001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 */ 019package org.apache.commons.compress.compressors.xz; 020 021import java.util.HashMap; 022import java.util.Map; 023 024import org.apache.commons.compress.compressors.FileNameUtil; 025import org.apache.commons.compress.utils.OsgiUtils; 026 027/** 028 * Utility code for the XZ compression format. 029 * 030 * @ThreadSafe 031 * @since 1.4 032 */ 033public class XZUtils { 034 035 enum CachedAvailability { 036 DONT_CACHE, CACHED_AVAILABLE, CACHED_UNAVAILABLE 037 } 038 039 private static final FileNameUtil fileNameUtil; 040 041 /** 042 * XZ Header Magic Bytes begin a XZ file. 043 * 044 * <p>This is a copy of {@code org.tukaani.xz.XZ.HEADER_MAGIC} in 045 * XZ for Java version 1.5.</p> 046 */ 047 private static final byte[] HEADER_MAGIC = { 048 (byte) 0xFD, '7', 'z', 'X', 'Z', '\0' 049 }; 050 051 private static volatile CachedAvailability cachedXZAvailability; 052 053 static { 054 final Map<String, String> uncompressSuffix = new HashMap<>(); 055 uncompressSuffix.put(".txz", ".tar"); 056 uncompressSuffix.put(".xz", ""); 057 uncompressSuffix.put("-xz", ""); 058 fileNameUtil = new FileNameUtil(uncompressSuffix, ".xz"); 059 cachedXZAvailability = CachedAvailability.DONT_CACHE; 060 setCacheXZAvailablity(!OsgiUtils.isRunningInOsgiEnvironment()); 061 } 062 063 // only exists to support unit tests 064 static CachedAvailability getCachedXZAvailability() { 065 return cachedXZAvailability; 066 } 067 068 /** 069 * Maps the given file name to the name that the file should have after 070 * compression with xz. Common file types with custom suffixes for 071 * compressed versions are automatically detected and correctly mapped. 072 * For example the name "package.tar" is mapped to "package.txz". If no 073 * custom mapping is applicable, then the default ".xz" suffix is appended 074 * to the file name. 075 * 076 * @param fileName name of a file 077 * @return name of the corresponding compressed file 078 * @deprecated Use {@link #getCompressedFileName(String)}. 079 */ 080 @Deprecated 081 public static String getCompressedFilename(final String fileName) { 082 return fileNameUtil.getCompressedFileName(fileName); 083 } 084 085 /** 086 * Maps the given file name to the name that the file should have after 087 * compression with xz. Common file types with custom suffixes for 088 * compressed versions are automatically detected and correctly mapped. 089 * For example the name "package.tar" is mapped to "package.txz". If no 090 * custom mapping is applicable, then the default ".xz" suffix is appended 091 * to the file name. 092 * 093 * @param fileName name of a file 094 * @return name of the corresponding compressed file 095 * @since 1.25.0 096 */ 097 public static String getCompressedFileName(final String fileName) { 098 return fileNameUtil.getCompressedFileName(fileName); 099 } 100 101 /** 102 * Maps the given name of a xz-compressed file to the name that the 103 * file should have after uncompression. Commonly used file type specific 104 * suffixes like ".txz" are automatically detected and 105 * correctly mapped. For example the name "package.txz" is mapped to 106 * "package.tar". And any file names with the generic ".xz" suffix 107 * (or any other generic xz suffix) is mapped to a name without that 108 * suffix. If no xz suffix is detected, then the file name is returned 109 * unmapped. 110 * 111 * @param fileName name of a file 112 * @return name of the corresponding uncompressed file 113 * @deprecated Use {@link #getUncompressedFileName(String)}. 