dbus-ping-listen.c

#include <glib.h>
#include <dbus/dbus-glib.h>
#include <dbus/dbus.h>

static DBusHandlerResult signal_filter 
      (DBusConnection *connection, DBusMessage *message, void *user_data);

int
main (int argc, char **argv)
{
  GMainLoop *loop;
  DBusConnection *bus;
  DBusError error;

  loop = g_main_loop_new (NULL, FALSE);

  dbus_error_init (&error);
  bus = dbus_bus_get (DBUS_BUS_SESSION, &error);
  if (!bus) {
    g_warning ("Failed to connect to the D-BUS daemon: %s", error.message);
    dbus_error_free (&error);
    return 1;
  }
  dbus_connection_setup_with_g_main (bus, NULL);

  /* listening to messages from all objects as no path is specified */
  dbus_bus_add_match (bus, "type='signal',interface='com.burtonini.dbus.Signal'", &error);
  dbus_connection_add_filter (bus, signal_filter, loop, NULL);

  g_main_loop_run (loop);
  return 0;
}

static DBusHandlerResult
signal_filter (DBusConnection *connection, DBusMessage *message, void *user_data)
{
  /* User data is the event loop we are running in */
  GMainLoop *loop = user_data;

  /* A signal from the bus saying we are about to be disconnected */
  if (dbus_message_is_signal 
        (message, DBUS_INTERFACE_LOCAL, "Disconnected")) {
    /* Tell the main loop to quit */
    g_main_loop_quit (loop);
    /* We have handled this message, don't pass it on */
    return DBUS_HANDLER_RESULT_HANDLED;
  }
  /* A Ping signal on the com.burtonini.dbus.Signal interface */
  else if (dbus_message_is_signal (message, "com.burtonini.dbus.Signal", "Ping")) {
    DBusError error;
    char *s;
    dbus_error_init (&error);
    if (dbus_message_get_args 
       (message, &error, DBUS_TYPE_STRING, &s, DBUS_TYPE_INVALID)) {
      g_print("Ping received: %s\n", s);
    } else {
      g_print("Ping received, but error getting message: %s\n", error.message);
    }
    dbus_error_free (&error);
    return DBUS_HANDLER_RESULT_HANDLED;
  }
  return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
}