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TrueZIP is a Java based Virtual File System (VFS) to enable transparent, multi-threaded read/write access to archive files (ZIP, TAR etc.) as if they were directories. Archive files may be arbitrarily nested and the nesting level is only limited by heap and file system size.
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/*
 * Copyright (C) 2005-2010 Schlichtherle IT Services
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package de.schlichtherle.io.archive.tar;

import de.schlichtherle.io.archive.*;
import de.schlichtherle.io.rof.*;

import java.io.*;

import javax.swing.*;

import org.apache.tools.bzip2.*;

/**
 * An archive driver which builds TAR files compressed with BZIP2.
 * 
 * Instances of this class are immutable.
 * 
 * @author Christian Schlichtherle
 * @version $Id: TarBZip2Driver.java,v 1.4 2010/08/20 13:09:44 christian_schlichtherle Exp $
 * @since TrueZIP 6.0
 */
public class TarBZip2Driver extends TarDriver {

    private static final long serialVersionUID = 4966248471134003932L;

    private static final int BUFSIZE = 4096;

    /**
     * The minimum block size to use when writing a BZIP2 output stream,
     * which is {@value}.
     */
    public static final int MIN_BLOCKSIZE = 1;

    /**
     * The maximum block size to use when writing a BZIP2 output stream,
     * which is {@value}.
     */
    public static final int MAX_BLOCKSIZE = 9;

    /**
     * The default block size to use when writing a BZIP2 output stream,
     * which is {@value}.
     */
    public static final int DEFAULT_BLOCKSIZE = MAX_BLOCKSIZE;

    /**
     * @deprecated Use {@link #DEFAULT_BLOCKSIZE} instead.
     */
    public static final int DEFAULT_LEVEL = MAX_BLOCKSIZE;

    private final int inBlockSize;

    /**
     * Equivalent to {@link #TarBZip2Driver(String, Icon, Icon, int)
     * this(DEFAULT_CHARSET, null, null, DEFAULT_BLOCKSIZE)}.
     */
    public TarBZip2Driver() {
        this(DEFAULT_CHARSET, null, null, DEFAULT_BLOCKSIZE);
    }

    /**
     * Equivalent to {@link #TarBZip2Driver(String, Icon, Icon, int)
     * this(charset, null, null, DEFAULT_BLOCKSIZE)}.
     */
    public TarBZip2Driver(String charset) {
        this(charset, null, null, DEFAULT_BLOCKSIZE);
    }

    /**
     * Equivalent to {@link #TarBZip2Driver(String, Icon, Icon, int)
     * this(DEFAULT_CHARSET, null, null, inBlockSize)}.
     */
    public TarBZip2Driver(int inBlockSize) {
        this(DEFAULT_CHARSET, null, null,  inBlockSize);
    }

    /**
     * Equivalent to {@link #TarBZip2Driver(String, Icon, Icon, int)
     * this(charset, null, null, inBlockSize)}.
     */
    public TarBZip2Driver(String charset, int inBlockSize) {
        this(charset, null, null, inBlockSize);
    }

    /**
     * Constructs a new TAR.BZ2 driver.
     *
     * @param inBlockSize The compression block size to use when writing
     *        a BZIP2 output stream.
     * @throws IllegalArgumentException If {@code inBlockSize} is not
     *         in the range [1..9].
     */
    public TarBZip2Driver(
            final String charset,
            final Icon openIcon,
            final Icon closedIcon,
            final int inBlockSize) {
        super(charset, openIcon, closedIcon);
        if (inBlockSize < MIN_BLOCKSIZE || MAX_BLOCKSIZE < inBlockSize)
            throw new IllegalArgumentException(inBlockSize + "");
        this.inBlockSize = inBlockSize;
    }

    /**
     * Returns the value of the property {@code inBlockSize} which was
     * provided to the constructor.
     */
    public final int getLevel() {
        return inBlockSize;
    }

    //
    // Driver implementation:
    //

    /**
     * Returns a newly created and verified {@link CBZip2InputStream}.
     * This method performs a simple verification by computing the checksum
     * for the first record only.
     * This method is required because the {@code CBZip2InputStream}
     * unfortunately does not do sufficient verification!
     */
    protected InputStream createInputStream(Archive archive, ReadOnlyFile rof)
    throws IOException {
        final InputStream in = super.createInputStream(archive, rof);
        // Consume and check the first two magic bytes. This is required for
        // the CBZip2InputStream class. Bad design, I think...
        if (in.read() != 'B' || in.read() != 'Z')
            throw new IOException("Not a BZIP2 compressed input stream!");
        final byte[] magic = new byte[2];
        final InputStream vin = TarInputArchive.readAhead(in, magic);
        if (magic[0] != 'h' || magic[1] < '1' || '9' < magic[1])
            throw new IOException("Not a BZIP2 compressed input stream!");
        return new CBZip2InputStream(new BufferedInputStream(vin, BUFSIZE));
    }

    protected TarOutputArchive createTarOutputArchive(
            final Archive archive,
            final OutputStream out,
            final TarInputArchive source)
    throws IOException {
        // Produce the first two magic bytes. This is required for the
        // CBZip2OutputStream class.
        out.write(new byte[] { 'B', 'Z' });
        return super.createTarOutputArchive(
                archive,
                new CBZip2OutputStream(
                    new BufferedOutputStream(out, BUFSIZE),
                    inBlockSize),
                source);
    }
}