int main(void)
{
    return RT_EOK;
}

msh />onenet_mqtt_init
[I/onenet.mqtt] RT-Thread OneNET package(V1.0.0) initialize success.
msh />list device
device           type         ref count
-------- -------------------- ----------
MQTT0    Pipe                 0
uart2    Character Device     1
uart1    Character Device     2
pin      Pin Device           0

// 文件 dfs_posix.c
int open(const char *file, int flags, ...)
{
    int fd, result;
    struct dfs_file *d;
    /* allocate a fd */
    fd = fd_new();
    if (fd < 0)
    {
        rt_set_errno(-ENOMEM);
        return -1;
    }
    d = fd_get(fd);
    // 阻塞在以下代码 
    result = dfs_file_open(d, file, flags);
    .............
}