Line data    Source code

       1             : // Copyright (C) 2016 The Android Open Source Project
       2             : //
       3             : // Licensed under the Apache License, Version 2.0 (the "License");
       4             : // you may not use this file except in compliance with the License.
       5             : // You may obtain a copy of the License at
       6             : //
       7             : // http://www.apache.org/licenses/LICENSE-2.0
       8             : //
       9             : // Unless required by applicable law or agreed to in writing, software
      10             : // distributed under the License is distributed on an "AS IS" BASIS,
      11             : // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      12             : // See the License for the specific language governing permissions and
      13             : // limitations under the License.
      14             : 
      15             : package com.google.gerrit.server.ioutil;
      16             : 
      17             : import static com.google.common.base.Preconditions.checkArgument;
      18             : 
      19             : import java.io.ByteArrayOutputStream;
      20             : import java.io.IOException;
      21             : import java.io.OutputStream;
      22             : 
      23             : /** A stream that throws an exception if it consumes data beyond a configured byte count. */
      24             : public class LimitedByteArrayOutputStream extends OutputStream {
      25             : 
      26             :   private final int maxSize;
      27             :   private final ByteArrayOutputStream buffer;
      28             : 
      29             :   /**
      30             :    * Constructs a LimitedByteArrayOutputStream, which stores output in memory up to a certain
      31             :    * specified size. When the output exceeds the specified size a LimitExceededException is thrown.
      32             :    *
      33             :    * @param max the maximum size in bytes which may be stored.
      34             :    * @param initial the initial size. It must be smaller than the max size.
      35             :    */
      36           0 :   public LimitedByteArrayOutputStream(int max, int initial) {
      37           0 :     checkArgument(initial <= max);
      38           0 :     maxSize = max;
      39           0 :     buffer = new ByteArrayOutputStream(initial);
      40           0 :   }
      41             : 
      42             :   private void checkOversize(int additionalSize) throws IOException {
      43           0 :     if (buffer.size() + additionalSize > maxSize) {
      44           0 :       throw new LimitExceededException();
      45             :     }
      46           0 :   }
      47             : 
      48             :   @Override
      49             :   public void write(int b) throws IOException {
      50           0 :     checkOversize(1);
      51           0 :     buffer.write(b);
      52           0 :   }
      53             : 
      54             :   @Override
      55             :   public void write(byte[] b, int off, int len) throws IOException {
      56           0 :     checkOversize(len);
      57           0 :     buffer.write(b, off, len);
      58           0 :   }
      59             : 
      60             :   /** Returns a newly allocated byte array with contents of the buffer. */
      61             :   public byte[] toByteArray() {
      62           0 :     return buffer.toByteArray();
      63             :   }
      64             : 
      65           0 :   public static class LimitExceededException extends IOException {
      66             :     private static final long serialVersionUID = 1L;
      67             :   }
      68             : }