[at-spi2-core/gnome-42] listeners: Fix crash on NULL listener

[Mike Gorse <mgorse src gnome org>]

commit b49f7d025dbdeace79e7c9b598762b997ba023b8
Author: Samuel Thibault <samuel thibault ens-lyon org>
Date:   Sun Mar 13 23:54:07 2022 +0100

    listeners: Fix crash on NULL listener
    
    We shouldn't call _atspi_device_listener_get_path before checking that
    listener is not NULL.

 atspi/atspi-registry.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)
---
diff --git a/atspi/atspi-registry.c b/atspi/atspi-registry.c
index dea5878e..382308fd 100644
--- a/atspi/atspi-registry.c
+++ b/atspi/atspi-registry.c
@@ -270,19 +270,22 @@ atspi_deregister_keystroke_listener (AtspiDeviceListener *listener,
                                      GError             **error)
 {
   GArray *d_key_set;
-  gchar *path = _atspi_device_listener_get_path (listener);
+  gchar *path;
   gint i;
   dbus_uint32_t d_modmask = modmask;
   dbus_uint32_t d_event_types = event_types;
   DBusError d_error;
   GList *l;
 
-  dbus_error_init (&d_error);
   if (!listener)
     {
       return FALSE;
     }
 
+  dbus_error_init (&d_error);
+
+  path = _atspi_device_listener_get_path (listener);
+
   /* copy the keyval filter values from the C api into the DBind KeySet */
   if (key_set)
     {
@@ -363,15 +366,18 @@ atspi_register_device_event_listener (AtspiDeviceListener  *listener,
 {
   gboolean                          retval = FALSE;
   dbus_uint32_t d_event_types = event_types;
-  gchar *path = _atspi_device_listener_get_path (listener);
+  gchar *path;
   DBusError d_error;
 
-  dbus_error_init (&d_error);
   if (!listener)
     {
       return retval;
     }
 
+  dbus_error_init (&d_error);
+
+  path = _atspi_device_listener_get_path (listener);
+
     dbind_method_call_reentrant (_atspi_bus(), atspi_bus_registry, atspi_path_dec, atspi_interface_dec, 
"RegisterDeviceEventListener", &d_error, "ou=>b", path, d_event_types, &retval);
     if (dbus_error_is_set (&d_error))
       {
@@ -400,16 +406,18 @@ atspi_deregister_device_event_listener (AtspiDeviceListener *listener,
                                   void                     *filter, GError **error)
 {
   dbus_uint32_t event_types = 0;
-  gchar *path = _atspi_device_listener_get_path (listener);
+  gchar *path;
   DBusError d_error;
 
-  dbus_error_init (&d_error);
-
   if (!listener)
     {
       return FALSE;
     }
 
+  dbus_error_init (&d_error);
+
+  path = _atspi_device_listener_get_path (listener);
+
   event_types |= (1 << ATSPI_BUTTON_PRESSED_EVENT);
   event_types |= (1 << ATSPI_BUTTON_RELEASED_EVENT);