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.lz4; 020 021import java.io.IOException; 022import java.io.InputStream; 023import java.util.Arrays; 024 025import org.apache.commons.compress.compressors.CompressorInputStream; 026import org.apache.commons.compress.utils.BoundedInputStream; 027import org.apache.commons.compress.utils.ByteUtils; 028import org.apache.commons.compress.utils.ChecksumCalculatingInputStream; 029import org.apache.commons.compress.utils.CountingInputStream; 030import org.apache.commons.compress.utils.IOUtils; 031import org.apache.commons.compress.utils.InputStreamStatistics; 032 033/** 034 * CompressorInputStream for the LZ4 frame format. 035 * 036 * <p>Based on the "spec" in the version "1.5.1 (31/03/2015)"</p> 037 * 038 * @see <a href="http://lz4.github.io/lz4/lz4_Frame_format.html">LZ4 Frame Format Description</a> 039 * @since 1.14 040 * @NotThreadSafe 041 */ 042public class FramedLZ4CompressorInputStream extends CompressorInputStream 043 implements InputStreamStatistics { 044 045 // used by FramedLZ4CompressorOutputStream as well 046 static final byte[] LZ4_SIGNATURE = new byte[] { //NOSONAR 047 4, 0x22, 0x4d, 0x18 048 }; 049 private static final byte[] SKIPPABLE_FRAME_TRAILER = new byte[] { 050 0x2a, 0x4d, 0x18 051 }; 052 private static final byte SKIPPABLE_FRAME_PREFIX_BYTE_MASK = 0x50; 053 054 static final int VERSION_MASK = 0xC0; 055 static final int SUPPORTED_VERSION = 0x40; 056 static final int BLOCK_INDEPENDENCE_MASK = 0x20; 057 static final int BLOCK_CHECKSUM_MASK = 0x10; 058 static final int CONTENT_SIZE_MASK = 0x08; 059 static final int CONTENT_CHECKSUM_MASK = 0x04; 060 static final int BLOCK_MAX_SIZE_MASK = 0x70; 061 static final int UNCOMPRESSED_FLAG_MASK = 0x80000000; 062 063 // used in no-arg read method 064 private final byte[] oneByte = new byte[1]; 065 066 private final ByteUtils.ByteSupplier supplier = new ByteUtils.ByteSupplier() { 067 @Override 068 public int getAsByte() throws IOException { 069 return readOneByte(); 070 } 071 }; 072 073 private final CountingInputStream in; 074 private final boolean decompressConcatenated; 075 076 private boolean expectBlockChecksum; 077 private boolean expectBlockDependency; 078 private boolean expectContentSize; 079 private boolean expectContentChecksum; 080 081 private InputStream currentBlock; 082 private boolean endReached, inUncompressed; 083 084 // used for frame header checksum and content checksum, if present 085 private final XXHash32 contentHash = new XXHash32(); 086 087 // used for block checksum, if present 088 private final XXHash32 blockHash = new XXHash32(); 089 090 // only created if the frame doesn't set the block independence flag 091 private byte[] blockDependencyBuffer; 092 093 /** 094 * Creates a new input stream that decompresses streams compressed 095 * using the LZ4 frame format and stops after decompressing the 096 * first frame. 097 * @param in the InputStream from which to read the compressed data 098 * @throws IOException if reading fails 099 */ 100 public FramedLZ4CompressorInputStream(InputStream in) throws IOException { 101 this(in, false); 102 } 103 104 /** 105 * Creates a new input stream that decompresses streams compressed 106 * using the LZ4 frame format. 107 * @param in the InputStream from which to read the compressed data 108 * @param decompressConcatenated if true, decompress until the end 109 * of the input; if false, stop after the first LZ4 frame 110 * and leave the input position to point to the next byte 111 * after the frame stream 112 * @throws IOException if reading fails 113 */ 114 public FramedLZ4CompressorInputStream(InputStream in, boolean decompressConcatenated) throws IOException { 115 this.in = new CountingInputStream(in); 116 this.decompressConcatenated = decompressConcatenated; 117 init(true); 118 } 119 120 /** {@inheritDoc} */ 121 @Override 122 public int read() throws IOException { 123 return read(oneByte, 0, 1) == -1 ? -1 : oneByte[0] & 0xFF; 124 } 125 126 /** {@inheritDoc} */ 127 @Override 128 public void close() throws IOException { 129 if (currentBlock != null) { 130 