Add handshake to coordintate with connection of VNC client. fb_initialize() will not return until the connection is established

graphics/vnc/server/vnc_fbdev.c

@@ -123,9 +123,7 @@ static struct fb_cursorsize_s g_csize;
 #endif
 #endif
 
-/* The framebuffer object -- There is no private state information in this simple
+/* The framebuffer objects, one for each configured display. */
- * framebuffer simulation.
- */
 
 static struct vnc_fbinfo_s g_fbinfo[RFB_MAX_DISPLAYS];
 
@@ -133,6 +131,13 @@ static struct vnc_fbinfo_s g_fbinfo[RFB_MAX_DISPLAYS];
  * Public Data
  ****************************************************************************/
 
+/* Used to synchronize the server thread with the framebuffer driver.
+ * NOTE:  This depends on the fact that all zero is correct initial state
+ * for the semaphores.
+ */
+
+sem_t g_fbsem[RFB_MAX_DISPLAYS];
+
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
@@ -324,7 +329,7 @@ static int up_getcursor(FAR struct fb_vtable_s *vtable,
 #endif
 
 /****************************************************************************
- * Name:
+ * Name: up_setcursor
  ****************************************************************************/
 
 #ifdef CONFIG_FB_HWCURSOR
@@ -374,6 +379,57 @@ static int up_setcursor(FAR struct fb_vtable_s *vtable,
 }
 #endif
 
+/****************************************************************************
+ * Name: vnc_wait_server
+ *
+ * Description:
+ *   Wait for the server to be connected to the VNC client.  We can do
+ *   nothing until that connection is established.
+ *
+ * Input parameters:
+ *   display - In the case of hardware with multiple displays, this
+ *     specifies the display.  Normally this is zero.
+ *
+ * Returned Value:
+ *   Zero is returned on success; a negated errno value is returned on any
+ *   failure.
+ *
+ ****************************************************************************/
+
+static inline int vnc_wait_server(int display)
+{
+  /* Check if there has been a session allocated yet.  This is one of the
+   * first things that the VNC server will do with the kernel thread is
+   * started.  But we might be here before the thread has gotten that far.
+   *
+   * If it has been allocated, then wait until it is in the RUNNING state.
+   * The RUNNING state indicates that the server has started, it has
+   * established a connection with the VNC client, it is negotiated
+   * encodings and framebuffer characteristics, and it has started the
+   * updater thread.  The server is now ready to recieve Client-to-Server
+   * messages and to perform remote framebuffer updates.
+   */
+
+ while (g_vnc_sessions[display] == NULL ||
+        g_vnc_sessions[display]->state != VNCSERVER_RUNNING)
+   {
+     /* The server is not yet running.  Wait for the server to post the FB
+      * semaphore.  In certain error situations, the server may post the
+      * semaphore, then reset it to zero.  There are are certainly race
+      * conditions here, but I think none that are fatal.
+      */
+
+     while (sem_wait(&g_fbsem[display]) < 0)
+       {
+         /* sem_wait() should fail only if it is interrupt by a signal. */
+
+         DEBUGASSERT(get_errno() == EINTR);
+       }
+   }
+
+  return OK;
+}
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -408,23 +464,33 @@ int up_fbinitialize(int display)
   gvdbg("Starting the VNC server for display %d\n", display);
   DEBUGASSERT(display >= 0 && display < RFB_MAX_DISPLAYS);
 
-  (void)itoa(display, str, 10);
+  /* Check if the server is already running */
-  argv[0] = str;
-  argv[1] = NULL;
 
-  pid = kernel_thread("vnc_server", CONFIG_VNCSERVER_PRIO,
+  if (g_vnc_sessions[display] != NULL)
-                       CONFIG_VNCSERVER_STACKSIZE,
-                       (main_t)vnc_server, argv);
-  if (pid < 0)
     {
-      gdbg("ERROR: Failed to start the VNC server: %d\n", (int)pid);
+      DEBUGASSERT(g_vnc_sessions[display]->state >= VNCSERVER_INITIALIZED);
-      return (int)pid;
+    }
+  else
+    {
+      /* Format the kernel thread arguments (ASCII.. yech) */
+
+      (void)itoa(display, str, 10);
+      argv[0] = str;
+      argv[1] = NULL;
+
+      pid = kernel_thread("vnc_server", CONFIG_VNCSERVER_PRIO,
+                           CONFIG_VNCSERVER_STACKSIZE,
+                           (main_t)vnc_server, argv);
+      if (pid < 0)
+        {
+          gdbg("ERROR: Failed to start the VNC server: %d\n", (int)pid);
+          return (int)pid;
+        }
     }
 
