    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.xz;
    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 XZ compression format.
    029 *
    030 * @ThreadSafe
    031 * @since 1.4
    032 */
    033public class XZUtils {
    034
    035    enum CachedAvailability {
    036        DONT_CACHE, CACHED_AVAILABLE, CACHED_UNAVAILABLE
    037    }
    038
    039    private static final FileNameUtil fileNameUtil;
    040
    041    /**
    042     * XZ Header Magic Bytes begin a XZ file.
    043     *
    044     * <p>This is a copy of {@code org.tukaani.xz.XZ.HEADER_MAGIC} in
    045     * XZ for Java version 1.5.</p>
    046     */
    047    private static final byte[] HEADER_MAGIC = {
    048        (byte) 0xFD, '7', 'z', 'X', 'Z', '\0'
    049    };
    050
    051    private static volatile CachedAvailability cachedXZAvailability;
    052
    053    static {
    054        final Map<String, String> uncompressSuffix = new HashMap<>();
    055        uncompressSuffix.put(".txz", ".tar");
    056        uncompressSuffix.put(".xz", "");
    057        uncompressSuffix.put("-xz", "");
    058        fileNameUtil = new FileNameUtil(uncompressSuffix, ".xz");
    059        cachedXZAvailability = CachedAvailability.DONT_CACHE;
    060        setCacheXZAvailablity(!OsgiUtils.isRunningInOsgiEnvironment());
    061    }
    062
    063    // only exists to support unit tests
    064    static CachedAvailability getCachedXZAvailability() {
    065        return cachedXZAvailability;
    066    }
    067
    068    /**
    069     * Maps the given file name to the name that the file should have after
    070     * compression with xz. Common file types with custom suffixes for
    071     * compressed versions are automatically detected and correctly mapped.
    072     * For example the name "package.tar" is mapped to "package.txz". If no
    073     * custom mapping is applicable, then the default ".xz" suffix is appended
    074     * to the file name.
    075     *
    076     * @param fileName name of a file
    077     * @return name of the corresponding compressed file
    078     * @deprecated Use {@link #getCompressedFileName(String)}.
    079     */
    080    @Deprecated
    081    public static String getCompressedFilename(final String fileName) {
    082        return fileNameUtil.getCompressedFileName(fileName);
    083    }
    084
    085    /**
    086     * Maps the given file name to the name that the file should have after
    087     * compression with xz. Common file types with custom suffixes for
    088     * compressed versions are automatically detected and correctly mapped.
    089     * For example the name "package.tar" is mapped to "package.txz". If no
    090     * custom mapping is applicable, then the default ".xz" suffix is appended
    091     * to the file name.
    092     *
    093     * @param fileName name of a file
    094     * @return name of the corresponding compressed file
    095     * @since 1.25.0
    096     */
    097    public static String getCompressedFileName(final String fileName) {
    098        return fileNameUtil.getCompressedFileName(fileName);
    099    }
    100
    101    /**
    102     * Maps the given name of a xz-compressed file to the name that the
    103     * file should have after uncompression. Commonly used file type specific
    104     * suffixes like ".txz" are automatically detected and
    105     * correctly mapped. For example the name "package.txz" is mapped to
    106     * "package.tar". And any file names with the generic ".xz" suffix
    107     * (or any other generic xz suffix) is mapped to a name without that
    108     * suffix. If no xz suffix is detected, then the file name is returned
    109     * unmapped.
    110     *
    111     * @param fileName name of a file
    112     * @return name of the corresponding uncompressed file
    113     * @deprecated Use {@link #getUncompressedFileName(String)}.
    114     */
    115    @Deprecated
    116    public static String getUncompressedFilename(final String fileName) {
    117        return fileNameUtil.getUncompressedFileName(fileName);
    118    }
    119
    120    /**
    121     * Maps the given name of a xz-compressed file to the name that the
    122     * file should have after uncompression. Commonly used file type specific
    123     * suffixes like ".txz" are automatically detected and
    124     * correctly mapped. For example the name "package.txz" is mapped to
    125     * "package.tar". And any file names with the generic ".xz" suffix
    126     * (or any other generic xz suffix) is mapped to a name without that
    127     * suffix. If no xz suffix is detected, then the file name is returned
    128     * unmapped.
