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
019package org.apache.hadoop.util;
020
021import java.io.DataInput;
022import java.io.IOException;
023
024public 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}