    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}