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.lzma;
020
021import java.io.IOException;
022import java.io.InputStream;
023
024import org.apache.commons.compress.MemoryLimitException;
025import org.tukaani.xz.LZMAInputStream;
026
027import org.apache.commons.compress.compressors.CompressorInputStream;
028
029/**
030 * LZMA decompressor.
031 * @since 1.6
032 */
033public class LZMACompressorInputStream extends CompressorInputStream {
034    private final InputStream in;
035
036    /**
037     * Creates a new input stream that decompresses LZMA-compressed data
038     * from the specified input stream.
039     *
040     * @param       inputStream where to read the compressed data
041     *
042     * @throws      IOException if the input is not in the .lzma format,
043     *                          the input is corrupt or truncated, the .lzma
044     *                          headers specify sizes that are not supported
045     *                          by this implementation, or the underlying
046     *                          <code>inputStream</code> throws an exception
047     */
048    public LZMACompressorInputStream(final InputStream inputStream)
049            throws IOException {
050        in = new LZMAInputStream(inputStream, -1);
051    }
052
053    /**
054     * Creates a new input stream that decompresses LZMA-compressed data
055     * from the specified input stream.
056     *
057     * @param       inputStream where to read the compressed data
058     *
059     * @param       memoryLimitInKb calculated memory use threshold.  Throws MemoryLimitException
060     *                            if calculate memory use is above this threshold
061     *
062     * @throws      IOException if the input is not in the .lzma format,
063     *                          the input is corrupt or truncated, the .lzma
064     *                          headers specify sizes that are not supported
065     *                          by this implementation, or the underlying
066     *                          <code>inputStream</code> throws an exception
067     *
068     * @since 1.14
069     */
070    public LZMACompressorInputStream(final InputStream inputStream, int memoryLimitInKb)
071            throws IOException {
072        try {
073            in = new LZMAInputStream(inputStream, memoryLimitInKb);
074        } catch (org.tukaani.xz.MemoryLimitException e) {
075            //convert to commons-compress exception
076            throw new MemoryLimitException(e.getMemoryNeeded(), e.getMemoryLimit(), e);
077        }
078    }
079
080    /** {@inheritDoc} */
081    @Override
082    public int read() throws IOException {
083        final int ret = in.read();
084        count(ret == -1 ? 0 : 1);
085        return ret;
086    }
087
088    /** {@inheritDoc} */
089    @Override
090    public int read(final byte[] buf, final int off, final int len) throws IOException {
091        final int ret = in.read(buf, off, len);
092        count(ret);
093        return ret;
094    }
095
096    /** {@inheritDoc} */
097    @Override
098    public long skip(final long n) throws IOException {
099        return in.skip(n);
100    }
101
102    /** {@inheritDoc} */
103    @Override
104    public int available() throws IOException {
105        return in.available();
106    }
107
108    /** {@inheritDoc} */
109    @Override
110    public void close() throws IOException {
111        in.close();
112    }
113
114    /**
115     * Checks if the signature matches what is expected for an lzma file.
116     *
117     * @param signature
118     *            the bytes to check
119     * @param length
120     *            the number of bytes to check
121     * @return true, if this stream is an lzma  compressed stream, false otherwise
122     *
123     * @since 1.10
124     */
125    public static boolean matches(final byte[] signature, final int length) {
126        return signature != null && length >= 3 &&
127                signature[0] == 0x5d && signature[1] == 0 &&
128                signature[2] == 0;
129    }
130}