> I would appreciate if someone could review the patch and comment on the
> technique.

There are a few minor issues; overall, it looks correct:
- the test for "this is windows" should just use MS_WINDOWS.
- don't declare variables in the middle of a block; we use C89.
- the argument parsing looks incorrect; take a look at rename()
  for guidance. Supporting bytes is optional; IMO, requiring
  Unicode strings for the API would be fine.

I don't quite understand why you can't implement lstat, or why
you would want to call into ntpath. Take a look at how stat()
is implemented in the nt module.