关于rt-thread的mailbox

这几天再看rt-thread的使用例程，还没有深入到内核级别。编写采用类似Linux的封装形式，c语言面向对象风格。有个地方看得还是感觉不太懂，感觉有点怪。

{
    char *str;
    while (1)
    {
       rt_kprintf("thread1: try to recv a mail\n");

      
       if (rt_mb_recv(&mb, (rt_uint32_t *)&str, RT_WAITING_FOREVER) == RT_EOK)
//       if (rt_mb_recv(&mb, (rt_uint32_t *)str, RT_WAITING_FOREVER) == RT_EOK)
       {
          rt_kprintf("thread1: get a mail from mailbox, the content:%s\n", str);
           if (str == mb_str3)
              break;

          
          rt_thread_mdelay(100);
       }
    }
   
   rt_mb_detach(&mb);
}

char *str 是个野指针，通过取值操作在rt_mb_recv函数中初始化，比较难懂。试了下去掉取地址操作还不行。是不是有更好的表达方式呢？

在rt_err_t rt_mb_recv函数中的赋值操作如下

/**
 * This function will receive a mail from mailbox object, if there is no mail
 * in mailbox object, the thread shall wait for a specified time.
 *
 * @param mb the mailbox object
 * @param value the received mail will be saved in
 * @param timeout the waiting time
 *
 * @return the error code
 */
rt_err_t rt_mb_recv(rt_mailbox_t mb, rt_ubase_t *value, rt_int32_t timeout)

/* fill ptr */
*value = mb->msg_pool[mb->out_offset];