private static String decodeUTF(int utfSize, DataInput in) throws IOException {
    byte[] buf = new byte[utfSize];
    char[] out = new char[utfSize];
    in.readFully(buf, 0, utfSize);

    return convertUTF8WithBuf(buf, out, 0, utfSize);
  }
Reads a UTF format String from this Stream.

@return the next UTF String 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