Function pipe_fops_poll

components/drivers/ipc/pipe.c:357–401

* @brief This function will get the pipe status. * * @param fd is the file descriptor. * * @param req is the request type. * * @return mask of the pipe status. * POLLIN means there is data to be read. * POLLHUP means there is no thread that occupied the pipe to open for writing. * POLLOUT means there is space to be written. * POLLERR mea

 *           POLLERR means there is no thread that occupied the pipe to open for reading.
 */
static int pipe_fops_poll(struct dfs_file *fd, rt_pollreq_t *req)
{
    int mask = 0;
    rt_pipe_t *pipe;
    int mode = 0;
    pipe = (rt_pipe_t *)fd->vnode->data;

    rt_poll_add(&pipe->reader_queue, req);
    rt_poll_add(&pipe->writer_queue, req);

    switch (fd->flags & O_ACCMODE)
    {
    case O_RDONLY:
        mode = 1;
        break;
    case O_WRONLY:
        mode = 2;
        break;
    case O_RDWR:
        mode = 3;
        break;
    }

    if (mode & 1)
    {
        if (rt_ringbuffer_data_len(pipe->fifo) != 0)
        {
            mask |= POLLIN;
        }
        else if (pipe->writer == 0)
        {
            mask = POLLHUP;
        }
    }

    if (mode & 2)
    {
        if (rt_ringbuffer_space_len(pipe->fifo) != 0)
        {
            mask |= POLLOUT;
        }
    }

    return mask;
}

static const struct dfs_file_ops pipe_fops =
{