Currently, nullCheck() will attempt to invoke any truthy value
as a function if the path argument contains a null character.
This commit validates that the callback is actually a function
before trying to invoke it. fs.access() was vulnerable to this
bug, as nullCheck() was called prior to type checking its
callback.
PR-URL: https://github.com/iojs/io.js/pull/887
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
The copyright and license notice is already in the LICENSE file. There
is no justifiable reason to also require that it be included in every
file, since the individual files are not individually distributed except
as part of the entire package.
