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 }