    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 *   https://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.codec.digest.PureJavaCrc32C;
    027import org.apache.commons.compress.compressors.CompressorInputStream;
    028import org.apache.commons.compress.utils.ByteUtils;
    029import org.apache.commons.compress.utils.IOUtils;
    030import org.apache.commons.compress.utils.InputStreamStatistics;
    031import org.apache.commons.io.input.BoundedInputStream;
    032
    033/**
    034 * CompressorInputStream for the framing Snappy format.
    035 *
    036 * <p>
    037 * Based on the "spec" in the version "Last revised: 2013-10-25"
    038 * </p>
    039 *
    040 * @see <a href="https://github.com/google/snappy/blob/master/framing_format.txt">Snappy framing format description</a>
    041 * @since 1.7
    042 */
    043public class FramedSnappyCompressorInputStream extends CompressorInputStream implements InputStreamStatistics {
    044
    045    /**
    046     * package private for tests only.
    047     */
    048    static final long MASK_OFFSET = 0xa282ead8L;
    049
    050    private static final int STREAM_IDENTIFIER_TYPE = 0xff;
    051    static final int COMPRESSED_CHUNK_TYPE = 0;
    052    private static final int UNCOMPRESSED_CHUNK_TYPE = 1;
    053    private static final int PADDING_CHUNK_TYPE = 0xfe;
    054    private static final int MIN_UNSKIPPABLE_TYPE = 2;
    055    private static final int MAX_UNSKIPPABLE_TYPE = 0x7f;
    056    private static final int MAX_SKIPPABLE_TYPE = 0xfd;
    057
    058    // used by FramedSnappyCompressorOutputStream as well
    059    static final byte[] SZ_SIGNATURE = { // NOSONAR
    060            (byte) STREAM_IDENTIFIER_TYPE, // tag
    061            6, 0, 0, // length
    062            's', 'N', 'a', 'P', 'p', 'Y' };
    063
    064    /**
    065     * Checks if the signature matches what is expected for a .sz file.
    066     *
    067     * <p>
    068     * .sz files start with a chunk with tag 0xff and content sNaPpY.
    069     * </p>
    070     *
    071     * @param signature the bytes to check
    072     * @param length    the number of bytes to check
    073     * @return true if this is a .sz stream, false otherwise
    074     */
    075    public static boolean matches(final byte[] signature, final int length) {
    076
    077        if (length < SZ_SIGNATURE.length) {
    078            return false;
    079        }
    080
    081        byte[] shortenedSig = signature;
    082        if (signature.length > SZ_SIGNATURE.length) {
    083            shortenedSig = Arrays.copyOf(signature, SZ_SIGNATURE.length);
    084        }
    085
    086        return Arrays.equals(shortenedSig, SZ_SIGNATURE);
    087    }
    088
    089    static long unmask(long x) {
    090        // ugly, maybe we should just have used ints and deal with the
    091        // overflow
    092        x -= MASK_OFFSET;
    093        x &= 0xffffFFFFL;
    094        return (x >> 17 | x << 15) & 0xffffFFFFL;
    095    }
    096
    097    private long unreadBytes;
    098
    099    private final BoundedInputStream countingStream;
    100
    101    /** The underlying stream to read compressed data from */
    102    private final PushbackInputStream inputStream;
    103
    104    /** The dialect to expect */
    105    private final FramedSnappyDialect dialect;
    106
    107    private SnappyCompressorInputStream currentCompressedChunk;
    108
    109    // used in no-arg read method
    110    private final byte[] oneByte = new byte[1];
    111    private boolean endReached;
    112    private boolean inUncompressedChunk;
    113    private int uncompressedBytesRemaining;
    114    private long expectedChecksum = -1;
    115
    116    private final int blockSize;
    117
    118    private final PureJavaCrc32C checksum = new PureJavaCrc32C();
    119
    120    private final ByteUtils.ByteSupplier supplier = this::readOneByte;
    121
    122    /**
    123     * Constructs a new input stream that decompresses snappy-framed-compressed data from the specified input stream using the
    124     * {@link FramedSnappyDialect#STANDARD} dialect.
