Interface DBusMessageFilterFunction

All Superinterfaces:
FunctionPointer
Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface @Generated("org.javagi.JavaGI") public interface DBusMessageFilterFunction extends FunctionPointer

Functional interface declaration of the DBusMessageFilterFunction callback.

See Also:

  • Method Details

    • run

      DBusMessage run(DBusConnection connection, DBusMessage message, boolean incoming)

      Signature for function used in g_dbus_connection_add_filter().

      A filter function is passed a GDBusMessage and expected to return a GDBusMessage too. Passive filter functions that don't modify the message can simply return the message object:

      static GDBusMessage *
passive_filter (GDBusConnection *connection
                GDBusMessage    *message,
                gboolean         incoming,
                gpointer         user_data)
{
  // inspect @message
  return message;
}

      Filter functions that wants to drop a message can simply return null:

      static GDBusMessage *
drop_filter (GDBusConnection *connection
             GDBusMessage    *message,
             gboolean         incoming,
             gpointer         user_data)
{
  if (should_drop_message)
    {
      g_object_unref (message);
      message = NULL;
    }
  return message;
}

      Finally, a filter function may modify a message by copying it:

      static GDBusMessage *
modifying_filter (GDBusConnection *connection
                  GDBusMessage    *message,
                  gboolean         incoming,
                  gpointer         user_data)
{
  GDBusMessage *copy;
  GError *error;

  error = NULL;
  copy = g_dbus_message_copy (message, &error);
  // handle @error being set
  g_object_unref (message);

  // modify @copy

  return copy;
}

      If the returned GDBusMessage is different from message and cannot be sent on connection (it could use features, such as file descriptors, not compatible with connection), then a warning is logged to standard error. Applications can check this ahead of time using g_dbus_message_to_blob() passing a GDBusCapabilityFlags value obtained from connection.

      Parameters:
      connection - A GDBusConnection.
      message - A locked GDBusMessage that the filter function takes ownership of.
      incoming - true if it is a message received from the other peer, false if it is a message to be sent to the other peer.
      Returns:
      A GDBusMessage that will be freed with g_object_unref() or null to drop the message. Passive filter functions can simply return the passed message object.
      Since:
      2.26

    • upcall

      default MemorySegment upcall(MemorySegment connection, MemorySegment message, int incoming, MemorySegment userData)
      The upcall method is called from native code. The parameters are marshaled and run(DBusConnection, DBusMessage, boolean) is executed.

    • toCallback

      default MemorySegment toCallback(Arena arena)
      Creates a native function pointer to the upcall(MemorySegment, MemorySegment, int, MemorySegment) method.
      Specified by:
      toCallback in interface FunctionPointer
      Parameters:
      arena - the arena in which the function pointer is allocated
      Returns:
      the native function pointer