Bug 1382833 - Don't throw when dealing with CPOWs in the Object Actor;r=jimb

MozReview-Commit-ID: CaIS2IpaQme

--HG--
extra : rebase_source : 75b4fe1abd460978039d7f1085d56e64b9dd2765

devtools/server/actors/object.js

@@ -91,13 +91,25 @@ ObjectActor.prototype = {
       g.proxyTarget = this.hooks.createValueGrip(this.obj.proxyTarget);
       g.proxyHandler = this.hooks.createValueGrip(this.obj.proxyHandler);
     } else {
-      g.class = this.obj.class;
-      g.extensible = this.obj.isExtensible();
-      g.frozen = this.obj.isFrozen();
-      g.sealed = this.obj.isSealed();
+      try {
+        g.class = this.obj.class;
+        g.extensible = this.obj.isExtensible();
+        g.frozen = this.obj.isFrozen();
+        g.sealed = this.obj.isSealed();
+      } catch (e) {
+        // Handle cases where the underlying object's calls to isExtensible, etc throw.
+        // This is possible with ProxyObjects like CPOWs. Note these are different from
+        // scripted Proxies created via `new Proxy`, which match this.obj.isProxy above.
+      }
     }
 
-    if (g.class != "DeadObject") {
+    // Changing the class so that CPOWs will be visible in the UI
+    let isCPOW = DevToolsUtils.isCPOW(this.obj);
+    if (isCPOW) {
+      g.class = "CPOW: " + g.class;
+    }
+
+    if (g.class != "DeadObject" && !isCPOW) {
       if (g.class == "Promise") {
         g.promiseState = this._createPromiseState();
       }

devtools/shared/DevToolsUtils.js

@@ -28,6 +28,21 @@ for (let key of Object.keys(ThreadSafeDevToolsUtils)) {
   exports[key] = ThreadSafeDevToolsUtils[key];
 }
 
+/**
+ * Helper for Cu.isCrossProcessWrapper that works with Debugger.Objects.
+ * This will always return false in workers (see the implementation in
+ * ThreadSafeDevToolsUtils.js).
+ *
+ * @param Debugger.Object debuggerObject
+ * @return bool
+ */
+exports.isCPOW = function (debuggerObject) {
+  try {
+    return Cu.isCrossProcessWrapper(debuggerObject.unsafeDereference());
+  } catch (e) { }
+  return false;
+};
+
 /**
  * Waits for the next tick in the event loop to execute a callback.
  */

devtools/shared/ThreadSafeDevToolsUtils.js

@@ -69,6 +69,14 @@ exports.values = function values(object) {
   return Object.keys(object).map(k => object[k]);
 };
 
+/**
+ * This is overridden in DevToolsUtils for the main thread, where we have the
+ * Cu object available.
+ */
+exports.isCPOW = function () {
+  return false;
+};
+
 /**
  * Report that |who| threw an exception, |exception|.
  */