[cups-devel] [UNKN] STR #4370: When restarting avahi-daemon while CUPS is running, CUPS looses connection

[till.kamppeter at gmail.com]

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[STR New]

This is a follow-up to STR #4300

Original issue:

I use CUPS with shared printers and the shared printers are broadcasted by
Avahi. This works well when avahi-daemon is started before cups and both
keep running. But if I restart avahi-daemon while CUPS is running, CUPS
looses connection to avahi-daemon and so stops broadcasting. What I expect
is that CUPS reconnects after the restart of avahi-daemon. This can easily
happen if for example the avahi-daemon package gets updated or the admin
changes the configuration of avahi-daemon.

Suggestion for a solution:

While making cups-browsed runnable on-demand on mobile devices I have found
a way to allow avahi-daemon to restart and reconnect. See the section

How to Write a Client That Can Deal with Daemon Restarts

on

http://avahi.sourcearchive.com/documentation/0.6.17/main.html

It is simply passing AVAHI_CLIENT_NO_FAIL to avahi_client_new(). With this
I can run cups-browsed independent of avahi-daemon (not even important in
which order avahi-daemon and cups-browsed are started), and whenever
avahi-daemon is running, remote CUPS printers are detected and the
appropriate local raw queues created and whenever avahi-daemon disappears,
the local queues are taken down. The (re)connection with avahi-daemon
(registering services in case of cupsd has to be done in the client
callback function and so it happens automatically when avahi-daemon
appears.

Perhaps one can use this also for cupsd.

Link: https://www.cups.org/str.php?L4370
Version: 1.7.1
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