    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 */
    019
    020package org.apache.commons.compress.archivers.zip;
    021
    022import static java.nio.charset.StandardCharsets.UTF_8;
    023
    024import java.nio.ByteBuffer;
    025import java.nio.charset.Charset;
    026
    027import org.apache.commons.io.Charsets;
    028
    029/**
    030 * Static helper functions for robustly encoding file names in ZIP files.
    031 */
    032public abstract class ZipEncodingHelper {
    033
    034    /**
    035     * UTF-8.
    036     */
    037    static final ZipEncoding ZIP_ENCODING_UTF_8 = getZipEncoding(UTF_8);
    038
    039    /**
    040     * Instantiates a ZIP encoding. An NIO based character set encoder/decoder will be returned. As a special case, if the character set is UTF-8, the NIO
    041     * encoder will be configured replace malformed and unmappable characters with '?'. This matches existing behavior from the older fallback encoder.
    042     * <p>
    043     * If the requested character set cannot be found, the platform default will be used instead.
    044     * </p>
    045     *
    046     * @param charset The charset of the ZIP encoding. Specify {@code null} for the platform's default encoding.
    047     * @return A ZIP encoding for the given encoding name.
    048     * @since 1.26.0
    049     */
    050    public static ZipEncoding getZipEncoding(final Charset charset) {
    051        return new NioZipEncoding(Charsets.toCharset(charset));
    052    }
    053
    054    /**
    055     * Instantiates a ZIP encoding. An NIO based character set encoder/decoder will be returned. As a special case, if the character set is UTF-8, the NIO
    056     * encoder will be configured replace malformed and unmappable characters with '?'. This matches existing behavior from the older fallback encoder.
    057     * <p>
    058     * If the requested character set cannot be found, the platform default will be used instead.
    059     * </p>
    060     *
    061     * @param name The name of the ZIP encoding. Specify {@code null} for the platform's default encoding.
    062     * @return A ZIP encoding for the given encoding name.
    063     */
    064    public static ZipEncoding getZipEncoding(final String name) {
    065        return new NioZipEncoding(toSafeCharset(name));
    066    }
    067
    068    static ByteBuffer growBufferBy(final ByteBuffer buffer, final int increment) {
    069        buffer.limit(buffer.position());
    070        buffer.rewind();
    071        final ByteBuffer on = ByteBuffer.allocate(buffer.capacity() + increment);
    072        on.put(buffer);
    073        return on;
    074    }
    075
    076    /**
    077     * Tests whether a given encoding is UTF-8. If the given name is null, then check the platform's default encoding.
    078     *
    079     * @param charset If the given charset is null, then check the platform's default encoding.
    080     */
    081    static boolean isUTF8(final Charset charset) {
    082        return isUTF8Alias(Charsets.toCharset(charset).name());
    083    }
    084
    085    /**
    086     * Tests whether the given non-null charset name is a UTF-8 alias.
    087     *
    088     * @param name a non-null charset name.
    089     * @return whether the given non-null charset name is a UTF-8 alias.
    090     */
    091    private static boolean isUTF8Alias(final String name) {
    092        return UTF_8.name().equalsIgnoreCase(name) || UTF_8.aliases().stream().anyMatch(name::equalsIgnoreCase);
    093    }
    094
    095    /**
    096     * Returns a Charset for the named charset. If the name cannot find a charset, return {@link Charset#defaultCharset()}.
    097     *
    098     * @param name The name of the requested charset, may be null.
    099     * @return a Charset for the named charset.
    100     * @see Charset#defaultCharset()
    101     */
    102    private static Charset toSafeCharset(final String name) {
    103        try {
    104            return Charsets.toCharset(name);
    105        } catch (final IllegalArgumentException | NullPointerException ignored) {
    106            return Charset.defaultCharset();
    107        }
    108    }
    109}