Meteor, access MongoDB outside a fiber

I use the Meteor package tomi:upload-jquery that uses callbacks outside a fiber. Inside one callback I should use MongoDB, and MongoDB requires to be run inside a fiber.

After a lot of attempts with future, fibers, deasync, Meteor.bindEnvironment, Meteor.wrapAsync, a.s.o. I have found no solution.

The callback to be wrappen is:

Meteor.startup ->
  UploadServer.init
    getDirectory: (fileInfo, formData) ->
      # begin some sort of wrapping
        dir = ''
        u = Meteor.users.findOne({"uploadToken.token": formData.uploadToken })
        if u
          dir = u.username
        else
          throw new Error 'Anonymous calls not permitted'
      # end some sort of wrapping
      console.log 'dir', dir
      return dir
  return

EDIT 1

This code is working without crashing, but it should become synchronous:

Meteor.startup ->
  UploadServer.init
    getDirectory: (fileInfo, formData) ->
      getDir = (formData,callback) ->
        Fiber(()->
          console.log '0:',formData
          dir = ''
          u = Meteor.users.findOne({"uploadToken.token": formData.uploadToken })
          if u
            dir = u.username
          else
            callback new Error( 'Anonymous file upload not permitted.' ), null
          console.log '1:',dir
          callback null,dir
        ).run()
      dir = getDir(formData, (e,r)->
        console.log 'e,r:',e,r
      )
      console.log '2:',dir
      return ''
  return

In the log I get:

I20150905-08:33:13.171(2)? 0: { uploadToken: 'K2eEiFMRMagSuoKqf' }
I20150905-08:33:13.173(2)? 2: undefined
I20150905-08:33:13.174(2)? 0: { uploadToken: 'K2eEiFMRMagSuoKqf' }
I20150905-08:33:13.175(2)? 2: undefined
I20150905-08:33:13.177(2)? 1: test
I20150905-08:33:13.177(2)? e,r: null test
I20150905-08:33:13.177(2)? 1: test
I20150905-08:33:13.178(2)? e,r: null test

getDirectory is called twice.

What is missing now is how to make to code synchronous. That is to let return dir wait for getDir.

Any advice and suggestions will be greatly appreciated.

See solution to this question: Meteor Package for formidable.

To execute the MongeDB command inside a Fiber I wrapped an event handler in the package tomi:upload-server.