1 files changed, 29 insertions, 0 deletions
diff --git a/js/src/vm/SavedStacks-inl.h b/js/src/vm/SavedStacks-inl.h
new file mode 100644
index 0000000000..176d7e7272
--- /dev/null
+++ b/js/src/vm/SavedStacks-inl.h
@@ -0,0 +1,29 @@
+/* -*- 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/. */
+
+#ifndef vm_SavedStacksInl_h
+#define vm_SavedStacksInl_h
+
+#include "vm/SavedStacks.h"
+
+// Assert that if the given object is not null, it's Class is the
+// SavedFrame::class_ or the given object is a cross-compartment or Xray wrapper
+// around such an object.
+//
+// We allow wrappers here because the JSAPI functions for working with
+// SavedFrame objects and the SavedFrame accessors themselves handle wrappers
+// and use the original caller's compartment's principals to determine what
+// level of data to present. Unwrapping and entering the referent's compartment
+// would mess that up. See the module level documentation in
+// `js/src/vm/SavedStacks.h` as well as the comments in `js/src/jsapi.h`.
+inline void js::AssertObjectIsSavedFrameOrWrapper(JSContext* cx,
+                                                  HandleObject stack) {
+  if (stack) {
+    MOZ_RELEASE_ASSERT(stack->canUnwrapAs<SavedFrame>());
+  }
+}
+
+#endif  // vm_SavedStacksInl_h