Invoke chmod or lchmod on file, FILE, using mode MODE, in the directory
open on descriptor FD. If possible, do it without changing the
working directory. Otherwise, resort to using save_cwd/fchdir,
- then mkdir/restore_cwd. If either the save_cwd or the restore_cwd
- fails, then give a diagnostic and exit nonzero.
+ then (chmod|lchmod)/restore_cwd. If either the save_cwd or the
+ restore_cwd fails, then give a diagnostic and exit nonzero.
Note that an attempt to use a FLAG value of AT_SYMLINK_NOFOLLOW
on a system without lchmod support causes this function to fail. */