From 7c20ef784dc65f437f526845ab23cc8c7735599a Mon Sep 17 00:00:00 2001
From: Peter Van der Beken <peterv@propagandism.org>
Date: Mon, 9 Jan 2023 22:19:53 +0000
Subject: [PATCH] Bug 1806994 - Define @@toStringTag on Xrays for namespace
 objects. r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D165459
---
 dom/bindings/BindingUtils.cpp         | 16 ++++++++++++++--
 dom/bindings/Codegen.py               |  7 +++++--
 dom/bindings/DOMJSClass.h             |  5 +++--
 dom/bindings/test/test_dom_xrays.html |  9 +++++++++
 4 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/dom/bindings/BindingUtils.cpp b/dom/bindings/BindingUtils.cpp
index 25a7709def061..f76e7f30834bb 100644
--- a/dom/bindings/BindingUtils.cpp
+++ b/dom/bindings/BindingUtils.cpp
@@ -1632,7 +1632,7 @@ static bool XrayResolveProperty(
   switch (propertyInfo.type) {
     case eStaticMethod:
     case eStaticAttribute:
-      if (type != eInterface) {
+      if (type != eInterface && type != eNamespace) {
         return true;
       }
       break;
@@ -1814,6 +1814,18 @@ static bool ResolvePrototypeOrConstructor(
         return true;
       }
     }
+  } else if (type == eNamespace) {
+    if (id.isWellKnownSymbol(JS::SymbolCode::toStringTag)) {
+      JS::Rooted<JSString*> nameStr(
+          cx, JS_AtomizeString(cx, JS::GetClass(obj)->name));
+      if (!nameStr) {
+        return false;
+      }
+
+      desc.set(Some(JS::PropertyDescriptor::Data(
+          JS::StringValue(nameStr), {JS::PropertyAttribute::Configurable})));
+      return true;
+    }
   } else {
     MOZ_ASSERT(IsInterfacePrototype(type));
 
@@ -1954,7 +1966,7 @@ bool XrayOwnPropertyKeys(JSContext* cx, JS::Handle<JSObject*> wrapper,
     }
   } else {
     MOZ_ASSERT(type != eGlobalInterfacePrototype);
-    if (type == eInterface) {
+    if (type == eInterface || type == eNamespace) {
       ADD_KEYS_IF_DEFINED(StaticMethod);
       ADD_KEYS_IF_DEFINED(StaticAttribute);
     } else {
diff --git a/dom/bindings/Codegen.py b/dom/bindings/Codegen.py
index 71ddaae0c4128..4afddb5346c04 100644
--- a/dom/bindings/Codegen.py
+++ b/dom/bindings/Codegen.py
@@ -973,7 +973,7 @@ def define(self):
         if self.descriptor.interface.isNamespace():
             classString = self.descriptor.interface.getExtendedAttribute("ClassString")
             if classString is None:
-                classString = "Object"
+                classString = self.descriptor.interface.identifier.name
             else:
                 classString = classString[0]
             funToString = "nullptr"
@@ -999,7 +999,7 @@ def define(self):
                 JS_NULL_CLASS_EXT,
                 ${objectOps}
               },
-              eInterface,
+              ${type},
               ${needsHasInstance},
               ${prototypeID},
               ${depth},
@@ -1013,6 +1013,9 @@ def define(self):
             classOpsPtr=classOpsPtr,
             hooks=NativePropertyHooks(self.descriptor),
             objectOps=objectOps,
+            type="eNamespace"
+            if self.descriptor.interface.isNamespace()
+            else "eInterface",
             needsHasInstance=toStringBool(needsHasInstance),
             prototypeID=prototypeID,
             depth=depth,
diff --git a/dom/bindings/DOMJSClass.h b/dom/bindings/DOMJSClass.h
index 40b1796694a26..dd445792ef591 100644
--- a/dom/bindings/DOMJSClass.h
+++ b/dom/bindings/DOMJSClass.h
@@ -451,6 +451,7 @@ enum DOMObjectType : uint8_t {
   eInterface,
   eInterfacePrototype,
   eGlobalInterfacePrototype,
+  eNamespace,
   eNamedPropertiesObject
 };
 
@@ -549,8 +550,8 @@ struct DOMIfaceAndProtoJSClass {
   // initialization for aggregate/POD types.
   const JSClass mBase;
 
-  // Either eInterface, eInterfacePrototype, eGlobalInterfacePrototype or
-  // eNamedPropertiesObject.
+  // Either eInterface, eNamespace, eInterfacePrototype,
+  // eGlobalInterfacePrototype or eNamedPropertiesObject.
   DOMObjectType mType;  // uint8_t
 
   // Boolean indicating whether this object wants a @@hasInstance property
diff --git a/dom/bindings/test/test_dom_xrays.html b/dom/bindings/test/test_dom_xrays.html
index b2614f03481e6..12d8d230db25d 100644
--- a/dom/bindings/test/test_dom_xrays.html
+++ b/dom/bindings/test/test_dom_xrays.html
@@ -318,6 +318,15 @@
   checkXrayProperty(win.Image, Symbol.hasInstance,
                     [undefined, win.Function.prototype[Symbol.hasInstance]]);
 
+  // toString/@@toStringTag
+  let imageConstructor = win.Image;
+  is(win.Function.prototype.toString.apply(imageConstructor),
+     Function.prototype.toString.apply(Image),
+     "Applying Function.prototype.toString through an Xray should give the same result as applying it directly");
+  isDeeply(Object.getOwnPropertyDescriptor(win.CSS, Symbol.toStringTag),
+           Object.getOwnPropertyDescriptor(CSS, Symbol.toStringTag),
+           "Getting @@toStringTag on a namespace object through an Xray should give the same result as getting it directly");
+
   SimpleTest.finish();
 }