1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * https://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, 13 * software distributed under the License is distributed on an 14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 15 * KIND, either express or implied. See the License for the 16 * specific language governing permissions and limitations 17 * under the License. 18 */ 19 20 package org.apache.commons.compress.archivers.zip; 21 22 import static java.nio.charset.StandardCharsets.UTF_8; 23 24 import java.nio.ByteBuffer; 25 import java.nio.charset.Charset; 26 27 import org.apache.commons.io.Charsets; 28 29 /** 30 * Static helper functions for robustly encoding file names in ZIP files. 31 */ 32 public abstract class ZipEncodingHelper { 33 34 /** 35 * UTF-8. 36 */ 37 static final ZipEncoding ZIP_ENCODING_UTF_8 = getZipEncoding(UTF_8); 38 39 /** 40 * 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 41 * encoder will be configured replace malformed and unmappable characters with '?'. This matches existing behavior from the older fallback encoder. 42 * <p> 43 * If the requested character set cannot be found, the platform default will be used instead. 44 * </p> 45 * 46 * @param charset The charset of the ZIP encoding. Specify {@code null} for the platform's default encoding. 47 * @return A ZIP encoding for the given encoding name. 48 * @since 1.26.0 49 */ 50 public static ZipEncoding getZipEncoding(final Charset charset) { 51 return new NioZipEncoding(Charsets.toCharset(charset)); 52 } 53 54 /** 55 * 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 56 * encoder will be configured replace malformed and unmappable characters with '?'. This matches existing behavior from the older fallback encoder. 57 * <p> 58 * If the requested character set cannot be found, the platform default will be used instead. 59 * </p> 60 * 61 * @param name The name of the ZIP encoding. Specify {@code null} for the platform's default encoding. 62 * @return A ZIP encoding for the given encoding name. 63 */ 64 public static ZipEncoding getZipEncoding(final String name) { 65 return new NioZipEncoding(toSafeCharset(name)); 66 } 67 68 static ByteBuffer growBufferBy(final ByteBuffer buffer, final int increment) { 69 buffer.limit(buffer.position()); 70 buffer.rewind(); 71 final ByteBuffer on = ByteBuffer.allocate(buffer.capacity() + increment); 72 on.put(buffer); 73 return on; 74 } 75 76 /** 77 * Tests whether a given encoding is UTF-8. If the given name is null, then check the platform's default encoding. 78 * 79 * @param charset If the given charset is null, then check the platform's default encoding. 80 */ 81 static boolean isUTF8(final Charset charset) { 82 return isUTF8Alias(Charsets.toCharset(charset).name()); 83 } 84 85 /** 86 * Tests whether the given non-null charset name is a UTF-8 alias. 87 * 88 * @param name a non-null charset name. 89 * @return whether the given non-null charset name is a UTF-8 alias. 90 */ 91 private static boolean isUTF8Alias(final String name) { 92 return UTF_8.name().equalsIgnoreCase(name) || UTF_8.aliases().stream().anyMatch(name::equalsIgnoreCase); 93 } 94 95 /** 96 * Returns a Charset for the named charset. If the name cannot find a charset, return {@link Charset#defaultCharset()}. 97 * 98 * @param name The name of the requested charset, may be null. 99 * @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 }