import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

dom/workers/Principal.cpp

@@ -0,0 +1,51 @@
+/* -*- 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 "Principal.h"
+
+#include "jsapi.h"
+#include "mozilla/Assertions.h"
+
+BEGIN_WORKERS_NAMESPACE
+
+struct WorkerPrincipal final : public JSPrincipals
+{
+  bool write(JSContext* aCx, JSStructuredCloneWriter* aWriter) override {
+    MOZ_CRASH("WorkerPrincipal::write not implemented");
+    return false;
+  }
+};
+
+JSPrincipals*
+GetWorkerPrincipal()
+{
+  static WorkerPrincipal sPrincipal;
+
+  /*
+   * To make sure the the principals refcount is initialized to one, atomically
+   * increment it on every pass though this function. If we discover this wasn't
+   * the first time, decrement it again. This avoids the need for
+   * synchronization.
+   */
+  int32_t prevRefcount = sPrincipal.refcount++;
+  if (prevRefcount > 0) {
+    --sPrincipal.refcount;
+  } else {
+#ifdef DEBUG
+    sPrincipal.debugToken = kJSPrincipalsDebugToken;
+#endif
+  }
+
+  return &sPrincipal;
+}
+
+void
+DestroyWorkerPrincipals(JSPrincipals* aPrincipals)
+{
+  MOZ_ASSERT_UNREACHABLE("Worker principals refcount should never fall below one");
+}
+
+END_WORKERS_NAMESPACE