de.intarsys.pdf.st.XRefFallbackParser Maven / Gradle / Ivy

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/*
 * Copyright (c) 2007, intarsys consulting GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * - Neither the name of intarsys nor the names of its contributors may be used
 *   to endorse or promote products derived from this software without specific
 *   prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package de.intarsys.pdf.st;

import de.intarsys.pdf.cos.COSDictionary;
import de.intarsys.pdf.cos.COSTrailer;
import de.intarsys.pdf.parser.COSDocumentParser;
import de.intarsys.pdf.parser.COSLoadError;
import de.intarsys.pdf.parser.COSLoadException;
import de.intarsys.pdf.parser.PDFParser;
import de.intarsys.tools.randomaccess.IRandomAccess;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

/**
 * 
 * A simple xref rebuilding parser.
 * 
 * 
 * The parser reads lines in the document and looks if the line begins with a
 * object definition, which looks like: number number "obj". Every object
 * definition found is added as a XRefEntry to the STDocument.
 * 
 * 
 * False object definitions can be read and they can cause a problem, if a
 * real  object with the same object number is read after the false one.
 * On the other side: the document was already broke before this parser was
 * called.
 * 
 */
public class XRefFallbackParser extends AbstractXRefParser {
    private STTrailerXRefSection xRefSection;

    private List trailers = new ArrayList();

    public XRefFallbackParser(STDocument doc, COSDocumentParser parser) {
        super(doc, parser);
        this.xRefSection = new STTrailerXRefSection(doc);
    }

    /**
     * Check if we found a root object
     *
     * @throws IOException
     * @throws COSLoadException
     */
    private void checkXRefSections() throws COSLoadException {
        if (trailers.isEmpty()) {
            COSLoadError e = new COSLoadError("no trailer found");
            handleError(e);
        }
        boolean rootFound = false;
        for (int i = trailers.size() - 1; i >= 0; i--) {
            COSDictionary trailer = (COSDictionary) trailers.get(i);
            if (trailer.containsKey(COSTrailer.DK_Root)) {
                getXRefSection().cosSetDict(trailer);
                rootFound = true;
                break;
            }
        }
        if (!rootFound) {
            COSLoadError e = new COSLoadError("trailer doesn't contain a root entry");
            handleError(e);
        }
        getXRefSection().setSize(getXRefSection().getMaxObjectNumber());
    }

    protected STTrailerXRefSection getXRefSection() {
        return xRefSection;
    }

    /*
     * (non-Javadoc)
     *
     * @see de.intarsys.pdf.st.AbstractXRefParser#parse(de.intarsys.tools.randomaccess.IRandomAccess)
     */
    @Override
    public STXRefSection parse(IRandomAccess input) throws IOException, COSLoadException {
        input.seek(0);
        int objNumber;
        int genNumber;
        byte[] token;
        long offset;

        while (readUptoNewLine(input)) {
            offset = input.getOffset();
            try {
                COSDictionary trailer = getParser().parseTrailer(input);
                trailers.add(trailer);
                continue;
            } catch (IOException | COSLoadException e) {
                // no trailer
            }
            try {
                objNumber = getParser().readInteger(input, true);
                if (objNumber != 0) {
                    genNumber = getParser().readInteger(input, true);
                    token = getParser().readToken(input);
                    if (Arrays.equals(PDFParser.TOKEN_obj, token)) {
                        getXRefSection().addEntry(new STXRefEntryOccupied(objNumber, genNumber, (int) offset));
                        continue;
                    }
                }
            } catch (IOException e) {
                // no obj
            }
            input.seek(offset);
        }

        checkXRefSections();
        return getXRefSection();
    }

    private boolean readUptoNewLine(IRandomAccess input) throws IOException {
        int i;
        while (true) {
            i = input.read();
            if (i == -1) {
                return false;
            }
            if (PDFParser.isEOL(i)) {
                if (i == PDFParser.CHAR_CR) {
                    i = input.read();
                    if (i == -1) {
                        return false;
                    }
                    if (i != PDFParser.CHAR_LF) {
                        input.seekBy(-1);
                    }
                }
                return true;
            }
        }
    }
}