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.compress.utils.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. 041 * As a special case, if the character set is UTF-8, theNIOencoder will be configured replace malformed and 042 * unmappable characters with '?'. This matches existing behavior from the older fallback encoder. 043 * <p> 044 * If the requested character set cannot be found, the platform default will 045 * be used instead. 046 * </p> 047 * @param name The name of the ZIP encoding. Specify {@code null} for 048 * the platform's default encoding. 049 * @return A ZIP encoding for the given encoding name. 050 */ 051 public static ZipEncoding getZipEncoding(final String name) { 052 Charset cs = Charset.defaultCharset(); 053 try { 054 cs = Charsets.toCharset(name); 055 } catch (final UnsupportedCharsetException ignore) { // NOSONAR we use the default encoding instead 056 } 057 final boolean useReplacement = isUTF8(cs.name()); 058 return new NioZipEncoding(cs, useReplacement); 059 } 060 061 static ByteBuffer growBufferBy(final ByteBuffer buffer, final int increment) { 062 buffer.limit(buffer.position()); 063 buffer.rewind(); 064 065 final ByteBuffer on = ByteBuffer.allocate(buffer.capacity() + increment); 066 067 on.put(buffer); 068 return on; 069 } 070 071 /** 072 * Tests whether a given encoding is UTF-8. If the given name is null, then check the platform's default encoding. 073 * 074 * @param charsetName If the given name is null, then check the platform's default encoding. 075 */ 076 static boolean isUTF8(final String charsetName) { 077 final String actual = charsetName != null ? charsetName : Charset.defaultCharset().name(); 078 if (UTF_8.name().equalsIgnoreCase(actual)) { 079 return true; 080 } 081 return UTF_8.aliases().stream().anyMatch(alias -> alias.equalsIgnoreCase(actual)); 082 } 083}