@Override
  public final int readUnsignedByte() throws IOException {
    int temp = in.read();
    if (temp < 0) {
      throw new EOFException();
    }
    return temp;
  }
Reads an unsigned 8-bit <code>byte</code> value from this stream and
returns it as an int.

@return the next unsigned byte value from the source stream.

@throws IOException
          If a problem occurs reading from this DataInputStream.
ql/src/java/org/apache/hadoop/hive/ql/io/NonSyncDataInputBuffer.java