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

[Felipe Sateler]

On Fri, Aug 22, 2014 at 6:12 AM, Tanu Kaskinen
<tanu.kaskinen at linux.intel.com> wrote:
> On Thu, 2014-08-21 at 16:55 -0600, Glenn Golden wrote:
>> A side issue that I came across, related to the --check option, but not the
>> doc issue itself:
>>
>> Suppose the root user wishes to use the --check option to see if user xyz
>> has a PA daemon running. He does this:
>>
>>     #  XDG_RUNTIME_DIR=/run/user/1234  pulseaudio --check -v
>>
>> which dutifully reports (correctly) that "Daemon running as PID xxx".  But
>> it also has the silent side effect that the directory /run/user/1234/pulse is
>> chowned to root.root, thus preventing user xyz from further communication
>> with the daemon due to accesss permission violation.
>>
>> Two questions:
>>
>>   * Can you reproduce this?
>>   * What is your view as to whether this is a bug? (IMO it is, and was going
>>     to report it, but wanted to hear your view.)
>
> It's not a bug, because --check isn't documented to be a tool for
> checking if other users' daemons are running. If such functionality is
> useful for people, then maybe we should extend the scope of --check, but
> setting XDG_RUNTIME_DIR to point to another user's directory seems like
> a hack to me, because it's against the usual semantics of the variable.
> If there is some API for querying the runtime directory of arbitrary
> users, we could implement this e.g. by adding --check-for-user=foo, but
> I'm not aware of such API. In my opinion, such system API is necessary
> before we should officially support this use case for --check.
>
> I'm not against making this an undocumented feature, though, if it turns
> out that there's no good reason to chown the runtime directory when
> running --check. If the user's intention is to check the status of
> another user's pulseaudio, then the chowning is of course unnecessary
> and harmful, but if the user's intention is to check whether his/her own
> pulseaudio is running, then it's perhaps a different situation. We need
> to understand why the runtime directory is ever chowned. I don't see
> very good reasons for that myself, but on the other hand, I'm hesitant
> to change that without understanding the original motivation.

Note that the directory is chowned if pacmd or pactl are called as
root with the "wrong" runtime dir. While I have no opinion on the
merits of allowing --check to work as root, I think that calling
`pacmd list-sinks` as root should not break the user's pulseaudio.


-- 

Saludos,
Felipe Sateler