Extending printers.conf with own attributes

[Johannes Grumboeck]

Hi,

Can anyone tell me which files are involved in saving/reading an attribute from/to printers.conf?
I'd like to extend the add/modify printer dialog with some attributes we would need to be saved with each printer. So I found out that
scheduler/ipp.c, scheduler/printers.c, cgi-bin/admin.c ... and some more are all involved in editing printers.conf.
I also extended it as far as my attribute keys are saved into printers.conf, but not the value. Also if I've entered a value manually into printers.conf the templates (especially modify-printer.tmpl) are not filled out with the values.
Can anybody give me a hint or howto extend printers.conf?

Or would it be possible to implement a generic solution for attributes in printers.conf: Let's say every attribute key which starts like "X_" (e.g. X_newkey) would be read/saved by cups and the value of this could be used in templates.
What do you think about it?

Best regards,
Johannes