Object: Add tests about the safety of tail destruction

(cherry picked from commit bb77520599)
This commit is contained in:
Pedro J. Estébanez 2024-09-12 10:52:47 +02:00 committed by Rémi Verschelde
parent 018f8be3d5
commit 3030d4b806
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3 changed files with 133 additions and 0 deletions

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@ -0,0 +1,50 @@
# https://github.com/godotengine/godot/issues/75658
class MyObj:
var callable: Callable
func run():
callable.call()
var prop:
set(value):
callable.call()
get:
callable.call()
return 0
func _on_some_signal():
callable.call()
func _init(p_callable: Callable):
self.callable = p_callable
signal some_signal
var obj: MyObj
func test():
# Call.
obj = MyObj.new(nullify_obj)
obj.run()
print(obj)
# Get.
obj = MyObj.new(nullify_obj)
var _aux = obj.prop
print(obj)
# Set.
obj = MyObj.new(nullify_obj)
obj.prop = 1
print(obj)
# Signal handling.
obj = MyObj.new(nullify_obj)
@warning_ignore("return_value_discarded")
some_signal.connect(obj._on_some_signal)
some_signal.emit()
print(obj)
func nullify_obj():
obj = null

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GDTEST_OK
<null>
<null>
<null>
<null>

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@ -37,6 +37,16 @@
#include "tests/test_macros.h"
#ifdef SANITIZERS_ENABLED
#ifdef __has_feature
#if __has_feature(address_sanitizer) || __has_feature(thread_sanitizer)
#define ASAN_OR_TSAN_ENABLED
#endif
#elif defined(__SANITIZE_ADDRESS__) || defined(__SANITIZE_THREAD__)
#define ASAN_OR_TSAN_ENABLED
#endif
#endif
// Declared in global namespace because of GDCLASS macro warning (Windows):
// "Unqualified friend declaration referring to type outside of the nearest enclosing namespace
// is a Microsoft extension; add a nested name specifier".
@ -499,6 +509,74 @@ TEST_CASE("[Object] Notification order") { // GH-52325
memdelete(test_notification_object);
}
TEST_CASE("[Object] Destruction at the end of the call chain is safe") {
Object *object = memnew(Object);
ObjectID obj_id = object->get_instance_id();
class _SelfDestroyingScriptInstance : public _MockScriptInstance {
Object *self = nullptr;
// This has to be static because ~Object() also destroys the script instance.
static void free_self(Object *p_self) {
#if defined(ASAN_OR_TSAN_ENABLED)
// Regular deletion is enough becausa asan/tsan will catch a potential heap-after-use.
memdelete(p_self);
#else
// Without asan/tsan, try at least to force a crash by replacing the otherwise seemingly good data with garbage.
// Operations such as dereferencing pointers or decreasing a refcount would fail.
// Unfortunately, we may not poison the memory after the deletion, because the memory would no longer belong to us
// and on doing so we may cause a more generalized crash on some platforms (allocator implementations).
p_self->~Object();
memset((void *)p_self, 0, sizeof(Object));
Memory::free_static(p_self, false);
#endif
}
public:
Variant callp(const StringName &p_method, const Variant **p_args, int p_argcount, Callable::CallError &r_error) override {
free_self(self);
return Variant();
}
Variant call_const(const StringName &p_method, const Variant **p_args, int p_argcount, Callable::CallError &r_error) override {
free_self(self);
return Variant();
}
bool has_method(const StringName &p_method) const override {
return p_method == "some_method";
}
public:
_SelfDestroyingScriptInstance(Object *p_self) :
self(p_self) {}
};
_SelfDestroyingScriptInstance *script_instance = memnew(_SelfDestroyingScriptInstance(object));
object->set_script_instance(script_instance);
SUBCASE("Within callp()") {
SUBCASE("Through call()") {
object->call("some_method");
}
SUBCASE("Through callv()") {
object->callv("some_method", Array());
}
}
SUBCASE("Within call_const()") {
Callable::CallError call_error;
object->call_const("some_method", nullptr, 0, call_error);
}
SUBCASE("Within signal handling (from emit_signalp(), through emit_signal())") {
Object emitter;
emitter.add_user_signal(MethodInfo("some_signal"));
emitter.connect("some_signal", Callable(object, "some_method"));
emitter.emit_signal("some_signal");
}
CHECK_MESSAGE(
ObjectDB::get_instance(obj_id) == nullptr,
"Object was tail-deleted without crashes.");
}
} // namespace TestObject
#endif // TEST_OBJECT_H