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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   *   https://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.apache.commons.compress.utils;
20  
21  import java.io.IOException;
22  import java.nio.ByteBuffer;
23  import java.nio.channels.SeekableByteChannel;
24  
25  /**
26   * InputStream that delegates requests to the underlying SeekableByteChannel, making sure that only bytes from a certain range can be read.
27   *
28   * @ThreadSafe
29   * @since 1.21
30   */
31  public class BoundedSeekableByteChannelInputStream extends BoundedArchiveInputStream {
32  
33      private final SeekableByteChannel channel;
34  
35      /**
36       * Constructs a bounded stream on the underlying {@link SeekableByteChannel}
37       *
38       * @param start     Position in the stream from where the reading of this bounded stream starts
39       * @param remaining Amount of bytes which are allowed to read from the bounded stream
40       * @param channel   Channel which the reads will be delegated to
41       */
42      public BoundedSeekableByteChannelInputStream(final long start, final long remaining, final SeekableByteChannel channel) {
43          super(start, remaining);
44          this.channel = channel;
45      }
46  
47      @Override
48      protected int read(final long pos, final ByteBuffer buf) throws IOException {
49          final int read;
50          synchronized (channel) {
51              channel.position(pos);
52              read = channel.read(buf);
53          }
54          buf.flip();
55          return read;
56      }
57  }