dom/workers/Principal.cpp

   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
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "Principal.h"
   8
   9 #include "jsapi.h"
  10 #include "mozilla/Assertions.h"
  11 #include "mozilla/dom/StructuredCloneTags.h"
  12
  13 namespace mozilla {
  14 namespace dom {
  15
  16 struct WorkerPrincipal final : public JSPrincipals {
  17   bool write(JSContext* aCx, JSStructuredCloneWriter* aWriter) override {
  18     return JS_WriteUint32Pair(aWriter, SCTAG_DOM_WORKER_PRINCIPAL, 0);
  19   }
  20 };
  21
  22 JSPrincipals* GetWorkerPrincipal() {
  23   static WorkerPrincipal sPrincipal;
  24
  25   /*
  26    * To make sure the the principals refcount is initialized to one, atomically
  27    * increment it on every pass though this function. If we discover this wasn't
  28    * the first time, decrement it again. This avoids the need for
  29    * synchronization.
  30    */
  31   int32_t prevRefcount = sPrincipal.refcount++;
  32   if (prevRefcount > 0) {
  33     --sPrincipal.refcount;
  34   } else {
  35 #ifdef DEBUG
  36     sPrincipal.debugToken = workerinternals::kJSPrincipalsDebugToken;
  37 #endif
  38   }
  39
  40   return &sPrincipal;
  41 }
  42
  43 void DestroyWorkerPrincipals(JSPrincipals* aPrincipals) {
  44   MOZ_ASSERT_UNREACHABLE(
  45       "Worker principals refcount should never fall below one");
  46 }
  47
  48 }  // namespace dom
  49 }  // namespace mozilla