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.snappy; 020 021import java.io.IOException; 022import java.io.InputStream; 023import java.io.PushbackInputStream; 024import java.util.Arrays; 025 026import org.apache.commons.compress.compressors.CompressorInputStream; 027import org.apache.commons.compress.utils.BoundedInputStream; 028import org.apache.commons.compress.utils.IOUtils; 029 030/** 031 * CompressorInputStream for the framing Snappy format. 032 * 033 * <p>Based on the "spec" in the version "Last revised: 2013-10-25"</p> 034 * 035 * @see <a href="https://github.com/google/snappy/blob/master/framing_format.txt">Snappy framing format description</a> 036 * @since 1.7 037 */ 038public class FramedSnappyCompressorInputStream extends CompressorInputStream { 039 040 /** 041 * package private for tests only. 042 */ 043 static final long MASK_OFFSET = 0xa282ead8L; 044 045 private static final int STREAM_IDENTIFIER_TYPE = 0xff; 046 private static final int COMPRESSED_CHUNK_TYPE = 0; 047 private static final int UNCOMPRESSED_CHUNK_TYPE = 1; 048 private static final int PADDING_CHUNK_TYPE = 0xfe; 049 private static final int MIN_UNSKIPPABLE_TYPE = 2; 050 private static final int MAX_UNSKIPPABLE_TYPE = 0x7f; 051 private static final int MAX_SKIPPABLE_TYPE = 0xfd; 052 053 private static final byte[] SZ_SIGNATURE = new byte[] { 054 (byte) STREAM_IDENTIFIER_TYPE, // tag 055 6, 0, 0, // length 056 's', 'N', 'a', 'P', 'p', 'Y' 057 }; 058 059 /** The underlying stream to read compressed data from */ 060 private final PushbackInputStream in; 061 /** The dialect to expect */ 062 private final FramedSnappyDialect dialect; 063 064 private SnappyCompressorInputStream currentCompressedChunk; 065 066 // used in no-arg read method 067 private final byte[] oneByte = new byte[1]; 068 069 private boolean endReached, inUncompressedChunk; 070 071 private int uncompressedBytesRemaining; 072 private long expectedChecksum = -1; 073 private final PureJavaCrc32C checksum = new PureJavaCrc32C(); 074 075 /** 076 * Constructs a new input stream that decompresses 077 * snappy-framed-compressed data from the specified input stream 078 * using the {@link FramedSnappyDialect#STANDARD} dialect. 079 * @param in the InputStream from which to read the compressed data 080 * @throws IOException if reading fails 081 */ 082 public FramedSnappyCompressorInputStream(final InputStream in) throws IOException { 083 this(in, FramedSnappyDialect.STANDARD); 084 } 085 086 /** 087 * Constructs a new input stream that decompresses snappy-framed-compressed data 088 * from the specified input stream. 089 * @param in the InputStream from which to read the compressed data 090 * @param dialect the dialect used by the compressed stream 091 * @throws IOException if reading fails 092 */ 093 public FramedSnappyCompressorInputStream(final InputStream in, 094 final FramedSnappyDialect dialect) 095 throws IOException { 096 this.in = new PushbackInputStream(in, 1); 097 this.dialect = dialect; 098 if (dialect.hasStreamIdentifier()) { 099 readStreamIdentifier(); 100 } 101 } 102 103 /** {@inheritDoc} */ 104 @Override 105 public int read() throws IOException { 106 return read(oneByte, 0, 1) == -1 ? -1 : oneByte[0] & 0xFF; 107 } 108 109 /** {@inheritDoc} */ 110 @Override 111 public void close() throws IOException { 112 if (currentCompressedChunk != null) { 113 currentCompressedChunk.close(); 114 currentCompressedChunk = null; 115 } 116 in.close(); 117 } 118 119 /** {@inheritDoc} */ 120 @Override 121 public int read(final byte[] b, final int off, final int len) throws IOException { 122 int read = readOnce(b, off, len); 123 if (read == -1) { 124 readNextBlock(); 125 if (endReached) { 126 return -1; 127 } 128 read = readOnce(b, off, len); 129 } 130 return read; 131 } 132 133 /** {@inheritDoc} */ 134 @Override 135 public int available() throws IOException { 136 if (inUncompressedChunk) { 137 return Math.min(uncompressedBytesRemaining, 138 in.available()); 139 } else if (currentCompressedChunk != null) { 140 return currentCompressedChunk.available(); 141 } 142 return 0; 143 } 144 145 /** 146 * Read from the current chunk into the given array. 147 * 148 * @return -1 if there is no current chunk or the number of bytes 149 * read from the current chunk (which may be -1 if the end of the 150 * chunk is reached). 