There was a slight race in name ownership: a gap between calling
`RequestName` (or receiving its reply) and subscribing to `NameLost`. In
that gap, another process could request and receive the name, and this
one wouldn’t know about it.
Fix that by subscribing to `NameAcquired` and `NameLost` before calling
`RequestName`, and then unsubscribing again if the subscriptions turn
out not to be necessary (if the process can’t own the requested name).
Spotted and diagnosed by Miika Karanki.
One of the tests needs an additional iteration of the main loop in order
to free all the signal closures before it can complete its checks.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #1517
As with all D-Bus signal subscriptions, it’s possible for a signal
callback to be invoked in one thread (T1) while another thread (T2) is
unsubscribing from that signal. In this case, T1 is the main thread, and
T2 is the D-Bus connection worker thread which is unsubscribing all
signals as it’s in the process of closing.
Due to this possibility, all `user_data` for signal callbacks needs to
be referenced outside the lifecycle of the code which
subscribes/unsubscribes the signal. In other words, it’s not safe to
subscribe to a signal, store the subscription ID in a struct,
unsubscribe from the signal when freeing the struct, and dereference the
struct in the signal callback. The data passed to the signal callback
has to have its own strong reference.
Instead, it’s safe to subscribe to a signal and add a strong reference
to the struct, store the subscription ID in that struct, and unsubscribe
from the signal when the last external reference to your struct is
dropped. That unsubscription should break the refcount cycle between the
signal connection and the struct, and allow the struct to be completely
freed. Only with that approach is it safe to dereference the struct in
the signal callback, if there’s any possibility that the signal might be
unsubscribed from a separate thread.
The tests need specific additional main loop cycles to completely emit
the NameLost signal callback. Ideally they need refactoring, but this
will do (1000 test cycles passed).
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #978
This reverts commit c37cd19fee.
Now that we've reverted the commit "gtestdbus: Properly close server
connections", g_test_dbus_down() no longer returns early and we no
longer need this workaround. Since the gdbus-names test seems to
properly unref its GDBusConnection objects it's not clear to me why it
needed the sleep to succeed. However even at the time the failure wasn't
reproducible according to this comment[1] so it's probably not worth
spending more effort trying to reproduce it now.
[1] https://gitlab.gnome.org/GNOME/glib/issues/787#note_214235
Very many testcases, some GLib tools (resource compiler, etc) and
GApplication were calling g_type_init().
Remove those uses, as they are no longer required.
https://bugzilla.gnome.org/show_bug.cgi?id=686161
Since we make message buses come and go, we need to ensure that the
singleton connection instance goes away before attempting to call
g_bus_get_sync() or similar.
Signed-off-by: David Zeuthen <davidz@redhat.com>
The GClosure API is a bit funky (and badly documented), and requires
you to set a marshaller on the closure, and the marshaller has an
implicit 'this' argument, and the caller is reponsible for unsetting
the values after invoking the closure.
I've added some calls of the _with_closures variants to the
gdbus-names test now.
This allows the caller to specify the reply type that they are expecting
for this call. If the reply comes back with the wrong type, GDBus will
generate an appropriate error internally.
- add a GVariantType * argument to g_dbus_connection_call() and
_call_sync().
- move the internal API for computing message types from introspection
data to be based on GVariantType instead of strings. Update users
of this code.
- have GDBusProxy pass this calculated GVariantType into
g_dbus_connection_call(). Remove the checks done in GDBusProxy.
- Update other users of the code (test cases, gdbus-tool, GSettings
tool, etc). In some cases, remove redundant checks; in some other
cases, we are fixing bugs because no checking was done where it
should have been.
Closes bug #619391.
Lots of people been suggesting this. We still use MethodInvocation /
method_invocation for handling incoming method calls so use call()
instead of invoke_method() helps to separate the client and server
facilities. Which is a good thing(tm).
Things compile and the test-suite passes. Still need to hook up
gio.symbols and docs. There are still a bunch of TODOs left in the
sources that needs to be addressed.
Signed-off-by: David Zeuthen <davidz@redhat.com>
