Function read_frame_bytes 

pub fn read_frame_bytes(r: &mut impl Read) -> Result<Option<Vec<u8>>, Error>

The next frame’s bytes; None where the stream ends between frames.

Errors

The reader’s I/O error; io::ErrorKind::UnexpectedEof when the stream ends inside a length or a frame; io::ErrorKind::InvalidData for a length over MAX_FRAME.