From 5f43f1c2cd8a66f367883b43e98c0f54a1acf35e Mon Sep 17 00:00:00 2001
From: toaster <rollerorbital@gmail.com>
Date: Sun, 5 Nov 2023 18:49:41 +0000
Subject: [PATCH] ACS: Invalidate mapscope before PU_LEVEL purge occours

Fixes the MapWarp memory corruption conclusively.
---
 src/acs/interface.cpp | 34 +++++++++++++++++++++++++++++++---
 src/acs/interface.h   | 17 +++++++++++++++++
 src/p_setup.c         |  2 ++
 3 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/src/acs/interface.cpp b/src/acs/interface.cpp
index 941a3e66a..cc84dd41c 100644
--- a/src/acs/interface.cpp
+++ b/src/acs/interface.cpp
@@ -78,6 +78,28 @@ void ACS_Shutdown(void)
 #endif
 }
 
+/*--------------------------------------------------
+	void ACS_InvalidateMapScope(size_t mapID)
+
+		See header file for description.
+--------------------------------------------------*/
+void ACS_InvalidateMapScope(void)
+{
+	Environment *env = &ACSEnv;
+
+	ACSVM::GlobalScope *const global = env->getGlobalScope(0);
+	ACSVM::HubScope *hub = NULL;
+	ACSVM::MapScope *map = NULL;
+
+	// Conclude hub scope, even if we are not using it.
+	hub = global->getHubScope(0);
+	hub->reset();
+
+	// Conclude current map scope.
+	map = hub->getMapScope(0); // This is where you'd put in mapID if you add hub support.
+	map->reset();
+}
+
 /*--------------------------------------------------
 	void ACS_LoadLevelScripts(size_t mapID)
 
@@ -111,14 +133,20 @@ void ACS_LoadLevelScripts(size_t mapID)
 	// hubs are to be implemented, this logic would need
 	// to be far more sophisticated.
 
-	// Reset hub scope, even if we are not using it.
+	// Extra note regarding the commented out ->reset()'s:
+	// This is too late! That needs to be done before
+	// PU_LEVEL is purged. Call ACS_InvalidateMapScope
+	// to take care of that. Those lines are left in
+	// only as a warning to future code spelunkers.
+
+	// Restart hub scope, even if we are not using it.
 	hub = global->getHubScope(0);
-	hub->reset();
+	//hub->reset();
 	hub->active = true;
 
 	// Start up new map scope.
 	map = hub->getMapScope(0); // This is where you'd put in mapID if you add hub support.
-	map->reset();
+	//map->reset();
 	map->active = true;
 
 	// Insert BEHAVIOR lump into the list.
diff --git a/src/acs/interface.h b/src/acs/interface.h
index 2758d4b25..beb7e30ae 100644
--- a/src/acs/interface.h
+++ b/src/acs/interface.h
@@ -40,6 +40,23 @@ void ACS_Init(void);
 void ACS_Shutdown(void);
 
 
+/*--------------------------------------------------
+	void ACS_InvalidateMapScope(size_t mapID);
+
+		Resets the ACS hub and map scopes to remove
+		existing running scripts, without starting
+		any new scripts.
+
+	Input Arguments:-
+		None
+
+	Return:-
+		None
+--------------------------------------------------*/
+
+void ACS_InvalidateMapScope(void);
+
+
 /*--------------------------------------------------
 	void ACS_LoadLevelScripts(size_t mapID);
 
diff --git a/src/p_setup.c b/src/p_setup.c
index 6430b5c0f..405879261 100644
--- a/src/p_setup.c
+++ b/src/p_setup.c
@@ -8281,6 +8281,8 @@ boolean P_LoadLevel(boolean fromnetsave, boolean reloadinggamestate)
 	// Close text prompt before freeing the old level
 	F_EndTextPrompt(false, true);
 
+	ACS_InvalidateMapScope();
+
 	LUA_InvalidateLevel();
 
 	for (ss = sectors; sectors+numsectors != ss; ss++)