_IO_OVERFLOW
int builtinbuf::overflow(int ch) { return _IO_OVERFLOW (this, ch); }
if (_IO_OVERFLOW (f, EOF) == EOF)
_IO_OVERFLOW (_IO_stdout, EOF);
if (_IO_OVERFLOW (fp, EOF) == EOF)
return _IO_OVERFLOW (f, ch);
if (more == 0 || _IO_OVERFLOW (f, (unsigned char) *s++) == EOF)
&& _IO_OVERFLOW (fp, EOF) == EOF)
_IO_OVERFLOW (fp, EOF);
_IO_OVERFLOW (_IO_stdout, EOF);
return _IO_OVERFLOW (f, wch);