Get backing file descriptor for Node file stream

node.js

Solution

var stream = fs.createWriteStream('./something.txt');

stream.on('open', function (fd) {
  // here is an fd
})

this is actually documented (http://nodejs.org/api/fs.html#fs_event_open_1), whereas both `fd` option and property are not

Problem

When I've opened a file as a stream, e.g. with `fs.createWriteStream`, how do I reliably get the backing file descriptor of the stream? (I need the file descriptor to call functions like `fs.futimes` on it.) There appears to be `stream.fd`, but it's `null` for a fraction of a second before it gets set. So how do I get the file descriptor once it's available?

Original source