SetConsoleCtrlHandler not processing close messages

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2 total messages Started by Mike Collins Wed, 08 Aug 2007 12:11

#1469

Author: Mike Collins
Date: Wed, 08 Aug 2007 12:11

85 lines
3564 bytes

Hi all, posted a few days ago about a console application i was writing, 
specifically processing messages within.  I found some code that remy had 
posted and tried to impliment it.  The code seems to work but when i hit 
Ctrl+Break the console application does not terminate.  The 
SetConsoleCtrlHandler callback seems to be called and the PostQuitMessage() 
is sent but the console app does not terminate.  Thus i can't find any way 
to drop out of the message processing and my console app does not clean up 
after it's self.  My code looks like this:

BOOL CALLBACK HandlerRoutine(DWORD dwCtrlType)
{
   PostQuitMessage(0);
   return TRUE;
}

//---------------------------------------------------------------------------

int main(int argc, char* argv[])
{
   if ((argc > 1)&&(stricmp(argv[1], "/?") == 0))
   {
      // Show help options
      ...
   }
   else
   {
      int iPort        = DEF_SERVER_PORT_NO;
      int iServerType  = DEF_SERVER_TYPE;
      int iThreadCache = DEF_THREAD_CACHE_COUNT;
      int iReturnErr   = DEF_ERROR_RETURN_VALUE;
      AnsiString szExponent, szModulus;

      int iRtn = 0;
      TWebMod *WebMod = NULL;
      try
      {
         try
         {
            SetConsoleCtrlHandler(&HandlerRoutine, TRUE);
            WebMod = new TWebMod(NULL);
            WebMod->InitialiseSocket(iPort, iServerType, iThreadCache, 
szExponent, szModulus);

            MSG msg;
            while (GetMessage(&msg, NULL, 0, 0) > 0)   //&&(!bEnd))//&&(ch 
!= 'x'))
            {
               TranslateMessage(&msg);
               DispatchMessage(&msg);
               switch (msg.message)
               {
                  case WM_SYSCOMMAND    : if ((msg.wParam & 0xFFF0) != 
SC_CLOSE)
                                            break;
                                          // fall though to the next 
block...
                  case WM_CLOSE         : if (PeekMessage(&msg, NULL, 
WM_QUIT, WM_QUIT, PM_NOREMOVE) == 0)
                                            PostQuitMessage(0);
                                          break;
               }
            }
         }
         catch (...)
         {
            printf("\t\t\t  ERROR");
            iRtn = iReturnErr;
         }
      }
      __finally
      {
         if (WebMod)
         {
            delete WebMod;
            WebMod = NULL;
         }
         SetConsoleCtrlHandler(&HandlerRoutine, FALSE);
      }
      return iRtn;
   }
}

Any pointers would be greatfully recieved.

Mike C

Re: SetConsoleCtrlHandler not processing close messages

#1470

Author: Bob Gonder
Date: Thu, 09 Aug 2007 14:41

67 lines
2945 bytes

Mike Collins wrote:

>Hi all, posted a few days ago about a console application i was writing, 
>specifically processing messages within.

I don't use a message loop in my console app, but this is how I handle the handler.


static void EmergencyShutdown(void)	/*  we are getting out of here the hard way  */
{	throw_away_keys();		/*  toss any queued keys  */	
#if	UDP
	if( UDPRunning )
		KillUDP();	/* up to 5 sec delay */
#endif
	AppCanceled = TRUE;

	UnwindLockQue();
	UnwindFileQue();
	UnwindManagedIndexes();

	/*  remove myself from the handler queue  */
	SetConsoleCtrlHandler( &CtrlHandler, FALSE);
}

static BOOL _stdcall CtrlHandler(DWORD fdwCtrlType)
{
    switch (fdwCtrlType)
    { 
	/* Handle the CTRL+C signal. */ 
	case CTRL_C_EVENT: 
		push_key(CtrlC);	/*  pass Ctrl-C to app  */
		return TRUE;
 
	/* CTRL+CLOSE: confirm that the user wants to exit. */
/*	Ctrl_Close _needs_ to return False because I don't want a dialog poping up.
	Other events return True because I handled them this time,
	 and disabled myself so subsequent events will be false.
*/
	case CTRL_CLOSE_EVENT:
	case CTRL_BREAK_EVENT:
		EmergencyShutdown();
		return FALSE;	// next handler terminates me
 
	/* Pass other signals to the next handler. */ 
	/* Next handler will pop a terminate dialog */
	case CTRL_LOGOFF_EVENT:
	case CTRL_SHUTDOWN_EVENT: 
		EmergencyShutdown();
		return TRUE;
	default:
		return FALSE;
    }; 
}

Then, all sub-threads, such as a watchdog timer, check AppCanceled.
The application itself isn't going to run after I return.

>  The code seems to work but when i hit 
>Ctrl+Break the console application does not terminate.

Thanks, mine wasn't working either, then I switched it to FALSE
(see above), it terminated fine.

It could well be that because you don't discriminate in the handler,
that you enter an endless PostQuit-Close loop.
I would suggest turning off the handler within the handler.
That would eliminate the looping.

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