Avoid "Non-negative number required" Exception

[iquirino]

_lexer.Position = -1 cause System.IO.MemoryStream.set_Position to be -1.
https://imgur.com/a/hy8TKdu

[mitchcapper]

It should be noted that PR only handles one condition in which this exception can occur, does not fix all non-negative number errors

[iquirino]

I work with thousands pdf in a day.
This one is the only non negative exception tha i have catched.

I think it can be merged...
And then you can solve other point...
?

[iquirino]

Is clear to me that idx validation need to be inside of startxref var instantiation

[mitchcapper]

Sorry @iquirino didn't mean to be rude, I actually am tracking down a dictionary read error on opening a PDF from an online system. It also generates this error and between this pr AND #95 I was hoping one of them addressed i (as pdfs open fine in acrobat). Sadly not.

My warning was just to others that this may not resolve all the stream seek isues.

 	PdfSharp-wpf.dll!PdfSharp.Pdf.IO.Lexer.Position.set(int value) Line 71	C#
 	PdfSharp-wpf.dll!PdfSharp.Pdf.IO.Parser.MoveToObject(PdfSharp.Pdf.PdfObjectID objectID) Line 80	C#
>	PdfSharp-wpf.dll!PdfSharp.Pdf.IO.Parser.ReadObject(PdfSharp.Pdf.PdfObject pdfObject, PdfSharp.Pdf.PdfObjectID objectID, bool includeReferences, bool fromObjecStream) Line 121	C#
 	PdfSharp-wpf.dll!PdfSharp.Pdf.IO.Parser.GetStreamLength(PdfSharp.Pdf.PdfDictionary dict) Line 317	C#
 	PdfSharp-wpf.dll!PdfSharp.Pdf.IO.Parser.ReadStream(PdfSharp.Pdf.PdfDictionary dict) Line 287	C#
 	PdfSharp-wpf.dll!PdfSharp.Pdf.IO.Parser.ReadObject(PdfSharp.Pdf.PdfObject pdfObject, PdfSharp.Pdf.PdfObjectID objectID, bool includeReferences, bool fromObjecStream) Line 269	C#
 	PdfSharp-wpf.dll!PdfSharp.Pdf.IO.PdfReader.Open(System.IO.Stream stream, string password, PdfSharp.Pdf.IO.PdfDocumentOpenMode openmode, PdfSharp.Pdf.IO.PdfPasswordProvider passwordProvider) Line 433	C#
 	PdfSharp-wpf.dll!PdfSharp.Pdf.IO.PdfReader.Open(string path, string password, PdfSharp.Pdf.IO.PdfDocumentOpenMode openmode, PdfSharp.Pdf.IO.PdfPasswordProvider provider) Line 216	C#
 	PdfSharp-wpf.dll!PdfSharp.Pdf.IO.PdfReader.Open(string path, PdfSharp.Pdf.IO.PdfDocumentOpenMode openmode) Line 186	C#
 	testParse.dll!testParse.MainWindow.MainWindow_Loaded(object sender, System.Windows.RoutedEventArgs e) Line 51	C#

[iquirino]

PR #95 will solve this issue too or you need to replicate this in PR #95?

[mitchcapper]

#95 actually did not, it seems its an issue when reading the dictionary during opening so while #95 solves some it didn't solve this. I am digging into it more but the .net core port seems more maintained so will probably submit more PR over there.

[ThomasHoevel]

Fixed in current internal builds of PDFsharp.

[iquirino]

Thank you! ;)