Function timerfd_read

components/libc/posix/io/timerfd/timerfd.c:119–176

static ssize_t timerfd_read(struct dfs_file *file, void *buf, size_t count)
#else
static ssize_t timerfd_read(struct dfs_file *file, void *buf, size_t count, off_t *pos)
#endif
{
    struct rt_timerfd *tfd;
    rt_uint64_t *buffer;
    int ret = 0;

    buffer = (rt_uint64_t *)buf;

    if (sizeof(buffer) > count)
    {
        rt_set_errno(EINVAL);
        return -1;
    }

    tfd = file->vnode->data;

    if (!tfd)
    {
        rt_set_errno(EINVAL);
        return -1;
    }

    if ((rt_atomic_load(&(tfd->ticks)) == 0) && (file->flags & O_NONBLOCK))
    {
        rt_set_errno(EAGAIN);
        return -EAGAIN;
    }
    else
    {
        if (rt_atomic_load(&(tfd->ticks)) == 0)
        {
            tfd->wqn.polling_thread = rt_thread_self();

            if (tfd->wqn.wqueue)
            {
                rt_wqueue_remove(&tfd->wqn);
            }
            rt_wqueue_add(&tfd->timerfd_queue, &tfd->wqn);

            ret = rt_thread_suspend_with_flag(tfd->wqn.polling_thread, RT_INTERRUPTIBLE);
            if (ret == RT_EOK)
            {
                rt_schedule();
            }
            else
            {
                return ret;
            }
        }

        (*buffer) = rt_atomic_load(&(tfd->timeout_num));
        rt_atomic_store(&(tfd->timeout_num), 0);
        rt_atomic_store(&(tfd->ticks), 0);
    }

    return sizeof(buffer);
}