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.xz;
020
021import java.io.IOException;
022import java.io.InputStream;
023import org.tukaani.xz.XZ;
024import org.tukaani.xz.SingleXZInputStream;
025import org.tukaani.xz.XZInputStream;
026
027import org.apache.commons.compress.compressors.CompressorInputStream;
028
029/**
030 * XZ decompressor.
031 * @since 1.4
032 */
033public class XZCompressorInputStream extends CompressorInputStream {
034    private final InputStream in;
035
036    /**
037     * Checks if the signature matches what is expected for a .xz file.
038     *
039     * @param   signature     the bytes to check
040     * @param   length        the number of bytes to check
041     * @return  true if signature matches the .xz magic bytes, false otherwise
042     */
043    public static boolean matches(byte[] signature, int length) {
044        if (length < XZ.HEADER_MAGIC.length) {
045            return false;
046        }
047
048        for (int i = 0; i < XZ.HEADER_MAGIC.length; ++i) {
049            if (signature[i] != XZ.HEADER_MAGIC[i]) {
050                return false;
051            }
052        }
053
054        return true;
055    }
056
057    /**
058     * Creates a new input stream that decompresses XZ-compressed data
059     * from the specified input stream. This doesn't support
060     * concatenated .xz files.
061     *
062     * @param       inputStream where to read the compressed data
063     *
064     * @throws      IOException if the input is not in the .xz format,
065     *                          the input is corrupt or truncated, the .xz
066     *                          headers specify options that are not supported
067     *                          by this implementation, or the underlying
068     *                          <code>inputStream</code> throws an exception
069     */
070    public XZCompressorInputStream(InputStream inputStream)
071            throws IOException {
072        this(inputStream, false);
073    }
074
075    /**
076     * Creates a new input stream that decompresses XZ-compressed data
077     * from the specified input stream.
078     *
079     * @param       inputStream where to read the compressed data
080     * @param       decompressConcatenated
081     *                          if true, decompress until the end of the
082     *                          input; if false, stop after the first .xz
083     *                          stream and leave the input position to point
084     *                          to the next byte after the .xz stream
085     *
086     * @throws      IOException if the input is not in the .xz format,
087     *                          the input is corrupt or truncated, the .xz
088     *                          headers specify options that are not supported
089     *                          by this implementation, or the underlying
090     *                          <code>inputStream</code> throws an exception
091     */
092    public XZCompressorInputStream(InputStream inputStream,
093                                   boolean decompressConcatenated)
094            throws IOException {
095        if (decompressConcatenated) {
096            in = new XZInputStream(inputStream);
097        } else {
098            in = new SingleXZInputStream(inputStream);
099        }
100    }
101
102    @Override
103    public int read() throws IOException {
104        int ret = in.read();
105        count(ret == -1 ? -1 : 1);
106        return ret;
107    }
108
109    @Override
110    public int read(byte[] buf, int off, int len) throws IOException {
111        int ret = in.read(buf, off, len);
112        count(ret);
113        return ret;
114    }
115
116    @Override
117    public long skip(long n) throws IOException {
118        return in.skip(n);
119    }
120
121    @Override
122    public int available() throws IOException {
123        return in.available();
124    }
125
126    @Override
127    public void close() throws IOException {
128        in.close();
129    }
130}