Bug 856067 - Add some helpful logging to the console when we deny access to a non-Xrayable object. r=gabor

js/xpconnect/wrappers/XrayWrapper.cpp

@@ -69,6 +69,8 @@ IsTypedArrayKey(JSProtoKey key)
     return key >= JSProto_Int8Array && key <= JSProto_Uint8ClampedArray;
 }
 
+bool SilentFailure(JSContext *cx, JS::HandleId id, const char *reason);
+
 // Whitelist for the standard ES classes we can Xray to.
 static bool
 IsJSXraySupported(JSProtoKey key)
@@ -493,6 +495,17 @@ public:
         MOZ_CRASH("resolveNativeProperty hook should never be called with HasPrototype = 1");
     }
 
+    virtual bool resolveOwnProperty(JSContext *cx, const Wrapper &jsWrapper, HandleObject wrapper,
+                                    HandleObject holder, HandleId id,
+                                    MutableHandle<JSPropertyDescriptor> desc) MOZ_OVERRIDE
+    {
+        bool ok = XrayTraits::resolveOwnProperty(cx, jsWrapper, wrapper, holder, id, desc);
+        if (!ok || desc.object())
+            return ok;
+
+        return SilentFailure(cx, id, "Object is not safely Xrayable");
+    }
+
     bool defineProperty(JSContext *cx, HandleObject wrapper, HandleId id,
                         MutableHandle<JSPropertyDescriptor> desc,
                         Handle<JSPropertyDescriptor> existingDesc, bool *defined)
@@ -560,7 +573,7 @@ public:
     static OpaqueXrayTraits singleton;
 };
 
-inline bool
+bool
 SilentFailure(JSContext *cx, HandleId id, const char *reason)
 {
 #ifdef DEBUG
@@ -570,7 +583,7 @@ SilentFailure(JSContext *cx, HandleId id, const char *reason)
     AutoFilename filename;
     unsigned line = 0;
     DescribeScriptedCaller(cx, &filename, &line);
-    NS_WARNING(nsPrintfCString("Denied access to property |%s| on Xrayed Object: %s (@%s:%u)",
+    NS_WARNING(nsPrintfCString("Silently denied access to property |%s|: %s (@%s:%u)",
                                NS_LossyConvertUTF16toASCII(name).get(), reason,
                                filename.get(), line).get());
 #endif