core: add nm_dbus_g_method_invocation_get_g_connection()

This method exists in dbus-glib >= 101, but if it doesn't, emulate it.

See https://bugs.freedesktop.org/show_bug.cgi?id=55729

configure.ac

@@ -212,6 +212,9 @@ PKG_CHECK_MODULES(DBUS, dbus-1 >= 1.1 dbus-glib-1 >= 0.94)
 AC_SUBST(DBUS_CFLAGS)
 AC_SUBST(DBUS_LIBS)
 
+AC_CHECK_LIB([dbus-glib-1], [dbus_g_method_invocation_get_g_connection], ac_have_gmi_get_con="1", ac_have_gmi_get_con="0")
+AC_DEFINE_UNQUOTED(HAVE_DBUS_GLIB_GMI_GET_CONNECTION, $ac_have_gmi_get_con, [Define if you have a dbus-glib with dbus_g_method_invocation_get_g_connection()])
+
 PKG_CHECK_MODULES(GLIB, gio-unix-2.0 >= 2.32 gmodule-2.0)
 
 dnl GLIB_VERSION_MIN_REQUIRED should match the version above.

src/nm-dbus-manager.c

@@ -410,3 +410,18 @@ nm_dbus_manager_unregister_object (NMDBusManager *self, gpointer object)
 	dbus_g_connection_unregister_g_object (priv->g_connection, G_OBJECT (object));
 }
 
+#if !HAVE_DBUS_GLIB_GMI_GET_CONNECTION
+struct _HACKDBusGMethodInvocation {
+  DBusGConnection *connection;
+  /* ... */
+};
+
+DBusGConnection *
+dbus_g_method_invocation_get_g_connection (DBusGMethodInvocation *context)
+{
+	/* Evil hack; this method exists in dbus-glib >= 101, but if we don't
+	 * have that, emulate it.
+	 */
+	return ((struct _HACKDBusGMethodInvocation *) context)->connection;
+}
+#endif  /* HAVE_DBUS_GLIB_GMI_GET_CONNECTION */

src/nm-dbus-manager.h

@@ -22,6 +22,7 @@
 #ifndef __NM_DBUS_MANAGER_H__
 #define __NM_DBUS_MANAGER_H__
 
+#include <config.h>
 #include <glib-object.h>
 #include <dbus/dbus.h>
 #include <dbus/dbus-glib.h>
@@ -81,6 +82,10 @@ void nm_dbus_manager_register_object (NMDBusManager *self,
 
 void nm_dbus_manager_unregister_object (NMDBusManager *self, gpointer object);
 
+#if !HAVE_DBUS_GLIB_GMI_GET_CONNECTION
+DBusGConnection *dbus_g_method_invocation_get_g_connection (DBusGMethodInvocation *context);
+#endif
+
 G_END_DECLS
 
 #endif /* __NM_DBUS_MANAGER_H__ */