Function read_frame 

pub fn read_frame<R: Read>(
    reader: &mut R,
    buf: &mut Vec<u8>,
) -> Result<(), TpmDeviceError>

Reads one complete TPM frame from a blocking stream into buf.

The header is read first to learn the frame’s declared size, then exactly that many bytes (header included) are read; buf is cleared beforehand. The framing is identical for command and response frames, so this serves a host reading responses and a responder reading commands alike.

Errors

Returns UnexpectedEof when the stream ends before a complete frame, Io on any other read failure, or InvalidResponse when the header declares an out-of-range size.