godot/core/reference.cpp
Hein-Pieter van Braam cacced7e50 Convert Object::cast_to() to the static version
Currently we rely on some undefined behavior when Object->cast_to() gets
called with a Null pointer. This used to work fine with GCC < 6 but
newer versions of GCC remove all codepaths in which the this pointer is
Null. However, the non-static cast_to() was supposed to be null safe.

This patch makes cast_to() Null safe and removes the now redundant Null
checks where they existed.

It is explained in this article: https://www.viva64.com/en/b/0226/
2017-08-24 23:08:24 +02:00

168 lines
4.8 KiB
C++

/*************************************************************************/
/* reference.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* http://www.godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md) */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#include "reference.h"
#include "script_language.h"
bool Reference::init_ref() {
if (refcount.ref()) {
// 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)
// so don't do it.
if (refcount_init.get() > 0) {
refcount_init.unref();
refcount.unref(); // first referencing is already 1, so compensate for the ref above
}
return true;
} else {
return false;
}
}
void Reference::_bind_methods() {
ClassDB::bind_method(D_METHOD("init_ref"), &Reference::init_ref);
ClassDB::bind_method(D_METHOD("reference"), &Reference::reference);
ClassDB::bind_method(D_METHOD("unreference"), &Reference::unreference);
}
int Reference::reference_get_count() const {
return refcount.get();
}
void Reference::reference() {
refcount.ref();
if (get_script_instance()) {
get_script_instance()->refcount_incremented();
}
}
bool Reference::unreference() {
bool die = refcount.unref();
if (get_script_instance()) {
bool script_ret = get_script_instance()->refcount_decremented();
die = die && script_ret;
}
return die;
}
Reference::Reference() {
refcount.init();
refcount_init.init();
}
Reference::~Reference() {
}
Variant WeakRef::get_ref() const {
if (ref == 0)
return Variant();
Object *obj = ObjectDB::get_instance(ref);
if (!obj)
return Variant();
Reference *r = cast_to<Reference>(obj);
if (r) {
return REF(r);
}
return obj;
}
void WeakRef::set_obj(Object *p_object) {
ref = p_object ? p_object->get_instance_id() : 0;
}
void WeakRef::set_ref(const REF &p_ref) {
ref = p_ref.is_valid() ? p_ref->get_instance_id() : 0;
}
WeakRef::WeakRef() {
ref = 0;
}
void WeakRef::_bind_methods() {
ClassDB::bind_method(D_METHOD("get_ref"), &WeakRef::get_ref);
}
#if 0
Reference * RefBase::get_reference_from_ref(const RefBase &p_base) {
return p_base.get_reference();
}
void RefBase::ref_inc(Reference *p_reference) {
p_reference->refcount.ref();
}
bool RefBase::ref_dec(Reference *p_reference) {
bool ref = p_reference->refcount.unref();
return ref;
}
Reference *RefBase::first_ref(Reference *p_reference) {
if (p_reference->refcount.ref()) {
// 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)
// so don't do it.
if (p_reference->refcount_init.get()>0) {
p_reference->refcount_init.unref();
p_reference->refcount.unref(); // first referencing is already 1, so compensate for the ref above
}
return p_reference;
} else {
return 0;
}
}
char * RefBase::get_refptr_data(const RefPtr &p_refptr) const {
return p_refptr.data;
}
#endif