Function login_cap_sys::secure_path

pub unsafe extern "C" fn secure_path(_path: *mut c_char) -> c_int

From login_getclass(3):

The secure_path() function takes a path name and returns 0 if the path
name is secure, -1 if not.  To be secure a path must exist, be a regular
file (and not a directory), owned by root, and only writable by the owner
(root).