Change from 0.10 => 1.2; enumerable of this.escape in vm.runInNewContext was false, now true

Here's the behavior from node 0.10:

$ node -p 'require("vm").runInNewContext("Object.getOwnPropertyDescriptor(this,\"escape\")", {})'
{ value: [Function: escape],
  writable: true,
  enumerable: false,
  configurable: true }

And in io.js@1.2.0:

$ nvm use 1.2
Now using io.js v1.2.0
$ node -p 'require("vm").runInNewContext("Object.getOwnPropertyDescriptor(this,\"escape\")", {})'
{ value: [Function: escape],
  writable: true,
  enumerable: true,
  configurable: true }

Is this an intentional change? Is it documented anywhere? FWIW this is present in node@0.11 as well

I guess this is related to https://code.google.com/p/v8/issues/detail?id=3861. GetOwnPropertyNames() is called here.

Testing with cloneProperty in the REPL correctly generates an escape with enumerable: false:

> c = require('./cloneProperty')
[Function: cloneProperty]
> s = {}
{}
> c(global, "escape", s)
undefined
> s
{}
> Object.getOwnPropertyDescriptor(s, "escape")
{ value: [Function: escape],
  writable: true,
  enumerable: false,
  configurable: true }

where cloneProperty.js is:

function cloneProperty(source, key, target) {
                if (key === 'Proxy') return;
                try {
                  var desc = Object.getOwnPropertyDescriptor(source, key);
                  if (desc.value === source) desc.value = target;
                  Object.defineProperty(target, key, desc);
                } catch (e) {
                 // Catch sealed properties errors
                }
              }

module.exports = cloneProperty;

I suspect that's caused by the named property interceptor for the global object here.

if (!in_sandbox || !in_proxy_global) {
  args.GetReturnValue().Set(None);
}

Not sure what the best way to fix it is. The interceptor needs to retrieve the actual property attributes somehow without causing infinite recursion.

vm: pass attributes from sandbox

@boordhuis - Indeed, getting attributes for properties of the global is tricky. I have a PR (#885) for the sandbox side, which was easy.

I tried something like this:

    Local<Context> context = PersistentToLocal(isolate, ctx->context_);
    attr = context->Global()->GetPropertyAttributes(property);

But that set off an infinite recursion, as you predicted. Any suggestions?

@smikes

@smikes I commented on that here. It looks like V8 needs to grow some new APIs to fix this issue. I have it on my radar but I'm stretched rather thin at the moment.

https://codereview.chromium.org/942003003/

Add v8::Object::GetRealNamedPropertyAttributes()

Looks like the v8 patch landed.

vm: fix property descriptors of sandbox properties

This can be closed as it's fixed in next.

vm: fix property descriptors of sandbox properties

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Change from 0.10 => 1.2; `enumerable` of `this.escape` in `vm.runInNewContext` was false, now true #864

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Change from 0.10 => 1.2; enumerable of this.escape in vm.runInNewContext was false, now true #864

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anba commented on Feb 17, 2015

smikes commented on Feb 17, 2015

bnoordhuis commented on Feb 17, 2015

smikes commented on Feb 19, 2015

bnoordhuis commented on Feb 19, 2015

bnoordhuis commented on Feb 20, 2015

Fishrock123 commented on Mar 6, 2015

domenic commented on Jun 5, 2015

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Change from 0.10 => 1.2; `enumerable` of `this.escape` in `vm.runInNewContext` was false, now true #864