text: /****************************************************************************
   * libnx/nxmu/nx_block.c
   *
   *   Copyright (C) 2012-2013 Gregory Nutt. All rights reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   * 3. Neither the name NuttX nor the names of its contributors may be
   *    used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
   * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <tinyara/config.h>
  
  #include <errno.h>
  #include <debug.h>
  
  #include <tinyara/nx/nx.h>
  #include <tinyara/nx/nxbe.h>
  #include <tinyara/nx/nxmu.h>
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: nx_block
   *
   * Description:
   *   This is callback will do to things:  (1) any queue a 'blocked' callback
   *   to the window and then (2) block any further window messaging.
   *
   *   The 'blocked' callback is the response from nx_block (or nxtk_block).
   *   Those blocking interfaces are used to assure that no further messages are
   *   are directed to the window. Receipt of the blocked callback signifies
   *   that (1) there are no further pending callbacks and (2) that the
   *   window is now 'defunct' and will receive no further callbacks.
   *
   *   This callback supports coordinated destruction of a window in multi-
   *   user mode.  In multi-use mode, the client window logic must stay
   *   intact until all of the queued callbacks are processed.  Then the
   *   window may be safely closed.  Closing the window prior with pending
   *   callbacks can lead to bad behavior when the callback is executed.
   *
   * Input Parameters:
   *   wnd - The window to be blocked
   *   arg - An argument that will accompany the block messages (This is arg2
   *         in the blocked callback).
   *
   * Return:
   *   OK on success; ERROR on failure with errno set appropriately
   *
   ****************************************************************************/
  
  int nx_block(NXWINDOW hwnd, FAR void *arg)
  {
    FAR struct nxbe_window_s *wnd = (FAR struct nxbe_window_s *)hwnd;
    struct nxsvrmsg_blocked_s outmsg;
    int ret = OK;
  
  #ifdef CONFIG_DEBUG_FEATURES
    if (!hwnd)
      {
        set_errno(EINVAL);
        return ERROR;
      }
  #endif
  
    /* Ignore additional attempts to block messages (no errors reported) */
  
    if (!NXBE_ISBLOCKED(wnd))
      {
        /* Mark the window as blocked.  This will stop all messages to the window
         * (EXCEPT the NX_SVRMSG_BLOCKED).  Blocking the messages before sending the
         * blocked message is awkward but assures that no other messages sneak into
         * the message queue before we can set the blocked state.
         */
  
        NXBE_SETBLOCKED(wnd);
  
        /* Send the message inicating that the window is blocked (and because of
         * queue also that there are no additional queue messages for the window)
         */
  
        outmsg.msgid = NX_SVRMSG_BLOCKED;
        outmsg.wnd   = wnd;
        outmsg.arg   = arg;
  
        /* Send the window message via nxmu_sendserver (vs. nxmu_sendwindow) so
         * that it will not be blocked.
         */
  
        ret = nxmu_sendserver(wnd->conn, &outmsg, sizeof(struct nxsvrmsg_blocked_s));
      }
  
    return ret;
  }
  