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authorwolfbeast <mcwerewolf@wolfbeast.com>2019-02-07 10:39:40 +0100
committerwolfbeast <mcwerewolf@wolfbeast.com>2019-02-07 10:39:40 +0100
commit88db0108b14d58cf5d82ed7346f48f010feaaf0d (patch)
tree1d78ae8cd21d7d17293f66c166ca44718501d4aa /js/xpconnect/wrappers/WaiveXrayWrapper.cpp
parent8db772d2ca44ff44f32d434e7f62acba289b4155 (diff)
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Align `instanceof` with the final ES6 spec.
Diffstat (limited to 'js/xpconnect/wrappers/WaiveXrayWrapper.cpp')
-rw-r--r--js/xpconnect/wrappers/WaiveXrayWrapper.cpp31
1 files changed, 31 insertions, 0 deletions
diff --git a/js/xpconnect/wrappers/WaiveXrayWrapper.cpp b/js/xpconnect/wrappers/WaiveXrayWrapper.cpp
index 27c010d34..dca3daa58 100644
--- a/js/xpconnect/wrappers/WaiveXrayWrapper.cpp
+++ b/js/xpconnect/wrappers/WaiveXrayWrapper.cpp
@@ -88,6 +88,37 @@ WaiveXrayWrapper::nativeCall(JSContext* cx, JS::IsAcceptableThis test,
}
bool
+WaiveXrayWrapper::hasInstance(JSContext* cx, HandleObject wrapper,
+ MutableHandleValue v, bool* bp) const {
+ if (v.isObject() && WrapperFactory::IsXrayWrapper(&v.toObject())) {
+ // If |v| is an XrayWrapper and in the same compartment as the value
+ // wrapped by |wrapper|, then the Xrays of |v| would be waived upon
+ // calling CrossCompartmentWrapper::hasInstance. This may trigger
+ // getters and proxy traps of unwrapped |v|. To prevent that from
+ // happening, we exit early.
+
+ // |wrapper| is the right operand of "instanceof", and must either be
+ // a function or an object with a @@hasInstance method. We are not going
+ // to call @@hasInstance, so only check whether it is a function.
+ // This check is here for consistency with usual "instanceof" behavior,
+ // which throws if the right operand is not a function. Without this
+ // check, the "instanceof" operator would return false and potentially
+ // hide errors in the code that uses the "instanceof" operator.
+ if (!JS::IsCallable(wrapper)) {
+ RootedValue wrapperv(cx, JS::ObjectValue(*wrapper));
+ js::ReportIsNotFunction(cx, wrapperv);
+ return false;
+ }
+
+ *bp = false;
+ return true;
+ }
+
+ // Both |wrapper| and |v| have no Xrays here.
+ return CrossCompartmentWrapper::hasInstance(cx, wrapper, v, bp);
+}
+
+bool
WaiveXrayWrapper::getPrototype(JSContext* cx, HandleObject wrapper, MutableHandleObject protop) const
{
return CrossCompartmentWrapper::getPrototype(cx, wrapper, protop) &&