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 * http://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.archivers.zip;
020
021import java.util.zip.ZipException;
022
023/**
024 * General format of extra field data.
025 *
026 * <p>Extra fields usually appear twice per file, once in the local
027 * file data and once in the central directory.  Usually they are the
028 * same, but they don't have to be.  {@link
029 * java.util.zip.ZipOutputStream java.util.zip.ZipOutputStream} will
030 * only use the local file data in both places.</p>
031 *
032 */
033public interface ZipExtraField {
034    /**
035     * The Header-ID.
036     *
037     * @return The HeaderId value
038     */
039    ZipShort getHeaderId();
040
041    /**
042     * Length of the extra field in the local file data - without
043     * Header-ID or length specifier.
044     * @return the length of the field in the local file data
045     */
046    ZipShort getLocalFileDataLength();
047
048    /**
049     * Length of the extra field in the central directory - without
050     * Header-ID or length specifier.
051     * @return the length of the field in the central directory
052     */
053    ZipShort getCentralDirectoryLength();
054
055    /**
056     * The actual data to put into local file data - without Header-ID
057     * or length specifier.
058     * @return the data
059     */
060    byte[] getLocalFileDataData();
061
062    /**
063     * The actual data to put into central directory - without Header-ID or
064     * length specifier.
065     * @return the data
066     */
067    byte[] getCentralDirectoryData();
068
069    /**
070     * Populate data from this array as if it was in local file data.
071     *
072     * @param buffer the buffer to read data from
073     * @param offset offset into buffer to read data
074     * @param length the length of data
075     * @throws ZipException on error
076     */
077    void parseFromLocalFileData(byte[] buffer, int offset, int length)
078        throws ZipException;
079
080    /**
081     * Populate data from this array as if it was in central directory data.
082     *
083     * @param buffer the buffer to read data from
084     * @param offset offset into buffer to read data
085     * @param length the length of data
086     * @throws ZipException on error
087     */
088    void parseFromCentralDirectoryData(byte[] buffer, int offset, int length)
089        throws ZipException;
090}