_IO_seekoff
extern _IO_fpos64_t _IO_seekoff(_IO_FILE *, _IO_off64_t, int, int);
{ return _IO_seekoff (this, o, d, mode); }
streampos pos = _IO_seekoff (_strbuf, off, (int) dir, _IOS_INPUT);
streampos pos = _IO_seekoff (_strbuf, 0, _IO_seek_cur, _IOS_INPUT);
streampos pos = _IO_seekoff (_strbuf, off, (int) dir, _IOS_OUTPUT);
streampos pos = _IO_seekoff (_strbuf, 0, _IO_seek_cur, _IOS_OUTPUT);
return _IO_seekoff (this, o, d, m);
extern _IO_off64_t _IO_seekoff (_IO_FILE *, _IO_off64_t, int, int);