    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.compressors.lzma;
    020
    021import java.util.HashMap;
    022import java.util.Map;
    023
    024import org.apache.commons.compress.compressors.FileNameUtil;
    025import org.apache.commons.compress.utils.OsgiUtils;
    026
    027/**
    028 * Utility code for the LZMA compression format.
    029 *
    030 * @ThreadSafe
    031 * @since 1.10
    032 */
    033public class LZMAUtils {
    034
    035    enum CachedAvailability {
    036        DONT_CACHE, CACHED_AVAILABLE, CACHED_UNAVAILABLE
    037    }
    038
    039    private static final FileNameUtil fileNameUtil;
    040
    041    /**
    042     * LZMA Header Magic Bytes begin a LZMA file.
    043     */
    044    private static final byte[] HEADER_MAGIC = { (byte) 0x5D, 0, 0 };
    045
    046    private static volatile CachedAvailability cachedLZMAAvailability;
    047
    048    static {
    049        final Map<String, String> uncompressSuffix = new HashMap<>();
    050        uncompressSuffix.put(".lzma", "");
    051        uncompressSuffix.put("-lzma", "");
    052        fileNameUtil = new FileNameUtil(uncompressSuffix, ".lzma");
    053        cachedLZMAAvailability = CachedAvailability.DONT_CACHE;
    054        setCacheLZMAAvailablity(!OsgiUtils.isRunningInOsgiEnvironment());
    055    }
    056
    057    // only exists to support unit tests
    058    static CachedAvailability getCachedLZMAAvailability() {
    059        return cachedLZMAAvailability;
    060    }
    061
    062    /**
    063     * Maps the given file name to the name that the file should have after compression with LZMA.
    064     *
    065     * @param fileName name of a file
    066     * @return name of the corresponding compressed file
    067     * @deprecated Use {@link #getCompressedFileName(String)}.
    068     */
    069    @Deprecated
    070    public static String getCompressedFilename(final String fileName) {
    071        return fileNameUtil.getCompressedFileName(fileName);
    072    }
    073
    074    /**
    075     * Maps the given file name to the name that the file should have after compression with LZMA.
    076     *
    077     * @param fileName name of a file
    078     * @return name of the corresponding compressed file
    079     * @since 1.25.0
    080     */
    081    public static String getCompressedFileName(final String fileName) {
    082        return fileNameUtil.getCompressedFileName(fileName);
    083    }
    084
    085    /**
    086     * Maps the given name of a LZMA-compressed file to the name that the file should have after uncompression. Any file names with the generic ".lzma" suffix
    087     * (or any other generic LZMA suffix) is mapped to a name without that suffix. If no LZMA suffix is detected, then the file name is returned unmapped.
    088     *
    089     * @param fileName name of a file
    090     * @return name of the corresponding uncompressed file
    091     * @deprecated Use {@link #getUncompressedFileName(String)}.
    092     */
    093    @Deprecated
    094    public static String getUncompressedFilename(final String fileName) {
    095        return fileNameUtil.getUncompressedFileName(fileName);
    096    }
    097
    098    /**
    099     * Maps the given name of a LZMA-compressed file to the name that the file should have after uncompression. Any file names with the generic ".lzma" suffix
    100     * (or any other generic LZMA suffix) is mapped to a name without that suffix. If no LZMA suffix is detected, then the file name is returned unmapped.
    101     *
    102     * @param fileName name of a file
    103     * @return name of the corresponding uncompressed file
    104     * @since 1.25.0
    105     */
    106    public static String getUncompressedFileName(final String fileName) {
    107        return fileNameUtil.getUncompressedFileName(fileName);
    108    }
    109
    110    private static boolean internalIsLZMACompressionAvailable() {
    111        try {
    112            LZMACompressorInputStream.matches(null, 0);
    113            return true;
    114        } catch (final NoClassDefFoundError error) { // NOSONAR
    115            return false;
    116        }
    117    }
    118
    119    /**
    120     * Detects common LZMA suffixes in the given file name.
    121     *
    122     * @param fileName name of a file
    123     * @return {@code true} if the file name has a common LZMA suffix, {@code false} otherwise
    124     * @deprecated Use {@link #isCompressedFileName(String)}.
    125     */
    126    @Deprecated
    127    public static boolean isCompressedFilename(final String fileName) {
    128        return fileNameUtil.isCompressedFileName(fileName);
    129    }
    130
    131    /**
    132     * Detects common LZMA suffixes in the given file name.
    133     *
    134     * @param fileName name of a file
    135     * @return {@code true} if the file name has a common LZMA suffix, {@code false} otherwise
    136     * @since 1.25.0
    137     */
    138    public static boolean isCompressedFileName(final String fileName) {
    139        return fileNameUtil.isCompressedFileName(fileName);
    140    }
    141
    142    /**
    143     * Are the classes required to support LZMA compression available?
    144     *
    145     * @return true if the classes required to support LZMA compression are available
    146     */
    147    public static boolean isLZMACompressionAvailable() {
    148        final CachedAvailability cachedResult = cachedLZMAAvailability;
    149        if (cachedResult != CachedAvailability.DONT_CACHE) {
    150            return cachedResult == CachedAvailability.CACHED_AVAILABLE;
    151        }
    152        return internalIsLZMACompressionAvailable();
    153    }
    154
    155    /**
    156     * Checks if the signature matches what is expected for a .lzma file.
    157     *
    158     * @param signature the bytes to check
    159     * @param length    the number of bytes to check
    160     * @return true if signature matches the .lzma magic bytes, false otherwise
    161     */
    162    public static boolean matches(final byte[] signature, final int length) {
    163        if (length < HEADER_MAGIC.length) {
    164            return false;
    165        }
    166
    167        for (int i = 0; i < HEADER_MAGIC.length; ++i) {
    168            if (signature[i] != HEADER_MAGIC[i]) {
    169                return false;
    170            }
    171        }
    172
    173        return true;
    174    }
    175
    176    /**
    177     * Whether to cache the result of the LZMA check.
    178     *
    179     * <p>
    180     * This defaults to {@code false} in an OSGi environment and {@code true} otherwise.
    181     * </p>
    182     *
    183     * @param doCache whether to cache the result
    184     */
    185    public static void setCacheLZMAAvailablity(final boolean doCache) {
    186        if (!doCache) {
    187            cachedLZMAAvailability = CachedAvailability.DONT_CACHE;
    188        } else if (cachedLZMAAvailability == CachedAvailability.DONT_CACHE) {
    189            final boolean hasLzma = internalIsLZMACompressionAvailable();
    190            cachedLZMAAvailability = hasLzma ? CachedAvailability.CACHED_AVAILABLE // NOSONAR
    191                    : CachedAvailability.CACHED_UNAVAILABLE;
    192        }
    193    }
    194
    195    /** Private constructor to prevent instantiation of this utility class. */
    196    private LZMAUtils() {
    197    }
    198}