[cups] debugging file auto-typing

Tim Mooney Tim.Mooney at ndsu.edu
Wed Feb 20 14:08:10 PST 2019

In regard to: Re: [cups] debugging file auto-typing, Helge Blischke said...:

>> Am 14.02.2019 um 21:23 schrieb Tim Mooney <Tim.Mooney at ndsu.edu>:
>> I've considered that (although by replicating the rule to local.types),
>> and I've also considered replicating the application/vnd.cups-raw rule
>> to local.types with a priority(150), but doing either of them before
>> I understand why auto-typing is treating some files differently strikes
>> me as the wrong approach.  I might be able to accidentally solve this
>> problem, but I won't actually know what the problem was.
>> I'm pretty sure I'm going to end up doing something with local.types, but
>> ideally I would first understand the problem, rather than randomly trying
>> things.
>> Tim
> Without going too much into the details of how cups determined the type
> of the print data, the main principle of this algorithm is to check the
> rules increasing from the lowest to the highest complexity (roughly with
> respect to computational effort).

Understood.  And you're talking about the rules for a particular super/type,
like application/pdf.  mimeFileType checks all of the super/type entries.

> So, the checking the file name extension is by far the simplest thing
> and is tested first.
> So, eliminating the pdf file name extension from the rules is certainly
> one of the first methods I’d try in your case.

I agree that is almost certainly what I'm going to end up doing to work
around this problem.

The issue that I apparently haven't communicated very clearly is that
these print jobs are behaving differently from any of the other
pre-converted PDFs that this server receives regularly.  CUPS chooses
application/vnd.cups-raw for those, but it's choosing application/pdf
for these specific PDFs.  I'm trying to understand why.


Tim Mooney                                             Tim.Mooney at ndsu.edu
Enterprise Computing & Infrastructure                  701-231-1076 (Voice)
Room 242-J6, Quentin Burdick Building                  701-231-8541 (Fax)
North Dakota State University, Fargo, ND 58105-5164

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