From ce69e9898915e8544ed0374cdb2e2787dd751780 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Tue, 11 Feb 2025 13:00:52 -0800
Subject: [PATCH] Copy SDL2_SYSWMEVENT data into temporary memory for the event

---
 src/events/SDL_events.c | 61 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/src/events/SDL_events.c b/src/events/SDL_events.c
index 7404234380..ebce863bb5 100644
--- a/src/events/SDL_events.c
+++ b/src/events/SDL_events.c
@@ -52,6 +52,52 @@
 // Make sure the type in the SDL_Event aligns properly across the union
 SDL_COMPILE_TIME_ASSERT(SDL_Event_type, sizeof(Uint32) == sizeof(SDL_EventType));
 
+#define SDL2_SYSWMEVENT 0x201
+
+#ifdef SDL_VIDEO_DRIVER_WINDOWS
+#include "../core/windows/SDL_windows.h"
+#endif
+
+#ifdef SDL_VIDEO_DRIVER_X11
+#include <X11/Xlib.h>
+#endif
+
+typedef struct SDL2_version
+{
+    Uint8 major;
+    Uint8 minor;
+    Uint8 patch;
+} SDL2_version;
+
+typedef enum
+{
+  SDL2_SYSWM_UNKNOWN
+} SDL2_SYSWM_TYPE;
+
+typedef struct SDL2_SysWMmsg
+{
+    SDL2_version version;
+    SDL2_SYSWM_TYPE subsystem;
+    union
+    {
+#ifdef SDL_VIDEO_DRIVER_WINDOWS
+        struct {
+            HWND hwnd;                  /**< The window for the message */
+            UINT msg;                   /**< The type of message */
+            WPARAM wParam;              /**< WORD message parameter */
+            LPARAM lParam;              /**< LONG message parameter */
+        } win;
+#endif
+#ifdef SDL_VIDEO_DRIVER_X11
+        struct {
+            XEvent event;
+        } x11;
+#endif
+        /* Can't have an empty union */
+        int dummy;
+    } msg;
+} SDL2_SysWMmsg;
+
 typedef struct SDL_EventWatcher
 {
     SDL_EventFilter callback;
@@ -214,6 +260,17 @@ static void SDL_LinkTemporaryMemoryToEvent(SDL_EventEntry *event, const void *me
     }
 }
 
+static void SDL_TransferSysWMMemoryToEvent(SDL_EventEntry *event)
+{
+    SDL2_SysWMmsg **wmmsg = (SDL2_SysWMmsg **)((&event->event.common)+1);
+    SDL2_SysWMmsg *mem = SDL_AllocateTemporaryMemory(sizeof(*mem));
+    if (mem) {
+        SDL_copyp(mem, *wmmsg);
+        *wmmsg = mem;
+        SDL_LinkTemporaryMemoryToEvent(event, mem);
+    }
+}
+
 // Transfer the event memory from the thread-local event memory list to the event
 static void SDL_TransferTemporaryMemoryToEvent(SDL_EventEntry *event)
 {
@@ -238,6 +295,10 @@ static void SDL_TransferTemporaryMemoryToEvent(SDL_EventEntry *event)
     case SDL_EVENT_CLIPBOARD_UPDATE:
         SDL_LinkTemporaryMemoryToEvent(event, event->event.clipboard.mime_types);
         break;
+    case SDL2_SYSWMEVENT:
+        // We need to copy the stack pointer into temporary memory
+        SDL_TransferSysWMMemoryToEvent(event);
+        break;
     default:
         break;
     }