    001/*
    002 *  Licensed to the Apache Software Foundation (ASF) under one or more
    003 *  contributor license agreements.  See the NOTICE file distributed with
    004 *  this work for additional information regarding copyright ownership.
    005 *  The ASF licenses this file to You under the Apache License, Version 2.0
    006 *  (the "License"); you may not use this file except in compliance with
    007 *  the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 *  Unless required by applicable law or agreed to in writing, software
    012 *  distributed under the License is distributed on an "AS IS" BASIS,
    013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 *  See the License for the specific language governing permissions and
    015 *  limitations under the License.
    016 */
    017
    018package org.apache.commons.compress.archivers.zip;
    019
    020import static java.nio.charset.StandardCharsets.UTF_8;
    021
    022import java.nio.ByteBuffer;
    023import java.nio.charset.Charset;
    024import java.nio.charset.UnsupportedCharsetException;
    025
    026import org.apache.commons.compress.utils.CharsetNames;
    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(CharsetNames.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        final Charset actual = Charsets.toCharset(charset);
    052        final boolean useReplacement = isUTF8(actual);
    053        return new NioZipEncoding(actual, useReplacement);
    054    }
    055
    056    /**
    057     * 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
    058     * encoder will be configured replace malformed and unmappable characters with '?'. This matches existing behavior from the older fallback encoder.
    059     * <p>
    060     * If the requested character set cannot be found, the platform default will be used instead.
    061     * </p>
    062     *
    063     * @param name The name of the ZIP encoding. Specify {@code null} for the platform's default encoding.
    064     * @return A ZIP encoding for the given encoding name.
    065     */
    066    public static ZipEncoding getZipEncoding(final String name) {
    067        Charset charset = Charset.defaultCharset();
    068        try {
    069            charset = Charsets.toCharset(name);
    070        } catch (final UnsupportedCharsetException ignore) { // NOSONAR we use the default encoding instead
    071        }
    072        final boolean useReplacement = isUTF8(charset.name());
    073        return new NioZipEncoding(charset, useReplacement);
    074    }
    075
    076    static ByteBuffer growBufferBy(final ByteBuffer buffer, final int increment) {
    077        buffer.limit(buffer.position());
    078        buffer.rewind();
    079        final ByteBuffer on = ByteBuffer.allocate(buffer.capacity() + increment);
    080        on.put(buffer);
    081        return on;
    082    }
    083
    084    /**
    085     * Tests whether a given encoding is UTF-8. If the given name is null, then check the platform's default encoding.
    086     *
    087     * @param charset If the given charset is null, then check the platform's default encoding.
    088     */
    089    static boolean isUTF8(final Charset charset) {
    090        return isUTF8Alias(Charsets.toCharset(charset).name());
    091    }
    092
    093    /**
    094     * Tests whether a given encoding is UTF-8. If the given name is null, then check the platform's default encoding.
    095     *
    096     * @param charsetName If the given name is null, then check the platform's default encoding.
    097     */
    098    static boolean isUTF8(final String charsetName) {
    099        return isUTF8Alias(charsetName != null ? charsetName : Charset.defaultCharset().name());
    100    }
    101
    102    private static boolean isUTF8Alias(final String actual) {
    103        return UTF_8.name().equalsIgnoreCase(actual) || UTF_8.aliases().stream().anyMatch(alias -> alias.equalsIgnoreCase(actual));
    104    }
    105}