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Add workaround for redefinition of __proto__ property.

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This is a temporary workaround when the __proto__ property is being
redefined (e.g. by Object.freeze()) to not loose the foreign callback.
Once the __proto__ property is a real JavaScript accessor this hack is
no longer necessary. This change also makes __proto__ configurable.

R=rossberg@chromium.org
BUG=v8:2565
TEST=mjsunit/regress/regress-2565

Review URL: https://codereview.chromium.org/12398010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13817 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
mstarzinger@chromium.org 2013-03-04 17:53:40 +00:00
parent 867b23246a
commit 2aabf6257d
3 changed files with 41 additions and 2 deletions
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3
src/bootstrapper.cc
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@ -493,8 +493,7 @@ Handle<JSFunction> Genesis::CreateEmptyFunction(Isolate* isolate) {
Handle<Foreign> object_prototype(
factory->NewForeign(&Accessors::ObjectPrototype));
PropertyAttributes attribs = static_cast<PropertyAttributes>(
DONT_ENUM | DONT_DELETE);
PropertyAttributes attribs = static_cast<PropertyAttributes>(DONT_ENUM);
object_prototype_map->set_instance_descriptors(*prototype_descriptors);
{ // Add __proto__.

8
src/runtime.cc
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@ -4099,6 +4099,14 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DefineOrRedefineDataProperty) {
if (callback->IsAccessorInfo()) {
return isolate->heap()->undefined_value();
}
// TODO(mstarzinger): The __proto__ property should actually be a real
// JavaScript accessor instead of a foreign callback. But for now we just
// avoid changing the writability and configurability attribute of this
// property.
Handle<Name> proto_string = isolate->factory()->proto_string();
if (callback->IsForeign() && proto_string->Equals(*name)) {
attr = static_cast<PropertyAttributes>(attr & ~(READ_ONLY | DONT_DELETE));
}
// Avoid redefining foreign callback as data property, just use the stored
// setter to update the value instead.
// TODO(mstarzinger): So far this only works if property attributes don't

32
test/mjsunit/regress/regress-2565.js Normal file
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@ -0,0 +1,32 @@
// Copyright 2013 the V8 project authors. 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
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Object.freeze(Object.prototype);
var p = {};
var o = Object.create(p);
assertSame(p, o.__proto__);
assertSame(p, Object.getPrototypeOf(o));