[update] format code

Author: liukangcc

components/finsh/shell.c

@@ -162,9 +162,13 @@ int finsh_getchar(void)
     RT_ASSERT(shell != RT_NULL);
 
     device = shell->device;
+    if (device == RT_NULL)
+    {
+        return -1; /* EOF */
+    }
 
     while (rt_device_read(device, -1, &ch, 1) != 1)
-    {        
+    {
         rt_sem_take(&shell->rx_sem, RT_WAITING_FOREVER);
         if (shell->device != device)
         {