    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.deflate;
    020
    021import java.io.IOException;
    022import java.io.InputStream;
    023import java.util.zip.Inflater;
    024import java.util.zip.InflaterInputStream;
    025
    026import org.apache.commons.compress.compressors.CompressorInputStream;
    027import org.apache.commons.compress.utils.InputStreamStatistics;
    028import org.apache.commons.io.input.BoundedInputStream;
    029
    030/**
    031 * Deflate decompressor.
    032 *
    033 * @since 1.9
    034 */
    035public class DeflateCompressorInputStream extends CompressorInputStream implements InputStreamStatistics {
    036
    037    private static final int MAGIC_1 = 0x78;
    038    private static final int MAGIC_2a = 0x01;
    039    private static final int MAGIC_2b = 0x5e;
    040    private static final int MAGIC_2c = 0x9c;
    041    private static final int MAGIC_2d = 0xda;
    042
    043    /**
    044     * Checks if the signature matches what is expected for a zlib / deflated file with the zlib header.
    045     *
    046     * @param signature the bytes to check
    047     * @param length    the number of bytes to check
    048     * @return true, if this stream is zlib / deflate compressed with a header stream, false otherwise
    049     * @since 1.10
    050     */
    051    public static boolean matches(final byte[] signature, final int length) {
    052        return length > 3 && signature[0] == MAGIC_1
    053                && (signature[1] == (byte) MAGIC_2a || signature[1] == (byte) MAGIC_2b || signature[1] == (byte) MAGIC_2c || signature[1] == (byte) MAGIC_2d);
    054    }
    055
    056    private final BoundedInputStream countingStream;
    057    private final InputStream in;
    058
    059    private final Inflater inflater;
    060
    061    /**
    062     * Creates a new input stream that decompresses Deflate-compressed data from the specified input stream.
    063     *
    064     * @param inputStream where to read the compressed data
    065     */
    066    public DeflateCompressorInputStream(final InputStream inputStream) {
    067        this(inputStream, new DeflateParameters());
    068    }
    069
    070    /**
    071     * Creates a new input stream that decompresses Deflate-compressed data from the specified input stream.
    072     *
    073     * @param inputStream where to read the compressed data
    074     * @param parameters  parameters
    075     */
    076    public DeflateCompressorInputStream(final InputStream inputStream, final DeflateParameters parameters) {
    077        inflater = new Inflater(!parameters.withZlibHeader());
    078        in = new InflaterInputStream(countingStream = BoundedInputStream.builder().setInputStream(inputStream).asSupplier().get(), inflater);
    079    }
    080
    081    /** {@inheritDoc} */
    082    @Override
    083    public int available() throws IOException {
    084        return in.available();
    085    }
    086
    087    /** {@inheritDoc} */
    088    @Override
    089    public void close() throws IOException {
    090        try {
    091            in.close();
    092        } finally {
    093            inflater.end();
    094        }
    095    }
    096
    097    /**
    098     * @since 1.17
    099     */
    100    @Override
    101    public long getCompressedCount() {
    102        return countingStream.getCount();
    103    }
    104
    105    /** {@inheritDoc} */
    106    @Override
    107    public int read() throws IOException {
    108        final int ret = in.read();
    109        count(ret == -1 ? 0 : 1);
    110        return ret;
    111    }
    112
    113    /** {@inheritDoc} */
    114    @Override
    115    public int read(final byte[] buf, final int off, final int len) throws IOException {
    116        if (len == 0) {
    117            return 0;
    118        }
    119        final int ret = in.read(buf, off, len);
    120        count(ret);
    121        return ret;
    122    }
    123
    124    /** {@inheritDoc} */
    125    @Override
    126    public long skip(final long n) throws IOException {
    127        return org.apache.commons.io.IOUtils.skip(in, n);
    128    }
    129}