Source code

Revision control

Copy as Markdown

Other Tools

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at */
* A simplere nsIGlobalObject implementation that can be used to set up a new
* global without anything interesting in it other than the JS builtins. This
* is safe to use on both mainthread and worker threads.
#ifndef mozilla_dom_SimpleGlobalObject_h__
#define mozilla_dom_SimpleGlobalObject_h__
#include "nsThreadUtils.h"
#include "nsContentUtils.h"
#include "nsCycleCollectionParticipant.h"
#include "nsIGlobalObject.h"
#include "nsISupportsImpl.h"
#include "nsWrapperCache.h"
#include "js/TypeDecls.h"
#include "js/Value.h"
namespace mozilla::dom {
class SimpleGlobalObject final : public nsIGlobalObject, public nsWrapperCache {
enum class GlobalType {
BindingDetail, // Should only be used by DOM bindings code.
NotSimpleGlobal // Sentinel to be used by BasicGlobalType.
// Create a new JS global object that can be used to do some work. This
// global will NOT have any DOM APIs exposed in it, will not be visible to the
// debugger, and will not have a useful concept of principals, so don't try to
// use it with any DOM objects. Apart from that, running code with
// side-effects is safe in this global. Importantly, when you are first
// handed this global it's guaranteed to have pristine built-ins. The
// corresponding nsIGlobalObject* for this global object will be a
// SimpleGlobalObject of the type provided; JS::GetPrivate on the returned
// JSObject* will return the SimpleGlobalObject*.
// If the provided prototype value is undefined, it is ignored. If it's an
// object or null, it's set as the prototype of the created global. If it's
// anything else, this function returns null.
// Note that creating new globals is not cheap and should not be done
// gratuitously. Please think carefully before you use this function.
static JSObject* Create(GlobalType globalType, JS::Handle<JS::Value> proto =
// Gets the GlobalType of this SimpleGlobalObject.
GlobalType Type() const { return mType; }
// Gets the GlobalType of the SimpleGlobalObject for the given JSObject*, if
// the given JSObject* is the global corresponding to a SimpleGlobalObject.
// Oherwise, returns GlobalType::NotSimpleGlobal.
static GlobalType SimpleGlobalType(JSObject* obj);
JSObject* GetGlobalJSObject() override { return GetWrapper(); }
JSObject* GetGlobalJSObjectPreserveColor() const override {
return GetWrapperPreserveColor();
OriginTrials Trials() const override { return {}; }
nsISerialEventTarget* SerialEventTarget() const final {
return NS_GetCurrentThread();
nsresult Dispatch(already_AddRefed<nsIRunnable>&& aRunnable) const final {
return NS_DispatchToCurrentThread(std::move(aRunnable));
JSObject* WrapObject(JSContext* cx,
JS::Handle<JSObject*> aGivenProto) override {
MOZ_CRASH("SimpleGlobalObject doesn't use DOM bindings!");
bool ShouldResistFingerprinting(RFPTarget aTarget) const override {
return nsContentUtils::ShouldResistFingerprinting(
"Presently we don't have enough context to make an informed decision"
"on JS Sandboxes. See 1782853",
SimpleGlobalObject(JSObject* global, GlobalType type) : mType(type) {
virtual ~SimpleGlobalObject() { MOZ_ASSERT(!GetWrapperMaybeDead()); }
const GlobalType mType;
} // namespace mozilla::dom
#endif /* mozilla_dom_SimpleGlobalObject_h__ */