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.archivers.zip;
019
020import java.util.zip.ZipException;
021
022import org.apache.commons.compress.utils.ByteUtils;
023
024/**
025 * If this extra field is added as the very first extra field of the
026 * archive, Solaris will consider it an executable jar file.
027 * @Immutable
028 */
029public final class JarMarker implements ZipExtraField {
030
031    private static final ZipShort ID = new ZipShort(0xCAFE);
032    private static final ZipShort NULL = new ZipShort(0);
033    private static final JarMarker DEFAULT = new JarMarker();
034
035    /** No-arg constructor */
036    public JarMarker() {
037        // empty
038    }
039
040    /**
041     * Since JarMarker is stateless we can always use the same instance.
042     * @return the DEFAULT jarmaker.
043     */
044    public static JarMarker getInstance() {
045        return DEFAULT;
046    }
047
048    /**
049     * The Header-ID.
050     * @return the header id
051     */
052    @Override
053    public ZipShort getHeaderId() {
054        return ID;
055    }
056
057    /**
058     * Length of the extra field in the local file data - without
059     * Header-ID or length specifier.
060     * @return 0
061     */
062    @Override
063    public ZipShort getLocalFileDataLength() {
064        return NULL;
065    }
066
067    /**
068     * Length of the extra field in the central directory - without
069     * Header-ID or length specifier.
070     * @return 0
071     */
072    @Override
073    public ZipShort getCentralDirectoryLength() {
074        return NULL;
075    }
076
077    /**
078     * The actual data to put into local file data - without Header-ID
079     * or length specifier.
080     * @return the data
081     */
082    @Override
083    public byte[] getLocalFileDataData() {
084        return ByteUtils.EMPTY_BYTE_ARRAY;
085    }
086
087    /**
088     * The actual data to put central directory - without Header-ID or
089     * length specifier.
090     * @return the data
091     */
092    @Override
093    public byte[] getCentralDirectoryData() {
094        return ByteUtils.EMPTY_BYTE_ARRAY;
095    }
096
097    /**
098     * Populate data from this array as if it was in local file data.
099     * @param data an array of bytes
100     * @param offset the start offset
101     * @param length the number of bytes in the array from offset
102     *
103     * @throws ZipException on error
104     */
105    @Override
106    public void parseFromLocalFileData(final byte[] data, final int offset, final int length)
107        throws ZipException {
108        if (length != 0) {
109            throw new ZipException("JarMarker doesn't expect any data");
110        }
111    }
112
113    /**
114     * Doesn't do anything special since this class always uses the
115     * same data in central directory and local file data.
116     */
117    @Override
118    public void parseFromCentralDirectoryData(final byte[] buffer, final int offset,
119                                              final int length)
120        throws ZipException {
121        parseFromLocalFileData(buffer, offset, length);
122    }
123}