[debugger] allow debug-evaluate to change stack and context values.

src/contexts.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/contexts.h"
 
 #include "src/ast/scopeinfo.h"
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
@@ skipping 215 matching lines @@
 
 Handle<Object> Context::Lookup(Handle<String> name,
                                ContextLookupFlags flags,
                                int* index,
                                PropertyAttributes* attributes,
                                BindingFlags* binding_flags) {
   Isolate* isolate = GetIsolate();
   Handle<Context> context(this, isolate);
 
   bool follow_context_chain = (flags & FOLLOW_CONTEXT_CHAIN) != 0;
+  bool failed_whitelist = false;
   *index = kNotFound;
   *attributes = ABSENT;
   *binding_flags = MISSING_BINDING;
 
   if (FLAG_trace_contexts) {
     PrintF("Context::Lookup(");
     name->ShortPrint();
     PrintF(")\n");
   }
 
@@ skipping 125 matching lines @@
       // Catch contexts have the variable name in the extension slot.
       if (String::Equals(name, handle(context->catch_name()))) {
         if (FLAG_trace_contexts) {
           PrintF("=> found in catch context\n");
         }
         *index = Context::THROWN_OBJECT_INDEX;
         *attributes = NONE;
         *binding_flags = MUTABLE_IS_INITIALIZED;
         return context;
       }
+    } else if (context->IsDebugEvaluateContext()) {
+      // Check materialized locals.
+      Object* obj = context->get(EXTENSION_INDEX);
+      if (obj->IsJSReceiver()) {
+        Handle<JSReceiver> extension(JSReceiver::cast(obj));
+        LookupIterator it(extension, name, extension);
+        Maybe<bool> found = JSReceiver::HasProperty(&it);
+        if (found.FromMaybe(false)) {
+          *attributes = NONE;
+          return extension;
+        }
+      }
+      // Check the original context, but do not follow its context chain.
+      obj = context->get(WRAPPED_CONTEXT_INDEX);
+      if (obj->IsContext()) {
+        Handle<Object> result = Context::cast(obj)->Lookup(
+            name, DONT_FOLLOW_CHAINS, index, attributes, binding_flags);
+        if (!result.is_null()) return result;
+      }
+      // Check whitelist. Names that do not pass whitelist shall only resolve
+      // to with, script or native contexts up the context chain.
+      obj = context->get(WHITE_LIST_INDEX);
+      if (obj->IsStringSet()) {
+        failed_whitelist = failed_whitelist || !StringSet::cast(obj)->Has(name);
+      }
     }
 
     // 3. Prepare to continue with the previous (next outermost) context.
     if (context->IsNativeContext() ||
         ((flags & STOP_AT_DECLARATION_SCOPE) != 0 &&
          context->is_declaration_context())) {
       follow_context_chain = false;
     } else {
-      context = Handle<Context>(context->previous(), isolate);
+      do {
+        context = Handle<Context>(context->previous(), isolate);
+        // If we come across a whitelist context, and the name is not
+        // whitelisted, then only consider with, script or native contexts.
+      } while (failed_whitelist && !context->IsScriptContext() &&
+               !context->IsNativeContext() && !context->IsWithContext());
     }
   } while (follow_context_chain);
 
   if (FLAG_trace_contexts) {
     PrintF("=> no property/slot found\n");
   }
   return Handle<Object>::null();
 }
 
 
@@ skipping 182 matching lines @@
 
   int previous_value = errors_thrown()->value();
   set_errors_thrown(Smi::FromInt(previous_value + 1));
 }
 
 
 int Context::GetErrorsThrown() { return errors_thrown()->value(); }
 
 }  // namespace internal
 }  // namespace v8