Emacs and DBUS
Fri Aug 27 15:02:00 GMT 2010
On 8/27/2010 3:41 AM, Michael Albinus wrote:
> Ken Brown<email@example.com> writes:
>>> This is also a D-Bus client, which connects to the *same* session bus as
>>> Emacs did due to $DBUS_SESSION_BUS_ADDRESS. Now you should see the
>>> signal sent by dbus-monitor in Emacs.
>> OK, I started the session bus the right way this time, but I still
>> didn't see any signal from dbus-monitor in Emacs. I assume I should
>> have seen something in the echo area?
> Yes. You could test whether both Emacs and dbus-monitor use the same bus
> by reordering the calls:
> - apply dbus-launch as described
> - echo $DBUS_SESSION_BUS_ADDRESS
> - in *another* shell, set $DBUS_SESSION_BUS_ADDRESS to this value, and
> start dbus-monitor
> - start Emacs in the first shell, and load dbus.el. You shall see in
> the other shell output from dbus-monitor, telling that an application
> has started. It will also tell you the name of that application, like
This doesn't happen. Is it possible that dbus.el doesn't complete its
initialization because the system bus isn't running? (Keep in mind that
I can't do *anything* with dbus in Emacs unless I load dbus.el before
starting the system bus.) I note that when I use the version of Emacs
built with MYCPPFLAGS='-DDBUS_DEBUG', loading dbus.el results in the
following error message in the echo area:
D-Bus error: "Failed to connect to socket
/var/run/dbus/system_bus_socket: Interrupted system call"
> - apply (dbus-get-unique-name :session) in Emacs. The result shall be
> the same name.
> - start dbus-monitor in the same shell as Emacs. In the other
> dbus-monitor, you should be notified, that an application has been started.
>>> Maybe you can compile dbusbind.c with the compiler flag DBUS_DEBUG,
>>> something like this in the Emacs source tree:
>>> # MYCPPFLAGS='-DDBUS_DEBUG' make
>>> This enables test traces sent to Emacs' stdout (the shell where you have
>>> started it). I've introduced this flag while testing dbusbind.c, when it
>>> has blocked Emacs, and I didn't want to start gdb ...
>>> Maybe I can see something suspicious in the traces.
>> There's very little there. It prints the two lines
>> xd_add_watch: fd 8
>> xd_add_watch: fd 9
>> and no more. Does this tell you anything?
> It's the initialization phase. Two watch functions are installed on file
> descriptors 8 and 9 (connected to the system and session buses), polling
> for incoming messages in Emacs' mainloop.
> When you call dbus-get-unique-name, there shall be more output. But this
> works, as you have confirmed, so this is not the interesting case.
> I've hoped to see more :-( Did you play with the running/non-running
> system bus?
Yes, the traces above were produced when starting Emacs with the system
bus running. I'm stuck at that point and can't do anything to produce
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