[pulseaudio-discuss] --check option seems not to work from su(1) as daemon user

[Tanu Kaskinen]

On Sat, 2014-09-13 at 09:12 -0600, Glenn Golden wrote:
> A few loose-end questions if you have time:
> 
>   * Can you point me to any doc that describes the semantics of
>     PULSE_RUNTIME_PATH? It's not mentioned in pulse-daemon.conf.5 or in
>     pulseaudio.1.  (It doesn't even show up on the first page of results
>     from Google. How's that for 'obscure'? :) )

There's probably no documentation for that.

Since the XDG_RUNTIME_DIR environment variable exists,
PULSE_RUNTIME_PATH appears to be redundant. I think we should remove it
(since it's undocumented, this doesn't count as an interface break).
That's a bit tricky, though, because PULSE_RUNTIME_PATH is currently
used internally to set the runtime directory in the system mode. It
would probably not too hard to modify the code so that the system mode
doesn't rely on PULSE_RUNTIME_PATH, but even easier would be to always
unset the environment variable at startup, and set it again in the
system mode. That way the old logic for figuring out the runtime
directory in the system mode would work as before, but any values set by
the user would be ignored.

I suggest that you write the documentation with the assumption that
PULSE_RUNTIME_PATH doesn't exist. I'll write a patch today or next week
that removes it from the code. If it turns out that the patch will not
be accepted, then the documentation will have to be updated.

>   * Do you have a pointer to any doc which describes how PA distinguishes
>     between the concepts of "user", "seat", and "session"?

PA doesn't have any understanding of the "seat" and "session" concepts.
I mentioned these concepts earlier, because they affect what hardware
devices PulseAudio will try to access, but PulseAudio doesn't directly
use those concepts. logind or ConsoleKit is responsible for managing the
device permissions based on which user currently has an active session
on which seat, and PulseAudio reacts to the permission changes. If the
user loses permission to a device, PulseAudio will stop using that
device until the user gains access to it again.

logind's multiseat concept is documented here:
http://www.freedesktop.org/wiki/Software/systemd/multiseat/

-- 
Tanu