currentBlock.close(); 131 currentBlock = null; 132 } 133 in.close(); 134 } 135 136 /** {@inheritDoc} */ 137 @Override 138 public int read(final byte[] b, final int off, final int len) throws IOException { 139 if (endReached) { 140 return -1; 141 } 142 int r = readOnce(b, off, len); 143 if (r == -1) { 144 nextBlock(); 145 if (!endReached) { 146 r = readOnce(b, off, len); 147 } 148 } 149 if (r != -1) { 150 if (expectBlockDependency) { 151 appendToBlockDependencyBuffer(b, off, r); 152 } 153 if (expectContentChecksum) { 154 contentHash.update(b, off, r); 155 } 156 } 157 return r; 158 } 159 160 /** 161 * @since 1.17 162 */ 163 @Override 164 public long getCompressedCount() { 165 return in.getBytesRead(); 166 } 167 168 private void init(boolean firstFrame) throws IOException { 169 if (readSignature(firstFrame)) { 170 readFrameDescriptor(); 171 nextBlock(); 172 } 173 } 174 175 private boolean readSignature(boolean firstFrame) throws IOException { 176 String garbageMessage = firstFrame ? "Not a LZ4 frame stream" : "LZ4 frame stream followed by garbage"; 177 final byte[] b = new byte[4]; 178 int read = IOUtils.readFully(in, b); 179 count(read); 180 if (0 == read && !firstFrame) { 181 // good LZ4 frame and nothing after it 182 endReached = true; 183 return false; 184 } 185 if (4 != read) { 186 throw new IOException(garbageMessage); 187 } 188 189 read = skipSkippableFrame(b); 190 if (0 == read && !firstFrame) { 191 // good LZ4 frame with only some skippable frames after it 192 endReached = true; 193 return false; 194 } 195 if (4 != read || !matches(b, 4)) { 196 throw new IOException(garbageMessage); 197 } 198 return true; 199 } 200 201 private void readFrameDescriptor() throws IOException { 202 int flags = readOneByte(); 203 if (flags == -1) { 204 throw new IOException("Premature end of stream while reading frame flags"); 205 } 206 contentHash.update(flags); 207 if ((flags & VERSION_MASK) != SUPPORTED_VERSION) { 208 throw new IOException("Unsupported version " + (flags >> 6)); 209 } 210 expectBlockDependency = (flags & BLOCK_INDEPENDENCE_MASK) == 0; 211 if (expectBlockDependency) { 212 if (blockDependencyBuffer == null) { 213 blockDependencyBuffer = new byte[BlockLZ4CompressorInputStream.WINDOW_SIZE]; 214 } 215 } else { 216 blockDependencyBuffer = null; 217 } 218 expectBlockChecksum = (flags & BLOCK_CHECKSUM_MASK) != 0; 219 expectContentSize = (flags & CONTENT_SIZE_MASK) != 0; 220 expectContentChecksum = (flags & CONTENT_CHECKSUM_MASK) != 0; 221 int bdByte = readOneByte(); 222 if (bdByte == -1) { // max size is irrelevant for this implementation 223 throw new IOException("Premature end of stream while reading frame BD byte"); 224 } 225 contentHash.update(bdByte); 226 if (expectContentSize) { // for now we don't care, contains the uncompressed size 227 byte[] contentSize = new byte[8]; 228 int skipped = IOUtils.readFully(in, contentSize); 229 count(skipped); 230 if (8 != skipped) { 231 throw new IOException("Premature end of stream while reading content size"); 232 } 233 contentHash.update(contentSize, 0, contentSize.length); 234 } 235 int headerHash = readOneByte(); 236 if (headerHash == -1) { // partial hash of header. 237 throw new IOException("Premature end of stream while reading frame header checksum"); 238 } 239 int expectedHash = (int) ((contentHash.getValue() >> 8) & 0xff); 240 contentHash.reset(); 241 if (headerHash != expectedHash) { 242 throw new IOException("frame header checksum mismatch."); 243 } 244 } 245 246 private void nextBlock() throws IOException { 247 maybeFinishCurrentBlock(); 248 long len = ByteUtils.fromLittleEndian(supplier, 4); 249 boolean uncompressed = (len & UNCOMPRESSED_FLAG_MASK) != 0; 250 int realLen = (int) (len & (~UNCOMPRESSED_FLAG_MASK)); 251 if (realLen == 0) { 252 verifyContentChecksum(); 253 if (!decompressConcatenated) { 254 endReached = true; 255 } else { 256 init(false); 257 } 258 return; 259 } 260 InputStream capped = new BoundedInputStream(in, realLen); 261 if (expectBlockChecksum) { 262 capped = new ChecksumCalculatingInputStream(blockHash, capped); 263 } 264 if (uncompressed) { 265 