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}