From: Julien Danjou <julien@danjou.info>
To: 9581@debbugs.gnu.org
Subject: bug#9581: 24.0.50; dbus-unregister-object fails if service is nil
Date: Fri, 23 Sep 2011 01:01:17 +0200 [thread overview]
Message-ID: <87pqisi3lu.fsf@keller.adm.naquadah.org> (raw)
If you use `dbus-register-signal' with a nil SERVICE value, like:
(dbus-register-signal :session nil
"/org/gtk/Private/RemoteVolumeMonitor"
"org.gtk.Private.RemoteVolumeMonitor" "VolumeAdded"
'identity)
This is valid and works fine. However, on unregister it fails:
Debugger entered--Lisp error: (dbus-error "Call to ReleaseName has wrong args (b, expected s)")
dbus-call-method(:session "org.freedesktop.DBus" "/org/freedesktop/DBus" "org.freedesktop.DBus" "ReleaseName" nil)
dbus-unregister-object(((:session "org.gtk.Private.RemoteVolumeMonitor" "VolumeAdded") (nil "/org/gtk/Private/RemoteVolumeMonitor" identity)))
Why does it fail? Because of the following code in
`dbus-unregister-object':
#+begin_src emacs-lisp
(unless found
(dbus-call-method
bus dbus-service-dbus dbus-path-dbus dbus-interface-dbus
"ReleaseName" service))))
+end_src
And here service is… nil. Which is translated to a boolean (b) but
should be a string (s).
But honestly, I'm not sure what the good fix is. To me, this code is
totally wrong in such a case.
When using `dbus-register-signal', this happens:
1. the dbus_bus_add_match() function is called to add a match on the bus
2. the (match callback) pair is recorded into
`dbus-registered-objets-table'
This makes things work. When a signal happens, something is looking into
`dbus-registered-objets-table' and call the callback function.
But to stop listening for a signal, the function to use is
`dbus-unregister-object', and it is doing this:
1. remove the (match callback) pair from `dbus-registered-objets-table'
2. call ReleaseName on the service we were listening
While I agree on point 1., the point 2. is totally irrelevant in such a
case. There's no need to do such a thing, the name has never been
requested with RequestName before.
I think that:
- step 2 should be removed or another function should be created which
does not send a ReleaseName
- dbus_bus_remove_match() should be used to remove the watch from the
bus, which would be a lot cleaner.
--
Julien Danjou
next reply other threads:[~2011-09-22 23:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-22 23:01 Julien Danjou [this message]
2011-09-23 15:37 ` bug#9581: 24.0.50; dbus-unregister-object fails if service is nil Michael Albinus
2011-09-23 16:12 ` Julien Danjou
2011-09-24 11:50 ` Michael Albinus
2011-09-24 14:19 ` Julien Danjou
2011-09-24 14:37 ` Michael Albinus
2011-09-25 11:38 ` Julien Danjou
2011-09-25 11:59 ` Michael Albinus
2011-09-25 12:19 ` Julien Danjou
2011-09-25 16:03 ` Michael Albinus
2011-09-26 12:16 ` Julien Danjou
2011-09-26 13:57 ` Michael Albinus
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