inUncompressed = true; 266 currentBlock = capped; 267 } else { 268 inUncompressed = false; 269 BlockLZ4CompressorInputStream s = new BlockLZ4CompressorInputStream(capped); 270 if (expectBlockDependency) { 271 s.prefill(blockDependencyBuffer); 272 } 273 currentBlock = s; 274 } 275 } 276 277 private void maybeFinishCurrentBlock() throws IOException { 278 if (currentBlock != null) { 279 currentBlock.close(); 280 currentBlock = null; 281 if (expectBlockChecksum) { 282 verifyChecksum(blockHash, "block"); 283 blockHash.reset(); 284 } 285 } 286 } 287 288 private void verifyContentChecksum() throws IOException { 289 if (expectContentChecksum) { 290 verifyChecksum(contentHash, "content"); 291 } 292 contentHash.reset(); 293 } 294 295 private void verifyChecksum(XXHash32 hash, String kind) throws IOException { 296 byte[] checksum = new byte[4]; 297 int read = IOUtils.readFully(in, checksum); 298 count(read); 299 if (4 != read) { 300 throw new IOException("Premature end of stream while reading " + kind + " checksum"); 301 } 302 long expectedHash = hash.getValue(); 303 if (expectedHash != ByteUtils.fromLittleEndian(checksum)) { 304 throw new IOException(kind + " checksum mismatch."); 305 } 306 } 307 308 private int readOneByte() throws IOException { 309 final int b = in.read(); 310 if (b != -1) { 311 count(1); 312 return b & 0xFF; 313 } 314 return -1; 315 } 316 317 private int readOnce(byte[] b, int off, int len) throws IOException { 318 if (inUncompressed) { 319 int cnt = currentBlock.read(b, off, len); 320 count(cnt); 321 return cnt; 322 } 323 BlockLZ4CompressorInputStream l = (BlockLZ4CompressorInputStream) currentBlock; 324 long before = l.getBytesRead(); 325 int cnt = currentBlock.read(b, off, len); 326 count(l.getBytesRead() - before); 327 return cnt; 328 } 329 330 private static boolean isSkippableFrameSignature(byte[] b) { 331 if ((b[0] & SKIPPABLE_FRAME_PREFIX_BYTE_MASK) != SKIPPABLE_FRAME_PREFIX_BYTE_MASK) { 332 return false; 333 } 334 for (int i = 1; i < 4; i++) { 335 if (b[i] != SKIPPABLE_FRAME_TRAILER[i - 1]) { 336 return false; 337 } 338 } 339 return true; 340 } 341 342 /** 343 * Skips over the contents of a skippable frame as well as 344 * skippable frames following it. 345 * 346 * <p>It then tries to read four more bytes which are supposed to 347 * hold an LZ4 signature and returns the number of bytes read 348 * while storing the bytes in the given array.</p> 349 */ 350 private int skipSkippableFrame(byte[] b) throws IOException { 351 int read = 4; 352 while (read == 4 && isSkippableFrameSignature(b)) { 353 long len = ByteUtils.fromLittleEndian(supplier, 4); 354 long skipped = IOUtils.skip(in, len); 355 count(skipped); 356 if (len != skipped) { 357 throw new IOException("Premature end of stream while skipping frame"); 358 } 359 read = IOUtils.readFully(in, b); 360 count(read); 361 } 362 return read; 363 } 364 365 private void appendToBlockDependencyBuffer(final byte[] b, final int off, int len) { 366 len = Math.min(len, blockDependencyBuffer.length); 367 if (len > 0) { 368 int keep = blockDependencyBuffer.length - len; 369 if (keep > 0) { 370 // move last keep bytes towards the start of the buffer 371 System.arraycopy(blockDependencyBuffer, len, blockDependencyBuffer, 0, keep); 372 } 373 // append new data 374 System.arraycopy(b, off, blockDependencyBuffer, keep, len); 375 } 376 } 377 378 /** 379 * Checks if the signature matches what is expected for a .lz4 file. 380 * 381 * <p>.lz4 files start with a four byte signature.</p> 382 * 383 * @param signature the bytes to check 384 * @param length the number of bytes to check 385 * @return true if this is a .sz stream, false otherwise 386 */ 387 public static boolean matches(final byte[] signature, final int length) { 388 389 if (length < LZ4_SIGNATURE.length) { 390 return false; 391 } 392 393 byte[] shortenedSig = signature; 394 if (signature.length > LZ4_SIGNATURE.length) { 395 shortenedSig = new byte[LZ4_SIGNATURE.length]; 396 System.arraycopy(signature, 0, shortenedSig, 0, LZ4_SIGNATURE.length); 397 } 398 399 return Arrays.equals(shortenedSig, LZ4_SIGNATURE); 400 } 401}