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.lzma; 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 LZMA compression format. 029 * 030 * @ThreadSafe 031 * @since 1.10 032 */ 033public class LZMAUtils { 034 035 enum CachedAvailability { 036 DONT_CACHE, CACHED_AVAILABLE, CACHED_UNAVAILABLE 037 } 038 039 private static final FileNameUtil fileNameUtil; 040 041 /** 042 * LZMA Header Magic Bytes begin a LZMA file. 043 */ 044 private static final byte[] HEADER_MAGIC = { 045 (byte) 0x5D, 0, 0 046 }; 047 048 private static volatile CachedAvailability cachedLZMAAvailability; 049 050 static { 051 final Map<String, String> uncompressSuffix = new HashMap<>(); 052 uncompressSuffix.put(".lzma", ""); 053 uncompressSuffix.put("-lzma", ""); 054 fileNameUtil = new FileNameUtil(uncompressSuffix, ".lzma"); 055 cachedLZMAAvailability = CachedAvailability.DONT_CACHE; 056 setCacheLZMAAvailablity(!OsgiUtils.isRunningInOsgiEnvironment()); 057 } 058 059 // only exists to support unit tests 060 static CachedAvailability getCachedLZMAAvailability() { 061 return cachedLZMAAvailability; 062 } 063 064 /** 065 * Maps the given file name to the name that the file should have after 066 * compression with LZMA. 067 * 068 * @param fileName name of a file 069 * @return name of the corresponding compressed file 070 * @deprecated Use {@link #getCompressedFileName(String)}. 071 */ 072 @Deprecated 073 public static String getCompressedFilename(final String fileName) { 074 return fileNameUtil.getCompressedFileName(fileName); 075 } 076 077 /** 078 * Maps the given file name to the name that the file should have after 079 * compression with LZMA. 080 * 081 * @param fileName name of a file 082 * @return name of the corresponding compressed file 083 * @since 1.25.0 084 */ 085 public static String getCompressedFileName(final String fileName) { 086 return fileNameUtil.getCompressedFileName(fileName); 087 } 088 089 /** 090 * Maps the given name of a LZMA-compressed file to the name that 091 * the file should have after uncompression. Any file names with 092 * the generic ".lzma" suffix (or any other generic LZMA suffix) 093 * is mapped to a name without that suffix. If no LZMA suffix is 094 * detected, then the file name is returned unmapped. 095 * 096 * @param fileName name of a file 097 * @return name of the corresponding uncompressed file 098 * @deprecated Use {@link #getUncompressedFileName(String)}. 099 */ 100 @Deprecated 101 public static String getUncompressedFilename(final String fileName) { 102 return fileNameUtil.getUncompressedFileName(fileName); 103 } 104 105 /** 106 * Maps the given name of a LZMA-compressed file to the name that 107 * the file should have after uncompression. Any file names with 108 * the generic ".lzma" suffix (or any other generic LZMA suffix) 109 * is mapped to a name without that suffix. If no LZMA suffix is 110 * detected, then the file name is returned unmapped. 111 * 112 * @param fileName name of a file 113 * @return name of the corresponding uncompressed file 114 * @since 1.25.0 115 */ 116 public static String getUncompressedFileName(final String fileName) { 117 return fileNameUtil.getUncompressedFileName(fileName); 118 } 119 120 private static boolean internalIsLZMACompressionAvailable() { 121 try { 122 LZMACompressorInputStream.matches(null, 0); 123 return true; 124 } catch (final NoClassDefFoundError error) { // NOSONAR 125 return false; 126 } 127 } 128 129 /** 130 * Detects common LZMA suffixes in the given file name. 131 * 132 * @param fileName name of a file 133 * @return {@code true} if the file name has a common LZMA suffix, 134 * {@code false} otherwise 135 * @deprecated Use {@link #isCompressedFileName(String)}. 136 */ 137 @Deprecated 138 public static boolean isCompressedFilename(final String fileName) { 139 return fileNameUtil.isCompressedFileName(fileName); 140 } 141 142 /** 143 * Detects common LZMA suffixes in the given file name. 144 * 145 * @param fileName name of a file 146 * @return {@code true} if the file name has a common LZMA suffix, 147 * {@code false} otherwise 148 * @since 1.25.0 149 */ 150 public static boolean isCompressedFileName(final String fileName) { 151 return fileNameUtil.isCompressedFileName(fileName); 152 } 153 154 /** 155 * Are the classes required to support LZMA compression available? 156 * @return true if the classes required to support LZMA 157 * compression are available 158 */ 159 public static boolean isLZMACompressionAvailable() { 160 final CachedAvailability cachedResult = cachedLZMAAvailability; 161 if (cachedResult != CachedAvailability.DONT_CACHE) { 162 return cachedResult == CachedAvailability.CACHED_AVAILABLE; 163 } 164 return internalIsLZMACompressionAvailable(); 165 } 166 167 /** 168 * Checks if the signature matches what is expected for a .lzma file. 169 * 170 * @param signature the bytes to check 171 * @param length the number of bytes to check 172 * @return true if signature matches the .lzma magic bytes, false otherwise 173 */ 174 public static boolean matches(final byte[] signature, final int length) { 175 if (length < HEADER_MAGIC.length) { 176 return false; 177 } 178 179 for (int i = 0; i < HEADER_MAGIC.length; ++i) { 180 if (signature[i] != HEADER_MAGIC[i]) { 181 return false; 182 } 183 } 184 185 return true; 186 } 187 188 /** 189 * Whether to cache the result of the LZMA check. 190 * 191 * <p>This defaults to {@code false} in an OSGi environment and {@code true} otherwise.</p> 192 * @param doCache whether to cache the result 193 */ 194 public static void setCacheLZMAAvailablity(final boolean doCache) { 195 if (!doCache) { 196 cachedLZMAAvailability = CachedAvailability.DONT_CACHE; 197 } else if (cachedLZMAAvailability == CachedAvailability.DONT_CACHE) { 198 final boolean hasLzma = internalIsLZMACompressionAvailable(); 199 cachedLZMAAvailability = hasLzma ? CachedAvailability.CACHED_AVAILABLE // NOSONAR 200 : CachedAvailability.CACHED_UNAVAILABLE; 201 } 202 } 203 204 /** Private constructor to prevent instantiation of this utility class. */ 205 private LZMAUtils() { 206 } 207}