Parses Section 5's header from a buffer that starts at the file's first byte. Throws IncompleteBufferError if buf is too short to tell (the caller should retry with more bytes), or a plain Error for a genuine format problem.
buf
Parses Section 5's header from a buffer that starts at the file's first byte. Throws IncompleteBufferError if
bufis too short to tell (the caller should retry with more bytes), or a plain Error for a genuine format problem.