fs: execute mkdtemp's callback with no context

All the callback functions in `fs` module are supposed to be executed
with no context (`this` value should not be a valid object). But
`mkdtemp`'s callback will have the `FSReqWrap` object as the context.

Sample code to reproduce the problem

    'use strict';

    const fs = require('fs');
    fs.mkdtemp('/tmp/abcd', null, function() {
      console.log(this);
    });

This would print

    FSReqWrap { oncomplete: [Function] }

But that should have printed `null` and this patch fixes that.

PR-URL: https://github.com/nodejs/node/pull/7068
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/fs.js b/lib/fs.js
index d5dc746e89..39bb3777bf 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -1596,8 +1596,7 @@ fs.realpath = function realpath(path, options, callback) {
 };
 
 
-fs.mkdtemp = function(prefix, options, callback_) {
-  var callback = maybeCallback(callback_);
+fs.mkdtemp = function(prefix, options, callback) {
   if (!prefix || typeof prefix !== 'string')
     throw new TypeError('filename prefix is required');
 
@@ -1611,6 +1610,7 @@ fs.mkdtemp = function(prefix, options, callback_) {
   if (typeof options !== 'object')
     throw new TypeError('"options" must be a string or an object');
 
+  callback = makeCallback(callback);
   if (!nullCheck(prefix, callback)) {
     return;
   }