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vm: fix a variety of bugs, using V8 4.3 APIs #1773

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vm: fix a variety of bugs, using V8 4.3 APIs #1773

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99104df
vm: fix property descriptors of sandbox properties
domenic May 22, 2015
6443054
vm: remove unnecessary access checks
domenic May 23, 2015
5f69cda
vm: fix symbol access
domenic Jun 1, 2015
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84 changes: 43 additions & 41 deletions src/node_contextify.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -26,10 +26,15 @@ using v8::HandleScope;
using v8::Integer;
using v8::Isolate;
using v8::Local;
using v8::Maybe;
using v8::MaybeLocal;
using v8::Name;
using v8::NamedPropertyHandlerConfiguration;
using v8::None;
using v8::Object;
using v8::ObjectTemplate;
using v8::Persistent;
using v8::PropertyAttribute;
using v8::PropertyCallbackInfo;
using v8::Script;
using v8::ScriptCompiler;
Expand Down Expand Up @@ -201,14 +206,14 @@ class ContextifyContext {

Local<ObjectTemplate> object_template =
function_template->InstanceTemplate();
object_template->SetNamedPropertyHandler(GlobalPropertyGetterCallback,

NamedPropertyHandlerConfiguration config(GlobalPropertyGetterCallback,
GlobalPropertySetterCallback,
GlobalPropertyQueryCallback,
GlobalPropertyDeleterCallback,
GlobalPropertyEnumeratorCallback,
CreateDataWrapper(env));
object_template->SetAccessCheckCallbacks(GlobalPropertyNamedAccessCheck,
GlobalPropertyIndexedAccessCheck);
object_template->SetHandler(config);

Local<Context> ctx = Context::New(env->isolate(), nullptr, object_template);
if (!ctx.IsEmpty())
Expand Down Expand Up @@ -342,24 +347,8 @@ class ContextifyContext {
}


static bool GlobalPropertyNamedAccessCheck(Local<Object> host,
Local<Value> key,
AccessType type,
Local<Value> data) {
return true;
}


static bool GlobalPropertyIndexedAccessCheck(Local<Object> host,
uint32_t key,
AccessType type,
Local<Value> data) {
return true;
}


static void GlobalPropertyGetterCallback(
Local<String> property,
Local<Name> property,
const PropertyCallbackInfo<Value>& args) {
Isolate* isolate = args.GetIsolate();
HandleScope scope(isolate);
Expand All @@ -368,22 +357,26 @@ class ContextifyContext {
Unwrap<ContextifyContext>(args.Data().As<Object>());

Local<Object> sandbox = PersistentToLocal(isolate, ctx->sandbox_);
Local<Value> rv = sandbox->GetRealNamedProperty(property);
if (rv.IsEmpty()) {
MaybeLocal<Value> maybe_rv =
sandbox->GetRealNamedProperty(ctx->context(), property);
if (maybe_rv.IsEmpty()) {
Local<Object> proxy_global = PersistentToLocal(isolate,
ctx->proxy_global_);
rv = proxy_global->GetRealNamedProperty(property);
}
if (!rv.IsEmpty() && rv == ctx->sandbox_) {
rv = PersistentToLocal(isolate, ctx->proxy_global_);
maybe_rv = proxy_global->GetRealNamedProperty(ctx->context(), property);
}

args.GetReturnValue().Set(rv);
Local<Value> rv;
if (maybe_rv.ToLocal(&rv)) {
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Maybe you can write this as:

if (!maybe_rv.ToLocal(&rv))
  return;

Saves a level of indent. Purely aesthetic though, I'll leave it up to you.

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I was thinking of this but I kind of thought there was a prohibition against early return given some other code in this file. I'll leave it since otherwise I'd feel compelled to go and fix the other cases.

if (rv == ctx->sandbox_)
rv = PersistentToLocal(isolate, ctx->proxy_global_);

args.GetReturnValue().Set(rv);
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Aside, is nothing / undefined / the hole the right value to return on error, here and elsewhere?

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I am pretty sure, but not positive, based on looking through similar V8 source code (which is buried in macros). I am a bit surprised that GetReturnValue().Set() does not take a Maybe...