    129     *
    130     * @param fileName name of a file
    131     * @return name of the corresponding uncompressed file
    132     * @since 1.25.0
    133     */
    134    public static String getUncompressedFileName(final String fileName) {
    135        return fileNameUtil.getUncompressedFileName(fileName);
    136    }
    137
    138    private static boolean internalIsXZCompressionAvailable() {
    139        try {
    140            XZCompressorInputStream.matches(null, 0);
    141            return true;
    142        } catch (final NoClassDefFoundError error) { // NOSONAR
    143            return false;
    144        }
    145    }
    146
    147    /**
    148     * Detects common xz suffixes in the given file name.
    149     *
    150     * @param fileName name of a file
    151     * @return {@code true} if the file name has a common xz suffix,
    152     *         {@code false} otherwise
    153     * @deprecated Use {@link #isCompressedFileName(String)}.
    154     */
    155    @Deprecated
    156    public static boolean isCompressedFilename(final String fileName) {
    157        return fileNameUtil.isCompressedFileName(fileName);
    158    }
    159
    160    /**
    161     * Detects common xz suffixes in the given file name.
    162     *
    163     * @param fileName name of a file
    164     * @return {@code true} if the file name has a common xz suffix,
    165     *         {@code false} otherwise
    166     * @since 1.25.0
    167     */
    168    public static boolean isCompressedFileName(final String fileName) {
    169        return fileNameUtil.isCompressedFileName(fileName);
    170    }
    171
    172    /**
    173     * Are the classes required to support XZ compression available?
    174     * @since 1.5
    175     * @return true if the classes required to support XZ compression are available
    176     */
    177    public static boolean isXZCompressionAvailable() {
    178        final CachedAvailability cachedResult = cachedXZAvailability;
    179        if (cachedResult != CachedAvailability.DONT_CACHE) {
    180            return cachedResult == CachedAvailability.CACHED_AVAILABLE;
    181        }
    182        return internalIsXZCompressionAvailable();
    183    }
    184
    185    /**
    186     * Checks if the signature matches what is expected for a .xz file.
    187     *
    188     * <p>This is more or less a copy of the version found in {@link
    189     * XZCompressorInputStream} but doesn't depend on the presence of
    190     * XZ for Java.</p>
    191     *
    192     * @param   signature     the bytes to check
    193     * @param   length        the number of bytes to check
    194     * @return  true if signature matches the .xz magic bytes, false otherwise
    195     * @since 1.9
    196     */
    197    public static boolean matches(final byte[] signature, final int length) {
    198        if (length < HEADER_MAGIC.length) {
    199            return false;
    200        }
    201
    202        for (int i = 0; i < HEADER_MAGIC.length; ++i) {
    203            if (signature[i] != HEADER_MAGIC[i]) {
    204                return false;
    205            }
    206        }
    207
    208        return true;
    209    }
    210
    211    /**
    212     * Whether to cache the result of the XZ for Java check.
    213     *
    214     * <p>This defaults to {@code false} in an OSGi environment and {@code true} otherwise.</p>
    215     * @param doCache whether to cache the result
    216     * @since 1.9
    217     */
    218    public static void setCacheXZAvailablity(final boolean doCache) {
    219        if (!doCache) {
    220            cachedXZAvailability = CachedAvailability.DONT_CACHE;
    221        } else if (cachedXZAvailability == CachedAvailability.DONT_CACHE) {
    222            final boolean hasXz = internalIsXZCompressionAvailable();
    223            cachedXZAvailability = hasXz ? CachedAvailability.CACHED_AVAILABLE // NOSONAR
    224                : CachedAvailability.CACHED_UNAVAILABLE;
    225        }
    226    }
    227
    228    /** Private constructor to prevent instantiation of this utility class. */
    229    private XZUtils() {
    230    }
    231}