Function pipe_fops_open

components/drivers/ipc/pipe.c:59–110

* @brief This function will open a pipe. * * @param fd is the file descriptor. * * @return Return the operation status. * When the return value is 0, it means the operation is successful. * When the return value is -1, it means the file descriptor is invalid. * When the return value is -RT_ENOMEM, it means insufficient memory allocation failed. */

 *           When the return value is -RT_ENOMEM, it means insufficient memory allocation failed.
 */
static int pipe_fops_open(struct dfs_file *fd)
{
    int rc = 0;
    rt_pipe_t *pipe;

    pipe = (rt_pipe_t *)fd->vnode->data;
    if (!pipe)
    {
        return -1;
    }

    rt_mutex_take(&pipe->lock, RT_WAITING_FOREVER);

    if ((fd->flags & O_ACCMODE) == O_RDONLY)
    {
        pipe->reader += 1;
    }

    if ((fd->flags & O_ACCMODE) == O_WRONLY)
    {
        pipe->writer += 1;
    }
    if (fd->vnode->ref_count == 1)
    {
        pipe->fifo = rt_ringbuffer_create(pipe->bufsz);
        if (pipe->fifo == RT_NULL)
        {
            rc = -RT_ENOMEM;
            goto __exit;
        }
    }

    if ((fd->flags & O_ACCMODE) == O_RDONLY && !pipe->writer)
    {
        /* wait for partner */
        rc = rt_condvar_timedwait(&pipe->waitfor_parter, &pipe->lock,
                                  RT_INTERRUPTIBLE, RT_WAITING_FOREVER);
        if (rc != 0)
        {
            pipe->reader--;
        }
    }
    else if ((fd->flags & O_ACCMODE) == O_WRONLY)
    {
        rt_condvar_broadcast(&pipe->waitfor_parter);
    }

__exit:
    rt_mutex_release(&pipe->lock);

    return rc;
}

/**
 * @brief    This function will close a pipe.