Thanks Paulo. I downloaded and built the SVN tip and was able to reproduce the problem. The gist of it is that if you use PdfWriter to import a page and re-create link annotations, and those annotations contain indirect references (such as a Parent, i.e. "/P 8 0 R"), you get the exception. Enclosed is a PDF file that I clobbered together with such a link, along with a few line demo program that will crash when you copy the page out to a new file and re-create links. It will succeed when the patch I suggested is applied.
Note that I stripped everything down to the bare bones - this code is not useful for any particular purpose other than to demonstrate the bug. My guess is that most folks use PdfCopy or PdfSmartCopy for operations like this, so perhaps that's why nobody has run into this before. It is not clear to me whether the problem is purely Annotation related - I suspect that this could happen during other operations as well. Upon further testing, I noticed is that the patch I suggested creates a reference to a non-existent object, but Acrobat doesn't care as the parent reference is redundant, but it may cause problems for other tools/parsers. This makes me believe that there is a better way to fix the problem although we are getting by at the moment. Any feedback would be greatly appreciated. Thanks - Gylfi -----Original Message----- From: Paulo Soares [mailto:psoa...@glintt.com] Sent: Wednesday, August 04, 2010 12:36 PM To: Post all your questions about iText here Subject: Re: [iText-questions] Null pointer exception in PdfWriter This area was extensively changed in 5.0.3 (when it's out this weekend but you can get it from the SVN), it would be worth to see if the problem is already fixed. Paulo -----Original Message----- From: Gylfi Ingvason [mailto:gylfi.ingva...@solimarsystems.com] Sent: Wednesday, August 04, 2010 4:52 PM To: itext-questions@lists.sourceforge.net Subject: [iText-questions] Null pointer exception in PdfWriter Gents, I'm using an older version of iTextSharp (4.1.6 equivalent), and recently ran into a null pointer exception in PdfWriter while splitting a PDF file. Never seen this before despite running all kinds of data for years. The error happens on the PdfDocument Close() call, that leads to a RotateAnnotations call, that calls writer.AddToBody, and eventually GetNewObjectNumber in the PdfWriter is called and that method looks like this: protected internal virtual int GetNewObjectNumber(PdfReader reader, int number, int generation) { return currentPdfReaderInstance.GetNewObjectNumber(number, generation); } At the time the call is made, the currentPdfReaderInstance is null causing the exception. I looked at the code in the repository for the latest, and this method has not changed. I patched the code to check for null as such: protected internal virtual int GetNewObjectNumber(PdfReader reader, int number, int generation) { if (currentPdfReaderInstance == null) { currentPdfReaderInstance = reader.GetPdfReaderInstance(this); } return currentPdfReaderInstance.GetNewObjectNumber(number, generation); } This creates proper output. My question is, is this an acceptable patch or should this be handled differently? Furthermore, it worries me that this has not come up before - is it normal that the currentPdfReaderInstance is null under these circumstances? I have not tried this under 5.0.2 but I suspect that the same thing will happen - would it make sense to patch the latest? Any feedback would be appreciated. Thanks - Gylfi Aviso Legal: Esta mensagem i destinada exclusivamente ao destinatario. Pode conter informagco confidencial ou legalmente protegida. A incorrecta transmissco desta mensagem nco significa a perca de confidencialidade. Se esta mensagem for recebida por engano, por favor envie-a de volta para o remetente e apague-a do seu sistema de imediato. I proibido a qualquer pessoa que nco o destinatario de usar, revelar ou distribuir qualquer parte desta mensagem. Disclaimer: This message is destined exclusively to the intended receiver. It may contain confidential or legally protected information. The incorrect transmission of this message does not mean the loss of its confidentiality. If this message is received by mistake, please send it back to the sender and delete it from your system immediately. It is forbidden to any person who is not the intended receiver to use, distribute or copy any part of this message.
LinkTest.pdf
Description: Adobe PDF document
using System;
using System.IO;
using System.Collections.Generic;
using System.Text;
using iTextSharp.text;
using iTextSharp.text.pdf;
namespace SplitTest
{
class Program
{
static void Main(string[] args)
{
string inputFileName = @"..\..\..\LinkTest.pdf";
PdfReader reader = new PdfReader(inputFileName);
int pageNumber = 1;
while (pageNumber <= reader.NumberOfPages)
{
string outputFileName =
Path.Combine(Path.GetDirectoryName(inputFileName), ("Page_" + pageNumber +
".pdf"));
Document document = new Document();
PdfWriter writer = PdfWriter.GetInstance(document, new
FileStream(outputFileName, FileMode.Create, FileAccess.Write));
document.Open();
document.SetPageSize(reader.GetPageSizeWithRotation(pageNumber));
document.NewPage();
PdfImportedPage page = writer.GetImportedPage(reader,
pageNumber);
writer.DirectContent.AddTemplate(page, 1, 0, 0, 1, 0, 0);
// re-create links...
List<PdfAnnotation.PdfImportedLink> links =
reader.GetLinks(pageNumber);
foreach (PdfAnnotation.PdfImportedLink link in links)
{
PdfAnnotation annot = link.CreateAnnotation(writer);
PdfDictionary actionDictionary =
(PdfDictionary)PdfReader.GetPdfObject(annot.Get(PdfName.A));
PdfString uri =
(PdfString)actionDictionary.Get(PdfName.URI);
PdfAction action = new PdfAction(uri.ToString());
annot.Action = action;
writer.AddAnnotation(annot);
}
document.Close();
++pageNumber;
}
}
}
}
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