    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.gzip;
    020
    021import java.io.BufferedInputStream;
    022import java.io.ByteArrayOutputStream;
    023import java.io.DataInput;
    024import java.io.DataInputStream;
    025import java.io.EOFException;
    026import java.io.IOException;
    027import java.io.InputStream;
    028import java.util.zip.CRC32;
    029import java.util.zip.DataFormatException;
    030import java.util.zip.Deflater;
    031import java.util.zip.Inflater;
    032
    033import org.apache.commons.compress.compressors.CompressorInputStream;
    034import org.apache.commons.compress.utils.ByteUtils;
    035import org.apache.commons.compress.utils.CountingInputStream;
    036import org.apache.commons.compress.utils.IOUtils;
    037import org.apache.commons.compress.utils.InputStreamStatistics;
    038
    039/**
    040 * Input stream that decompresses .gz files.
    041 *
    042 * <p>This supports decompressing concatenated .gz files which is important
    043 * when decompressing standalone .gz files.</p>
    044 *
    045 * <p>
    046 * {@link java.util.zip.GZIPInputStream} doesn't decompress concatenated .gz
    047 * files: it stops after the first member and silently ignores the rest.
    048 * It doesn't leave the read position to point to the beginning of the next
    049 * member, which makes it difficult workaround the lack of concatenation
    050 * support.
    051 * </p>
    052 *
    053 * <p>
    054 * Instead of using {@code GZIPInputStream}, this class has its own .gz
    055 * container format decoder. The actual decompression is done with
    056 * {@link java.util.zip.Inflater}.
    057 * </p>
    058 *
    059 * <p>If you use the constructor {@code GzipCompressorInputStream(in)}
    060 * or {@code GzipCompressorInputStream(in, false)} with some {@code
    061 * InputStream} {@code in} then {@link #read} will return -1 as soon
    062 * as the first internal member has been read completely. The stream
    063 * {@code in} will be positioned at the start of the second gzip
    064 * member if there is one.</p>
    065 *
    066 * <p>If you use the constructor {@code GzipCompressorInputStream(in,
    067 * true)} with some {@code InputStream} {@code in} then {@link #read}
    068 * will return -1 once the stream {@code in} has been exhausted. The
    069 * data read from a stream constructed this way will consist of the
    070 * concatenated data of all gzip members contained inside {@code
    071 * in}.</p>
    072 *
    073 * @see "https://tools.ietf.org/html/rfc1952"
    074 */
    075public class GzipCompressorInputStream extends CompressorInputStream
    076    implements InputStreamStatistics {
    077
    078    // Header flags
    079    // private static final int FTEXT = 0x01; // Uninteresting for us
    080    private static final int FHCRC = 0x02;
    081    private static final int FEXTRA = 0x04;
    082    private static final int FNAME = 0x08;
    083    private static final int FCOMMENT = 0x10;
    084    private static final int FRESERVED = 0xE0;
    085
    086    /**
    087     * Checks if the signature matches what is expected for a .gz file.
    088     *
    089     * @param signature the bytes to check
    090     * @param length    the number of bytes to check
    091     * @return          true if this is a .gz stream, false otherwise
    092     *
    093     * @since 1.1
    094     */
    095    public static boolean matches(final byte[] signature, final int length) {
    096        return length >= 2 && signature[0] == 31 && signature[1] == -117;
    097    }
    098
    099    private static byte[] readToNull(final DataInput inData) throws IOException {
    100        try (final ByteArrayOutputStream bos = new ByteArrayOutputStream()) {
    101            int b = 0;
    102            while ((b = inData.readUnsignedByte()) != 0x00) { // NOPMD NOSONAR
    103                bos.write(b);
    104            }
    105            return bos.toByteArray();
    106        }
    107    }
    108
    109    private final CountingInputStream countingStream;
    110
    111    // Compressed input stream, possibly wrapped in a
    112    // BufferedInputStream, always wrapped in countingStream above
    113    private final InputStream in;
    114
    115    // True if decompressing multi member streams.
    116    private final boolean decompressConcatenated;
    117
    118    // Buffer to hold the input data
    119    private final byte[] buf = new byte[8192];
    120
    121    // Amount of data in buf.