}
}


static void GlobalPropertySetterCallback(
Local<String> property,
Local<Name> property,
Local<Value> value,
const PropertyCallbackInfo<Value>& args) {
Isolate* isolate = args.GetIsolate();
Expand All @@ -397,7 +390,7 @@ class ContextifyContext {


static void GlobalPropertyQueryCallback(
Local<String> property,
Local<Name> property,
const PropertyCallbackInfo<Integer>& args) {
Isolate* isolate = args.GetIsolate();
HandleScope scope(isolate);
Expand All @@ -406,30 +399,39 @@ class ContextifyContext {
Unwrap<ContextifyContext>(args.Data().As<Object>());

Local<Object> sandbox = PersistentToLocal(isolate, ctx->sandbox_);
Local<Object> proxy_global = PersistentToLocal(isolate,
ctx->proxy_global_);

bool in_sandbox = sandbox->GetRealNamedProperty(property).IsEmpty();
bool in_proxy_global =
proxy_global->GetRealNamedProperty(property).IsEmpty();
if (!in_sandbox || !in_proxy_global) {
args.GetReturnValue().Set(None);
Maybe<PropertyAttribute> maybe_prop_attr =
sandbox->GetRealNamedPropertyAttributes(ctx->context(), property);

if (maybe_prop_attr.IsNothing()) {
Local<Object> proxy_global = PersistentToLocal(isolate,
ctx->proxy_global_);

maybe_prop_attr =
proxy_global->GetRealNamedPropertyAttributes(ctx->context(),
property);
}

if (maybe_prop_attr.IsJust()) {
PropertyAttribute prop_attr = maybe_prop_attr.FromJust();
args.GetReturnValue().Set(prop_attr);
}
}


static void GlobalPropertyDeleterCallback(
Local<String> property,
Local<Name> property,
const PropertyCallbackInfo<Boolean>& args) {
Isolate* isolate = args.GetIsolate();
HandleScope scope(isolate);

ContextifyContext* ctx =
Unwrap<ContextifyContext>(args.Data().As<Object>());
Local<Object> sandbox = PersistentToLocal(isolate, ctx->sandbox_);

Maybe<bool> success = sandbox->Delete(ctx->context(), property);

bool success = PersistentToLocal(isolate,
ctx->sandbox_)->Delete(property);
args.GetReturnValue().Set(success);
if (success.IsJust())
args.GetReturnValue().Set(success.FromJust());
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could this also be:

args.GetReturnValue().Set(success.FromMaybe(false));

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Not saying that's the preferred way. It's currently more explicit and easier for others scanning the code.

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No; I don't want to return anything if success is a Nothing.

(It probably doesn't make a difference... would have to dig in to how V8 actually uses GlobalPropertyDeleterCallback. But in general I try to not return anything on failure in this maybe-world.)

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Good to know. I was basing my assumption from the old code that always returned a bool.

}


Expand Down
25 changes: 25 additions & 0 deletions test/parallel/test-vm-preserves-property.js
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@@ -0,0 +1,25 @@
'use strict';

var common = require('../common');
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'use strict', maybe? Does it pass linter?

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Fixing lint errors now, feeling dumb. Surprisingly none of the other tests have use strict but the linter still wants it.

var assert = require('assert');

var vm = require('vm');

var x = {};
Object.defineProperty(x, 'prop', {
configurable: false,
enumerable: false,
writable: false,
value: 'val'
});
var o = vm.createContext(x);

var code = 'Object.getOwnPropertyDescriptor(this, "prop")';
var res = vm.runInContext(code, o, 'test');

assert(res);
assert.equal(typeof res, 'object');
assert.equal(res.value, 'val');
assert.equal(res.configurable, false, 'should not be configurable');
assert.equal(res.enumerable, false, 'should not be enumerable');
assert.equal(res.writable, false, 'should not be writable');
25 changes: 25 additions & 0 deletions test/parallel/test-vm-symbols.js
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@@ -0,0 +1,25 @@
'use strict';

var common = require('../common');
var assert = require('assert');

var vm = require('vm');

var symbol = Symbol();

function Document() {
this[symbol] = 'foo';
}

Document.prototype.getSymbolValue = function() {
return this[symbol];
};

var context = new Document();
vm.createContext(context);

assert.equal(context.getSymbolValue(), 'foo',
'should return symbol-keyed value from the outside');

assert.equal(vm.runInContext('this.getSymbolValue()', context), 'foo',
'should return symbol-keyed value from the inside');