151 */ 152 private int readOnce(final byte[] b, final int off, final int len) throws IOException { 153 int read = -1; 154 if (inUncompressedChunk) { 155 final int amount = Math.min(uncompressedBytesRemaining, len); 156 if (amount == 0) { 157 return -1; 158 } 159 read = in.read(b, off, amount); 160 if (read != -1) { 161 uncompressedBytesRemaining -= read; 162 count(read); 163 } 164 } else if (currentCompressedChunk != null) { 165 final long before = currentCompressedChunk.getBytesRead(); 166 read = currentCompressedChunk.read(b, off, len); 167 if (read == -1) { 168 currentCompressedChunk.close(); 169 currentCompressedChunk = null; 170 } else { 171 count(currentCompressedChunk.getBytesRead() - before); 172 } 173 } 174 if (read > 0) { 175 checksum.update(b, off, read); 176 } 177 return read; 178 } 179 180 private void readNextBlock() throws IOException { 181 verifyLastChecksumAndReset(); 182 inUncompressedChunk = false; 183 final int type = readOneByte(); 184 if (type == -1) { 185 endReached = true; 186 } else if (type == STREAM_IDENTIFIER_TYPE) { 187 in.unread(type); 188 pushedBackBytes(1); 189 readStreamIdentifier(); 190 readNextBlock(); 191 } else if (type == PADDING_CHUNK_TYPE 192 || (type > MAX_UNSKIPPABLE_TYPE && type <= MAX_SKIPPABLE_TYPE)) { 193 skipBlock(); 194 readNextBlock(); 195 } else if (type >= MIN_UNSKIPPABLE_TYPE && type <= MAX_UNSKIPPABLE_TYPE) { 196 throw new IOException("unskippable chunk with type " + type 197 + " (hex " + Integer.toHexString(type) + ")" 198 + " detected."); 199 } else if (type == UNCOMPRESSED_CHUNK_TYPE) { 200 inUncompressedChunk = true; 201 uncompressedBytesRemaining = readSize() - 4 /* CRC */; 202 expectedChecksum = unmask(readCrc()); 203 } else if (type == COMPRESSED_CHUNK_TYPE) { 204 boolean expectChecksum = dialect.usesChecksumWithCompressedChunks(); 205 final long size = readSize() - (expectChecksum ? 4 : 0); 206 if (expectChecksum) { 207 expectedChecksum = unmask(readCrc()); 208 } else { 209 expectedChecksum = -1; 210 } 211 currentCompressedChunk = 212 new SnappyCompressorInputStream(new BoundedInputStream(in, size)); 213 // constructor reads uncompressed size 214 count(currentCompressedChunk.getBytesRead()); 215 } else { 216 // impossible as all potential byte values have been covered 217 throw new IOException("unknown chunk type " + type 218 + " detected."); 219 } 220 } 221 222 private long readCrc() throws IOException { 223 final byte[] b = new byte[4]; 224 final int read = IOUtils.readFully(in, b); 225 count(read); 226 if (read != 4) { 227 throw new IOException("premature end of stream"); 228 } 229 long crc = 0; 230 for (int i = 0; i < 4; i++) { 231 crc |= (b[i] & 0xFFL) << (8 * i); 232 } 233 return crc; 234 } 235 236 static long unmask(long x) { 237 // ugly, maybe we should just have used ints and deal with the 238 // overflow 239 x -= MASK_OFFSET; 240 x &= 0xffffFFFFL; 241 return ((x >> 17) | (x << 15)) & 0xffffFFFFL; 242 } 243 244 private int readSize() throws IOException { 245 int b = 0; 246 int sz = 0; 247 for (int i = 0; i < 3; i++) { 248 b = readOneByte(); 249 if (b == -1) { 250 throw new IOException("premature end of stream"); 251 } 252 sz |= (b << (i * 8)); 253 } 254 return sz; 255 } 256 257 private void skipBlock() throws IOException { 258 final int size = readSize(); 259 final long read = IOUtils.skip(in, size); 260 count(read); 261 if (read != size) { 262 throw new IOException("premature end of stream"); 263 } 264 } 265 266 private void readStreamIdentifier() throws IOException { 267 final byte[] b = new byte[10]; 268 final int read = IOUtils.readFully(in, b); 269 count(read); 270 if (10 != read || !matches(b, 10)) { 271 throw new IOException("Not a framed Snappy stream"); 272 } 273 } 274 275 private int readOneByte() throws IOException { 276 final int b = in.read(); 277 if (b != -1) { 278 count(1); 279 return b & 0xFF; 280 } 281 return -1; 282 } 283 284 private void verifyLastChecksumAndReset() throws IOException { 285 if (expectedChecksum >= 0 && expectedChecksum != checksum.getValue()) { 286 throw new IOException("Checksum verification failed"); 287 } 288 expectedChecksum = -1; 289 checksum.reset(); 290 } 291 292 /** 293 * Checks if the signature matches what is expected for a .sz file. 294 * 295 * <p>.sz files start with a chunk with tag 0xff and content sNaPpY.</p> 296 * 297 * @param signature the bytes to check 298 * @param length the number of bytes to check 299 * @return true if this is a .sz stream, false otherwise 300 */ 301 public static boolean matches(final byte[] signature, final int length) { 302 303 if (length < SZ_SIGNATURE.length) { 304 return false; 305 } 306 307 byte[] shortenedSig = signature; 308 if (signature.length > SZ_SIGNATURE.length) { 309 shortenedSig = new byte[SZ_SIGNATURE.length]; 310 System.arraycopy(signature, 0, shortenedSig, 0, SZ_SIGNATURE.length); 311 } 312 313 return Arrays.equals(shortenedSig, SZ_SIGNATURE); 314 } 315 316}