Broken example for vm.runInDebugContext(code)

[MylesBorins]

The current example fails

const Debug = vm.runInDebugContext('Debug');
Debug.scripts().forEach(function(script) { console.log(script.name); });

The error I receive is

Debug.scripts().forEach(function(script) {
      ^
illegal access

Will do more research and post in this thread

[MylesBorins]

/cc @nodejs/documentation

[bnoordhuis]

Oh, that's because you need to start the debugger first now before you have access to Debug.scripts(). I'd swap it out for a different example.

[bnoordhuis]

Like this:

> vm.runInDebugContext('Debug').findScript(process.exit).name
'node.js'

> vm.runInDebugContext('Debug').findScript(process.emit).name
'events.js'

[MylesBorins]

@bnoordhuis can you share an example of running arbitrary in a vm context?

I think I can get a test for #4819 by running some code in a debug context, but perhaps I am missing some... context (sorry couldn't help it).

When I try something like

const Debug = vm.runInDebugContext('var util = require("util");');

I get

undefined:1
var util = require("util");
           ^
ReferenceError: require is not defined
    at <anonymous>:1:12

As the definition of runInDebugContext is vm.runInDebugContext(code) I thought I could feed arbitrary code. It appears that this context does not by default have access to all the node bits in the main context (this is a guess).

I'll dig into the c++ and report back

[bnoordhuis]

As the definition of runInDebugContext is vm.runInDebugContext(code) I thought I could feed arbitrary code. It appears that this context does not by default have access to all the node bits in the main context (this is a guess).

That's correct. It's a clean slate JS VM with debugger bits but no node bits. It's similar to vm.runInNewContext(code) in that respect, except that doesn't even have debugger bits.

[MylesBorins]

@bnoordhuis ahhh. That makes a lot of sense. I'll dig into the debugger source and see how it sets up the environment. That is a bit out of scope for this issue though, so I'll try and put together a working example for VM and perhaps some documentation about the context

[yorickvP]

Did you figure out how to do it?