How to create destination path for node.js stream pipe?

I would like to pipe a node.js stream into an output file. But I would also like to make sure that output destination exists before I start piping. The problem with the following code is that event handlers from pipe are added late (after assurePath callback is called) so data is not available anymore in the input stream. I would not like to use sync fs methods to not block the whole process.

assurePath = (path, callback) ->
  path = path.split path.sep
  i = 0
  async.eachSeries path[1...path.length-1], (segment, callback) =>
    i++
    p = path[0..i].join path.sep
    fs.exists p, (exists) =>
      return callback() if exists
      fs.mkdir p, callback
  ,
    callback

saveStream = (filename, stream, callback) ->
  path = fullPath filename
  assurePath path, (error) ->
    return callback error if error

    finished = false
    stream.on('error', (error) ->
      return if finished
      finished = true
      callback error
    ).pipe(
      fs.createWriteStream path
    ).on('finish', ->
      return if finished
      finished = true
      callback()
    ).on('error', (error) ->
      return if finished
      finished = true
      callback error
    )