001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package org.apache.hadoop.util;
020    
021    import java.io.DataInput;
022    import java.io.IOException;
023    
024    public abstract class ProtoUtil {
025    
026      /**
027       * Read a variable length integer in the same format that ProtoBufs encodes.
028       * @param in the input stream to read from
029       * @return the integer
030       * @throws IOException if it is malformed or EOF.
031       */
032      public static int readRawVarint32(DataInput in) throws IOException {
033        byte tmp = in.readByte();
034        if (tmp >= 0) {
035          return tmp;
036        }
037        int result = tmp & 0x7f;
038        if ((tmp = in.readByte()) >= 0) {
039          result |= tmp << 7;
040        } else {
041          result |= (tmp & 0x7f) << 7;
042          if ((tmp = in.readByte()) >= 0) {
043            result |= tmp << 14;
044          } else {
045            result |= (tmp & 0x7f) << 14;
046            if ((tmp = in.readByte()) >= 0) {
047              result |= tmp << 21;
048            } else {
049              result |= (tmp & 0x7f) << 21;
050              result |= (tmp = in.readByte()) << 28;
051              if (tmp < 0) {
052                // Discard upper 32 bits.
053                for (int i = 0; i < 5; i++) {
054                  if (in.readByte() >= 0) {
055                    return result;
056                  }
057                }
058                throw new IOException("Malformed varint");
059              }
060            }
061          }
062        }
063        return result;
064      }
065    
066    }