Parse error on indirect object reference

[stollcri]

I have some PDF files - ones already signed by Jotform - that cause the following error to be raised. There seems to be an invalid reference in the PDF files; when I catch the error on line 279 of the same file and handle it (ignore that missing reference by naively just returning BooleanObject(False)) I can load and manipulate the file as expected.

I know that is not the correct fix. My question is, how can I debug this error to get more specific information about the conditions causing the problem, so that I can implement the correct fix?

I used an old tool called 'peepdf' and it suggested that the stream location referenced by the raised error was inside of an embedded image, which doesn't' seem correct.

raise PdfReadError(
    f"Parse error on indirect object reference around {pos}"
)

https://github.com/MatthiasValvekens/pyHanko/blob/6da540450eee75a00d7379a3b202bd31c2fb9922/pyhanko/pdf_utils/generic.py#L616C1-L618C14

[MatthiasValvekens]

Unless you can share the file in question, I'm afraid that there's not much to say about this :).

PDF syntax is already quite fungible, and while pyHanko's parser is indeed a bit pickier than most, allowing malformed object refs (and e.g. defaulting them to latest(doesn't really sit well with me for various reasons... Mainly the risk of accidentally introducing parsing ambiguities.

[stollcri]

Here is an example document.

Yeah, I don't want to suggest any changes that would cause fragility. I just wanted to dig in, validate the problem, and see if there are any potential enhancements; I just wasn't sure of the best way to debug the issue.

2024-11-15.pdf