/*
 * Copyright  2001,2004 The Apache Software Foundation
 *
 *  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 org.apache.tools.zip;

import java.util.zip.ZipException;

/**
 * General format of extra field data.
 *
 * <p>Extra fields usually appear twice per file, once in the local
 * file data and once in the central directory.  Usually they are the
 * same, but they don't have to be.  {@link
 * java.util.zip.ZipOutputStream java.util.zip.ZipOutputStream} will
 * only use the local file data in both places.</p>
 *
 * @version $Revision: 1.5.2.4 $
 */
public interface ZipExtraField {

    /**
     * The Header-ID.
     *
     * @since 1.1
     */
    ZipShort getHeaderId();

    /**
     * Length of the extra field in the local file data - without
     * Header-ID or length specifier.
     *
     * @since 1.1
     */
    ZipShort getLocalFileDataLength();

    /**
     * Length of the extra field in the central directory - without
     * Header-ID or length specifier.
     *
     * @since 1.1
     */
    ZipShort getCentralDirectoryLength();

    /**
     * The actual data to put into local file data - without Header-ID
     * or length specifier.
     *
     * @since 1.1
     */
    byte[] getLocalFileDataData();

    /**
     * The actual data to put central directory - without Header-ID or
     * length specifier.
     *
     * @since 1.1
     */
    byte[] getCentralDirectoryData();

    /**
     * Populate data from this array as if it was in local file data.
     *
     * @since 1.1
     */
    void parseFromLocalFileData(byte[] data, int offset, int length)
        throws ZipException;
}