winstreambuf.h

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#ifndef winstreambuf_h
#define winstreambuf_h
/*
________________________________________________________________________

 (C) dGB Beheer B.V.; (LICENSE) http://opendtect.org/OpendTect_license.txt
 Author:        Bert
 Date:          Feb 2009
________________________________________________________________________

*/

#define private protected
#include <fstream>
#undef private
#ifdef __win32__
# define fpos_t od_int64
#endif

#ifndef _POS_TYPE_FROM_STATE
//TODO this is a hack for VS >= 15.8.7, try to get rid of this winstreambuf hack altogether
#define _POS_TYPE_FROM_STATE(postype, state, position) postype(state, position)
#define _POS_TYPE_TO_STATE(pos) pos.state()
#define _BADOFF -1
#endif

namespace std
{

mClass(Basic) winfilebuf : public filebuf
{
public:
winfilebuf( const char* fnm, ios_base::openmode om )
    : realpos_(0)
{
    isok_ = open( fnm, om );
}

bool            isOK() const    { return isok_; }
od_int64        getRealPos() const      { return realpos_; }
protected:

#define defom (ios_base::openmode)(ios_base::in | ios_base::out)

virtual pos_type seekoff( off_type _Off, ios_base::seekdir _Way,
                          ios_base::openmode = defom )
{
    fpos_t _Fileposition;

    if ( _Mysb::gptr() == &_Mychar && _Way == ios_base::cur && _Pcvt == 0 )
        _Off -= (off_type)sizeof (char);

    if ( _Myfile==0 || !_Endwrite() || (_Off!=0 || _Way!=ios_base::cur) &&
         _fseeki64(_Myfile,_Off,_Way) != 0 ||
         fgetpos(_Myfile,&_Fileposition) != 0 )
        return (pos_type(_BADOFF));

    if ( _Mysb::gptr() == &_Mychar )
        _Mysb::setg( &_Mychar, &_Mychar+1, &_Mychar+1 );

    realpos_ = (od_int64)_Fileposition;
    return (_POS_TYPE_FROM_STATE(pos_type,_State,_Fileposition));
}

bool        isok_;
od_int64    realpos_;
};


mClass(Basic) winifstream : public istream
{
public:

winifstream( const char* fnm, ios_base::openmode om )
    : istream(0)
{
    fb_ = new winfilebuf( fnm, om );
    rdbuf( fb_ );

    if ( fb_->isOK() )
        clear();
    else
        setstate( ios_base::failbit );
}

~winifstream()
{
    if ( !fb_->close() )
        setstate( ios_base::failbit );
}

bool is_open()
{ return fb_->is_open(); }

    winfilebuf* fb_;
};


mClass(Basic) winofstream : public ostream
{
public:

winofstream( const char* fnm, ios_base::openmode om )
    : ostream(0)
{
    fb_ = new winfilebuf( fnm, om );
    rdbuf( fb_ );

    if ( fb_->isOK() )
        clear();
    else
        setstate( ios_base::failbit );
}

~winofstream()
{
    if ( !fb_->close() )
        setstate( ios_base::failbit );
}

bool is_open()
{ return fb_->is_open(); }

    winfilebuf* fb_;
};


} // namespace std


#endif