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 *   https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.commons.compress.utils;
020
021import java.io.IOException;
022import java.nio.ByteBuffer;
023import java.nio.channels.SeekableByteChannel;
024
025/**
026 * InputStream that delegates requests to the underlying SeekableByteChannel, making sure that only bytes from a certain range can be read.
027 *
028 * @ThreadSafe
029 * @since 1.21
030 */
031public class BoundedSeekableByteChannelInputStream extends BoundedArchiveInputStream {
032
033    private final SeekableByteChannel channel;
034
035    /**
036     * Constructs a bounded stream on the underlying {@link SeekableByteChannel}
037     *
038     * @param start     Position in the stream from where the reading of this bounded stream starts
039     * @param remaining Amount of bytes which are allowed to read from the bounded stream
040     * @param channel   Channel which the reads will be delegated to
041     */
042    public BoundedSeekableByteChannelInputStream(final long start, final long remaining, final SeekableByteChannel channel) {
043        super(start, remaining);
044        this.channel = channel;
045    }
046
047    @Override
048    protected int read(final long pos, final ByteBuffer buf) throws IOException {
049        final int read;
050        synchronized (channel) {
051            channel.position(pos);
052            read = channel.read(buf);
053        }
054        buf.flip();
055        return read;
056    }
057}