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