    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 = { //NOSONAR
    047        4, 0x22, 0x4d, 0x18
    048    };
    049    private static final byte[] SKIPPABLE_FRAME_TRAILER = {
    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    private static boolean isSkippableFrameSignature(final byte[] b) {
    064        if ((b[0] & SKIPPABLE_FRAME_PREFIX_BYTE_MASK) != SKIPPABLE_FRAME_PREFIX_BYTE_MASK) {
    065            return false;
    066        }
    067        for (int i = 1; i < 4; i++) {
    068            if (b[i] != SKIPPABLE_FRAME_TRAILER[i - 1]) {
    069                return false;
    070            }
    071        }
    072        return true;
    073    }
    074
    075    /**
    076     * Checks if the signature matches what is expected for a .lz4 file.
    077     *
    078     * <p>.lz4 files start with a four byte signature.</p>
    079     *
    080     * @param signature the bytes to check
    081     * @param length    the number of bytes to check
    082     * @return          true if this is a .sz stream, false otherwise
    083     */
    084    public static boolean matches(final byte[] signature, final int length) {
    085
    086        if (length < LZ4_SIGNATURE.length) {
    087            return false;
    088        }
    089
    090        byte[] shortenedSig = signature;
    091        if (signature.length > LZ4_SIGNATURE.length) {
    092            shortenedSig = Arrays.copyOf(signature, LZ4_SIGNATURE.length);
    093        }
    094
    095        return Arrays.equals(shortenedSig, LZ4_SIGNATURE);
    096    }
    097
    098    // used in no-arg read method
    099    private final byte[] oneByte = new byte[1];
    100    private final ByteUtils.ByteSupplier supplier = this::readOneByte;
    101
    102    private final CountingInputStream inputStream;
    103    private final boolean decompressConcatenated;
    104    private boolean expectBlockChecksum;
    105    private boolean expectBlockDependency;
    106
    107    private boolean expectContentSize;
    108    private boolean expectContentChecksum;
    109
    110    private InputStream currentBlock;
    111
    112    private boolean endReached, inUncompressed;
    113
    114    // used for frame header checksum and content checksum, if present
    115    private final XXHash32 contentHash = new XXHash32();
    116
    117    // used for block checksum, if present
    118    private final XXHash32 blockHash = new XXHash32();
    119
    120    // only created if the frame doesn't set the block independence flag
    121    private byte[] blockDependencyBuffer;
    122
    123    /**
    124     * Creates a new input stream that decompresses streams compressed
    125     * using the LZ4 frame format and stops after decompressing the
    126     * first frame.
    127     * @param in  the InputStream from which to read the compressed data
    128     * @throws IOException if reading fails
    129     */
    130    public FramedLZ4CompressorInputStream(final InputStream in) throws IOException {
    131        this(in, false);
    132    }
    133
    134    /**
    135     * Creates a new input stream that decompresses streams compressed
    136     * using the LZ4 frame format.
    137     * @param in  the InputStream from which to read the compressed data
    138     * @param decompressConcatenated if true, decompress until the end
    139     *          of the input; if false, stop after the first LZ4 frame
    140     *          and leave the input position to point to the next byte
    141     *          after the frame stream
    142     * @throws IOException if reading fails
    143     */
    144    public FramedLZ4CompressorInputStream(final InputStream in, final boolean decompressConcatenated) throws IOException {
    145        this.inputStream = new CountingInputStream(in);
    146        this.decompressConcatenated = decompressConcatenated;
    147        init(true);
    148    }
    149
    150    private void appendToBlockDependencyBuffer(final byte[] b, final int off, int len) {
    151        len = Math.min(len, blockDependencyBuffer.length);
    152        if (len > 0) {
    153            final int keep = blockDependencyBuffer.length - len;
    154            if (keep > 0) {
    155                // move last keep bytes towards the start of the buffer
    156                System.arraycopy(blockDependencyBuffer, len, blockDependencyBuffer, 0, keep);
    157            }
    158            // append new data
    159            System.arraycopy(b, off, blockDependencyBuffer, keep, len);
    160        }
    161    }
    162
    163    /** {@inheritDoc} */
    164    @Override
    165    public void close() throws IOException {
    166        try {
    167            if (currentBlock != null) {
    168                currentBlock.close();
    169                currentBlock = null;
    170            }
    171        } finally {
    172            inputStream.close();
    173        }
    174    }
    175
    176    /**
    177     * @since 1.17
    178     */
    179    @Override
    180    public long getCompressedCount() {
