    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.StandardCharsets;
    025import java.nio.charset.UnsupportedCharsetException;
    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(StandardCharsets.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), isUTF8(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), isUTF8(toSafeCharset(name).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 a given encoding is UTF-8. If the given name is null, then check the platform's default encoding.
    087     *
    088     * @param charsetName If the given name is null, then check the platform's default encoding.
    089     */
    090    static boolean isUTF8(final String charsetName) {
    091        return isUTF8Alias(charsetName != null ? charsetName : Charset.defaultCharset().name());
    092    }
    093
    094    private static boolean isUTF8Alias(final String actual) {
    095        return UTF_8.name().equalsIgnoreCase(actual) || UTF_8.aliases().stream().anyMatch(alias -> alias.equalsIgnoreCase(actual));
    096    }
    097
    098    private static Charset toSafeCharset(final String name) {
    099        Charset charset = Charset.defaultCharset();
    100        try {
    101            charset = Charsets.toCharset(name);
    102        } catch (final UnsupportedCharsetException ignore) { // NOSONAR we use the default encoding instead
    103        }
    104        return charset;
    105    }
    106}