    122    private int bufUsed;
    123
    124    // Decompressor
    125    private Inflater inf = new Inflater(true);
    126
    127    // CRC32 from uncompressed data
    128    private final CRC32 crc = new CRC32();
    129
    130    // True once everything has been decompressed
    131    private boolean endReached;
    132
    133    // used in no-arg read method
    134    private final byte[] oneByte = new byte[1];
    135
    136    private final GzipParameters parameters = new GzipParameters();
    137
    138    /**
    139     * Constructs a new input stream that decompresses gzip-compressed data
    140     * from the specified input stream.
    141     * <p>
    142     * This is equivalent to
    143     * {@code GzipCompressorInputStream(inputStream, false)} and thus
    144     * will not decompress concatenated .gz files.
    145     *
    146     * @param inputStream  the InputStream from which this object should
    147     *                     be created of
    148     *
    149     * @throws IOException if the stream could not be created
    150     */
    151    public GzipCompressorInputStream(final InputStream inputStream)
    152            throws IOException {
    153        this(inputStream, false);
    154    }
    155
    156    /**
    157     * Constructs a new input stream that decompresses gzip-compressed data
    158     * from the specified input stream.
    159     * <p>
    160     * If {@code decompressConcatenated} is {@code false}:
    161     * This decompressor might read more input than it will actually use.
    162     * If {@code inputStream} supports {@code mark} and
    163     * {@code reset}, then the input position will be adjusted
    164     * so that it is right after the last byte of the compressed stream.
    165     * If {@code mark} isn't supported, the input position will be
    166     * undefined.
    167     *
    168     * @param inputStream  the InputStream from which this object should
    169     *                     be created of
    170     * @param decompressConcatenated
    171     *                     if true, decompress until the end of the input;
    172     *                     if false, stop after the first .gz member
    173     *
    174     * @throws IOException if the stream could not be created
    175     */
    176    public GzipCompressorInputStream(final InputStream inputStream,
    177                                     final boolean decompressConcatenated)
    178            throws IOException {
    179        countingStream = new CountingInputStream(inputStream);
    180        // Mark support is strictly needed for concatenated files only,
    181        // but it's simpler if it is always available.
    182        if (countingStream.markSupported()) {
    183            in = countingStream;
    184        } else {
    185            in = new BufferedInputStream(countingStream);
    186        }
    187
    188        this.decompressConcatenated = decompressConcatenated;
    189        init(true);
    190    }
    191
    192    /**
    193     * Closes the input stream (unless it is System.in).
    194     *
    195     * @since 1.2
    196     */
    197    @Override
    198    public void close() throws IOException {
    199        if (inf != null) {
    200            inf.end();
    201            inf = null;
    202        }
    203
    204        if (this.in != System.in) {
    205            this.in.close();
    206        }
    207    }
    208
    209    /**
    210     * @since 1.17
    211     */
    212    @Override
    213    public long getCompressedCount() {
    214        return countingStream.getBytesRead();
    215    }
    216
    217    /**
    218     * Provides the stream's meta data - may change with each stream
    219     * when decompressing concatenated streams.
    220     * @return the stream's meta data
    221     * @since 1.8
    222     */
    223    public GzipParameters getMetaData() {
    224        return parameters;
    225    }
    226
    227    private boolean init(final boolean isFirstMember) throws IOException {
    228        assert isFirstMember || decompressConcatenated;
    229
    230        // Check the magic bytes without a possibility of EOFException.
    231        final int magic0 = in.read();
    232
    233        // If end of input was reached after decompressing at least
    234        // one .gz member, we have reached the end of the file successfully.
    235        if (magic0 == -1 && !isFirstMember) {
    236            return false;
    237        }
    238
    239        if (magic0 != 31 || in.read() != 139) {
    240            throw new IOException(isFirstMember
    241                                  ? "Input is not in the .gz format"
    242                                  : "Garbage after a valid .gz stream");
    243        }
    244
    245        // Parsing the rest of the header may throw EOFException.
    246        final DataInput inData = new DataInputStream(in);
    247        final int method = inData.readUnsignedByte();
    248        if (method != Deflater.DEFLATED) {
    249            throw new IOException("Unsupported compression method "
    250                                  + method + " in the .gz header");
    251        }
    252
    253        final int flg = inData.readUnsignedByte();
    254        if ((flg & FRESERVED) != 0) {
    255            throw new IOException(
    256                    "Reserved flags are set in the .gz header");
    257        }
    258
    259        parameters.setModificationTime(ByteUtils.fromLittleEndian(inData, 4) * 1000);
    260        switch (inData.readUnsignedByte()) { // extra flags
    261        case 2:
    262            parameters.setCompressionLevel(Deflater.BEST_COMPRESSION);
    263            break;
    264        case 4:
    265            parameters.setCompressionLevel(Deflater.BEST_SPEED);
    266            break;
    267        default:
    268            // ignored for now
    269            break;
    270        }
    271        parameters.setOperatingSystem(inData.readUnsignedByte());
    272
    273        // Extra field, ignored
    274        if ((flg & FEXTRA) != 0) {
    275            int xlen = inData.readUnsignedByte();
    276            xlen |= inData.readUnsignedByte() << 8;
    277
    278            // This isn't as efficient as calling in.skip would be,
    279            // but it's lazier to handle unexpected end of input this way.
