    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.compressors.gzip;
    020
    021import java.nio.charset.Charset;
    022import java.nio.charset.StandardCharsets;
    023import java.util.LinkedHashMap;
    024import java.util.Map;
    025
    026import org.apache.commons.compress.compressors.FileNameUtil;
    027
    028/**
    029 * Utility code for the GZIP compression format.
    030 *
    031 * @see <a href="https://datatracker.ietf.org/doc/html/rfc1952">RFC 1952 GZIP File Format Specification</a>
    032 * @ThreadSafe
    033 */
    034public class GzipUtils {
    035
    036    /** Header flag indicating a comment follows the header. */
    037    static final int FCOMMENT = 0x10;
    038
    039    /** Header flag indicating an EXTRA subfields collection follows the header. */
    040    static final int FEXTRA = 0x04;
    041
    042    /** Header flag indicating a header CRC follows the header. */
    043    static final int FHCRC = 0x02;
    044
    045    private static final FileNameUtil fileNameUtil;
    046
    047    /** Header flag indicating a file name follows the header. */
    048    static final int FNAME = 0x08;
    049
    050    static final int FRESERVED = 0xE0;
    051
    052    /**
    053     * Charset for file name and comments per the <a href="https://tools.ietf.org/html/rfc1952">GZIP File Format Specification</a>.
    054     */
    055    static final Charset GZIP_ENCODING = StandardCharsets.ISO_8859_1;
    056
    057    /**
    058     * Member header ID1 (IDentification 1).
    059     *
    060     * See <a href="https://datatracker.ietf.org/doc/html/rfc1952#page-5">RFC1952</a> 2.3.1. Member header and trailer.
    061     */
    062    static final int ID1 = 31;
    063
    064    /**
    065     * Member header ID2 (IDentification 2).
    066     *
    067     * See <a href="https://datatracker.ietf.org/doc/html/rfc1952#page-5">RFC1952</a> 2.3.1. Member header and trailer.
    068     */
    069    static final int ID2 = 139;
    070
    071    /**
    072     * Member header XFL (eXtra FLags) when the "deflate" method (CM = 8) is set, then XFL = 2 means the compressor used maximum compression (slowest
    073     * algorithm).
    074     *
    075     * See <a href="https://datatracker.ietf.org/doc/html/rfc1952#page-5">RFC1952</a> 2.3.1. Member header and trailer.
    076     */
    077    static final byte XFL_MAX_COMPRESSION = 2;
    078
    079    /**
    080     * Member header XFL (eXtra FLags) when the "deflate" method (CM = 8) is set, then XFL = 4 means the compressor used the fastest algorithm.
    081     *
    082     * See <a href="https://datatracker.ietf.org/doc/html/rfc1952#page-5">RFC1952</a> 2.3.1. Member header and trailer.
    083     */
    084    static final byte XFL_MAX_SPEED = 4;
    085
    086    static final byte XFL_UNKNOWN = 0;
    087
    088    /**
    089     * Using {@link LinkedHashMap} so {@code .tgz} is preferred over {@code .taz} as compressed extension of {@code .tar} as FileNameUtil will use the first one
    090     * found.
    091     */
    092    static {
    093        final Map<String, String> uncompressSuffix = new LinkedHashMap<>();
    094        uncompressSuffix.put(".tgz", ".tar");
    095        uncompressSuffix.put(".taz", ".tar");
    096        uncompressSuffix.put(".svgz", ".svg");
    097        uncompressSuffix.put(".cpgz", ".cpio");
    098        uncompressSuffix.put(".wmz", ".wmf");
    099        uncompressSuffix.put(".emz", ".emf");
    100        uncompressSuffix.put(".gz", "");
    101        uncompressSuffix.put(".z", "");
    102        uncompressSuffix.put("-gz", "");
    103        uncompressSuffix.put("-z", "");
    104        uncompressSuffix.put("_z", "");
    105        fileNameUtil = new FileNameUtil(uncompressSuffix, ".gz");
    106    }
    107    /**
    108     * Maps the given file name to the name that the file should have after compression with gzip. Common file types with custom suffixes for compressed
    109     * versions are automatically detected and correctly mapped. For example the name "package.tar" is mapped to "package.tgz". If no custom mapping is
    110     * applicable, then the default ".gz" suffix is appended to the file name.
