int ff_close(int fd)
{
    f_close(&fd_pool[fd].f);
    if (fd_pool[fd].used)
        fd_pool[fd].used = 0;
    return 0;
}
int ff_close(int fd)
{
    f_close(&fd_pool[fd].f);
    if (fd_pool[fd].used)
        fd_pool[fd].used = 0;
    return 0;
}