glibc源代码声称系统调用在Linux上不会失败：@H_301_3@

time_t res = INTERNAL_SYSCALL (time,err,1,NULL);
  /* There cannot be any error.  */

如果你看一下内核源代码就是这种情况：@H_301_3@

SYSCALL_DEFINE1(time,time_t __user *,tloc)
{
        time_t i = get_seconds();

        if (tloc) {
                if (put_user(i,tloc))
                        return -EFAULT;
        }
        force_successful_syscall_return();
        return i;
}