    001/*
    002 *  Licensed to the Apache Software Foundation (ASF) under one or more
    003 *  contributor license agreements.  See the NOTICE file distributed with
    004 *  this work for additional information regarding copyright ownership.
    005 *  The ASF licenses this file to You under the Apache License, Version 2.0
    006 *  (the "License"); you may not use this file except in compliance with
    007 *  the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 *  Unless required by applicable law or agreed to in writing, software
    012 *  distributed under the License is distributed on an "AS IS" BASIS,
    013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 *  See the License for the specific language governing permissions and
    015 *  limitations under the License.
    016 *
    017 */
    018package org.apache.commons.compress.utils;
    019
    020import java.io.IOException;
    021import java.nio.ByteBuffer;
    022import java.nio.channels.SeekableByteChannel;
    023
    024/**
    025 * InputStream that delegates requests to the underlying SeekableByteChannel, making sure that only bytes from a certain
    026 * range can be read.
    027 * @ThreadSafe
    028 * @since 1.21
    029 */
    030public class BoundedSeekableByteChannelInputStream extends BoundedArchiveInputStream {
    031
    032    private final SeekableByteChannel channel;
    033
    034    /**
    035     * Create a bounded stream on the underlying {@link SeekableByteChannel}
    036     *
    037     * @param start     Position in the stream from where the reading of this bounded stream starts
    038     * @param remaining Amount of bytes which are allowed to read from the bounded stream
    039     * @param channel   Channel which the reads will be delegated to
    040     */
    041    public BoundedSeekableByteChannelInputStream(final long start, final long remaining,
    042            final SeekableByteChannel channel) {
    043        super(start, remaining);
    044        this.channel = channel;
    045    }
    046
    047    @Override
    048    protected int read(long pos, ByteBuffer buf) throws IOException {
    049        int read;
    050        synchronized (channel) {
    051            channel.position(pos);
    052            read = channel.read(buf);
    053        }
    054        buf.flip();
    055        return read;
    056    }
    057}