Correctly set ReadOnly flag on indexed properties when using the API Set method (fixes issue 1470)

src/runtime.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
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 //
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@@ skipping 3977 matching lines @@
     // of a string using [] notation.  We need to support this too in
     // JavaScript.
     // In the case of a String object we just need to redirect the assignment to
     // the underlying string if the index is in range.  Since the underlying
     // string does nothing with the assignment then we can ignore such
     // assignments.
     if (js_object->IsStringObjectWithCharacterAt(index)) {
       return *value;
     }
 
+    // Special case for elements if any of the flags are true.
+    // If elements are in fast case we always implicitly assume that:
+    // DONT_DELETE: false, DONT_ENUM: false, READ_ONLY: false.
+    if (((attr & (DONT_DELETE | DONT_ENUM | READ_ONLY)) != 0)) {
+      // Normalize the elements to enable attributes on the property.
+      NormalizeElements(js_object);
+      Handle<NumberDictionary> dictionary(js_object->element_dictionary());
+      // Make sure that we never go back to fast case.
+      dictionary->set_requires_slow_elements();
+      PropertyDetails details = PropertyDetails(attr, NORMAL);
+      Handle<NumberDictionary> extended_dictionary =
+          NumberDictionarySet(dictionary, index, value, details);
+      if (*extended_dictionary != *dictionary) {
+        js_object->set_elements(*extended_dictionary);
+      }
+      return *value;
+    }
+
     Handle<Object> result = SetElement(js_object, index, value, strict_mode);
     if (result.is_null()) return Failure::Exception();
     return *value;
   }
 
   if (key->IsString()) {
     Handle<Object> result;
     if (Handle<String>::cast(key)->AsArrayIndex(&index)) {

[Erik Corry, 2011/06/14 13:21:51]

There's a ton of copied code here.
You could create a helper or just recurse:  return SetObjectProperty(isolate,
object, Smi::fromInt(index), value, attr, strict_mode);

[Rico, 2011/06/14 13:44:23]

Done.

+      // Special case for elements if any of the flags are true.
+      // If elements are in fast case we always implicitly assume that:
+      // DONT_DELETE: false, DONT_ENUM: false, READ_ONLY: false.
+      if (((attr & (DONT_DELETE | DONT_ENUM | READ_ONLY)) != 0)) {
+        // Normalize the elements to enable attributes on the property.
+        NormalizeElements(js_object);
+        Handle<NumberDictionary> dictionary(js_object->element_dictionary());
+        // Make sure that we never go back to fast case.
+        dictionary->set_requires_slow_elements();
+        PropertyDetails details = PropertyDetails(attr, NORMAL);
+        Handle<NumberDictionary> extended_dictionary =
+            NumberDictionarySet(dictionary, index, value, details);
+        if (*extended_dictionary != *dictionary) {
+          js_object->set_elements(*extended_dictionary);
+        }
+        return *value;
+      }
       result = SetElement(js_object, index, value, strict_mode);
     } else {
       Handle<String> key_string = Handle<String>::cast(key);
       key_string->TryFlatten();
       result = SetProperty(js_object, key_string, value, attr, strict_mode);
     }
     if (result.is_null()) return Failure::Exception();
     return *value;
   }
 
@@ skipping 8343 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal