protected: virtual int sync(); virtual int showmanyc() const; virtual streamsize xsgetn(char_type* s, streamsize n); virtual int_type underflow(); virtual int_type uflow(); virtual int_type pbackfail(int_type c = eof); virtual streamsize xsputn(const char_type* s, streamsize n); virtual streamsize xsgetn(char_type* s, streamsize n); virtual int_type overflow(int_type c = eof); public: int pubsync(); virtual bool is_open() const; int read(void* buf, int len); int write(const void* buf, int len); long howmanyc() const;