src/main/java/org/apache/commons/compress/compressors/xz/XZCompressorInputStream.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.commons.compress.compressors.xz;

import java.io.IOException;
import java.io.InputStream;
import org.tukaani.xz.XZ;
import org.tukaani.xz.SingleXZInputStream;
import org.tukaani.xz.XZInputStream;

import org.apache.commons.compress.compressors.CompressorInputStream;

/**
 * XZ decompressor.
 * @since 1.4
 */
public class XZCompressorInputStream extends CompressorInputStream {
    private final InputStream in;

    /**
     * Checks if the signature matches what is expected for a .xz file.
     *
     * @param   signature     the bytes to check
     * @param   length        the number of bytes to check
     * @return  true if signature matches the .xz magic bytes, false otherwise
     */
    public static boolean matches(byte[] signature, int length) {
        if (length < XZ.HEADER_MAGIC.length) {
            return false;
        }

        for (int i = 0; i < XZ.HEADER_MAGIC.length; ++i) {
            if (signature[i] != XZ.HEADER_MAGIC[i]) {
                return false;
            }
        }

        return true;
    }

    /**
     * Creates a new input stream that decompresses XZ-compressed data
     * from the specified input stream. This doesn't support
     * concatenated .xz files.
     *
     * @param       inputStream where to read the compressed data
     *
     * @throws      IOException if the input is not in the .xz format,
     *                          the input is corrupt or truncated, the .xz
     *                          headers specify options that are not supported
     *                          by this implementation, or the underlying
     *                          <code>inputStream</code> throws an exception
     */
    public XZCompressorInputStream(InputStream inputStream)
            throws IOException {
        this(inputStream, false);
    }

    /**
     * Creates a new input stream that decompresses XZ-compressed data
     * from the specified input stream.
     *
     * @param       inputStream where to read the compressed data
     * @param       decompressConcatenated
     *                          if true, decompress until the end of the
     *                          input; if false, stop after the first .xz
     *                          stream and leave the input position to point
     *                          to the next byte after the .xz stream
     *
     * @throws      IOException if the input is not in the .xz format,
     *                          the input is corrupt or truncated, the .xz
     *                          headers specify options that are not supported
     *                          by this implementation, or the underlying
     *                          <code>inputStream</code> throws an exception
     */
    public XZCompressorInputStream(InputStream inputStream,
                                   boolean decompressConcatenated)
            throws IOException {
        if (decompressConcatenated) {
            in = new XZInputStream(inputStream);
        } else {
            in = new SingleXZInputStream(inputStream);
        }
    }

    @Override
    public int read() throws IOException {
        int ret = in.read();
        count(ret == -1 ? -1 : 1);
        return ret;
    }

    @Override
    public int read(byte[] buf, int off, int len) throws IOException {
        int ret = in.read(buf, off, len);
        count(ret);
        return ret;
    }

    @Override
    public long skip(long n) throws IOException {
        return in.skip(n);
    }

    @Override
    public int available() throws IOException {
        return in.available();
    }

    @Override
    public void close() throws IOException {
        in.close();
    }
}