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https://issues.apache.org/jira/browse/PDFBOX-5945?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17924385#comment-17924385
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ASF subversion and git services commented on PDFBOX-5945:
---------------------------------------------------------
Commit 1923601 from le...@apache.org in branch 'pdfbox/branches/3.0'
[ https://svn.apache.org/r1923601 ]
PDFBOX-5945: fix SIZE entry in trailer dictionary, add test provided by Lahcen
FTIH
> Wrong size entry in trailer after incremental save
> --------------------------------------------------
>
> Key: PDFBOX-5945
> URL: https://issues.apache.org/jira/browse/PDFBOX-5945
> Project: PDFBox
> Issue Type: Bug
> Components: Writing
> Affects Versions: 2.0.33, 3.0.4 PDFBox, 4.0.0
> Reporter: Andreas Lehmkühler
> Assignee: Andreas Lehmkühler
> Priority: Major
>
> Lahcen FTIH reports the following issue on users@pdfbox
>
> *Issue Description*
> When performing an incremental update on a PDF document that has a
> cross-reference table (not a cross-reference stream) without creating any
> new object references, the *trailer’s size entry* is set incorrectly.
> Specifically, it becomes 1 greater than the highest object number in the
> *current* trailer—rather than 1 greater than the highest object number in
> the *entire* document. This leads to problems because:
> 1. Some PDF editors determine the next reference to use based on this
> size value, leading to inconsistencies.
> 2. Some PDF readers may consider the file corrupt since, according to
> the PDF specification, any object in a cross-reference section whose number
> is greater than the *size* value “shall be ignored and defined to be
> missing.”
> Below is the minimal code example to reproduce this issue. As you can see
> in the log output, the input PDF has a last trailer size of 10, but after
> the incremental save, the last trailer size becomes 6, even though the
> highest object number remains 9.
> {code:java}
> package org.apache.pdfbox;
> import org.apache.pdfbox.cos.COSDocument;import
> org.apache.pdfbox.cos.COSName;import
> org.apache.pdfbox.cos.COSObjectKey;import
> org.apache.pdfbox.pdfwriter.compress.CompressParameters;import
> org.apache.pdfbox.pdmodel.PDDocument;import
> org.apache.pdfbox.pdmodel.PDPage;import
> org.apache.pdfbox.pdmodel.PDResources;import
> org.apache.pdfbox.pdmodel.common.PDRectangle;import
> org.apache.pdfbox.pdmodel.font.PDFont;import
> org.apache.pdfbox.pdmodel.font.PDType1Font;import
> org.apache.pdfbox.pdmodel.font.Standard14Fonts;import
> org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotationWidget;import
> org.apache.pdfbox.pdmodel.interactive.form.PDAcroForm;import
> org.apache.pdfbox.pdmodel.interactive.form.PDTextField;
> import java.io.ByteArrayOutputStream;import java.io.IOException;
> public class ReproduceBug {
> private static final String FIELD_NAME = "textFieldName";
> public static void main(String[] args) {
> byte[] input = create();
> printInfo(input, "input");
> byte[] output = edit(input);
> printInfo(output, "output");
> }
> private static byte[] create() {
> try (PDDocument pdDocument = new PDDocument()) {
> PDAcroForm acroForm = addAcroForm(pdDocument);
> addFonts(acroForm);
> PDPage page = addPage(pdDocument);
> addTextField(acroForm, page);
> ByteArrayOutputStream out = new ByteArrayOutputStream();
> pdDocument.save(out, CompressParameters.NO_COMPRESSION);
> return out.toByteArray();
> } catch (IOException e) {
> throw new RuntimeException(e);
> }
> }
> private static byte[] edit(byte[] input) {
> try (PDDocument pdDocument = loadPDF(input)) {
> PDTextField textField = (PDTextField)
> pdDocument.getDocumentCatalog().getAcroForm().getField(FIELD_NAME);
> assert textField != null;
> textField.setMultiline(true);
> ByteArrayOutputStream out = new ByteArrayOutputStream();
> pdDocument.saveIncremental(out);
> return out.toByteArray();
> } catch (IOException e) {
> throw new RuntimeException(e);
> }
> }
> private static PDDocument loadPDF(byte[] content) throws IOException {
> return org.apache.pdfbox.Loader.loadPDF(content);
> }
> private static void addFonts(PDAcroForm acroForm) throws IOException {
> PDFont font1 = new PDType1Font(Standard14Fonts.FontName.HELVETICA);
> PDFont font2 = new
> PDType1Font(Standard14Fonts.FontName.ZAPF_DINGBATS);
> PDResources resources = new PDResources();
> resources.put(COSName.getPDFName("Helv"), font1);
> resources.put(COSName.getPDFName("ZaDb"), font2);
> acroForm.setDefaultResources(resources);
> }
> private static PDAcroForm addAcroForm(PDDocument pdDocument)
> throws IOException {
> PDAcroForm acroForm = new PDAcroForm(pdDocument);
> pdDocument.getDocumentCatalog().setAcroForm(acroForm);
> return acroForm;
> }
> private static PDPage addPage(PDDocument pdDocument) throws IOException {
> PDPage page = new PDPage(PDRectangle.A4);
> pdDocument.addPage(page);
> return page;
> }
> private static void addTextField(PDAcroForm acroForm, PDPage page)
> throws IOException {
> PDTextField textField = new PDTextField(acroForm);
> textField.setPartialName(FIELD_NAME);
> acroForm.getFields().add(textField);
> PDAnnotationWidget widget = textField.getWidgets().get(0);
> widget.setPage(page);
> page.getAnnotations().add(widget);
> PDRectangle rectangle = new PDRectangle(10, 200, 200, 15);
> widget.setRectangle(rectangle);
> }
> private static void printInfo(byte[] content, String name) {
>
> System.out.println("------------------------------------------------------");
> System.out.println("-- " + name);
> try (PDDocument pdDocument = loadPDF(content)) {
> COSDocument cosDocument = pdDocument.getDocument();
> System.out.println("getXrefTable.keySet.maxNumber: " +
> cosDocument.getXrefTable().keySet().stream()
> .mapToLong(COSObjectKey::getNumber)
> .max().getAsLong());
> System.out.println("lastTrailer.size: " +
> cosDocument.getTrailer().getLong(COSName.SIZE));
> } catch (IOException e) {
> throw new RuntimeException(e);
> }
>
> System.out.println("------------------------------------------------------");
> }
> }
> {code}
> *Console Output*
> ------------------------------------------------------
> -- input
> getXrefTable.keySet.maxNumber: 9lastTrailer.size: 10
> ------------------------------------------------------** lastEntry is: 5
> ------------------------------------------------------
> -- output
> getXrefTable.keySet.maxNumber: 9lastTrailer.size: 6
> ------------------------------------------------------
> As the output shows:
> - The highest object number remains 9.
> - The final trailer size is incorrectly set to 6 after the incremental
> save, whereas it should remain 10.
> *Impact*
> - PDF editors that use the trailer’s size to determine the next free
> object reference can fail to handle the PDF correctly.
> - Some readers may reject or treat the PDF as corrupted if they strictly
> follow the specification about ignored objects.
> *Request*
> Could you please confirm whether this is indeed a regression? I would
> appreciate any workaround suggestions or information on whether a fix is
> planned in upcoming releases.
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