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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase.protobuf;
19  
20  import java.io.IOException;
21  
22  import org.apache.hadoop.hbase.util.Bytes;
23  
24  /**
25   * Protobufs utility.
26   */
27  @SuppressWarnings("deprecation")
28  public final class ProtobufUtil {
29  
30    private ProtobufUtil() {
31    }
32  
33    /**
34     * Magic we put ahead of a serialized protobuf message.
35     * For example, all znode content is protobuf messages with the below magic
36     * for preamble.
37     */
38    public static final byte [] PB_MAGIC = new byte [] {'P', 'B', 'U', 'F'};
39    private static final String PB_MAGIC_STR = Bytes.toString(PB_MAGIC);
40  
41    /**
42     * Prepend the passed bytes with four bytes of magic, {@link #PB_MAGIC}, to flag what
43     * follows as a protobuf in hbase.  Prepend these bytes to all content written to znodes, etc.
44     * @param bytes Bytes to decorate
45     * @return The passed <code>bytes</codes> with magic prepended (Creates a new
46     * byte array that is <code>bytes.length</code> plus {@link #PB_MAGIC}.length.
47     */
48    public static byte [] prependPBMagic(final byte [] bytes) {
49      return Bytes.add(PB_MAGIC, bytes);
50    }
51  
52    /**
53     * @param bytes Bytes to check.
54     * @return True if passed <code>bytes</code> has {@link #PB_MAGIC} for a prefix.
55     */
56    public static boolean isPBMagicPrefix(final byte [] bytes) {
57      if (bytes == null || bytes.length < PB_MAGIC.length) return false;
58      return Bytes.compareTo(PB_MAGIC, 0, PB_MAGIC.length, bytes, 0, PB_MAGIC.length) == 0;
59    }
60  
61    /**
62     * @return Length of {@link #PB_MAGIC}
63     */
64    public static int lengthOfPBMagic() {
65      return PB_MAGIC.length;
66    }
67  }