    111     *
    112     * @param fileName name of a file
    113     * @return name of the corresponding compressed file
    114     * @deprecated Use {@link #getCompressedFileName(String)}.
    115     */
    116    @Deprecated
    117    public static String getCompressedFilename(final String fileName) {
    118        return fileNameUtil.getCompressedFileName(fileName);
    119    }
    120
    121    /**
    122     * Maps the given file name to the name that the file should have after compression with gzip. Common file types with custom suffixes for compressed
    123     * versions are automatically detected and correctly mapped. For example the name "package.tar" is mapped to "package.tgz". If no custom mapping is
    124     * applicable, then the default ".gz" suffix is appended to the file name.
    125     *
    126     * @param fileName name of a file
    127     * @return name of the corresponding compressed file
    128     * @since 1.25.0
    129     */
    130    public static String getCompressedFileName(final String fileName) {
    131        return fileNameUtil.getCompressedFileName(fileName);
    132    }
    133
    134    /**
    135     * Maps the given name of a gzip-compressed file to the name that the file should have after uncompression. Commonly used file type specific suffixes like
    136     * ".tgz" or ".svgz" are automatically detected and correctly mapped. For example the name "package.tgz" is mapped to "package.tar". And any file names with
    137     * the generic ".gz" suffix (or any other generic gzip suffix) is mapped to a name without that suffix. If no gzip suffix is detected, then the file name is
    138     * returned unmapped.
    139     *
    140     * @param fileName name of a file
    141     * @return name of the corresponding uncompressed file
    142     * @deprecated Use {@link #getUncompressedFileName(String)}.
    143     */
    144    @Deprecated
    145    public static String getUncompressedFilename(final String fileName) {
    146        return fileNameUtil.getUncompressedFileName(fileName);
    147    }
    148
    149    /**
    150     * Maps the given name of a gzip-compressed file to the name that the file should have after uncompression. Commonly used file type specific suffixes like
    151     * ".tgz" or ".svgz" are automatically detected and correctly mapped. For example the name "package.tgz" is mapped to "package.tar". And any file names with
    152     * the generic ".gz" suffix (or any other generic gzip suffix) is mapped to a name without that suffix. If no gzip suffix is detected, then the file name is
    153     * returned unmapped.
    154     *
    155     * @param fileName name of a file
    156     * @return name of the corresponding uncompressed file
    157     * @since 1.25.0
    158     */
    159    public static String getUncompressedFileName(final String fileName) {
    160        return fileNameUtil.getUncompressedFileName(fileName);
    161    }
    162
    163    /**
    164     * Detects common gzip suffixes in the given file name.
    165     *
    166     * @param fileName name of a file
    167     * @return {@code true} if the file name has a common gzip suffix, {@code false} otherwise
    168     * @deprecated Use {@link #isCompressedFileName(String)}.
    169     */
    170    @Deprecated
    171    public static boolean isCompressedFilename(final String fileName) {
    172        return fileNameUtil.isCompressedFileName(fileName);
    173    }
    174
    175    /**
    176     * Detects common gzip suffixes in the given file name.
    177     *
    178     * @param fileName name of a file
    179     * @return {@code true} if the file name has a common gzip suffix, {@code false} otherwise
    180     * @since 1.25.0
    181     */
    182    public static boolean isCompressedFileName(final String fileName) {
    183        return fileNameUtil.isCompressedFileName(fileName);
    184    }
    185
    186    /** Private constructor to prevent instantiation of this utility class. */
    187    private GzipUtils() {
    188    }
    189
    190}