
  -spec get_cwd() -> {ok, Dir} | {error, Reason}
                   when Dir :: filename(), Reason :: posix().

  Returns {ok, Dir}, where Dir is the current working directory
  of the file server.

  Note:
    In rare circumstances, this function can fail on Unix. It can
    occur if read permission does not exist for the parent
    directories of the current directory.

  A typical error reason:

  eacces:
    Missing read permission for one of the parents of the current
    directory.
