vm writing to stderr

[reggi]

The issue is that the code below writes to stderr. Because it's wrapped in a try catch it shouldn't be writing to stderr.

try {
  var vm = require('vm')
  global.require = require
  vm.createScript("require('missing')")
  .runInNewContext(global)
} catch (e) {
}

It only writes this. Not even a complete throw w/ error stack trace.

module.js:338
    throw err;
          ^

I've tried to catch it with this, but it never fires.

process.on('unhandledRejection', function(reason, p){
  console.log(arguments)
})

The code example is here

The tests are here, it only started happening in version 11+.

• node_js:
  • "0.12" ×
  • "0.11" ×
  • "0.10" ✓
  • "0.8" ✓
  • "0.6" ✓
  • "iojs" ×
  • "iojs-v1.0.4" ×
  • "iojs-v2.5.0" ×
  • "iojs-v3.0.0" ×

[reggi]

@thefourtheye this is a bug, no?

[thefourtheye]

I am not sure if it is related to #2104. cc @indutny @domenic

[reggi]

@thefourtheye I tested it out and I was editing and executing different files, I removed it. Sorry.

[reggi]

This is interesting.

try {
  var vm = require('vm')
  global.require = require
  var code = [
    'try {',
    'require("missing")',
    '} catch (e) {',
    'throw e ',
    '}'
  ].join('\n')
  vm.createScript(code)
  .runInNewContext(global)
} catch (e) {
}

Writes

evalmachine.<anonymous>:4
 throw e 
       ^

[reggi]

Ugg, it has nothing to do explicitly with require.

try {
  var vm = require('vm')
  vm.createScript('throw new Error("hamburger")', "known")
  .runInNewContext(global, "known")
} catch (e) {
}

known:1
throw new Error("hamburger")

[reggi]

The error is being caught properly without global...

try {
  var vm = require('vm')
  vm.createScript('throw new Error("hamburger")', "known")
  .runInNewContext({}, "known")
} catch (e) {
}

[indutny]

Oh god, again :)

[reggi]

I found a way to catch the trace, if you clone the require (specifically with lodash _.clone) it allows you to catch the error and get the full stack trace. Perhaps this issue has to do with sharing global variables.

try {
  var _ = require('lodash')
  var vm = require('vm')
  var sb = {}
  sb.require = _.clone(require)
  vm.createScript("require('missing')")
  .runInNewContext(sb)
} catch (e) {
  throw e
}

evalmachine.<anonymous>:1
require('missing')
^
TypeError: require is not a function
    at evalmachine.<anonymous>:1:1
    at ContextifyScript.Script.runInNewContext (vm.js:18:15)
    at Object.<anonymous> (/Users/thomas/Desktop/node-vm-stderr-bug/bug.js:7:4)
    at Module._compile (module.js:430:26)
    at Object.Module._extensions..js (module.js:448:10)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Function.Module.runMain (module.js:471:10)
    at startup (node.js:117:18)
    at node.js:953:3

[reggi]

Ug, didn't realize it said require is not a function, grr this is so frustrating...

[reggi]

I dont get why half the thrown error is in the stack trace and half is written to stderr......

stderr

module.js:338
    throw err;
          ^

in stack trace

Error: Cannot find module 'missing'
    at Function.Module._resolveFilename (module.js:336:15)
    at Function.Module._load (module.js:286:25)
    at Module.require (module.js:365:17)
    at require (module.js:384:17)
    at evalmachine.<anonymous>:1:1
    at ContextifyScript.Script.runInNewContext (vm.js:18:15)
    at Object.<anonymous> (/Users/thomas/Desktop/node-vm-stderr-bug/bug.js:7:4)
    at Module._compile (module.js:430:26)
    at Object.Module._extensions..js (module.js:448:10)
    at Module.load (module.js:355:32)

[reggi]

There's an option in vm, did the trick!!!!!!!!!!

try {
  var _ = require('lodash')
  var vm = require('vm')
  var sb = {}
  sb.require = require
  var script = new vm.Script("require('missing')")
  script.runInNewContext(sb, {
     displayErrors: false
  })
} catch (e) {
   throw e
}