1 files changed, 103 insertions, 0 deletions
diff --git a/dom/bindings/SimpleGlobalObject.h b/dom/bindings/SimpleGlobalObject.h
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+/* -*- 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 http://mozilla.org/MPL/2.0/. */
+
+/**
+ * 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 {
+ public:
+  enum class GlobalType {
+    BindingDetail,  // Should only be used by DOM bindings code.
+    WorkerDebuggerSandbox,
+    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 =
+                                                     JS::UndefinedHandleValue);
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_WRAPPERCACHE_CLASS(SimpleGlobalObject)
+
+  // 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",
+        aTarget);
+  }
+
+ private:
+  SimpleGlobalObject(JSObject* global, GlobalType type) : mType(type) {
+    SetWrapper(global);
+  }
+
+  virtual ~SimpleGlobalObject() { MOZ_ASSERT(!GetWrapperMaybeDead()); }
+
+  const GlobalType mType;
+};
+
+}  // namespace mozilla::dom
+
+#endif /* mozilla_dom_SimpleGlobalObject_h__ */