test-privserver-client: wait for server to die between iterations

This fixes a race condition: the server exits while the client continues
to the next iteration. If the server wins, the test passes. If the client
wins, it sends a message to the dying service, never gets a reply, and the
test fails.

My branch to refactor the main loop for fd.o #23194 seems to make the
client more likely to win this race, resulting in intermittent test
failures.

This is an instance of the general problem described by fd.o #11454.

1 files changed, 66 insertions, 14 deletions

diff --git a/test/name-test/test-privserver-client.c b/test/name-test/test-privserver-client.c
index d02eea89..1c43faee 100644
--- a/test/name-test/test-privserver-client.c
+++ b/test/name-test/test-privserver-client.c
@@ -11,18 +11,52 @@ die (const char *message, ...)
   exit (1);
 }
 
+#define PRIVSERVER_SERVICE "org.freedesktop.DBus.TestSuite.PrivServer"
+#define PRIVSERVER_INTERFACE PRIVSERVER_SERVICE
+#define PRIVSERVER_DIED_RULE \
+      "type='signal',sender='" DBUS_SERVICE_DBUS "'," \
+      "interface='" DBUS_INTERFACE_DBUS "',member='NameOwnerChanged'," \
+      "arg0='" PRIVSERVER_SERVICE "',arg2=''"
+
+static DBusHandlerResult
+filter_session_message (DBusConnection     *connection,
+                        DBusMessage        *message,
+                        void               *user_data)
+{
+  dbus_bool_t *service_died_p = user_data;
+  const char *name, *old_owner, *new_owner;
+
+  if (dbus_message_is_signal (message,
+                              DBUS_INTERFACE_DBUS,
+                              "NameOwnerChanged") &&
+      dbus_message_has_sender (message, DBUS_SERVICE_DBUS) &&
+      dbus_message_get_args (message, NULL,
+                             DBUS_TYPE_STRING, &name,
+                             DBUS_TYPE_STRING, &old_owner,
+                             DBUS_TYPE_STRING, &new_owner,
+                             DBUS_TYPE_INVALID) &&
+      strcmp (name, PRIVSERVER_SERVICE) == 0 &&
+      old_owner[0] != '\0' &&
+      new_owner[0] == '\0')
+    {
+      *service_died_p = TRUE;
+    }
+
+  return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
+}
+
 static DBusHandlerResult 
 filter_private_message (DBusConnection     *connection,
                         DBusMessage        *message,
                         void               *user_data)
 {
+  dbus_bool_t *private_conn_lost_p = user_data;
+
   if (dbus_message_is_signal (message,
                               DBUS_INTERFACE_LOCAL,
                               "Disconnected"))
     {
-       DBusLoop *loop = user_data;      
-       _dbus_loop_quit (loop);
-       return DBUS_HANDLER_RESULT_HANDLED;
+      *private_conn_lost_p = TRUE;
     }
   return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
 }
@@ -38,8 +72,12 @@ open_shutdown_private_connection (dbus_bool_t use_guid)
   DBusConnection *privconn;
   char *addr;
   char *comma;
+  dbus_bool_t service_died;
+  dbus_bool_t private_conn_lost;
 
   dbus_error_init (&error);
+  service_died = FALSE;
+  private_conn_lost = FALSE;
 
   loop = _dbus_loop_new ();
 
@@ -47,10 +85,19 @@ open_shutdown_private_connection (dbus_bool_t use_guid)
   if (!session)
     die ("couldn't access session bus\n");
   dbus_connection_set_exit_on_disconnect (session, FALSE);
-  msg = dbus_message_new_method_call ("org.freedesktop.DBus.TestSuite.PrivServer",
-                                      "/",
-                                      "org.freedesktop.DBus.TestSuite.PrivServer",
-                                      "GetPrivateAddress");
+  test_connection_setup (loop, session);
+
+  dbus_bus_add_match (session, PRIVSERVER_DIED_RULE, &error);
+  if (dbus_error_is_set (&error))
+    die ("couldn't add match rule \"%s\": %s: %s", PRIVSERVER_DIED_RULE,
+         error.name, error.message);
+
+  if (!dbus_connection_add_filter (session, filter_session_message,
+                                   &service_died, NULL))
+    die ("couldn't add filter to session bus\n");
+
+  msg = dbus_message_new_method_call (PRIVSERVER_SERVICE, "/",
+                                      PRIVSERVER_INTERFACE, "GetPrivateAddress");
   if (!(reply = dbus_connection_send_with_reply_and_block (session, msg, -1, &error)))
     die ("couldn't send message: %s\n", error.message);
   dbus_message_unref (msg);
@@ -71,24 +118,29 @@ open_shutdown_private_connection (dbus_bool_t use_guid)
   dbus_message_unref (reply);
 
   dbus_connection_set_exit_on_disconnect (privconn, FALSE);
-  dbus_connection_add_filter (privconn, filter_private_message, loop, NULL);
+  if (!dbus_connection_add_filter (privconn, filter_private_message,
+                                   &private_conn_lost, NULL))
+    die ("couldn't add filter to private connection\n");
   test_connection_setup (loop, privconn);
 
-  msg = dbus_message_new_method_call ("org.freedesktop.DBus.TestSuite.PrivServer",
-                                      "/",
-                                      "org.freedesktop.DBus.TestSuite.PrivServer",
-                                      "Quit");
+  msg = dbus_message_new_method_call (PRIVSERVER_SERVICE, "/",
+                                      PRIVSERVER_INTERFACE, "Quit");
   if (!dbus_connection_send (session, msg, NULL))
     die ("couldn't send Quit message\n");
   dbus_message_unref (msg);
 
-  _dbus_loop_run (loop);  
+  while (!service_died || !private_conn_lost)
+    _dbus_loop_iterate (loop, TRUE);
 
+  dbus_connection_remove_filter (session, filter_session_message,
+                                 &service_died);
+  dbus_bus_remove_match (session, PRIVSERVER_DIED_RULE, NULL);
   test_connection_shutdown (loop, session);
   dbus_connection_unref (session);
 
   test_connection_shutdown (loop, privconn);
-  dbus_connection_remove_filter (privconn, filter_private_message, loop);
+  dbus_connection_remove_filter (privconn, filter_private_message,
+                                 &private_conn_lost);
   dbus_connection_unref (privconn);
 
   _dbus_loop_unref (loop);