Reads up to p.byteLength bytes of the tar entry into p. It resolves to the number of bytes read (0 < n <= p.byteLength) and rejects if any error encountered. Even if read() resolves to n < p.byteLength, it may use all of p as scratch space during the call. If some data is available but not p.byteLength bytes, read() conventionally resolves to what is available instead of waiting for more.