   /* Wait for the VNC client to connect and for the RFB to be ready */
-#warning Missing logic
 
-  return OK;
+  return vnc_wait_server(display);
 }
 
 /****************************************************************************
@@ -503,6 +569,7 @@ FAR struct fb_vtable_s *up_fbgetvplane(int display, int vplane)
 
 void up_fbuninitialize(int display)
 {
+#if 0 /* Do nothing */
   FAR struct vnc_session_s *session = vnc_find_session(display);
   FAR struct vnc_fbinfo_s *fbinfo;
 
@@ -511,6 +578,7 @@ void up_fbuninitialize(int display)
 #warning Missing logic
   UNUSED(session);
   UNUSED(fbinfo);
+#endif
 }
 
 /****************************************************************************

graphics/vnc/server/vnc_receiver.c

@@ -159,7 +159,7 @@ int vnc_receiver(FAR struct vnc_session_s *session)
                 }
               else
                 {
-#warning Missing logic
+                  /* REVISIT: SetPixelFormat is currently ignored */
                 }
             }
             break;
@@ -198,7 +198,7 @@ int vnc_receiver(FAR struct vnc_session_s *session)
                     }
                   else
                     {
-#warning Missing logic
+                      /* REVISIT: SetEncodings is currently ignored */
                     }
                 }
             }
@@ -353,7 +353,7 @@ int vnc_receiver(FAR struct vnc_session_s *session)
                     }
                   else
                     {
-#warning Missing logic
+                      /* REVISIT: ClientCutText is currently ignored */
                     }
                 }
             }

graphics/vnc/server/vnc_server.c

@@ -62,14 +62,14 @@
  ****************************************************************************/
 
 /****************************************************************************
- * Private Data
+ * Public Data
  ****************************************************************************/
 
 /* Given a display number as an index, the following array can be used to
  * look-up the session structure for that display.
  */
 
-static FAR struct vnc_session_s *g_vnc_sessions[RFB_MAX_DISPLAYS];
+FAR struct vnc_session_s *g_vnc_sessions[RFB_MAX_DISPLAYS];
 
 /****************************************************************************
  * Private Functions
@@ -281,6 +281,7 @@ int vnc_server(int argc, FAR char *argv[])
        */
 
       vnc_reset_session(session, fb);
+      sem_reset(&g_fbsem[display], 0);
 
       /* Establish a connection with the VNC client */
 
@@ -313,7 +314,13 @@ int vnc_server(int argc, FAR char *argv[])
               continue;
             }
 
-          /* Start the VNC receiver on this this.  The VNC receiver handles
+          /* Let the framebuffer driver know that we are ready to preform
+           * updates.
+           */
+
+          sem_post(&g_fbsem[display]);
+
+          /* Run the VNC receiver on this trhead.  The VNC receiver handles
            * all Client-to-Server messages.  The VNC receiver function does
            * not return until the session has been terminated (or an error
            * occurs).

graphics/vnc/server/vnc_server.h

@@ -230,7 +230,7 @@ struct vnc_session_s
 };
 
 /****************************************************************************
- * Public Function Prototypes
+ * Public Data
  ****************************************************************************/
 
 #ifdef __cplusplus
@@ -241,6 +241,20 @@ extern "C"
 #define EXTERN extern
 #endif
 
+/* Given a display number as an index, the following array can be used to
+ * look-up the session structure for that display.
+ */
+
+EXTERN FAR struct vnc_session_s *g_vnc_sessions[RFB_MAX_DISPLAYS];
+
+/* Used to synchronize the server thread with the framebuffer driver. */
+
+EXTERN sem_t g_fbsem[RFB_MAX_DISPLAYS];
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
 /****************************************************************************
  * Name: vnc_server
  *