    181        return inputStream.getBytesRead();
    182    }
    183
    184    private void init(final boolean firstFrame) throws IOException {
    185        if (readSignature(firstFrame)) {
    186            readFrameDescriptor();
    187            nextBlock();
    188        }
    189    }
    190
    191    private void maybeFinishCurrentBlock() throws IOException {
    192        if (currentBlock != null) {
    193            currentBlock.close();
    194            currentBlock = null;
    195            if (expectBlockChecksum) {
    196                verifyChecksum(blockHash, "block");
    197                blockHash.reset();
    198            }
    199        }
    200    }
    201
    202    private void nextBlock() throws IOException {
    203        maybeFinishCurrentBlock();
    204        final long len = ByteUtils.fromLittleEndian(supplier, 4);
    205        final boolean uncompressed = (len & UNCOMPRESSED_FLAG_MASK) != 0;
    206        final int realLen = (int) (len & ~UNCOMPRESSED_FLAG_MASK);
    207        if (realLen == 0) {
    208            verifyContentChecksum();
    209            if (!decompressConcatenated) {
    210                endReached = true;
    211            } else {
    212                init(false);
    213            }
    214            return;
    215        }
    216        InputStream capped = new BoundedInputStream(inputStream, realLen);
    217        if (expectBlockChecksum) {
    218            capped = new ChecksumCalculatingInputStream(blockHash, capped);
    219        }
    220        if (uncompressed) {
    221            inUncompressed = true;
    222            currentBlock = capped;
    223        } else {
    224            inUncompressed = false;
    225            final BlockLZ4CompressorInputStream s = new BlockLZ4CompressorInputStream(capped);
    226            if (expectBlockDependency) {
    227                s.prefill(blockDependencyBuffer);
    228            }
    229            currentBlock = s;
    230        }
    231    }
    232
    233    /** {@inheritDoc} */
    234    @Override
    235    public int read() throws IOException {
    236        return read(oneByte, 0, 1) == -1 ? -1 : oneByte[0] & 0xFF;
    237    }
    238
    239    /** {@inheritDoc} */
    240    @Override
    241    public int read(final byte[] b, final int off, final int len) throws IOException {
    242        if (len == 0) {
    243            return 0;
    244        }
    245        if (endReached) {
    246            return -1;
    247        }
    248        int r = readOnce(b, off, len);
    249        if (r == -1) {
    250            nextBlock();
    251            if (!endReached) {
    252                r = readOnce(b, off, len);
    253            }
    254        }
    255        if (r != -1) {
    256            if (expectBlockDependency) {
    257                appendToBlockDependencyBuffer(b, off, r);
    258            }
    259            if (expectContentChecksum) {
    260                contentHash.update(b, off, r);
    261            }
    262        }
    263        return r;
    264    }
    265
    266    private void readFrameDescriptor() throws IOException {
    267        final int flags = readOneByte();
    268        if (flags == -1) {
    269            throw new IOException("Premature end of stream while reading frame flags");
    270        }
    271        contentHash.update(flags);
    272        if ((flags & VERSION_MASK) != SUPPORTED_VERSION) {
    273            throw new IOException("Unsupported version " + (flags >> 6));
    274        }
    275        expectBlockDependency = (flags & BLOCK_INDEPENDENCE_MASK) == 0;
    276        if (expectBlockDependency) {
    277            if (blockDependencyBuffer == null) {
    278                blockDependencyBuffer = new byte[BlockLZ4CompressorInputStream.WINDOW_SIZE];
    279            }
    280        } else {
    281            blockDependencyBuffer = null;
    282        }
    283        expectBlockChecksum = (flags & BLOCK_CHECKSUM_MASK) != 0;
    284        expectContentSize = (flags & CONTENT_SIZE_MASK) != 0;
    285        expectContentChecksum = (flags & CONTENT_CHECKSUM_MASK) != 0;
    286        final int bdByte = readOneByte();
    287        if (bdByte == -1) { // max size is irrelevant for this implementation
    288            throw new IOException("Premature end of stream while reading frame BD byte");
    289        }
    290        contentHash.update(bdByte);
    291        if (expectContentSize) { // for now, we don't care, contains the uncompressed size
    292            final byte[] contentSize = new byte[8];
    293            final int skipped = IOUtils.readFully(inputStream, contentSize);
    294            count(skipped);
    295            if (8 != skipped) {
    296                throw new IOException("Premature end of stream while reading content size");
    297            }
    298            contentHash.update(contentSize, 0, contentSize.length);
    299        }
    300        final int headerHash = readOneByte();
    301        if (headerHash == -1) { // partial hash of header.
