Bug 1570115 - Add do_QueryActor to query JS-implemented interfaces. r=kmag

This allows querying an actor for interfaces implemented in JS.

Differential Revision: https://phabricator.services.mozilla.com/D44050

--HG--
extra : moz-landing-system : lando

dom/ipc/JSWindowActor.cpp

@@ -10,6 +10,8 @@
 #include "mozilla/dom/PWindowGlobal.h"
 #include "mozilla/dom/Promise.h"
 #include "js/Promise.h"
+#include "xpcprivate.h"
+#include "nsIXPConnect.h"
 
 namespace mozilla {
 namespace dom {
@@ -31,6 +33,7 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(JSWindowActor)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPendingQueries)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mWrappedJS)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(JSWindowActor)
@@ -71,6 +74,26 @@ void JSWindowActor::InvokeCallback(CallbackFunction callback) {
   }
 }
 
+nsresult JSWindowActor::QueryInterfaceActor(const nsIID& aIID, void** aPtr) {
+  if (!mWrappedJS) {
+    AutoEntryScript aes(GetParentObject(), "JSWindowActor query interface");
+    JSContext* cx = aes.cx();
+
+    JS::Rooted<JSObject*> self(cx, GetWrapper());
+    JSAutoRealm ar(cx, self);
+
+    RefPtr<nsXPCWrappedJS> wrappedJS;
+    nsresult rv = nsXPCWrappedJS::GetNewOrUsed(
+        cx, self, NS_GET_IID(nsISupports), getter_AddRefs(wrappedJS));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    mWrappedJS = do_QueryInterface(wrappedJS);
+    MOZ_ASSERT(mWrappedJS);
+  }
+
+  return mWrappedJS->QueryInterface(aIID, aPtr);
+}
+
 void JSWindowActor::RejectPendingQueries() {
   // Take our queries out, in case somehow rejecting promises can trigger
   // additions or removals.

dom/ipc/JSWindowActor.h

@@ -13,8 +13,10 @@
 #include "mozilla/ErrorResult.h"
 #include "mozilla/dom/PromiseNativeHandler.h"
 #include "nsRefPtrHashtable.h"
+#include "nsIXPConnect.h"
 
 class nsIGlobalObject;
+class nsQueryActor;
 
 namespace mozilla {
 namespace dom {
@@ -77,6 +79,10 @@ class JSWindowActor : public nsISupports, public nsWrapperCache {
   void InvokeCallback(CallbackFunction willDestroy);
 
  private:
+  friend class ::nsQueryActor; // for QueryInterfaceActor
+
+  nsresult QueryInterfaceActor(const nsIID& aIID, void** aPtr);
+
   void ReceiveMessageOrQuery(JSContext* aCx,
                              const JSWindowActorMessageMeta& aMetadata,
                              JS::Handle<JS::Value> aData, ErrorResult& aRv);
@@ -112,6 +118,7 @@ class JSWindowActor : public nsISupports, public nsWrapperCache {
     uint64_t mQueryId;
   };
 
+  nsCOMPtr<nsISupports> mWrappedJS;
   nsString mName;
   nsRefPtrHashtable<nsUint64HashKey, Promise> mPendingQueries;
   uint64_t mNextQueryId;

dom/ipc/moz.build

@@ -78,6 +78,10 @@ EXPORTS.mozilla += [
     'ProcessPriorityManager.h',
 ]
 
+EXPORTS += [
+    'nsQueryActor.h',
+]
+
 UNIFIED_SOURCES += [
     'BrowserBridgeChild.cpp',
     'BrowserBridgeHost.cpp',

dom/ipc/nsQueryActor.h

@@ -0,0 +1,49 @@
+/* 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 nsQueryActor_h
+#define nsQueryActor_h
+
+#include "nsCOMPtr.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/dom/JSWindowActorChild.h"
+#include "mozilla/dom/WindowGlobalChild.h"
+
+class MOZ_STACK_CLASS nsQueryActor final : public nsCOMPtr_helper {
+ public:
+  nsQueryActor(const nsDependentString aActorName, nsPIDOMWindowOuter* aWindow)
+      : mActorName(aActorName), mWindow(aWindow) {}
+
+  virtual nsresult NS_FASTCALL operator()(const nsIID& aIID,
+                                          void** aResult) const override {
+    if (NS_WARN_IF(!mWindow) || NS_WARN_IF(!mWindow->GetCurrentInnerWindow())) {
+      return NS_ERROR_NO_INTERFACE;
+    }
+
+    RefPtr<mozilla::dom::WindowGlobalChild> wgc(
+        mWindow->GetCurrentInnerWindow()->GetWindowGlobalChild());
+    if (!wgc) {
+      return NS_ERROR_NO_INTERFACE;
+    }
+
+    RefPtr<mozilla::dom::JSWindowActorChild> actor =
+        wgc->GetActor(mActorName, mozilla::IgnoreErrors());
+    if (!actor) {
+      return NS_ERROR_NO_INTERFACE;
+    }
+
+    return actor->QueryInterfaceActor(aIID, aResult);
+  }
+
+ private:
+  const nsDependentString mActorName;
+  nsPIDOMWindowOuter* mWindow;
+};
+
+inline nsQueryActor do_QueryActor(const char16_t* aActorName,
+                                  nsPIDOMWindowOuter* aWindow) {
+  return nsQueryActor(nsDependentString(aActorName), aWindow);
+}
+
+#endif  // defined nsQueryActor_h