GHOST/Wayland: add additional locks for correctness

Some of these functions should use locks although they didn't show up
as needing locks at runtime (using valgrind's helgrind), as some aren't
called often or aren't used at all. Add locks for correctness & to
prevent errors in the future.

- GHOST_SystemWayland::disposeContext
- GHOST_SystemWayland::getAllDisplayDimensions
- GHOST_SystemWayland::getButtons
- GHOST_SystemWayland::getMainDisplayDimensions
- GHOST_SystemWayland::getNumDisplays
- GHOST_WindowWayland::setWindowCustomCursorShape

intern/ghost/intern/GHOST_SystemWayland.cpp

@@ -5580,6 +5580,10 @@ GHOST_TSuccess GHOST_SystemWayland::getModifierKeys(GHOST_ModifierKeys &keys) co
 
 GHOST_TSuccess GHOST_SystemWayland::getButtons(GHOST_Buttons &buttons) const
 {
+#ifdef USE_EVENT_BACKGROUND_THREAD
+  std::lock_guard lock_server_guard{*server_mutex};
+#endif
+
   GWL_Seat *seat = gwl_display_seat_active_get(display_);
   if (UNLIKELY(!seat)) {
     return GHOST_kFailure;
@@ -5808,6 +5812,10 @@ void GHOST_SystemWayland::putClipboard(const char *buffer, bool selection) const
 
 uint8_t GHOST_SystemWayland::getNumDisplays() const
 {
+#ifdef USE_EVENT_BACKGROUND_THREAD
+  std::lock_guard lock_server_guard{*server_mutex};
+#endif
+
   return display_ ? uint8_t(display_->outputs.size()) : 0;
 }
 
@@ -5926,7 +5934,11 @@ GHOST_TSuccess GHOST_SystemWayland::setCursorPosition(const int32_t x, const int
 
 void GHOST_SystemWayland::getMainDisplayDimensions(uint32_t &width, uint32_t &height) const
 {
-  if (getNumDisplays() == 0) {
+#ifdef USE_EVENT_BACKGROUND_THREAD
+  std::lock_guard lock_server_guard{*server_mutex};
+#endif
+
+  if (display_->outputs.empty()) {
     return;
   }
   /* We assume first output as main. */
@@ -5936,6 +5948,10 @@ void GHOST_SystemWayland::getMainDisplayDimensions(uint32_t &width, uint32_t &he
 
 void GHOST_SystemWayland::getAllDisplayDimensions(uint32_t &width, uint32_t &height) const
 {
+#ifdef USE_EVENT_BACKGROUND_THREAD
+  std::lock_guard lock_server_guard{*server_mutex};
+#endif
+
   int32_t xy_min[2] = {INT32_MAX, INT32_MAX};
   int32_t xy_max[2] = {INT32_MIN, INT32_MIN};
 
@@ -5959,6 +5975,7 @@ static GHOST_Context *createOffscreenContext_impl(GHOST_SystemWayland *system,
                                                   struct wl_display *wl_display,
                                                   wl_egl_window *egl_window)
 {
+  /* Caller must lock `system->server_mutex`. */
   GHOST_Context *context;
 
   for (int minor = 6; minor >= 0; --minor) {
@@ -6028,6 +6045,10 @@ GHOST_IContext *GHOST_SystemWayland::createOffscreenContext(GHOST_GLSettings /*g
 
 GHOST_TSuccess GHOST_SystemWayland::disposeContext(GHOST_IContext *context)
 {
+#ifdef USE_EVENT_BACKGROUND_THREAD
+  std::lock_guard lock_server_guard{*server_mutex};
+#endif
+
   struct wl_surface *wl_surface = (struct wl_surface *)((GHOST_Context *)context)->getUserData();
   wl_egl_window *egl_window = (wl_egl_window *)wl_surface_get_user_data(wl_surface);
   wl_egl_window_destroy(egl_window);
@@ -6268,7 +6289,8 @@ static bool cursor_is_software(const GHOST_TGrabCursorMode mode, const bool use_
 
 GHOST_TSuccess GHOST_SystemWayland::cursor_shape_set(const GHOST_TStandardCursor shape)
 {
-  /* No need to lock (caller must lock). */
+  /* Caller must lock `server_mutex`. */
+
   GWL_Seat *seat = gwl_display_seat_active_get(display_);
   if (UNLIKELY(!seat)) {
     return GHOST_kFailure;
@@ -6311,6 +6333,7 @@ GHOST_TSuccess GHOST_SystemWayland::cursor_shape_set(const GHOST_TStandardCursor
 
 GHOST_TSuccess GHOST_SystemWayland::cursor_shape_check(const GHOST_TStandardCursor cursorShape)
 {
+  /* No need to lock `server_mutex`. */
   auto cursor_find = ghost_wl_cursors.find(cursorShape);
   if (cursor_find == ghost_wl_cursors.end()) {
     return GHOST_kFailure;
@@ -6690,6 +6713,8 @@ bool GHOST_SystemWayland::window_cursor_grab_set(const GHOST_TGrabCursorMode mod
                                                  wl_surface *wl_surface,
                                                  const int scale)
 {
+  /* Caller must lock `server_mutex`. */
+
   /* Ignore, if the required protocols are not supported. */
   if (UNLIKELY(!display_->wp_relative_pointer_manager || !display_->wp_pointer_constraints)) {
     return GHOST_kFailure;

intern/ghost/intern/GHOST_WindowWayland.cpp

@@ -989,6 +989,9 @@ bool GHOST_WindowWayland::getCursorGrabUseSoftwareDisplay()
 GHOST_TSuccess GHOST_WindowWayland::setWindowCustomCursorShape(
     uint8_t *bitmap, uint8_t *mask, int sizex, int sizey, int hotX, int hotY, bool canInvertColor)
 {
+#ifdef USE_EVENT_BACKGROUND_THREAD
+  std::lock_guard lock_server_guard{*system_->server_mutex};
+#endif
   return system_->cursor_shape_custom_set(bitmap, mask, sizex, sizey, hotX, hotY, canInvertColor);
 }