129 lines
4.6 KiB
Java
129 lines
4.6 KiB
Java
/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==================================================================== */
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package org.apache.poi.hmef;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.OutputStream;
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import java.nio.charset.Charset;
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import org.apache.poi.util.IOUtils;
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import org.apache.poi.util.LZWDecompresser;
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import org.apache.poi.util.LittleEndian;
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/**
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* Within a {@link HMEFMessage}, the content is often
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* stored in as RTF, but LZW compressed. This class
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* handles decompressing it for you.
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*/
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public final class CompressedRTF extends LZWDecompresser {
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public static final byte[] COMPRESSED_SIGNATURE =
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new byte[] { (byte)'L', (byte)'Z', (byte)'F', (byte)'u' };
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public static final byte[] UNCOMPRESSED_SIGNATURE =
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new byte[] { (byte)'M', (byte)'E', (byte)'L', (byte)'A' };
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public static final int COMPRESSED_SIGNATURE_INT =
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LittleEndian.getInt(COMPRESSED_SIGNATURE);
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public static final int UNCOMPRESSED_SIGNATURE_INT =
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LittleEndian.getInt(UNCOMPRESSED_SIGNATURE);
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// The 4096 byte LZW dictionary is pre-loaded with some common
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// RTF fragments. These come from RTFLIB32.LIB, which ships
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// with older versions of Visual Studio or the EDK
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public static final String LZW_RTF_PRELOAD =
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"{\\rtf1\\ansi\\mac\\deff0\\deftab720{\\fonttbl;}{\\f0\\fnil \\froman \\fswiss " +
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"\\fmodern \\fscript \\fdecor MS Sans SerifSymbolArialTimes New RomanCourier" +
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"{\\colortbl\\red0\\green0\\blue0\n\r\\par \\pard\\plain\\f0\\fs20\\b\\i\\u\\tab\\tx";
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private int compressedSize;
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private int decompressedSize;
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public CompressedRTF() {
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// Out flag has the normal meaning
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// Length wise, we're 2 longer than we say, so the max len is 18
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// Endian wise, we're big endian, so 0x1234 is pos 0x123
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super(true, 2, true);
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}
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/**
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* Decompresses the whole of the compressed RTF
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* stream, outputting the resulting RTF bytes.
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* Note - will decompress any padding at the end of
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* the input, if present, use {@link #getDeCompressedSize()}
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* if you need to know how much of the result is
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* real. (Padding may be up to 7 bytes).
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*/
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public void decompress(InputStream src, OutputStream res) throws IOException {
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// Validate the header on the front of the RTF
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compressedSize = LittleEndian.readInt(src);
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decompressedSize = LittleEndian.readInt(src);
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int compressionType = LittleEndian.readInt(src);
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@SuppressWarnings("unused")
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int dataCRC = LittleEndian.readInt(src);
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// TODO - Handle CRC checking on the output side
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// Do we need to do anything?
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if(compressionType == UNCOMPRESSED_SIGNATURE_INT) {
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// Nope, nothing fancy to do
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IOUtils.copy(src, res);
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} else if(compressionType == COMPRESSED_SIGNATURE_INT) {
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// We need to decompress it below
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} else {
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throw new IllegalArgumentException("Invalid compression signature " + compressionType);
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}
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// Have it processed
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super.decompress(src, res);
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}
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/**
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* Returns how big the compressed version was.
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*/
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public int getCompressedSize() {
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// Return the size less the header
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return compressedSize - 12;
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}
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/**
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* Returns how big the decompressed version was.
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*/
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public int getDeCompressedSize() {
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return decompressedSize;
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}
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/**
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* We use regular dictionary offsets, so no
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* need to change anything
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*/
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@Override
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protected int adjustDictionaryOffset(int offset) {
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return offset;
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}
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@Override
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protected int populateDictionary(byte[] dict) {
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// Copy in the RTF constants
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byte[] preload = LZW_RTF_PRELOAD.getBytes(Charset.forName("US-ASCII"));
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System.arraycopy(preload, 0, dict, 0, preload.length);
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// Start adding new codes after the constants
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return preload.length;
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}
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}
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