::WriteResult doWrite(ReaderWriter& rw, std::ostream& output) const { return rw.writeObject(_object, output, _options); }
};

struct OSGA_Archive::WriteImageFunctor : public OSGA_Archive::WriteFunctor
{
    WriteImageFunctor(const osg::Image& object, const std::string& filename, const ReaderWriter::Options* options):
        WriteFunctor(filename,options),
        _object(object) {}
    const osg::Image& _object;

    virtual ReaderWriter::WriteResult doWrite(ReaderWriter& rw, std::ostream& output) const { OSG_NOTICE<<"doWrite() rw.writeImage(), "<<std::endl; return rw.writeImage(_object, output, _options); }
};

struct OSGA_Archive::WriteHeightFieldFunctor : public OSGA_Archive::WriteFunctor
{
    WriteHeightFieldFunctor(const osg::HeightField& object, const std::string& filename, const ReaderWriter::Options* options):
        WriteFunctor(filename,options),
        _object(object) {}
    const osg::HeightField& _object;

    virtual ReaderWriter::WriteResult doWrite(ReaderWriter& rw, std::ostream& output) const { return rw.writeHeightField(_object, output, _options); }
};

struct OSGA_Archive::WriteNodeFunctor : public OSGA_Archive::WriteFunctor
{
    WriteNodeFunctor(const osg::Node& object, const std::string& filename, const ReaderWriter::Options* options):
        WriteFunctor(filename,options),
        _object(object) {}
    const osg::Node& _object;

    virtual ReaderWriter::WriteResult doWrite(ReaderWriter& rw, std::ostream& output) const { return rw.writeNode(_object, output, _options); }
};

struct OSGA_Archive::WriteShaderFunctor : public OSGA_Archive::WriteFunctor
{
    WriteShaderFunctor(const osg::Shader& object, const std::string& filename, const ReaderWriter::Options* options):
        WriteFunctor(filename,options),
        _object(object) {}
    const osg::Shader& _object;

    virtual ReaderWriter::WriteResult doWrite(ReaderWriter& rw, std::ostream& output) const { return rw.writeShader(_object, output, _options); }
};

ReaderWriter::WriteResult OSGA_Archive::write(const WriteFunctor& writeFunctor)
{
    SERIALIZER();

    if (_status!=WRITE)
    {
        OSG_INFO<<"OSGA_Archive::write(obj, "<<writeFunctor._filename<<") failed, archive opened as read only."<<std::endl;
        return WriteResult(WriteResult::FILE_NOT_HANDLED);
    }

    ReaderWriter* rw = osgDB::Registry::instance()->getReaderWriterForExtension(getLowerCaseFileExtension(writeFunctor._filename));
    if (!rw)
    {
        OSG_INFO<<"OSGA_Archive::write(obj, "<<writeFunctor._filename<<") failed to find appropriate plugin to write file."<<std::endl;
        return WriteResult(WriteResult::FILE_NOT_HANDLED);
    }

    OSG_INFO<<"OSGA_Archive::write(obj, "<<writeFunctor._filename<<")"<<std::endl;

    pos_type position = ARCHIVE_POS( _output.tellp() );

    WriteResult result = writeFunctor.doWrite(*rw,_output);

    pos_type final_position = ARCHIVE_POS( _output.tellp() );
    size_type size = size_type( final_position-position );

    if (result.success())
    {
        OSG_INFO<<"Adding file "<<writeFunctor._filename<<" reference to archive."<<std::endl;
        addFileReference(position, size, writeFunctor._filename);
    }
    else
    {
        OSG_INFO<<"writeFunctor unsuccessful."<<std::endl;
    }

    return result;
}


ReaderWriter::WriteResult OSGA_Archive::writeObject(const osg::Object& obj,const std::string& fileName,const Options* options) const
{
    OSG_INFO<<"OSGA_Archive::writeObject(obj, "<<fileName<<")"<<std::endl;
    return const_cast<OSGA_Archive*>(this)->write(WriteObjectFunctor(obj, fileName, options));
}

ReaderWriter::WriteResult OSGA_Archive::writeImage(const osg::Image& image,const std::string& fileName,const Options* options) const
{
    OSG_INFO<<"OSGA_Archive::writeImage(obj, "<<fileName<<")"<<std::endl;
    return const_cast<OSGA_Archive*>(this)->write(WriteImageFunctor(image, fileName, options));
}

ReaderWriter::WriteResult OSGA_Archive::writeHeightField(const osg::HeightField& heightField,const std::string& fileName,const Options* options) const
{
    OSG_INFO<<"OSGA_Archive::writeHeightField(obj, "<<fileName<<")"<<std::endl;
    return const_cast<OSGA_Archive*>(this)->write(WriteHeightFieldFunctor(heightField, fileName, options));
}

ReaderWriter::WriteResult OSGA_Archive::writeNode(const osg::Node& node,const std::string& fileName,const Options* options) const
{
    OSG_INFO<<"OSGA_Archive::writeNode(obj, "<<fileName<<")"<<std::endl;
    return const_cast<OSGA_Archive*>(this)->write(WriteNodeFunctor(node, fileName, options));
}

ReaderWriter::WriteResult OSGA_Archive::writeShader(const osg::Shader& shader,const std::string& fileName,const Options* options) const
{
    OSG_INFO<<"OSGA_Archive::writeShader(obj, "<<fileName<<")"<<std::endl;
    return const_cast<OSGA_Archive*>(this)->write(WriteShaderFunctor(shader, fileName, options));
}