Stop metatables from being overwritten/read from (#184)

WeaselGames · Nov 6, 2023 · a7c659a · a7c659a
1 parent 6c31c63
commit a7c659a
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Showing 5 changed files with 38 additions and 41 deletions.
diff --git a/doc_classes/LuaObjectMetatable.xml b/doc_classes/LuaObjectMetatable.xml
@@ -140,14 +140,6 @@
                 The less than (<) operation. Behavior similar to the addition operation, except that Lua will try a metamethod only when the values being compared are neither both numbers nor both strings. Moreover, the result of the call is always converted to a boolean. 
 			</description>
 		</method>
-		<method name="__metatable" qualifiers="virtual">
-			<return type="Variant" />
-			<param index="0" name="obj" type="Object" />
-			<param index="1" name="lua" type="LuaAPI" />
-			<description>
-                If object does not have a metatable, returns nil. Otherwise, if the object's metatable has a __metatable field, returns the associated value. Otherwise, returns the metatable of the given object. 
-			</description>
-		</method>
 		<method name="__mod" qualifiers="virtual">
 			<return type="Variant" />
 			<param index="0" name="obj" type="Object" />

diff --git a/src/classes/luaObjectMetatable.cpp b/src/classes/luaObjectMetatable.cpp
@@ -13,7 +13,6 @@ void LuaObjectMetatable::_bind_methods() {
 	GDVIRTUAL_BIND(__call, "obj", "lua", "args");
 	GDVIRTUAL_BIND(__gc, "obj", "lua");
 	GDVIRTUAL_BIND(__tostring, "obj", "lua");
-	GDVIRTUAL_BIND(__metatable, "obj", "lua");
 	GDVIRTUAL_BIND(__len, "obj", "lua");
 	GDVIRTUAL_BIND(__unm, "obj", "lua");
 	GDVIRTUAL_BIND(__add, "obj", "lua", "other");
@@ -65,12 +64,6 @@ String LuaObjectMetatable::__tostring(Object *obj, Ref<LuaAPI> api) {
 	return ret;
 }
 
-Variant LuaObjectMetatable::__metatable(Object *obj, Ref<LuaAPI> api) {
-	Variant ret;
-	VIRTUAL_CALL(__metatable, ret, obj, api);
-	return ret;
-}
-
 int LuaObjectMetatable::__len(Object *obj, Ref<LuaAPI> api) {
 	int ret = 0;
 	VIRTUAL_CALL(__len, ret, obj, api);
@@ -274,14 +267,6 @@ String LuaDefaultObjectMetatable::__tostring(Object *obj, Ref<LuaAPI> api) {
 	return String();
 }
 
-Variant LuaDefaultObjectMetatable::__metatable(Object *obj, Ref<LuaAPI> api) {
-	if (obj->has_method("__metatable")) {
-		return obj->call("__metatable", api);
-	}
-
-	return Variant();
-}
-
 Variant LuaDefaultObjectMetatable::__unm(Object *obj, Ref<LuaAPI> api) {
 	if (obj->has_method("__unm")) {
 		return obj->call("__unm", api);

diff --git a/src/classes/luaObjectMetatable.h b/src/classes/luaObjectMetatable.h
@@ -28,7 +28,6 @@ class LuaObjectMetatable : public RefCounted {
 	GDVIRTUAL3R(Variant, __call, Object *, Ref<LuaAPI>, Ref<LuaTuple>);
 	GDVIRTUAL2R(Ref<LuaError>, __gc, Object *, Ref<LuaAPI>);
 	GDVIRTUAL2R(String, __tostring, Object *, Ref<LuaAPI>);
-	GDVIRTUAL2R(Variant, __metatable, Object *, Ref<LuaAPI>);
 	GDVIRTUAL2R(int, __len, Object *, Ref<LuaAPI>);
 	GDVIRTUAL2R(Variant, __unm, Object *, Ref<LuaAPI>);
 	GDVIRTUAL3R(Variant, __add, Object *, Ref<LuaAPI>, Variant);
@@ -56,7 +55,6 @@ class LuaObjectMetatable : public RefCounted {
 	virtual Variant __call(Object *obj, Ref<LuaAPI> api, Ref<LuaTuple> args);
 	virtual Ref<LuaError> __gc(Object *obj, Ref<LuaAPI> api);
 	virtual String __tostring(Object *obj, Ref<LuaAPI> api);
-	virtual Variant __metatable(Object *obj, Ref<LuaAPI> api);
 	virtual int __len(Object *obj, Ref<LuaAPI> api);
 	virtual Variant __unm(Object *obj, Ref<LuaAPI> api);
 	virtual Variant __add(Object *obj, Ref<LuaAPI> api, Variant other);
@@ -94,7 +92,6 @@ class LuaDefaultObjectMetatable : public LuaObjectMetatable {
 	Variant __call(Object *obj, Ref<LuaAPI> api, Ref<LuaTuple> args) override;
 	Ref<LuaError> __gc(Object *obj, Ref<LuaAPI> api) override;
 	String __tostring(Object *obj, Ref<LuaAPI> api) override;
-	Variant __metatable(Object *obj, Ref<LuaAPI> api) override;
 	int __len(Object *obj, Ref<LuaAPI> api) override;
 	Variant __unm(Object *obj, Ref<LuaAPI> api) override;
 	Variant __add(Object *obj, Ref<LuaAPI> api, Variant other) override;

diff --git a/src/luaState.h b/src/luaState.h
@@ -13,6 +13,8 @@
 #include <classes/luaError.h>
 #include <lua/lua.hpp>
 
