    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;
    020
    021import java.util.Collections;
    022import java.util.HashMap;
    023import java.util.Locale;
    024import java.util.Map;
    025
    026/**
    027 * File name mapping code for the compression formats.
    028 * @ThreadSafe
    029 * @since 1.4
    030 */
    031public class FileNameUtil {
    032
    033    /**
    034     * Map from common filename suffixes to the suffixes that identify compressed
    035     * versions of those file types. For example: from ".tar" to ".tgz".
    036     */
    037    private final Map<String, String> compressSuffix =
    038        new HashMap<String, String>();
    039
    040    /**
    041     * Map from common filename suffixes of compressed files to the
    042     * corresponding suffixes of uncompressed files. For example: from
    043     * ".tgz" to ".tar".
    044     * <p>
    045     * This map also contains format-specific suffixes like ".gz" and "-z".
    046     * These suffixes are mapped to the empty string, as they should simply
    047     * be removed from the filename when the file is uncompressed.
    048     */
    049    private final Map<String, String> uncompressSuffix;
    050
    051    /**
    052     * Length of the longest compressed suffix.
    053     */
    054    private final int longestCompressedSuffix;
    055
    056    /**
    057     * Length of the shortest compressed suffix.
    058     */
    059    private final int shortestCompressedSuffix;
    060
    061    /**
    062     * Length of the longest uncompressed suffix.
    063     */
    064    private final int longestUncompressedSuffix;
    065
    066    /**
    067     * Length of the shortest uncompressed suffix longer than the
    068     * empty string.
    069     */
    070    private final int shortestUncompressedSuffix;
    071
    072    /**
    073     * The format's default extension.
    074     */
    075    private final String defaultExtension;
    076
    077    /**
    078     * sets up the utility with a map of known compressed to
    079     * uncompressed suffix mappings and the default extension of the
    080     * format.
    081     *
    082     * @param uncompressSuffix Map from common filename suffixes of
    083     * compressed files to the corresponding suffixes of uncompressed
    084     * files. For example: from ".tgz" to ".tar".  This map also
    085     * contains format-specific suffixes like ".gz" and "-z".  These
    086     * suffixes are mapped to the empty string, as they should simply
    087     * be removed from the filename when the file is uncompressed.
    088     *
    089     * @param defaultExtension the format's default extension like ".gz"
    090     */
    091    public FileNameUtil(final Map<String, String> uncompressSuffix,
    092                        final String defaultExtension) {
    093        this.uncompressSuffix = Collections.unmodifiableMap(uncompressSuffix);
    094        int lc = Integer.MIN_VALUE, sc = Integer.MAX_VALUE;
    095        int lu = Integer.MIN_VALUE, su = Integer.MAX_VALUE;
    096        for (final Map.Entry<String, String> ent : uncompressSuffix.entrySet()) {
    097            final int cl = ent.getKey().length();
    098            if (cl > lc) {
    099                lc = cl;
    100            }
    101            if (cl < sc) {
    102                sc = cl;
    103            }
    104
    105            final String u = ent.getValue();
    106            final int ul = u.length();
    107            if (ul > 0) {
    108                if (!compressSuffix.containsKey(u)) {
    109                    compressSuffix.put(u, ent.getKey());
    110                }
    111                if (ul > lu) {
    112                    lu = ul;
    113                }
    114                if (ul < su) {
    115                    su = ul;
    116                }
    117            }
    118        }
    119        longestCompressedSuffix = lc;
    120        longestUncompressedSuffix = lu;
    121        shortestCompressedSuffix = sc;
    122        shortestUncompressedSuffix = su;
    123        this.defaultExtension = defaultExtension;
    124    }
    125
    126    /**
    127     * Detects common format suffixes in the given filename.
    128     *
    129     * @param filename name of a file
    130     * @return {@code true} if the filename has a common format suffix,
    131     *         {@code false} otherwise
    132     */
    133    public boolean isCompressedFilename(final String filename) {
    134        final String lower = filename.toLowerCase(Locale.ENGLISH);
    135        final int n = lower.length();
    136        for (int i = shortestCompressedSuffix;
    137             i <= longestCompressedSuffix && i < n; i++) {
    138            if (uncompressSuffix.containsKey(lower.substring(n - i))) {
    139                return true;
    140            }
    141        }
    142        return false;
    143    }
    144
    145    /**
    146     * Maps the given name of a compressed file to the name that the
    147     * file should have after uncompression. Commonly used file type specific
    148     * suffixes like ".tgz" or ".svgz" are automatically detected and
    149     * correctly mapped. For example the name "package.tgz" is mapped to
    150     * "package.tar". And any filenames with the generic ".gz" suffix
    151     * (or any other generic gzip suffix) is mapped to a name without that
    152     * suffix. If no format suffix is detected, then the filename is returned
    153     * unmapped.
    154     *
    155     * @param filename name of a file
    156     * @return name of the corresponding uncompressed file
    157     */
    158    public String getUncompressedFilename(final String filename) {
    159        final String lower = filename.toLowerCase(Locale.ENGLISH);
    160        final int n = lower.length();
    161        for (int i = shortestCompressedSuffix;
    162             i <= longestCompressedSuffix && i < n; i++) {
    163            final String suffix = uncompressSuffix.get(lower.substring(n - i));
    164            if (suffix != null) {
    165                return filename.substring(0, n - i) + suffix;
    166            }
    167        }
    168        return filename;
    169    }
    170
    171    /**
    172     * Maps the given filename to the name that the file should have after
    173     * compression. Common file types with custom suffixes for
    174     * compressed versions are automatically detected and correctly mapped.
    175     * For example the name "package.tar" is mapped to "package.tgz". If no
    176     * custom mapping is applicable, then the default ".gz" suffix is appended
    177     * to the filename.
    178     *
    179     * @param filename name of a file
    180     * @return name of the corresponding compressed file
    181     */
    182    public String getCompressedFilename(final String filename) {
    183        final String lower = filename.toLowerCase(Locale.ENGLISH);
    184        final int n = lower.length();
    185        for (int i = shortestUncompressedSuffix;
    186             i <= longestUncompressedSuffix && i < n; i++) {
    187            final String suffix = compressSuffix.get(lower.substring(n - i));
    188            if (suffix != null) {
    189                return filename.substring(0, n - i) + suffix;
    190            }
    191        }
    192        // No custom suffix found, just append the default
    193        return filename + defaultExtension;
    194    }
    195
    196}