rem: errno = ENOSYS;
add: errno = EOPNOTSUPP;
context: lchown (const char *file, uid_t uid, gid_t gid){  struct stat stats;  if (lstat (file, &stats) == 0 && S_ISLNK (stats.st_mode))    {      errno = ENOSYS;      return -1;    }  return chown (file, uid, gid);}