    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 = {
    045        (byte) 0x5D, 0, 0
    046    };
    047
    048    private static volatile CachedAvailability cachedLZMAAvailability;
    049
    050    static {
    051        final Map<String, String> uncompressSuffix = new HashMap<>();
    052        uncompressSuffix.put(".lzma", "");
    053        uncompressSuffix.put("-lzma", "");
    054        fileNameUtil = new FileNameUtil(uncompressSuffix, ".lzma");
    055        cachedLZMAAvailability = CachedAvailability.DONT_CACHE;
    056        setCacheLZMAAvailablity(!OsgiUtils.isRunningInOsgiEnvironment());
    057    }
    058
    059    // only exists to support unit tests
    060    static CachedAvailability getCachedLZMAAvailability() {
    061        return cachedLZMAAvailability;
    062    }
    063
    064    /**
    065     * Maps the given file name to the name that the file should have after
    066     * compression with LZMA.
    067     *
    068     * @param fileName name of a file
    069     * @return name of the corresponding compressed file
    070     * @deprecated Use {@link #getCompressedFileName(String)}.
    071     */
    072    @Deprecated
    073    public static String getCompressedFilename(final String fileName) {
    074        return fileNameUtil.getCompressedFileName(fileName);
    075    }
    076
    077    /**
    078     * Maps the given file name to the name that the file should have after
    079     * compression with LZMA.
    080     *
    081     * @param fileName name of a file
    082     * @return name of the corresponding compressed file
    083     * @since 1.25.0
    084     */
    085    public static String getCompressedFileName(final String fileName) {
    086        return fileNameUtil.getCompressedFileName(fileName);
    087    }
    088
    089    /**
    090     * Maps the given name of a LZMA-compressed file to the name that
    091     * the file should have after uncompression.  Any file names with
    092     * the generic ".lzma" suffix (or any other generic LZMA suffix)
    093     * is mapped to a name without that suffix. If no LZMA suffix is
    094     * detected, then the file name is returned unmapped.
    095     *
    096     * @param fileName name of a file
    097     * @return name of the corresponding uncompressed file
    098     * @deprecated Use {@link #getUncompressedFileName(String)}.
    099     */
    100    @Deprecated
    101    public static String getUncompressedFilename(final String fileName) {
    102        return fileNameUtil.getUncompressedFileName(fileName);
    103    }
    104
    105    /**
    106     * Maps the given name of a LZMA-compressed file to the name that
    107     * the file should have after uncompression.  Any file names with
    108     * the generic ".lzma" suffix (or any other generic LZMA suffix)
    109     * is mapped to a name without that suffix. If no LZMA suffix is
    110     * detected, then the file name is returned unmapped.
    111     *
    112     * @param fileName name of a file
    113     * @return name of the corresponding uncompressed file
    114     * @since 1.25.0
    115     */
    116    public static String getUncompressedFileName(final String fileName) {
    117        return fileNameUtil.getUncompressedFileName(fileName);
    118    }
    119
    120    private static boolean internalIsLZMACompressionAvailable() {
    121        try {
    122            LZMACompressorInputStream.matches(null, 0);
    123            return true;
    124        } catch (final NoClassDefFoundError error) { // NOSONAR
    125            return false;
    126        }
    127    }
    128
    129    /**
    130     * Detects common LZMA suffixes in the given file name.
    131     *
    132     * @param fileName name of a file
    133     * @return {@code true} if the file name has a common LZMA suffix,
    134     *         {@code false} otherwise
    135     * @deprecated Use {@link #isCompressedFileName(String)}.
    136     */
    137    @Deprecated
    138    public static boolean isCompressedFilename(final String fileName) {
    139        return fileNameUtil.isCompressedFileName(fileName);
    140    }
    141
    142    /**
    143     * Detects common LZMA suffixes in the given file name.
    144     *
    145     * @param fileName name of a file
    146     * @return {@code true} if the file name has a common LZMA suffix,
    147     *         {@code false} otherwise
    148     * @since 1.25.0
    149     */
    150    public static boolean isCompressedFileName(final String fileName) {
    151        return fileNameUtil.isCompressedFileName(fileName);
    152    }
    153
    154    /**
    155     * Are the classes required to support LZMA compression available?
    156     * @return true if the classes required to support LZMA
    157     * compression are available
    158     */
    159    public static boolean isLZMACompressionAvailable() {
    160        final CachedAvailability cachedResult = cachedLZMAAvailability;
    161        if (cachedResult != CachedAvailability.DONT_CACHE) {
    162            return cachedResult == CachedAvailability.CACHED_AVAILABLE;
    163        }
    164        return internalIsLZMACompressionAvailable();
    165    }
    166
    167    /**
    168     * Checks if the signature matches what is expected for a .lzma file.
    169     *
    170     * @param   signature     the bytes to check
    171     * @param   length        the number of bytes to check
    172     * @return  true if signature matches the .lzma magic bytes, false otherwise
    173     */
    174    public static boolean matches(final byte[] signature, final int length) {
    175        if (length < HEADER_MAGIC.length) {
    176            return false;
    177        }
    178
    179        for (int i = 0; i < HEADER_MAGIC.length; ++i) {
    180            if (signature[i] != HEADER_MAGIC[i]) {
    181                return false;
    182            }
    183        }
    184
    185        return true;
    186    }
    187
    188    /**
    189     * Whether to cache the result of the LZMA check.
    190     *
    191     * <p>This defaults to {@code false} in an OSGi environment and {@code true} otherwise.</p>
    192     * @param doCache whether to cache the result
    193     */
    194    public static void setCacheLZMAAvailablity(final boolean doCache) {
    195        if (!doCache) {
    196            cachedLZMAAvailability = CachedAvailability.DONT_CACHE;
    197        } else if (cachedLZMAAvailability == CachedAvailability.DONT_CACHE) {
    198            final boolean hasLzma = internalIsLZMACompressionAvailable();
    199            cachedLZMAAvailability = hasLzma ? CachedAvailability.CACHED_AVAILABLE // NOSONAR
    200                : CachedAvailability.CACHED_UNAVAILABLE;
    201        }
    202    }
    203
    204    /** Private constructor to prevent instantiation of this utility class. */
    205    private LZMAUtils() {
    206    }
    207}