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     */
019    package org.apache.commons.compress.compressors.xz;
020    
021    import java.io.IOException;
022    import java.io.InputStream;
023    import org.tukaani.xz.XZ;
024    import org.tukaani.xz.SingleXZInputStream;
025    import org.tukaani.xz.XZInputStream;
026    
027    import org.apache.commons.compress.compressors.CompressorInputStream;
028    
029    /**
030     * XZ decompressor.
031     * @since Commons Compress 1.4
032     */
033    public 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        /** {@inheritDoc} */
103        @Override
104        public int read() throws IOException {
105            int ret = in.read();
106            count(ret == -1 ? -1 : 1);
107            return ret;
108        }
109    
110        /** {@inheritDoc} */
111        @Override
112        public int read(byte[] buf, int off, int len) throws IOException {
113            int ret = in.read(buf, off, len);
114            count(ret);
115            return ret;
116        }
117    
118        /** {@inheritDoc} */
119        @Override
120        public long skip(long n) throws IOException {
121            return in.skip(n);
122        }
123    
124        /** {@inheritDoc} */
125        @Override
126        public int available() throws IOException {
127            return in.available();
128        }
129    
130        /** {@inheritDoc} */
131        @Override
132        public void close() throws IOException {
133            in.close();
134        }
135    }