Run less.js in a sandbox

gistfile1.js

var fs = require('fs')
var path = require('path')
var vm = require('vm')
var util = require('util')
 
String.prototype.endsWith = function(suffix) {
  return this.indexOf(suffix, this.length - suffix.length) !== -1;
}
 
var basedir = path.join(__dirname, 'less_files')+path.sep
console.log('basedir', basedir)
 
function proxy(module) {
  var obj = {}
  for (var key in module) {
    if (module.hasOwnProperty(key)) {
      var value = module[key]
      if (value instanceof Function) {
        function proxyFunction(key, func) {
          return function() {
            var args = Array.prototype.slice.call(arguments)
            console.log(key, 'called with arguments', args)
            return module[key].apply(module, args)
          }
        }
        obj[key] = proxyFunction(key, value)
      }
    }
  }
  return obj
}
 
var _fs = {} // proxy(fs) // proxy just while developing more proxied functions
 
_fs.stat = function(filename) {
  if (filename.indexOf(basedir) !== 0) {
    return arguments[arguments.length-1](new Error('Forbidden'))
  }
  return fs.stat.apply(fs, arguments)
}
 
_fs.readFile = function(filename) {
  if (filename.indexOf(basedir) !== 0) {
    return arguments[arguments.length-1](new Error('Forbidden'))
  }
  return fs.readFile.apply(fs, arguments)
}
 
var _console = {
  log: function() {
    console.log(util.format.apply(null, Array.prototype.slice.call(arguments)))
  }
}
 
var modules = {}
modules['path'] = { exports: require('path') }
modules['url'] = { exports: require('url') }
modules['fs'] = { exports: _fs }
 
function createSandbox(dir) {
  var sandbox = {}
  sandbox.require = function(module) {
    if (modules[module]) {
      return modules[module].exports
    }
    var fullpath = null
    if (module.indexOf('./') !== 0 && module.indexOf('../') !== 0) {
      var json = JSON.parse(fs.readFileSync(path.join(dir, 'node_modules', module, 'package.json'), 'utf8'))
      var main = json.main
      var fullpath = path.join(dir, 'node_modules', module, main)
    } else {
      fullpath = path.join(dir, module)
    }
    if (!fullpath.endsWith('.js')) {
      fullpath += '.js'
    }
    if (modules[fullpath]) {
      return modules[fullpath].exports
    }
    var code = fs.readFileSync(fullpath, 'utf8')
    var _sandbox = createSandbox(path.dirname(fullpath))
    modules[fullpath] = _sandbox.module
    vm.runInNewContext(code, _sandbox, fullpath)
    return _sandbox.module.exports
  }
  sandbox.module = { exports: {} }
  sandbox.exports = sandbox.module.exports
  sandbox.console = _console
  return sandbox
}
 
var filename = 'bootstrap.less'
var lesscode = fs.readFileSync(path.join(basedir, filename), 'utf8')
var code =  "var less = require('less'); var parser = new(less.Parser)(lessoptions).parse(lesscode, completion)"
var lessoptions = {
  paths: [basedir],
  filename: filename
}
var completion = function(err, tree) {
  if (err) {
    return console.log('err', err)
  }
  // console.log('output', tree.toCSS({ compress: true }))
}
var sandbox = createSandbox(__dirname)
sandbox.basedir = basedir
sandbox.lesscode = lesscode
sandbox.lessoptions = lessoptions
sandbox.completion = completion

for (var i = 0; i < 100; i++) {
  // sandboxed
  // vm.runInNewContext(code, sandbox, 'file.js')
  // native
  var less = require('less'); var parser = new(less.Parser)(lessoptions).parse(lesscode, completion)
}