    302            throw new IOException("Premature end of stream while reading frame header checksum");
    303        }
    304        final int expectedHash = (int) (contentHash.getValue() >> 8 & 0xff);
    305        contentHash.reset();
    306        if (headerHash != expectedHash) {
    307            throw new IOException("Frame header checksum mismatch");
    308        }
    309    }
    310
    311    private int readOnce(final byte[] b, final int off, final int len) throws IOException {
    312        if (inUncompressed) {
    313            final int cnt = currentBlock.read(b, off, len);
    314            count(cnt);
    315            return cnt;
    316        }
    317        final BlockLZ4CompressorInputStream l = (BlockLZ4CompressorInputStream) currentBlock;
    318        final long before = l.getBytesRead();
    319        final int cnt = currentBlock.read(b, off, len);
    320        count(l.getBytesRead() - before);
    321        return cnt;
    322    }
    323
    324    private int readOneByte() throws IOException {
    325        final int b = inputStream.read();
    326        if (b != -1) {
    327            count(1);
    328            return b & 0xFF;
    329        }
    330        return -1;
    331    }
    332
    333    private boolean readSignature(final boolean firstFrame) throws IOException {
    334        final String garbageMessage = firstFrame ? "Not a LZ4 frame stream" : "LZ4 frame stream followed by garbage";
    335        final byte[] b = new byte[4];
    336        int read = IOUtils.readFully(inputStream, b);
    337        count(read);
    338        if (0 == read && !firstFrame) {
    339            // good LZ4 frame and nothing after it
    340            endReached = true;
    341            return false;
    342        }
    343        if (4 != read) {
    344            throw new IOException(garbageMessage);
    345        }
    346
    347        read = skipSkippableFrame(b);
    348        if (0 == read && !firstFrame) {
    349            // good LZ4 frame with only some skippable frames after it
    350            endReached = true;
    351            return false;
    352        }
    353        if (4 != read || !matches(b, 4)) {
    354            throw new IOException(garbageMessage);
    355        }
    356        return true;
    357    }
    358
    359    /**
    360     * Skips over the contents of a skippable frame as well as
    361     * skippable frames following it.
    362     *
    363     * <p>It then tries to read four more bytes which are supposed to
    364     * hold an LZ4 signature and returns the number of bytes read
    365     * while storing the bytes in the given array.</p>
    366     */
    367    private int skipSkippableFrame(final byte[] b) throws IOException {
    368        int read = 4;
    369        while (read == 4 && isSkippableFrameSignature(b)) {
    370            final long len = ByteUtils.fromLittleEndian(supplier, 4);
    371            if (len < 0) {
    372                throw new IOException("Found illegal skippable frame with negative size");
    373            }
    374            final long skipped = IOUtils.skip(inputStream, len);
    375            count(skipped);
    376            if (len != skipped) {
    377                throw new IOException("Premature end of stream while skipping frame");
    378            }
    379            read = IOUtils.readFully(inputStream, b);
    380            count(read);
    381        }
    382        return read;
    383    }
    384
    385    private void verifyChecksum(final XXHash32 hash, final String kind) throws IOException {
    386        final byte[] checksum = new byte[4];
    387        final int read = IOUtils.readFully(inputStream, checksum);
    388        count(read);
    389        if (4 != read) {
    390            throw new IOException("Premature end of stream while reading " + kind + " checksum");
    391        }
    392        final long expectedHash = hash.getValue();
    393        if (expectedHash != ByteUtils.fromLittleEndian(checksum)) {
    394            throw new IOException(kind + " checksum mismatch.");
    395        }
    396    }
    397
    398    private void verifyContentChecksum() throws IOException {
    399        if (expectContentChecksum) {
    400            verifyChecksum(contentHash, "content");
    401        }
    402        contentHash.reset();
    403    }
    404}