Improve Crypto::getRandomValues exception messages.

Source/bindings/v8/ExceptionState.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 26 matching lines @@
 #include "wtf/text/WTFString.h"
 #include <v8.h>
 
 namespace WebCore {
 
 typedef int ExceptionCode;
 
 class ExceptionState {
     WTF_MAKE_NONCOPYABLE(ExceptionState);
 public:
+    enum Context {
+        ConstructionContext,
+        ExecutionContext,
+        DeletionContext,
+        GetterContext,
+        SetterContext,
+        UnknownContext, // FIXME: Remove this once we've flipped over to the new API.
+    };
+
     explicit ExceptionState(const v8::Handle<v8::Object>& creationContext, v8::Isolate* isolate)
         : m_code(0)
+        , m_context(UnknownContext)
+        , m_property(0)
+        , m_interface(0)
         , m_creationContext(creationContext)
         , m_isolate(isolate) { }
 
+    ExceptionState(Context context, const char* property, const char* interface, const v8::Handle<v8::Object>& creationContext, v8::Isolate* isolate)
+        : m_code(0)
+        , m_context(context)
+        , m_property(property)
+        , m_interface(interface)
+        , m_creationContext(creationContext)
+        , m_isolate(isolate) { }
+
+    ExceptionState(Context context, const char* interface, const v8::Handle<v8::Object>& creationContext, v8::Isolate* isolate)
+        : m_code(0)
+        , m_context(context)
+        , m_property(0)
+        , m_interface(interface)
+        , m_creationContext(creationContext)
+        , m_isolate(isolate) { ASSERT(m_executionContext == ExceptionStateForConstruction); }
+
     virtual void throwDOMException(const ExceptionCode&, const String& message);
     virtual void throwTypeError(const String& message);
     virtual void throwSecurityError(const String& sanitizedMessage, const String& unsanitizedMessage = String());
 
     // Please don't use these methods. Use ::throwDOMException and ::throwTypeError, and pass in a useful exception message.
     virtual void throwUninformativeAndGenericDOMException(const ExceptionCode& ec) { throwDOMException(ec, String()); }
     virtual void throwUninformativeAndGenericTypeError() { throwTypeError(String()); }
 
     bool hadException() const { return !m_exception.isEmpty() || m_code; }
     void clearException();
 
     ExceptionCode code() { return m_code; }
 
     bool throwIfNeeded()
     {
         if (m_exception.isEmpty()) {
             if (!m_code)
                 return false;
             throwUninformativeAndGenericDOMException(m_code);
         }
 
         V8ThrowException::throwError(m_exception.newLocal(m_isolate), m_isolate);
         return true;
     }
 
+    Context context() { return m_context; }
+    const char* property() { return m_property; }
+    const char* interface() { return m_interface; }
+
 protected:
     ExceptionCode m_code;
+    Context m_context;
+    const char* m_property;
+    const char* m_interface;

[haraken, 2013/11/26 10:49:36]

Don't you want to use String instead of char*?

[Mike West, 2013/11/26 10:53:26]

I don't want the performance hit of converting to String unless we actually
throw an exception. This sort of thing has already popped up in a number of
microbenchmarks as potentially problematic, so I'm trying to preemptively avoid
it here.

 
 private:
     void setException(v8::Handle<v8::Value>);
 
     ScopedPersistent<v8::Value> m_exception;
     v8::Handle<v8::Object> m_creationContext;
     v8::Isolate* m_isolate;
 };
 
 class TrackExceptionState : public ExceptionState {
 public:
     TrackExceptionState(): ExceptionState(v8::Handle<v8::Object>(), 0) { }
     virtual void throwDOMException(const ExceptionCode&, const String& message) OVERRIDE FINAL;
     virtual void throwTypeError(const String& message = String()) OVERRIDE FINAL;
     virtual void throwSecurityError(const String& sanitizedMessage, const String& unsanitizedMessage = String()) OVERRIDE FINAL;
 };
 
 } // namespace WebCore
 
 #endif // ExceptionState_h