org.apache.tika.parser.pdf.PDFEncodedStringDecoder Maven / Gradle / Ivy
/*
* 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.tika.parser.pdf;
import static java.nio.charset.StandardCharsets.ISO_8859_1;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import org.apache.pdfbox.cos.COSString;
import org.apache.pdfbox.io.RandomAccessBuffer;
import org.apache.pdfbox.io.RandomAccessRead;
import org.apache.pdfbox.pdfparser.COSParser;
/**
* In fairly rare cases, a PDF's XMP will contain a string that
* has incorrectly been encoded with PDFEncoding: an octal for non-ascii and
* ascii for ascii, e.g. "\376\377\000M\000i\000c\000r\000o\000s\000o\000f\000t\000"
*
* This class can be used to decode those strings.
*
* See TIKA-1678. Many thanks to Andrew Jackson for raising this issue
* and Tilman Hausherr for the solution.
*
* As of this writing, we are only handling strings that start with
* an encoded BOM. Andrew Jackson found a handful of other examples (e.g.
* this ISO-8859-7 string:
* "Microsoft Word - \\323\\365\\354\\354\\345\\364\\357\\367\\336
* \\364\\347\\362 PRAKSIS \\363\\364\\357")
* that we aren't currently handling.
*/
class PDFEncodedStringDecoder {
private static final String[] PDF_ENCODING_BOMS = {
"\\376\\377", //UTF-16BE
"\\377\\376", //UTF-16LE
"\\357\\273\\277"//UTF-8
};
/**
* Does this string contain an octal-encoded UTF BOM?
* Call this statically to determine if you should bother creating a new parser to parse it.
* @param s
* @return
*/
static boolean shouldDecode(String s) {
if (s == null || s.length() < 8) {
return false;
}
for (String BOM : PDF_ENCODING_BOMS) {
if (s.startsWith(BOM)) {
return true;
}
}
return false;
}
/**
* This assumes that {@link #shouldDecode(String)} has been called
* and has returned true. If you run this on a non-octal encoded string,
* disaster will happen!
*
* @param value
* @return
*/
String decode(String value) {
try {
byte[] bytes = new String("(" + value + ")").getBytes(ISO_8859_1);
InputStream is = new ByteArrayInputStream(bytes);
COSStringParser p = new COSStringParser(new RandomAccessBuffer(is));
String parsed = p.myParseCOSString();
if (parsed != null) {
return parsed;
}
} catch (IOException e) {
//oh well, we tried.
}
//just return value if something went wrong
return value;
}
class COSStringParser extends COSParser {
COSStringParser(RandomAccessRead buffer) throws IOException {
super(buffer);
}
/**
*
* @return parsed string or null if something went wrong.
*/
String myParseCOSString() {
try {
COSString cosString = parseCOSString();
if (cosString != null) {
return cosString.getString();
}
} catch (IOException e) {
}
return null;
}
}
}