> Roberto Nibali <[email protected]> hat am 27. Juli 2015 um 10:29 geschrieben:
>
>
> Hi Andreas
>
> Thanks for the quick reply.
>
> On Mon, Jul 27, 2015 at 9:55 AM, Andreas Lehmkühler <[email protected]>
> wrote:
>
> >
> >
> > > Andreas Lehmkühler <[email protected]> hat am 27. Juli 2015 um 09:37
> > > geschrieben:
> > >
> > >
> > > Hi Roberto,
> > >
> > > > Roberto Nibali <[email protected]> hat am 27. Juli 2015 um 09:28
> > > > geschrieben:
> > > >
> > > >
> > > > Dear developers
> > > >
> > > > The last commit 1692730 by lehmi, 18:36, broke the PDFWriter. The
> > result
> > > > is: The file xx.pdf cannot be open; It may be damaged or use a file
> > format
> > > > that Preview doesn’t recognize. The same when using Acrobat
> > Professional.
> > > >
> > > > Reverting the commit to the old one makes everything work again. What
> > is
> > > > the reason for this change?
> > > >
> > > > // use previous startXref value as new PREV value
> > > > trailer.setLong(COSName.PREV, doc.getStartXref());
> > > > //trailer.removeItem(COSName.PREV);
> > > >
> > > > The trailer.removeItem(COSName.PREV) works, the new
> > > > trailer.setLong(COSName.PREV, doc.getStartXref()) code does not.
> > > Thanks for your hint.
> > >
> > > Can you be a little bit more specific, please? What kind of pdf did you
> > try to
> > > sign? Can you provide us with a sample pdf?
> >
>
> As far as I can tell, I'm not trying to sign any document. I'm working on a
> tool that migrates form fields from a source document to a new template
> document (containing the same fields, however some CI/CD changes), and
> subsequently saves the document as a new PDF with suffix "-migrated".
>
> In fact, I can trigger this behaviour with the following simple code (which
> does nothing else than open the source PDF, the template PDF, removes the
> security, sets the need for auto-generated appearances, and saves the
> template into a new PDF):
>
> private static PDDocument srcDoc;
> private static PDDocument tplDoc;
>
> @Test
> public static void SimpleTest() throws IOException {
> String ownerPassword = "limitedHappiness";
> srcDoc = PDDocument.load(new File("./ccalt.pdf"), ownerPassword);
> tplDoc = PDDocument.load(new File("./cctemp.pdf"), ownerPassword);
> tplDoc.setAllSecurityToBeRemoved(true);
> srcDoc.close();
> tplDoc.getDocumentCatalog().getAcroForm().setNeedAppearances(true);
> tplDoc.save("ccmig.pdf");
> tplDoc.close();
> }
>
> Due to signed NDAs, I cannot send you the PDF. If we can't solve the
> issue, I'll try to generate a stripped down version for you, however that's
> going to take a day or so, and I have other pending issues which I'd like
> to address first, as the deadline for the final delivery of the tool is now
> definitely coming up.
OK, I see you are not using an incremental update feature. The name of the
modified method "doWriteXRefInc" pretends to be limited to incremental updates,
but it isn't.
>
> > I just had another idea. Can you please check the following change
> >
> > if (trailer.getItem(COSName.PREV != null))
> > {
> > trailer.setLong(COSName.PREV, doc.getStartXref())
> > }
> >
> >
> I modified to the following code, so it compiles:
>
> COSDictionary trailer = doc.getTrailer();
> // use previous startXref value as new PREV value
> //trailer.setLong(COSName.PREV, doc.getStartXref());
> //trailer.removeItem(COSName.PREV);
> if (trailer.getItem(COSName.PREV) != null)
> {
> trailer.setLong(COSName.PREV, doc.getStartXref());
> }
>
> No change, it still breaks my simple test case.
I'm not at home, so that I can't check that myself, but I guess the following
should do the trick
if (incrementalUpdate)
{
trailer.setLong(COSName.PREV, doc.getStartXref());
}
>
> On a side note (not understanding anything about PDFBox internals): Your
> change seems pretty invasive just from an outsider's perspective
> interpreting the method's name. Before your change, you basically seem to
> have removed the COS entry PREV, after your change, you set it to the
> position of the xref section. I'm sure you know what you're doing, it just
> does not look minimally invasive in what I would call the hotpath of
> PDFWriter ;).
>
> Cheers
> Roberto
BR
Andreas
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