From f08bc0df7c16a6d12292628ec8cc2e015047c450 Mon Sep 17 00:00:00 2001
From: Ruslan Mustakov <r.mustakov@gmail.com>
Date: Sat, 19 Aug 2017 19:41:11 +0700
Subject: [PATCH] Construct Variants from Reference properly in GDNative

Previously godot_variant_new_object constructed Variant without
accounting for the fact that the Object can be a Reference, so refcount
was not increased and References were destructed prematurely.

Also, Reference::init_ref did not propagate refcount increment to the
script instance, which led to desync of refcount info on the script
side and Godot side.
---
 core/reference.cpp                    | 13 ++++++++-----
 core/reference.h                      |  2 +-
 core/variant.cpp                      |  4 ++--
 modules/gdnative/gdnative/variant.cpp | 17 ++++++++++++++++-
 4 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/core/reference.cpp b/core/reference.cpp
index bb70628cbe1..7f93922d221 100644
--- a/core/reference.cpp
+++ b/core/reference.cpp
@@ -33,7 +33,7 @@
 
 bool Reference::init_ref() {
 
-	if (refcount.ref()) {
+	if (reference()) {
 
 		// this may fail in the scenario of two threads assigning the pointer for the FIRST TIME
 		// at the same time, which is never likely to happen (would be crazy to do)
@@ -41,7 +41,7 @@ bool Reference::init_ref() {
 
 		if (refcount_init.get() > 0) {
 			refcount_init.unref();
-			refcount.unref(); // first referencing is already 1, so compensate for the ref above
+			unreference(); // first referencing is already 1, so compensate for the ref above
 		}
 
 		return true;
@@ -62,13 +62,16 @@ int Reference::reference_get_count() const {
 	return refcount.get();
 }
 
-void Reference::reference() {
+bool Reference::reference() {
+	bool success = refcount.ref();
 
-	refcount.ref();
-	if (get_script_instance()) {
+	if (success && get_script_instance()) {
 		get_script_instance()->refcount_incremented();
 	}
+
+	return success;
 }
+
 bool Reference::unreference() {
 
 	bool die = refcount.unref();
diff --git a/core/reference.h b/core/reference.h
index ca3ae604188..bafc1642767 100644
--- a/core/reference.h
+++ b/core/reference.h
@@ -51,7 +51,7 @@ protected:
 public:
 	_FORCE_INLINE_ bool is_referenced() const { return refcount_init.get() < 1; }
 	bool init_ref();
-	void reference();
+	bool reference(); // returns false if refcount is at zero and didn't get increased
 	bool unreference();
 	int reference_get_count() const;
 
diff --git a/core/variant.cpp b/core/variant.cpp
index 74f6b6a711e..10d86152eef 100644
--- a/core/variant.cpp
+++ b/core/variant.cpp
@@ -2259,8 +2259,8 @@ Variant::Variant(const RefPtr &p_resource) {
 
 	type = OBJECT;
 	memnew_placement(_data._mem, ObjData);
-	REF ref = p_resource;
-	_get_obj().obj = ref.ptr();
+	REF *ref = reinterpret_cast<REF *>(p_resource.get_data());
+	_get_obj().obj = ref->ptr();
 	_get_obj().ref = p_resource;
 }
 
diff --git a/modules/gdnative/gdnative/variant.cpp b/modules/gdnative/gdnative/variant.cpp
index b61f80b1f90..1b2aae607fd 100644
--- a/modules/gdnative/gdnative/variant.cpp
+++ b/modules/gdnative/gdnative/variant.cpp
@@ -29,6 +29,7 @@
 /*************************************************************************/
 #include "gdnative/variant.h"
 
+#include "core/reference.h"
 #include "core/variant.h"
 
 #ifdef __cplusplus
@@ -158,7 +159,21 @@ void GDAPI godot_variant_new_rid(godot_variant *r_dest, const godot_rid *p_rid)
 void GDAPI godot_variant_new_object(godot_variant *r_dest, const godot_object *p_obj) {
 	Variant *dest = (Variant *)r_dest;
 	Object *obj = (Object *)p_obj;
-	memnew_placement_custom(dest, Variant, Variant(obj));
+	Reference *reference = Object::cast_to<Reference>(obj);
+	REF ref;
+	if (reference) {
+		ref = REF(reference);
+	}
+	if (!ref.is_null()) {
+		memnew_placement_custom(dest, Variant, Variant(ref.get_ref_ptr()));
+	} else {
+#if defined(DEBUG_METHODS_ENABLED)
+		if (reference) {
+			ERR_PRINT("Reference object has 0 refcount in godot_variant_new_object - you lost it somewhere.");
+		}
+#endif
+		memnew_placement_custom(dest, Variant, Variant(obj));
+	}
 }
 
 void GDAPI godot_variant_new_dictionary(godot_variant *r_dest, const godot_dictionary *p_dict) {