connection-contact-list: don't crash if no Contacts

This situation would be stupid, but we still shouldn't crash.

Signed-off-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Reviewed-by: Guillaume Desmottes <guillaume.desmottes@collabora.co.uk>
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=49735

1 files changed, 14 insertions, 0 deletions

diff --git a/telepathy-glib/connection-contact-list.c b/telepathy-glib/connection-contact-list.c
index a0650a213..2e6d597bd 100644
--- a/telepathy-glib/connection-contact-list.c
+++ b/telepathy-glib/connection-contact-list.c
@@ -231,6 +231,7 @@ got_contact_list_attributes_cb (TpConnection *self,
     GObject *weak_object)
 {
   GSimpleAsyncResult *result = (GSimpleAsyncResult *) weak_object;
+  /* may be NULL if error != NULL, when calling directly */
   GArray *features = user_data;
   GHashTableIter iter;
   gpointer key, value;
@@ -305,6 +306,19 @@ prepare_roster (TpConnection *self,
   DEBUG ("CM has the roster for connection %s, fetch it now.",
       tp_proxy_get_object_path (self));
 
+  /* Pre-empt _tp_contacts_bind_to_signals, which assumes that Contacts
+   * is present and works correctly */
+  if (!tp_proxy_has_interface_by_id (self,
+        TP_IFACE_QUARK_CONNECTION_INTERFACE_CONTACTS))
+    {
+      GError error = { TP_DBUS_ERRORS, TP_DBUS_ERROR_NO_INTERFACE,
+          "Obsolete CM does not have the Contacts interface" };
+
+      got_contact_list_attributes_cb (self, NULL, &error, NULL,
+          (GObject *) result);
+      return;
+    }
+
   tp_cli_connection_interface_contact_list_connect_to_contacts_changed_with_id (
       self, contacts_changed_cb, NULL, NULL, NULL, NULL);