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 * http://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 package org.apache.commons.compress.compressors.xz;
20
21 import java.util.HashMap;
22 import java.util.Map;
23
24 import org.apache.commons.compress.compressors.FileNameUtil;
25 import org.apache.commons.compress.utils.OsgiUtils;
26
27 /**
28 * Utility code for the XZ compression format.
29 *
30 * @ThreadSafe
31 * @since 1.4
32 */
33 public class XZUtils {
34
35 enum CachedAvailability {
36 DONT_CACHE, CACHED_AVAILABLE, CACHED_UNAVAILABLE
37 }
38
39 private static final FileNameUtil fileNameUtil;
40
41 /**
42 * XZ Header Magic Bytes begin a XZ file.
43 *
44 * <p>
45 * This is a copy of {@code org.tukaani.xz.XZ.HEADER_MAGIC} in XZ for Java version 1.5.
46 * </p>
47 */
48 private static final byte[] HEADER_MAGIC = { (byte) 0xFD, '7', 'z', 'X', 'Z', '\0' };
49
50 private static volatile CachedAvailability cachedXZAvailability;
51
52 static {
53 final Map<String, String> uncompressSuffix = new HashMap<>();
54 uncompressSuffix.put(".txz", ".tar");
55 uncompressSuffix.put(".xz", "");
56 uncompressSuffix.put("-xz", "");
57 fileNameUtil = new FileNameUtil(uncompressSuffix, ".xz");
58 cachedXZAvailability = CachedAvailability.DONT_CACHE;
59 setCacheXZAvailablity(!OsgiUtils.isRunningInOsgiEnvironment());
60 }
61
62 // only exists to support unit tests
63 static CachedAvailability getCachedXZAvailability() {
64 return cachedXZAvailability;
65 }
66
67 /**
68 * Maps the given file name to the name that the file should have after compression with xz. Common file types with custom suffixes for compressed versions
69 * are automatically detected and correctly mapped. For example the name "package.tar" is mapped to "package.txz". If no custom mapping is applicable, then
70 * the default ".xz" suffix is appended to the file name.
71 *
72 * @param fileName name of a file
73 * @return name of the corresponding compressed file
74 * @deprecated Use {@link #getCompressedFileName(String)}.
75 */
76 @Deprecated
77 public static String getCompressedFilename(final String fileName) {
78 return fileNameUtil.getCompressedFileName(fileName);
79 }
80
81 /**
82 * Maps the given file name to the name that the file should have after compression with xz. Common file types with custom suffixes for compressed versions
83 * are automatically detected and correctly mapped. For example the name "package.tar" is mapped to "package.txz". If no custom mapping is applicable, then
84 * the default ".xz" suffix is appended to the file name.
85 *
86 * @param fileName name of a file
87 * @return name of the corresponding compressed file
88 * @since 1.25.0
89 */
90 public static String getCompressedFileName(final String fileName) {
91 return fileNameUtil.getCompressedFileName(fileName);
92 }
93
94 /**
95 * Maps the given name of a xz-compressed file to the name that the file should have after uncompression. Commonly used file type specific suffixes like
96 * ".txz" are automatically detected and correctly mapped. For example the name "package.txz" is mapped to "package.tar". And any file names with the
97 * generic ".xz" suffix (or any other generic xz suffix) is mapped to a name without that suffix. If no xz suffix is detected, then the file name is
98 * returned unmapped.
99 *
100 * @param fileName name of a file
101 * @return name of the corresponding uncompressed file
102 * @deprecated Use {@link #getUncompressedFileName(String)}.
103 */
104 @Deprecated
105 public static String getUncompressedFilename(final String fileName) {
106 return fileNameUtil.getUncompressedFileName(fileName);
107 }
108
109 /**
110 * Maps the given name of a xz-compressed file to the name that the file should have after uncompression. Commonly used file type specific suffixes like
111 * ".txz" are automatically detected and correctly mapped. For example the name "package.txz" is mapped to "package.tar". And any file names with the
112 * generic ".xz" suffix (or any other generic xz suffix) is mapped to a name without that suffix. If no xz suffix is detected, then the file name is
113 * returned unmapped.
114 *
115 * @param fileName name of a file
116 * @return name of the corresponding uncompressed file
117 * @since 1.25.0
118 */
119 public static String getUncompressedFileName(final String fileName) {
120 return fileNameUtil.getUncompressedFileName(fileName);
121 }
122
123 private static boolean internalIsXZCompressionAvailable() {
124 try {
125 XZCompressorInputStream.matches(null, 0);
126 return true;
127 } catch (final NoClassDefFoundError error) { // NOSONAR
128 return false;
129 }
130 }
131
132 /**
133 * Detects common xz suffixes in the given file name.
134 *
135 * @param fileName name of a file
136 * @return {@code true} if the file name has a common xz suffix, {@code false} otherwise
137 * @deprecated Use {@link #isCompressedFileName(String)}.
138 */
139 @Deprecated
140 public static boolean isCompressedFilename(final String fileName) {
141 return fileNameUtil.isCompressedFileName(fileName);
142 }
143
144 /**
145 * Detects common xz suffixes in the given file name.
146 *
147 * @param fileName name of a file
148 * @return {@code true} if the file name has a common xz suffix, {@code false} otherwise
149 * @since 1.25.0
150 */
151 public static boolean isCompressedFileName(final String fileName) {
152 return fileNameUtil.isCompressedFileName(fileName);
153 }
154
155 /**
156 * Are the classes required to support XZ compression available?
157 *
158 * @since 1.5
159 * @return true if the classes required to support XZ compression are available
160 */
161 public static boolean isXZCompressionAvailable() {
162 final CachedAvailability cachedResult = cachedXZAvailability;
163 if (cachedResult != CachedAvailability.DONT_CACHE) {
164 return cachedResult == CachedAvailability.CACHED_AVAILABLE;
165 }
166 return internalIsXZCompressionAvailable();
167 }
168
169 /**
170 * Checks if the signature matches what is expected for a .xz file.
171 *
172 * <p>
173 * This is more or less a copy of the version found in {@link XZCompressorInputStream} but doesn't depend on the presence of XZ for Java.
174 * </p>
175 *
176 * @param signature the bytes to check
177 * @param length the number of bytes to check
178 * @return true if signature matches the .xz magic bytes, false otherwise
179 * @since 1.9
180 */
181 public static boolean matches(final byte[] signature, final int length) {
182 if (length < HEADER_MAGIC.length) {
183 return false;
184 }
185
186 for (int i = 0; i < HEADER_MAGIC.length; ++i) {
187 if (signature[i] != HEADER_MAGIC[i]) {
188 return false;
189 }
190 }
191
192 return true;
193 }
194
195 /**
196 * Whether to cache the result of the XZ for Java check.
197 *
198 * <p>
199 * This defaults to {@code false} in an OSGi environment and {@code true} otherwise.
200 * </p>
201 *
202 * @param doCache whether to cache the result
203 * @since 1.9
204 */
205 public static void setCacheXZAvailablity(final boolean doCache) {
206 if (!doCache) {
207 cachedXZAvailability = CachedAvailability.DONT_CACHE;
208 } else if (cachedXZAvailability == CachedAvailability.DONT_CACHE) {
209 final boolean hasXz = internalIsXZCompressionAvailable();
210 cachedXZAvailability = hasXz ? CachedAvailability.CACHED_AVAILABLE // NOSONAR
211 : CachedAvailability.CACHED_UNAVAILABLE;
212 }
213 }
214
215 /** Private constructor to prevent instantiation of this utility class. */
216 private XZUtils() {
217 }
218 }