SimpleGlobalObject.h (4009B)
1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ 2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */ 3 /* This Source Code Form is subject to the terms of the Mozilla Public 4 * License, v. 2.0. If a copy of the MPL was not distributed with this file, 5 * You can obtain one at http://mozilla.org/MPL/2.0/. */ 6 7 /** 8 * A simplere nsIGlobalObject implementation that can be used to set up a new 9 * global without anything interesting in it other than the JS builtins. This 10 * is safe to use on both mainthread and worker threads. 11 */ 12 13 #ifndef mozilla_dom_SimpleGlobalObject_h__ 14 #define mozilla_dom_SimpleGlobalObject_h__ 15 16 #include "js/TypeDecls.h" 17 #include "js/Value.h" 18 #include "nsContentUtils.h" 19 #include "nsCycleCollectionParticipant.h" 20 #include "nsIGlobalObject.h" 21 #include "nsISupportsImpl.h" 22 #include "nsThreadUtils.h" 23 #include "nsWrapperCache.h" 24 25 namespace mozilla::dom { 26 27 class SimpleGlobalObject final : public nsIGlobalObject, public nsWrapperCache { 28 public: 29 enum class GlobalType { 30 BindingDetail, // Should only be used by DOM bindings code. 31 WorkerDebuggerSandbox, 32 NotSimpleGlobal // Sentinel to be used by BasicGlobalType. 33 }; 34 35 // Create a new JS global object that can be used to do some work. This 36 // global will NOT have any DOM APIs exposed in it, will not be visible to the 37 // debugger, and will not have a useful concept of principals, so don't try to 38 // use it with any DOM objects. Apart from that, running code with 39 // side-effects is safe in this global. Importantly, when you are first 40 // handed this global it's guaranteed to have pristine built-ins. The 41 // corresponding nsIGlobalObject* for this global object will be a 42 // SimpleGlobalObject of the type provided; JS::GetPrivate on the returned 43 // JSObject* will return the SimpleGlobalObject*. 44 // 45 // If the provided prototype value is undefined, it is ignored. If it's an 46 // object or null, it's set as the prototype of the created global. If it's 47 // anything else, this function returns null. 48 // 49 // Note that creating new globals is not cheap and should not be done 50 // gratuitously. Please think carefully before you use this function. 51 static JSObject* Create(GlobalType globalType, JS::Handle<JS::Value> proto = 52 JS::UndefinedHandleValue); 53 54 NS_DECL_CYCLE_COLLECTING_ISUPPORTS 55 NS_DECL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(SimpleGlobalObject) 56 57 // Gets the GlobalType of this SimpleGlobalObject. 58 GlobalType Type() const { return mType; } 59 60 // Gets the GlobalType of the SimpleGlobalObject for the given JSObject*, if 61 // the given JSObject* is the global corresponding to a SimpleGlobalObject. 62 // Oherwise, returns GlobalType::NotSimpleGlobal. 63 static GlobalType SimpleGlobalType(JSObject* obj); 64 65 JSObject* GetGlobalJSObject() override { return GetWrapper(); } 66 JSObject* GetGlobalJSObjectPreserveColor() const override { 67 return GetWrapperPreserveColor(); 68 } 69 70 OriginTrials Trials() const override { return {}; } 71 72 nsISerialEventTarget* SerialEventTarget() const final { 73 return NS_GetCurrentThread(); 74 } 75 nsresult Dispatch(already_AddRefed<nsIRunnable>&& aRunnable) const final { 76 return NS_DispatchToCurrentThread(std::move(aRunnable)); 77 } 78 79 JSObject* WrapObject(JSContext* cx, 80 JS::Handle<JSObject*> aGivenProto) override { 81 MOZ_CRASH("SimpleGlobalObject doesn't use DOM bindings!"); 82 } 83 84 bool ShouldResistFingerprinting(RFPTarget aTarget) const override { 85 return nsContentUtils::ShouldResistFingerprinting( 86 "Presently we don't have enough context to make an informed decision" 87 "on JS Sandboxes. See 1782853", 88 aTarget); 89 } 90 91 private: 92 SimpleGlobalObject(JSObject* global, GlobalType type) : mType(type) { 93 SetWrapper(global); 94 } 95 96 virtual ~SimpleGlobalObject() { MOZ_ASSERT(!GetWrapperMaybeDead()); } 97 98 const GlobalType mType; 99 }; 100 101 } // namespace mozilla::dom 102 103 #endif /* mozilla_dom_SimpleGlobalObject_h__ */