Package org.gnome.gio

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("io.github.jwharm.JavaGI")
public interface DBusMessageFilterFunction
extends FunctionPointer

Functional interface declaration of the DBusMessageFilterFunction callback.

See Also:

• run(org.gnome.gio.DBusConnection, org.gnome.gio.DBusMessage, boolean)

Method Summary

Modifier and Type	Method	Description
DBusMessage	run(DBusConnection connection, DBusMessage message, boolean incoming)	Signature for function used in g_dbus_connection_add_filter().
default MemorySegment	toCallback(Arena arena)	Creates a native function pointer to the upcall(java.lang.foreign.MemorySegment, java.lang.foreign.MemorySegment, int, java.lang.foreign.MemorySegment) method.
default MemorySegment	upcall(MemorySegment connection, MemorySegment message, int incoming, MemorySegment userData)	The upcall method is called from native code.

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.

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(org.gnome.gio.DBusConnection, org.gnome.gio.DBusMessage, boolean) is executed.

toCallback

default MemorySegment toCallback(Arena arena)

Creates a native function pointer to the upcall(java.lang.foreign.MemorySegment, java.lang.foreign.MemorySegment, int, java.lang.foreign.MemorySegment) method.

Specified by:

toCallback in interface FunctionPointer

Parameters:

arena - the function pointer will be allocated in this arena

Returns:

the native function pointer