[cups.general] Debugging the filter chain?

[William Pietri]

On 10/18/2010 12:13 PM, William Pietri wrote:
> I see in the logs that it starts a bunch of things (filters bannertops,
> pstopdf, pdftopdf, cpdftocps, and brlpdwrappermfc6490cw, and the lpd
> backend). Is there some easy way to me to peek into what's going on
> there in terms of inputs, arguments called, and outputs?
>
> Worst case I figure I'll run strace, but I figure there must be some
> better magic for debugging issues like this.
>
>    

Thanks, everybody, for your suggestions. I ended up just resorting to a 
bit of strace plus running filters manually, starting with the tail end 
of the chain. It turned out that because I was using CUPS to talk to an 
LPD driver, I had to install both the Brother CUPS and Brother LPD packages.

Since I'm pretty ignorant of CUPS, I don't know how much sense these 
suggestions make, but if I could wave a magic wand, these would have 
been nice:

   1. In debug logging, printing the full arguments of all filters called.
   2. In regular logging, calling out sending a zero-byte payload to the
      printer as an error.
   3. The ability to get a little information on what's getting passed
      between filters, so that I can tell where the failure is. E.g.,
      logging how many bytes each filter takes in and puts out.
   4. Getting dumps of the contents at each stage in the filter chain,
      so I could inspect things.


And thanks generally for CUPS, which is pretty swell.


William

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cups.org/pipermail/cups/attachments/20101019/28604ac6/attachment-0001.html>