gecko-dev/dom/workers/ChromeWorker.cpp

/* -*- 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/. */

#include "ChromeWorker.h"

#include "mozilla/dom/BindingUtils.h"
#include "mozilla/dom/WorkerBinding.h"
#include "nsContentUtils.h"
#include "WorkerPrivate.h"

namespace mozilla::dom {

/* static */
already_AddRefed<ChromeWorker> ChromeWorker::Constructor(
    const GlobalObject& aGlobal, const nsAString& aScriptURL,
    ErrorResult& aRv) {
  JSContext* cx = aGlobal.Context();

  RefPtr<WorkerPrivate> workerPrivate = WorkerPrivate::Constructor(
      cx, aScriptURL, true /* aIsChromeWorker */, WorkerKindDedicated, u""_ns,
      VoidCString(), nullptr /*aLoadInfo */, aRv);
  if (NS_WARN_IF(aRv.Failed())) {
    return nullptr;
  }

  nsCOMPtr<nsIGlobalObject> globalObject =
      do_QueryInterface(aGlobal.GetAsSupports());

  RefPtr<ChromeWorker> worker =
      new ChromeWorker(globalObject, workerPrivate.forget());
  return worker.forget();
}

/* static */
bool ChromeWorker::WorkerAvailable(JSContext* aCx, JSObject* /* unused */) {
  // Chrome is always allowed to use workers, and content is never
  // allowed to use ChromeWorker, so all we have to check is the
  // caller.  However, chrome workers apparently might not have a
  // system principal, so we have to check for them manually.
  if (NS_IsMainThread()) {
    return nsContentUtils::IsSystemCaller(aCx);
  }

  return GetWorkerPrivateFromContext(aCx)->IsChromeWorker();
}

ChromeWorker::ChromeWorker(nsIGlobalObject* aGlobalObject,
                           already_AddRefed<WorkerPrivate> aWorkerPrivate)
    : Worker(aGlobalObject, std::move(aWorkerPrivate)) {}

ChromeWorker::~ChromeWorker() = default;

JSObject* ChromeWorker::WrapObject(JSContext* aCx,
                                   JS::Handle<JSObject*> aGivenProto) {
  JS::Rooted<JSObject*> wrapper(
      aCx, ChromeWorker_Binding::Wrap(aCx, this, aGivenProto));
  if (wrapper) {
    // Most DOM objects don't assume they have a reflector. If they don't have
    // one and need one, they create it. But in workers code, we assume that the
    // reflector is always present.  In order to guarantee that it's always
    // present, we have to preserve it. Otherwise the GC will happily collect it
    // as needed.
    MOZ_ALWAYS_TRUE(TryPreserveWrapper(wrapper));
  }

  return wrapper;
}

}  // namespace mozilla::dom