    280            // Most files don't have an extra field anyway.
    281            while (xlen-- > 0) {
    282                inData.readUnsignedByte();
    283            }
    284        }
    285
    286        // Original file name
    287        if ((flg & FNAME) != 0) {
    288            parameters.setFilename(new String(readToNull(inData), GzipUtils.GZIP_ENCODING));
    289        }
    290
    291        // Comment
    292        if ((flg & FCOMMENT) != 0) {
    293            parameters.setComment(new String(readToNull(inData), GzipUtils.GZIP_ENCODING));
    294        }
    295
    296        // Header "CRC16" which is actually a truncated CRC32 (which isn't
    297        // as good as real CRC16). I don't know if any encoder implementation
    298        // sets this, so it's not worth trying to verify it. GNU gzip 1.4
    299        // doesn't support this field, but zlib seems to be able to at least
    300        // skip over it.
    301        if ((flg & FHCRC) != 0) {
    302            inData.readShort();
    303        }
    304
    305        // Reset
    306        inf.reset();
    307        crc.reset();
    308
    309        return true;
    310    }
    311
    312    @Override
    313    public int read() throws IOException {
    314        return read(oneByte, 0, 1) == -1 ? -1 : oneByte[0] & 0xFF;
    315    }
    316
    317    /**
    318     * {@inheritDoc}
    319     *
    320     * @since 1.1
    321     */
    322    @Override
    323    public int read(final byte[] b, int off, int len) throws IOException {
    324        if (len == 0) {
    325            return 0;
    326        }
    327        if (endReached) {
    328            return -1;
    329        }
    330
    331        int size = 0;
    332
    333        while (len > 0) {
    334            if (inf.needsInput()) {
    335                // Remember the current position because we may need to
    336                // rewind after reading too much input.
    337                in.mark(buf.length);
    338
    339                bufUsed = in.read(buf);
    340                if (bufUsed == -1) {
    341                    throw new EOFException();
    342                }
    343
    344                inf.setInput(buf, 0, bufUsed);
    345            }
    346
    347            final int ret;
    348            try {
    349                ret = inf.inflate(b, off, len);
    350            } catch (final DataFormatException e) { // NOSONAR
    351                throw new IOException("Gzip-compressed data is corrupt");
    352            }
    353
    354            crc.update(b, off, ret);
    355            off += ret;
    356            len -= ret;
    357            size += ret;
    358            count(ret);
    359
    360            if (inf.finished()) {
    361                // We may have read too many bytes. Rewind the read
    362                // position to match the actual amount used.
    363                in.reset();
    364
    365                final int skipAmount = bufUsed - inf.getRemaining();
    366                if (IOUtils.skip(in, skipAmount) != skipAmount) {
    367                    throw new IOException();
    368                }
    369
    370                bufUsed = 0;
    371
    372                final DataInput inData = new DataInputStream(in);
    373
    374                // CRC32
    375                final long crcStored = ByteUtils.fromLittleEndian(inData, 4);
    376
    377                if (crcStored != crc.getValue()) {
    378                    throw new IOException("Gzip-compressed data is corrupt "
    379                                          + "(CRC32 error)");
    380                }
    381
    382                // Uncompressed size modulo 2^32 (ISIZE in the spec)
    383                final long isize = ByteUtils.fromLittleEndian(inData, 4);
    384
    385                if (isize != (inf.getBytesWritten() & 0xffffffffL)) {
    386                    throw new IOException("Gzip-compressed data is corrupt"
    387                                          + "(uncompressed size mismatch)");
    388                }
    389
    390                // See if this is the end of the file.
    391                if (!decompressConcatenated || !init(false)) {
    392                    inf.end();
    393                    inf = null;
    394                    endReached = true;
    395                    return size == 0 ? -1 : size;
    396                }
    397            }
    398        }
    399
    400        return size;
    401    }
    402}