QPDF: Exception: operation for Name object attempted on object of wrong type

[Rodolfo]

Hello. I am trying to print the file at:

https://www.dropbox.com/s/a3v7afl7lajolvb/error1.pdf?dl=0

And I get this error:

Exception: operation for Name object attempted on object of wrong type

running "qpdf error1.pdf --show-pages" I get the same error.

Thanks

[Till Kamppeter (till-kamppeter)]

Jay, can you have a look into this? Looks like an upstream bug in QPDF.

[Jay Berkenbilt (ejb)]

The problem is that the root object of the pages tree does not have a /Type key in its dictionary. The PDF spec says that /Type is required and must be /Pages for the root.

qpdf could and should handle this particular type of damage or could at least give a better error message for it, but that's the problem in this case. Right now qpdf uses /Type to determine whether a node in the pages tree is a Pages dictionary or Page dictionary, but it could use the presence of /Kids instead, which would probably be a bit more robust since it would handle more types of broken files.

It would be a simple change.

[Jay Berkenbilt (ejb)]

Before I commit this for real, I need to create a test case, but this seems to be a correct fix.

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "page.diff" seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

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[Rodolfo (bopodelvalle)]

Is it possible to make a 5.1.2-3 version with this fix?

[Jay Berkenbilt (ejb)]

Debian is in freeze, but I could upload to experimental and ubuntu could sync from there if that works.

[Rodolfo (bopodelvalle)]

That may work, thanks ;)

[Till Kamppeter (till-kamppeter)]

Jay, do it this way, syncing from Experimental is no problem for us.

[Jay Berkenbilt (ejb)]

Sorry for the long delay. I have uploaded 5.1.2-3 to experimental.

[Till Kamppeter (till-kamppeter)]

Synced 5.1.2-3 to Vivid.

Jay, thanks for the fix.

[ccurelaru (cristian-curelaru)]

I have the same error from a file (that I can't share ) and this one has /Pages element. I compared against the sample from this bug using a tool that can read the internals.

I tried --check but it does not give me the details. Is there a way for me to find out what element is the problem in my case without having to debug (I am not too good with cpp) ?

This is the message:
Error in linearizing (QPDF) the PDF, result: [stderr] operation for Name object attempted on object of wrong type

thanks
Cris

[Jay Berkenbilt (ejb)]

Does your problem happen with 5.1.2-3?

[ccurelaru (cristian-curelaru)]

In the meantime, I was able to debug and found the issue : basically there is key 'Type' somewhere in the treee but the key is not a 'name' as expected but a string.

I browsed a bit the spec (PDF) and it does seem to suggest Type should always be a "name". However, other tools seem to not care about that and linearize the file (acrobat pro, pdftron). No preflight errors either from acrobat.

Thoughts ?

[Jay Berkenbilt (ejb)]

Having qpdf able to treat strings as names would be a pretty small enhancement and would probably improve its ability to handle a whole category of broken files. I'll try to work this in for the next update. Thanks for providing this detailed summary of the problem. Very helpful.

[Jay Berkenbilt (ejb)]

https://github.com/qpdf/qpdf/issues/45