From dd2e3182116c9b0e07a157adb0ef286a49708fda Mon Sep 17 00:00:00 2001
From: Frank Praznik <frank.praznik@gmail.com>
Date: Sat, 6 Aug 2022 12:31:06 -0400
Subject: [PATCH] wayland: Use libdecor visibility toggle for hiding/showing
 the window

The current method of toggling the libdecor window visibility by destroying and recreating the frame results in a race where a use-after-free bug can manifest itself within libdecor when window visibility is toggled quickly. Instead, use the libdecor function for toggling visibility instead of destroying and recreating the frame every time.
---
 src/video/wayland/SDL_waylandwindow.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/src/video/wayland/SDL_waylandwindow.c b/src/video/wayland/SDL_waylandwindow.c
index c5b997c7b..a94063d93 100644
--- a/src/video/wayland/SDL_waylandwindow.c
+++ b/src/video/wayland/SDL_waylandwindow.c
@@ -1228,15 +1228,20 @@ void Wayland_ShowWindow(_THIS, SDL_Window *window)
     /* Create the shell surface and map the toplevel/popup */
 #ifdef HAVE_LIBDECOR_H
     if (WINDOW_IS_LIBDECOR(c, window)) {
-        data->shell_surface.libdecor.frame = libdecor_decorate(c->shell.libdecor,
-                                                               data->surface,
-                                                               &libdecor_frame_interface,
-                                                               data);
-        if (data->shell_surface.libdecor.frame == NULL) {
-            SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "Failed to create libdecor frame!");
+        if (data->shell_surface.libdecor.frame) {
+            /* If the frame already exists, just set the visibility. */
+            libdecor_frame_set_visibility(data->shell_surface.libdecor.frame, true);
         } else {
-            libdecor_frame_set_app_id(data->shell_surface.libdecor.frame, c->classname);
-            libdecor_frame_map(data->shell_surface.libdecor.frame);
+            data->shell_surface.libdecor.frame = libdecor_decorate(c->shell.libdecor,
+                                                                   data->surface,
+                                                                   &libdecor_frame_interface,
+                                                                   data);
+            if (data->shell_surface.libdecor.frame == NULL) {
+                SDL_LogError(SDL_LOG_CATEGORY_VIDEO, "Failed to create libdecor frame!");
+            } else {
+                libdecor_frame_set_app_id(data->shell_surface.libdecor.frame, c->classname);
+                libdecor_frame_map(data->shell_surface.libdecor.frame);
+            }
         }
     } else
 #endif
@@ -1425,8 +1430,7 @@ void Wayland_HideWindow(_THIS, SDL_Window *window)
 #ifdef HAVE_LIBDECOR_H
     if (WINDOW_IS_LIBDECOR(data, window)) {
         if (wind->shell_surface.libdecor.frame) {
-            libdecor_frame_unref(wind->shell_surface.libdecor.frame);
-            wind->shell_surface.libdecor.frame = NULL;
+            libdecor_frame_set_visibility(wind->shell_surface.libdecor.frame, false);
         }
     } else
 #endif