    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 *   https://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.sevenz;
    020
    021import java.util.Arrays;
    022
    023/**
    024 * Enumerates the (partially) supported compression/encryption methods used in 7z archives.
    025 * <p>
    026 * All methods with a {@code _FILTER} suffix are used as preprocessors with the goal of creating a better compression ratio with the compressor that comes next
    027 * in the chain of methods. 7z will in general only allow them to be used together with a "real" compression method but Commons Compress doesn't enforce this.
    028 * </p>
    029 * <p>
    030 * The {@code BCJ_} filters work on executable files for the given platform and convert relative addresses to absolute addresses in CALL instructions. This
    031 * means they are only useful when applied to executables of the chosen platform.
    032 * </p>
    033 */
    034public enum SevenZMethod {
    035
    036    /** No compression at all. */
    037    COPY(new byte[] { (byte) 0x00 }),
    038
    039    /** LZMA - only supported when reading. */
    040    LZMA(new byte[] { (byte) 0x03, (byte) 0x01, (byte) 0x01 }),
    041
    042    /** LZMA2. */
    043    LZMA2(new byte[] { (byte) 0x21 }),
    044
    045    /** Deflate. */
    046    DEFLATE(new byte[] { (byte) 0x04, (byte) 0x01, (byte) 0x08 }),
    047
    048    /**
    049     * Deflate64.
    050     *
    051     * @since 1.16
    052     */
    053    DEFLATE64(new byte[] { (byte) 0x04, (byte) 0x01, (byte) 0x09 }),
    054
    055    /** BZIP2. */
    056    BZIP2(new byte[] { (byte) 0x04, (byte) 0x02, (byte) 0x02 }),
    057
    058    /**
    059     * AES encryption with a key length of 256 bit using SHA256 for hashes - only supported when reading.
    060     */
    061    AES256SHA256(new byte[] { (byte) 0x06, (byte) 0xf1, (byte) 0x07, (byte) 0x01 }),
    062
    063    /**
    064     * BCJ x86 platform version 1.
    065     *
    066     * @since 1.8
    067     */
    068    BCJ_X86_FILTER(new byte[] { 0x03, 0x03, 0x01, 0x03 }),
    069
    070    /**
    071     * BCJ PowerPC platform.
    072     *
    073     * @since 1.8
    074     */
    075    BCJ_PPC_FILTER(new byte[] { 0x03, 0x03, 0x02, 0x05 }),
    076
    077    /**
    078     * BCJ I64 platform.
    079     *
    080     * @since 1.8
    081     */
    082    BCJ_IA64_FILTER(new byte[] { 0x03, 0x03, 0x04, 0x01 }),
    083
    084    /**
    085     * BCJ ARM platform.
    086     *
    087     * @since 1.8
    088     */
    089    BCJ_ARM_FILTER(new byte[] { 0x03, 0x03, 0x05, 0x01 }),
    090
    091    /**
    092     * BCJ ARM Thumb platform.
    093     *
    094     * @since 1.8
    095     */
    096    BCJ_ARM_THUMB_FILTER(new byte[] { 0x03, 0x03, 0x07, 0x01 }),
    097
    098    /**
    099     * BCJ Sparc platform.
    100     *
    101     * @since 1.8
    102     */
    103    BCJ_SPARC_FILTER(new byte[] { 0x03, 0x03, 0x08, 0x05 }),
    104
    105    /**
    106     * Delta filter.
    107     *
    108     * @since 1.8
    109     */
    110    DELTA_FILTER(new byte[] { 0x03 });
    111
    112    static SevenZMethod byId(final byte[] id) {
    113        for (final SevenZMethod method : SevenZMethod.class.getEnumConstants()) {
    114            if (Arrays.equals(method.id, id)) {
    115                return method;
    116            }
    117        }
    118        return null;
    119    }
    120
    121    private final byte[] id;
    122
    123    SevenZMethod(final byte[] id) {
    124        this.id = id;
    125    }
    126
    127    byte[] getId() {
    128        return Arrays.copyOf(id, id.length);
    129    }
    130}