+#define METATABLE_DISCLAIMER "This metatable is protected."
+
 class LuaAPI;
 
 class LuaState {

diff --git a/src/metatables.cpp b/src/metatables.cpp
@@ -162,6 +162,10 @@ void LuaState::createVector2Metatable() {
 		return 1;
 	});
 
+	lua_pushliteral(L, "__metatable");
+	lua_pushliteral(L, METATABLE_DISCLAIMER);
+	lua_settable(L, -3);
+
 	lua_pop(L, 1); // Stack is now unmodified
 }
 
@@ -230,6 +234,10 @@ void LuaState::createVector3Metatable() {
 		return 1;
 	});
 
+	lua_pushliteral(L, "__metatable");
+	lua_pushliteral(L, METATABLE_DISCLAIMER);
+	lua_settable(L, -3);
+
 	lua_pop(L, 1); // Stack is now unmodified
 }
 
@@ -260,6 +268,10 @@ void LuaState::createRect2Metatable() {
 		return 1;
 	});
 
+	lua_pushliteral(L, "__metatable");
+	lua_pushliteral(L, METATABLE_DISCLAIMER);
+	lua_settable(L, -3);
+
 	lua_pop(L, 1); // Stack is now unmodified
 }
 
@@ -290,6 +302,10 @@ void LuaState::createPlaneMetatable() {
 		return 1;
 	});
 
+	lua_pushliteral(L, "__metatable");
+	lua_pushliteral(L, METATABLE_DISCLAIMER);
+	lua_settable(L, -3);
+
 	lua_pop(L, 1); // Stack is now unmodified
 }
 
@@ -358,6 +374,10 @@ void LuaState::createColorMetatable() {
 		return 1;
 	});
 
+	lua_pushliteral(L, "__metatable");
+	lua_pushliteral(L, METATABLE_DISCLAIMER);
+	lua_settable(L, -3);
+
 	lua_pop(L, 1); // Stack is now unmodified
 }
 
@@ -377,6 +397,10 @@ void LuaState::createSignalMetatable() {
 		return 1;
 	});
 
+	lua_pushliteral(L, "__metatable");
+	lua_pushliteral(L, METATABLE_DISCLAIMER);
+	lua_settable(L, -3);
+
 	lua_pop(L, 1); // Stack is now unmodified
 }
 
@@ -479,21 +503,6 @@ void LuaState::createObjectMetatable() {
 		return 0;
 	});
 
-	LUA_METAMETHOD_TEMPLATE(L, -1, "__metatable", {
-		Ref<LuaAPI> api = getAPI(inner_state);
-		Ref<LuaObjectMetatable> mt = arg1.get("lua_metatable");
-		if (!mt.is_valid()) {
-			mt = api->getObjectMetatable();
-		}
-
-		if (mt.is_valid()) {
-			LuaState::pushVariant(inner_state, mt->__metatable(arg1, api));
-			return 1;
-		}
-
-		return 0;
-	});
-
 	LUA_METAMETHOD_TEMPLATE(L, -1, "__len", {
 		Ref<LuaAPI> api = getAPI(inner_state);
 		Ref<LuaObjectMetatable> mt = arg1.get("lua_metatable");
@@ -783,6 +792,10 @@ void LuaState::createObjectMetatable() {
 		return 0;
 	});
 
+	lua_pushliteral(L, "__metatable");
+	lua_pushliteral(L, METATABLE_DISCLAIMER);
+	lua_settable(L, -3);
+
 	lua_pop(L, 1);
 }
 
@@ -794,6 +807,10 @@ void LuaState::createCallableMetatable() {
 	lua_pushcfunction(L, luaCallableCall);
 	lua_settable(L, -3);
 
+	lua_pushliteral(L, "__metatable");
+	lua_pushliteral(L, METATABLE_DISCLAIMER);
+	lua_settable(L, -3);
+
 	lua_pop(L, 1);
 }
 
@@ -814,5 +831,9 @@ void LuaState::createCallableExtraMetatable() {
 	lua_pushcfunction(L, LuaCallableExtra::call);
 	lua_settable(L, -3);
 
+	lua_pushliteral(L, "__metatable");
+	lua_pushliteral(L, METATABLE_DISCLAIMER);
+	lua_settable(L, -3);
+
 	lua_pop(L, 1);
 }