    125     *
    126     * @param in the InputStream from which to read the compressed data
    127     * @throws IOException if reading fails
    128     */
    129    public FramedSnappyCompressorInputStream(final InputStream in) throws IOException {
    130        this(in, FramedSnappyDialect.STANDARD);
    131    }
    132
    133    /**
    134     * Constructs a new input stream that decompresses snappy-framed-compressed data from the specified input stream.
    135     *
    136     * @param in      the InputStream from which to read the compressed data
    137     * @param dialect the dialect used by the compressed stream
    138     * @throws IOException if reading fails
    139     */
    140    public FramedSnappyCompressorInputStream(final InputStream in, final FramedSnappyDialect dialect) throws IOException {
    141        this(in, SnappyCompressorInputStream.DEFAULT_BLOCK_SIZE, dialect);
    142    }
    143
    144    /**
    145     * Constructs a new input stream that decompresses snappy-framed-compressed data from the specified input stream.
    146     *
    147     * @param in        the InputStream from which to read the compressed data
    148     * @param blockSize the block size to use for the compressed stream
    149     * @param dialect   the dialect used by the compressed stream
    150     * @throws IOException              if reading fails
    151     * @throws IllegalArgumentException if blockSize is not bigger than 0
    152     * @since 1.14
    153     */
    154    public FramedSnappyCompressorInputStream(final InputStream in, final int blockSize, final FramedSnappyDialect dialect) throws IOException {
    155        if (blockSize <= 0) {
    156            throw new IllegalArgumentException("blockSize must be bigger than 0");
    157        }
    158        countingStream = BoundedInputStream.builder().setInputStream(in).get();
    159        this.inputStream = new PushbackInputStream(countingStream, 1);
    160        this.blockSize = blockSize;
    161        this.dialect = dialect;
    162        if (dialect.hasStreamIdentifier()) {
    163            readStreamIdentifier();
    164        }
    165    }
    166
    167    /** {@inheritDoc} */
    168    @Override
    169    public int available() throws IOException {
    170        if (inUncompressedChunk) {
    171            return Math.min(uncompressedBytesRemaining, inputStream.available());
    172        }
    173        if (currentCompressedChunk != null) {
    174            return currentCompressedChunk.available();
    175        }
    176        return 0;
    177    }
    178
    179    /** {@inheritDoc} */
    180    @Override
    181    public void close() throws IOException {
    182        try {
    183            org.apache.commons.io.IOUtils.close(currentCompressedChunk);
    184            currentCompressedChunk = null;
    185        } finally {
    186            inputStream.close();
    187        }
    188    }
    189
    190    /**
    191     * @since 1.17
    192     */
    193    @Override
    194    public long getCompressedCount() {
    195        return countingStream.getCount() - unreadBytes;
    196    }
    197
    198    /** {@inheritDoc} */
    199    @Override
    200    public int read() throws IOException {
    201        return read(oneByte, 0, 1) == -1 ? -1 : oneByte[0] & 0xFF;
    202    }
    203
    204    /** {@inheritDoc} */
    205    @Override
    206    public int read(final byte[] b, final int off, final int len) throws IOException {
    207        if (len == 0) {
    208            return 0;
    209        }
    210        int read = readOnce(b, off, len);
    211        if (read == -1) {
    212            readNextBlock();
    213            if (endReached) {
    214                return -1;
    215            }
    216            read = readOnce(b, off, len);
    217        }
    218        return read;
    219    }
    220
    221    private long readCrc() throws IOException {
    222        final byte[] b = new byte[4];
    223        final int read = IOUtils.readFully(inputStream, b);
    224        count(read);
    225        if (read != 4) {
    226            throw new IOException("Premature end of stream");
    227        }
    228        return ByteUtils.fromLittleEndian(b);
    229    }
    230
    231    private void readNextBlock() throws IOException {
    232        verifyLastChecksumAndReset();
    233        inUncompressedChunk = false;
    234        final int type = readOneByte();
    235        if (type == -1) {
    236            endReached = true;
    237        } else if (type == STREAM_IDENTIFIER_TYPE) {
    238            inputStream.unread(type);
    239            unreadBytes++;
    240            pushedBackBytes(1);
    241            readStreamIdentifier();
    242            readNextBlock();
    243        } else if (type == PADDING_CHUNK_TYPE || type > MAX_UNSKIPPABLE_TYPE && type <= MAX_SKIPPABLE_TYPE) {
    244            skipBlock();
    245            readNextBlock();
