core: push PolicyKit unavailable error to callers instead of logging it

The error is now pushed to things that request PK auth so that we don't
lose it, because we don't want to unconditionally log it from NM, but
still want things to know that their request couldn't be fulfilled
because PK wasn't running.

src/nm-manager-auth.c

@@ -74,24 +74,16 @@ free_data (gpointer data)
 
 #if WITH_POLKIT
 static PolkitAuthority *
-pk_authority_get (void)
+pk_authority_get (GError **error)
 {
 	static PolkitAuthority *authority = NULL;
-	GError *error = NULL;
 
-	if (authority == NULL) {
+	if (authority == NULL)
-		authority = polkit_authority_get_sync (NULL, &error);
+		authority = polkit_authority_get_sync (NULL, error);
-		if (authority == NULL) {
-			nm_log_err (LOGD_CORE, "Failed to initialize PolicyKit: (%d) %s",
-			            error ? error->code : -1,
-			            (error && error->message) ? error->message : "(unknown)");
-			g_clear_error (&error);
-			return NULL;
-		}
-	}
 
 	/* Yes, ref every time; we want to keep the object alive */
-	return g_object_ref (authority);
+	g_warn_if_fail (authority);
+	return authority ? g_object_ref (authority) : NULL;
 }
 #endif
 
@@ -110,7 +102,7 @@ _auth_chain_new (DBusGMethodInvocation *context,
 	self = g_malloc0 (sizeof (NMAuthChain));
 	self->refcount = 1;
 #if WITH_POLKIT
-	self->authority = pk_authority_get ();
+	self->authority = pk_authority_get (&self->error);
 #endif
 	self->data = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, free_data);
 	self->done_func = done_func;
@@ -405,16 +397,17 @@ nm_auth_chain_add_call (NMAuthChain *self,
 	g_return_val_if_fail (self->owner != NULL, FALSE);
 	g_return_val_if_fail (permission != NULL, FALSE);
 
-	subject = polkit_system_bus_name_new (self->owner);
-	if (!subject)
-		return FALSE;
-
 	call = auth_call_new (self, permission);
 
 	if (self->authority == NULL) {
 		/* No polkit, no authorization */
 		auth_call_schedule_complete_with_error (call, "PolicyKit not running");
-		g_object_unref (subject);
+		return FALSE;
+	}
+
+	subject = polkit_system_bus_name_new (self->owner);
+	if (!subject) {
+		auth_call_schedule_complete_with_error (call, "Failed to create polkit subject");
 		return FALSE;
 	}
 
@@ -603,7 +596,7 @@ nm_auth_changed_func_register (GDestroyNotify callback, gpointer callback_data)
 	gboolean found = FALSE;
 
 #if WITH_POLKIT
-	authority = pk_authority_get ();
+	authority = pk_authority_get (NULL);
 	if (!authority)
 		return;