[cups-devel] Searching recursively for backends and filtes inside ServerBin directory?

[Mario Sanchez Prada]

Hi,

I've been playing a bit lately with some customizations we need in our
platforms related to how we integrate third-party printer drivers into
the CUPS infrastructure, and I was wondering whether it would make
sense to modify cups so it can search recursively for third party
backends & filters under the ServerBin (e.g. /usr/lib/cups) directory.
Pretty much as it already does when searching for PPD files inside
/usr/share/ppd.

The reason why I was thinking of doing such a thing is because we
would need to ship CUPS with ServerBin in the usual locations
(/usr/lib/cups), but anything under that path will be read-only stuff
once the system has booted, so any further installation of any other
driver afterwards won't be able to install anything in that location.

So I thought that, if it was possible for CUPS to search recursively
for filters and backends inside ServerBin, I guess I could implement
some solution similar to what many printers manufacturers seem to
follow for the PPD files: ship those files under some other
directories and then symlinking to those directories from /usr/cups/.

In my mind, it could be perhaps something like this, for instance

  /usr/lib/cups/filters/third-party ->  /opt/cups-third-party/filters
  /usr/lib/cups/backends/third-party  ->  /opt/cups-third-party/backends

(and we could include those symlinks as part of the base image
populating /usr/lib/cups).


I've checked the code and a quick grep shows that at least I'd need to
change a few files under scheduler/ (cupsfilter.c, job.c,
printers.c...) to achieve this, but I'm not aware yet of any side
effect/implication that might have, so I think I could use some early
advice here.

So, what do you think? Does this even make any sense, or is not
possible/good idea for any reason?

Thanks in advance,
Mario