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)
{
        std::filebuf* openstrm = open( fnm, om );
        isok_ = openstrm;
}
 
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(nullptr)
{
    fb_ = new winfilebuf( fnm, om );
    rdbuf( fb_ );
 
    if ( fb_->isOK() )
        clear();
    else
        setstate( ios_base::failbit );
}
 
~winifstream()
{
    if ( !fb_->close() )
        setstate( ios_base::failbit );
    delete fb_;
}
 
bool is_open()
{ return fb_->is_open(); }
 
    winfilebuf* fb_;
};
 
 
mClass(Basic) winofstream : public ostream
{
public:
 
winofstream( const char* fnm, ios_base::openmode om )
    : ostream(nullptr)
{
    fb_ = new winfilebuf( fnm, om );
    rdbuf( fb_ );
 
    if ( fb_->isOK() )
        clear();
    else
        setstate( ios_base::failbit );
}
 
~winofstream()
{
    if ( !fb_->close() )
        setstate( ios_base::failbit );
    delete fb_;
}
 
bool is_open()
{ return fb_->is_open(); }
 
    winfilebuf* fb_;
};
 
 
} // namespace std
 
 
#endif