[Tested in latest gnome-ostree; if accepted, I'll look at a followup
patch which fixes the other dbus_connection_send(reply, ...) calls
besides logind]
DBus messages can have a flag NO_REPLY associated that means "I don't
need a reply". This is for efficiency reasons - for one-off requests
that can't return an error, etc.
However, it's up to users to manually check
dbus_message_get_no_reply() from a message. libdbus will happily send
out a reply if you don't.
Unfortunately, doing so is not just less efficient - it also triggers
a security error, for complex reasons. This is something that will
eventually be fixed in dbus, but it's also correct to handle it in
client applications.
This new helper API is slightly nicer in that you don't have to pass
NULL to say you don't want a reply serial for your reply.
This patch also tweaks logind to use the API - there are more areas of
the code that need this treatment too.
Much like logind has a client in loginctl, and journald in journalctl
introduce timedatectl, to change the system time (incl. RTC), timezones
and related settings.
The MESSAGE_ID=... stanza will appear in countless number of places.
It is just too long to write it out in full each time.
Incidentally, this also fixes a typo of MESSSAGE is three places.
Previously, if X allocated all 6 TTYs (for multi-session for example) no
getty would be available anymore to guarantee console-based logins.
With the new ReserveVT= switch in logind.conf we can now choose one VT
(6 by default) that will always be subject to autovt-style activation,
i.e. we'll always have a getty on TTY6, and X will never take possession
of it.
Before, after the timeout, a session would be timestamped as idle
since 'last activity' + 'idle timeout'. Now, it is timestamped as idle
since 'last activity'.
Before, after all sessions were idle, the seat would be marked with as
idle with the timestamp of the oldest idle session. Now it is
marked with the timestamp of the youngest idle session.
Both changes seem to me to be closer to natural understanding of
idleness: the time since last activity counts.
This counts 'online sessions' in addition to 'active sessions' and 'sessions'.
In this context, an 'online session' covers all session in the 'active' state
in addition to the explicit 'online' state.
This provides an easy machanism to determin all relevant sessions easily
(i.e. those that are not 'closing') and adds new semantics to the sd-login.c
APIs sd_uid_get_sessions() and sd_uid_get_seats() where the require_active
argument can be supplied as a value 2 which only lists sessions which are
'online'.
This functionality should allow client applications to avoid deadlocks where
they only exit when all sessions are complete, such as a the problem where
PulseAudio will not exit until all sessions are gone, but in itself prevents
the session from exiting.
PulseAudio for example will keep a client connection open provided
at least one session exists. However, if all sessions are currently
in the process of closing, we should flag that as the overall state
appropriately to better reflect what is happening.
Although this does better reflect the status for any given user, it does
not actually solve the overall problem of PulseAudio still finding some
sessions active and thus not exiting and therefore actually preventing
the session from closing. Future commits will extend sd-login to cope
with this situation.
Lennart Poettering