window: Use client PID for meta_window_get_pid()

The shell uses the PID of windows to map them to apps or to find out
which window/app triggered a dialog. It currently fails to do that in
some situations on Wayland, because meta_window_get_pid() only returns a
valid PID for x11 clients.

So use the client PID instead of the X11-exclusive _NET_WM_PID property
to find out the PID of the process that started the window. We can do
that by simply renaming the already existing
meta_window_get_client_pid() API to meta_window_get_pid() and moving
the old API providing the _NET_WM_PID to meta_window_get_netwm_pid().

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1180

src/core/delete.c

@@ -95,7 +95,7 @@ meta_window_delete (MetaWindow  *window,
 void
 meta_window_kill (MetaWindow *window)
 {
-  pid_t pid = meta_window_get_client_pid (window);
+  pid_t pid = meta_window_get_pid (window);
 
   if (pid > 0)
     {

src/core/window-private.h

@@ -821,8 +821,6 @@ gboolean meta_window_handle_ui_frame_event (MetaWindow         *window,
 void meta_window_handle_ungrabbed_event (MetaWindow         *window,
                                          const ClutterEvent *event);
 
-uint32_t meta_window_get_client_pid (MetaWindow *window);
-
 void meta_window_get_client_area_rect (const MetaWindow      *window,
                                        cairo_rectangle_int_t *rect);
 void meta_window_get_titlebar_rect (MetaWindow    *window,

src/core/window.c

@@ -902,7 +902,7 @@ meta_window_update_sandboxed_app_id (MetaWindow *window)
 
   g_clear_pointer (&window->sandboxed_app_id, g_free);
 
-  pid = meta_window_get_client_pid (window);
+  pid = meta_window_get_pid (window);
 
   if (pid == 0)
     return;
@@ -7584,7 +7584,7 @@ meta_window_get_transient_for (MetaWindow *window)
 }
 
 /**
- * meta_window_get_client_pid:
+ * meta_window_get_pid:
  * @window: a #MetaWindow
  *
  * Returns the pid of the process that created this window, if available
@@ -7593,26 +7593,11 @@ meta_window_get_transient_for (MetaWindow *window)
  * Return value: the pid, or 0 if not known.
  */
 uint32_t
-meta_window_get_client_pid (MetaWindow *window)
-{
-  return META_WINDOW_GET_CLASS (window)->get_client_pid (window);
-}
-
-/**
- * meta_window_get_pid:
- * @window: a #MetaWindow
- *
- * Returns pid of the process that created this window, if known (obtained from
- * the _NET_WM_PID property).
- *
- * Return value: the pid, or -1 if not known.
- */
-int
 meta_window_get_pid (MetaWindow *window)
 {
-  g_return_val_if_fail (META_IS_WINDOW (window), -1);
+  g_return_val_if_fail (META_IS_WINDOW (window), 0);
 
-  return window->net_wm_pid;
+  return META_WINDOW_GET_CLASS (window)->get_client_pid (window);
 }
 
 /**

src/meta/window.h

@@ -328,7 +328,7 @@ META_EXPORT
 guint32     meta_window_get_user_time (MetaWindow *window);
 
 META_EXPORT
-int         meta_window_get_pid (MetaWindow *window);
+uint32_t    meta_window_get_pid (MetaWindow *window);
 
 META_EXPORT
 const char *meta_window_get_client_machine (MetaWindow *window);

src/wayland/meta-xwayland.c

@@ -713,7 +713,7 @@ window_created_cb (MetaDisplay         *display,
 {
   /* Ignore all internal windows */
   if (!window->xwindow ||
-      meta_window_get_client_pid (window) == getpid ())
+      meta_window_get_pid (window) == getpid ())
     return;
 
   manager->x11_windows = g_list_prepend (manager->x11_windows, window);