try_open
if (try_open(O_WRONLY, EINVAL) != 0)
if (try_open(O_RDWR, EINVAL) != 0)
if (try_open(O_RDONLY | O_EXCL, EINVAL) != 0)
if (try_open(O_RDONLY | O_NONBLOCK, EINVAL) != 0)
if (try_open(O_RDONLY | O_NDELAY, EINVAL) != 0)