[http calendar] Ref backend inside source_changed_cb()

In certain situation, the backend can be freed while the callback
is still in action, then the factory can crash inside
cal_backend_http_ensure_uri() or such.

diff --git a/calendar/backends/http/e-cal-backend-http.c b/calendar/backends/http/e-cal-backend-http.c
index 4943810..c2db383 100644 (file)
--- a/calendar/backends/http/e-cal-backend-http.c
+++ b/calendar/backends/http/e-cal-backend-http.c
@@ -781,6 +781,8 @@ source_changed_cb (ESource *source,
 {
        g_return_if_fail (E_IS_CAL_BACKEND_HTTP (cbhttp));
 
+       g_object_ref (cbhttp);
+
        if (cbhttp->priv->uri != NULL) {
                gboolean uri_changed;
                const gchar *new_uri;
@@ -804,6 +806,8 @@ source_changed_cb (ESource *source,
 
                g_free (old_uri);
        }
+
+       g_object_unref (cbhttp);
 }
 
 static void