    246        } else if (type >= MIN_UNSKIPPABLE_TYPE && type <= MAX_UNSKIPPABLE_TYPE) {
    247            throw new IOException("Unskippable chunk with type " + type + " (hex " + Integer.toHexString(type) + ") detected.");
    248        } else if (type == UNCOMPRESSED_CHUNK_TYPE) {
    249            inUncompressedChunk = true;
    250            uncompressedBytesRemaining = readSize() - 4 /* CRC */;
    251            if (uncompressedBytesRemaining < 0) {
    252                throw new IOException("Found illegal chunk with negative size");
    253            }
    254            expectedChecksum = unmask(readCrc());
    255        } else if (type == COMPRESSED_CHUNK_TYPE) {
    256            final boolean expectChecksum = dialect.usesChecksumWithCompressedChunks();
    257            final long size = readSize() - (expectChecksum ? 4L : 0L);
    258            if (size < 0) {
    259                throw new IOException("Found illegal chunk with negative size");
    260            }
    261            if (expectChecksum) {
    262                expectedChecksum = unmask(readCrc());
    263            } else {
    264                expectedChecksum = -1;
    265            }
    266            // @formatter:off
    267            currentCompressedChunk = new SnappyCompressorInputStream(BoundedInputStream.builder()
    268                    .setInputStream(inputStream)
    269                    .setMaxCount(size)
    270                    .setPropagateClose(false)
    271                    .get(),
    272                    blockSize);
    273            // @formatter:on
    274            // constructor reads uncompressed size
    275            count(currentCompressedChunk.getBytesRead());
    276        } else {
    277            // impossible as all potential byte values have been covered
    278            throw new IOException("Unknown chunk type " + type + " detected.");
    279        }
    280    }
    281
    282    /**
    283     * Reads from the current chunk into the given array.
    284     *
    285     * @return -1 if there is no current chunk or the number of bytes read from the current chunk (which may be -1 if the end of the chunk is reached).
    286     */
    287    private int readOnce(final byte[] b, final int off, final int len) throws IOException {
    288        int read = -1;
    289        if (inUncompressedChunk) {
    290            final int amount = Math.min(uncompressedBytesRemaining, len);
    291            if (amount == 0) {
    292                return -1;
    293            }
    294            read = inputStream.read(b, off, amount);
    295            if (read != -1) {
    296                uncompressedBytesRemaining -= read;
    297                count(read);
    298            }
    299        } else if (currentCompressedChunk != null) {
    300            final long before = currentCompressedChunk.getBytesRead();
    301            read = currentCompressedChunk.read(b, off, len);
    302            if (read == -1) {
    303                currentCompressedChunk.close();
    304                currentCompressedChunk = null;
    305            } else {
    306                count(currentCompressedChunk.getBytesRead() - before);
    307            }
    308        }
    309        if (read > 0) {
    310            checksum.update(b, off, read);
    311        }
    312        return read;
    313    }
    314
    315    private int readOneByte() throws IOException {
    316        final int b = inputStream.read();
    317        if (b != -1) {
    318            count(1);
    319            return b & 0xFF;
    320        }
    321        return -1;
    322    }
    323
    324    private int readSize() throws IOException {
    325        return (int) ByteUtils.fromLittleEndian(supplier, 3);
    326    }
    327
    328    private void readStreamIdentifier() throws IOException {
    329        final byte[] b = new byte[10];
    330        final int read = IOUtils.readFully(inputStream, b);
    331        count(read);
    332        if (10 != read || !matches(b, 10)) {
    333            throw new IOException("Not a framed Snappy stream");
    334        }
    335    }
    336
    337    private void skipBlock() throws IOException {
    338        final int size = readSize();
    339        if (size < 0) {
    340            throw new IOException("Found illegal chunk with negative size");
    341        }
    342        final long read = org.apache.commons.io.IOUtils.skip(inputStream, size);
    343        count(read);
    344        if (read != size) {
    345            throw new IOException("Premature end of stream");
    346        }
    347    }
    348
    349    private void verifyLastChecksumAndReset() throws IOException {
    350        if (expectedChecksum >= 0 && expectedChecksum != checksum.getValue()) {
    351            throw new IOException("Checksum verification failed");
    352        }
    353        expectedChecksum = -1;
    354        checksum.reset();
    355    }
    356
    357}