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     * Size of an extra field field header (id + length).
036     * @since 1.14
037     */
038    int EXTRAFIELD_HEADER_SIZE = 4;
039
040    /**
041     * The Header-ID.
042     *
043     * @return The HeaderId value
044     */
045    ZipShort getHeaderId();
046
047    /**
048     * Length of the extra field in the local file data - without
049     * Header-ID or length specifier.
050     * @return the length of the field in the local file data
051     */
052    ZipShort getLocalFileDataLength();
053
054    /**
055     * Length of the extra field in the central directory - without
056     * Header-ID or length specifier.
057     * @return the length of the field in the central directory
058     */
059    ZipShort getCentralDirectoryLength();
060
061    /**
062     * The actual data to put into local file data - without Header-ID
063     * or length specifier.
064     * @return the data
065     */
066    byte[] getLocalFileDataData();
067
068    /**
069     * The actual data to put into central directory - without Header-ID or
070     * length specifier.
071     * @return the data
072     */
073    byte[] getCentralDirectoryData();
074
075    /**
076     * Populate data from this array as if it was in local file data.
077     *
078     * @param buffer the buffer to read data from
079     * @param offset offset into buffer to read data
080     * @param length the length of data
081     * @throws ZipException on error
082     */
083    void parseFromLocalFileData(byte[] buffer, int offset, int length)
084        throws ZipException;
085
086    /**
087     * Populate data from this array as if it was in central directory data.
088     *
089     * @param buffer the buffer to read data from
090     * @param offset offset into buffer to read data
091     * @param length the length of data
092     * @throws ZipException on error
093     */
094    void parseFromCentralDirectoryData(byte[] buffer, int offset, int length)
095        throws ZipException;
096}