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.gzip;
020
021import java.util.LinkedHashMap;
022import java.util.Map;
023import org.apache.commons.compress.compressors.FileNameUtil;
024
025/**
026 * Utility code for the gzip compression format.
027 * @ThreadSafe
028 */
029public class GzipUtils {
030
031    private static final FileNameUtil fileNameUtil;
032
033    static {
034        // using LinkedHashMap so .tgz is preferred over .taz as
035        // compressed extension of .tar as FileNameUtil will use the
036        // first one found
037        final Map<String, String> uncompressSuffix =
038            new LinkedHashMap<>();
039        uncompressSuffix.put(".tgz", ".tar");
040        uncompressSuffix.put(".taz", ".tar");
041        uncompressSuffix.put(".svgz", ".svg");
042        uncompressSuffix.put(".cpgz", ".cpio");
043        uncompressSuffix.put(".wmz", ".wmf");
044        uncompressSuffix.put(".emz", ".emf");
045        uncompressSuffix.put(".gz", "");
046        uncompressSuffix.put(".z", "");
047        uncompressSuffix.put("-gz", "");
048        uncompressSuffix.put("-z", "");
049        uncompressSuffix.put("_z", "");
050        fileNameUtil = new FileNameUtil(uncompressSuffix, ".gz");
051    }
052
053    /** Private constructor to prevent instantiation of this utility class. */
054    private GzipUtils() {
055    }
056
057    /**
058     * Detects common gzip suffixes in the given filename.
059     *
060     * @param filename name of a file
061     * @return {@code true} if the filename has a common gzip suffix,
062     *         {@code false} otherwise
063     */
064    public static boolean isCompressedFilename(final String filename) {
065        return fileNameUtil.isCompressedFilename(filename);
066    }
067
068    /**
069     * Maps the given name of a gzip-compressed file to the name that the
070     * file should have after uncompression. Commonly used file type specific
071     * suffixes like ".tgz" or ".svgz" are automatically detected and
072     * correctly mapped. For example the name "package.tgz" is mapped to
073     * "package.tar". And any filenames with the generic ".gz" suffix
074     * (or any other generic gzip suffix) is mapped to a name without that
075     * suffix. If no gzip suffix is detected, then the filename is returned
076     * unmapped.
077     *
078     * @param filename name of a file
079     * @return name of the corresponding uncompressed file
080     */
081    public static String getUncompressedFilename(final String filename) {
082        return fileNameUtil.getUncompressedFilename(filename);
083    }
084
085    /**
086     * Maps the given filename to the name that the file should have after
087     * compression with gzip. 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.tgz". If no
090     * custom mapping is applicable, then the default ".gz" suffix is appended
091     * to the filename.
092     *
093     * @param filename name of a file
094     * @return name of the corresponding compressed file
095     */
096    public static String getCompressedFilename(final String filename) {
097        return fileNameUtil.getCompressedFilename(filename);
098    }
099
100}