114 */ 115 @Deprecated 116 public static String getUncompressedFilename(final String fileName) { 117 return fileNameUtil.getUncompressedFileName(fileName); 118 } 119 120 /** 121 * Maps the given name of a xz-compressed file to the name that the 122 * file should have after uncompression. Commonly used file type specific 123 * suffixes like ".txz" are automatically detected and 124 * correctly mapped. For example the name "package.txz" is mapped to 125 * "package.tar". And any file names with the generic ".xz" suffix 126 * (or any other generic xz suffix) is mapped to a name without that 127 * suffix. If no xz suffix is detected, then the file name is returned 128 * unmapped. 129 * 130 * @param fileName name of a file 131 * @return name of the corresponding uncompressed file 132 * @since 1.25.0 133 */ 134 public static String getUncompressedFileName(final String fileName) { 135 return fileNameUtil.getUncompressedFileName(fileName); 136 } 137 138 private static boolean internalIsXZCompressionAvailable() { 139 try { 140 XZCompressorInputStream.matches(null, 0); 141 return true; 142 } catch (final NoClassDefFoundError error) { // NOSONAR 143 return false; 144 } 145 } 146 147 /** 148 * Detects common xz suffixes in the given file name. 149 * 150 * @param fileName name of a file 151 * @return {@code true} if the file name has a common xz suffix, 152 * {@code false} otherwise 153 * @deprecated Use {@link #isCompressedFileName(String)}. 154 */ 155 @Deprecated 156 public static boolean isCompressedFilename(final String fileName) { 157 return fileNameUtil.isCompressedFileName(fileName); 158 } 159 160 /** 161 * Detects common xz suffixes in the given file name. 162 * 163 * @param fileName name of a file 164 * @return {@code true} if the file name has a common xz suffix, 165 * {@code false} otherwise 166 * @since 1.25.0 167 */ 168 public static boolean isCompressedFileName(final String fileName) { 169 return fileNameUtil.isCompressedFileName(fileName); 170 } 171 172 /** 173 * Are the classes required to support XZ compression available? 174 * @since 1.5 175 * @return true if the classes required to support XZ compression are available 176 */ 177 public static boolean isXZCompressionAvailable() { 178 final CachedAvailability cachedResult = cachedXZAvailability; 179 if (cachedResult != CachedAvailability.DONT_CACHE) { 180 return cachedResult == CachedAvailability.CACHED_AVAILABLE; 181 } 182 return internalIsXZCompressionAvailable(); 183 } 184 185 /** 186 * Checks if the signature matches what is expected for a .xz file. 187 * 188 * <p>This is more or less a copy of the version found in {@link 189 * XZCompressorInputStream} but doesn't depend on the presence of 190 * XZ for Java.</p> 191 * 192 * @param signature the bytes to check 193 * @param length the number of bytes to check 194 * @return true if signature matches the .xz magic bytes, false otherwise 195 * @since 1.9 196 */ 197 public static boolean matches(final byte[] signature, final int length) { 198 if (length < HEADER_MAGIC.length) { 199 return false; 200 } 201 202 for (int i = 0; i < HEADER_MAGIC.length; ++i) { 203 if (signature[i] != HEADER_MAGIC[i]) { 204 return false; 205 } 206 } 207 208 return true; 209 } 210 211 /** 212 * Whether to cache the result of the XZ for Java check. 213 * 214 * <p>This defaults to {@code false} in an OSGi environment and {@code true} otherwise.</p> 215 * @param doCache whether to cache the result 216 * @since 1.9 217 */ 218 public static void setCacheXZAvailablity(final boolean doCache) { 219 if (!doCache) { 220 cachedXZAvailability = CachedAvailability.DONT_CACHE; 221 } else if (cachedXZAvailability == CachedAvailability.DONT_CACHE) { 222 final boolean hasXz = internalIsXZCompressionAvailable(); 223 cachedXZAvailability = hasXz ? CachedAvailability.CACHED_AVAILABLE // NOSONAR 224 : CachedAvailability.CACHED_UNAVAILABLE; 225 } 226 } 227 228 /** Private constructor to prevent instantiation of this utility class. */ 229 private XZUtils() { 230 } 231}