Namedpipe - C / C++ / MFC Discussion Boards

Re: Access Violation.

David Crow18-Jul-07 2:41

David Crow

18-Jul-07 2:41

paras_s12 wrote:
i use debugger...

How exactly? Did you single-step through this code snippet?

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

help with files

josip cagalj17-Jul-07 23:53

josip cagalj

17-Jul-07 23:53

Is there any method known which can list all directories from an filepath.
E.g.
c:\dir1\dir2\dir3\name.abc -> directories are: dir1, dir2 and dir3?
Anything, using loops or something else?

Thanks for help!

Re: help with files

PravinSingh18-Jul-07 1:45

PravinSingh

18-Jul-07 1:45

Call FindFirstFile with c:\dir1\dir2\dir3\name.abc and an empty WIN32_FIND_DATA variable as parameter. Your WIN32_FIND_DATA variable.cFileName will give you the first matching file name. Then you can call FindNextFile in a while loop for subsequent matches. Use the same WIN32_FIND_DATA variable as a parameter to FindNextFile. (Looping through FindNextFile is required if you are searching using wildcards, like C:\Temp\*.*)
Refer http://msdn2.microsoft.com/en-us/library/aa365200.aspx[^] for complete example.

One more thing to take care, if you search for *.*, then the first two matches will be . and .. respectively, so you may choose to ignore them.

It's better to know some of the questions than all of the answers.

Pravin.

Re: help with files

David Crow18-Jul-07 2:44

David Crow

18-Jul-07 2:44

You'll want to use PathFindNextComponent().

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: help with files

Hamid_RT25-Jul-07 8:30

Hamid_RT

25-Jul-07 8:30

See DlgDirList does any help?

WhiteSky

Subclassing Issue

LoveCPlusplus17-Jul-07 23:42

LoveCPlusplus

17-Jul-07 23:42

Hi everyone,

When I use Instance Subclassing technique, SetWindowLong() or SetWindowLongPtr() returns NULL pointer. The last error is 50 ERROR_NOT_SUPPORT. I ran the same program on more than 10 XP machines. One of them failed. Does anybody here encounter such problem? Any suggestion?

Thank you in advanced

Re: Subclassing Issue

Mike Dimmick18-Jul-07 2:53

Mike Dimmick

18-Jul-07 2:53

From the SetWindowLongPtr documentation:

"If the previous value is zero and the function succeeds, the return value is zero, but the function does not clear the last error information. To determine success or failure, clear the last error information by calling SetLastError(0), then call SetWindowLongPtr. Function failure will be indicated by a return value of zero and a GetLastError result that is nonzero."

The only cases in which these functions should fail are if you pass an invalid window handle, or if you pass an invalid index value (more than the number of bytes associated with the window, or not one of the defined GWL/GWLP values).

Stability. What an interesting concept. -- Chris Maunder

Namedpipe

charian092017-Jul-07 23:35

charian0920

17-Jul-07 23:35

Hi!

Good day Smile | :)

I have this problem about synchronization on namedpipe ...
I have this namedpipe server that allows multiple instances.
The algorithm I have is I'll wait for a client to connect to the namedpipe then spawn a thread which will read the message from the namedpipe. My expectation on the spawned thread is that when the client has disconnected the spawned thread will end also. But when I tried testing my code, the thread count keeps on increasing due to the spawned thread, which i think means I was not able to detect that the client had disconnected or something else Frown | :(

Any help is greatly appreciated.

Below are my codes:
1. Createnamedpipe, wait for a client to connect, and spawned a thread.

<br />
UINT fnRcvMsgsFrmNamedpipeThread(LPVOID pParam)<br />
{<br />
<br />
	DWORD	dwResult = SUCCEED;	<br />
	CString strLog( _T( "" ) );<br />
<br />
	OVERLAPPED stClientConnectOverLap = {0};<br />
	stClientConnectOverLap.hEvent = CreateEvent(<br />
					NULL,    // no security attributes<br />
					TRUE,    // manual reset event<br />
					FALSE,   // not-signalled<br />
					NULL);   // no name<br />
<br />
	if( stClientConnectOverLap.hEvent == NULL )<br />
	{<br />
	 return 0;<br />
	}<br />
	<br />
	HANDLE	hEvents;<br />
	hEvents = stClientConnectOverLap.hEvent;<br />
<br />
	CString strFormatPipeName( _T( "" ) );<br />
	strFormatPipeName.Format( "\\\\%s\pipe\mypipename", STR_PERIOD );<br />
<br />
	HANDLE hClientReqPipe;<br />
	<br />
	while ( TRUE )<br />
	{<br />
	hClientReqPipe = CreateNamedPipe( strFormatPipeName,<br />
					 FILE_FLAG_OVERLAPPED | PIPE_ACCESS_DUPLEX,									          PIPE_TYPE_MESSAGE |  PIPE_READMODE_MESSAGE | PIPE_WAIT,<br />
				          PIPE_UNLIMITED_INSTANCES,	<br />
                                              0, 0, 10000, NULL );   <br />
	if( hClientReqPipe == INVALID_HANDLE_VALUE )<br />
	{	<br />
	dwResult = GetLastError();<br />
	break;<br />
	}<br />
<br />
	if( !ConnectNamedPipe( hClientReqPipe, &stClientConnectOverLap ) )<br />
	{<br />
	   if( GetLastError() != ERROR_PIPE_CONNECTED )<br />
	   {<br />
		DWORD dwRet = WaitForSingleObject( hEvents, INFINITE );<br />
		if( dwRet != WAIT_OBJECT_0 )<br />
		{<br />
		    dwResult = GetLastError();<br />
		    break;<br />
		}<br />
	   }<br />
<br />
	}<br />
	CWinThread *pReadMsgThread = AfxBeginThread( fnReadMsgFrmNamedpipe, (LPVOID) hClientReqPipe );<br />
	if( NULL == pReadMsgThread )<br />
	{<br />
	break;<br />
	}<br />
	<br />
        }<br />
<br />
	// Close handles<br />
	::CloseHandle( hClientReqPipe );<br />
	::CloseHandle( stClientConnectOverLap.hEvent );<br />
	<br />
	return dwResult;<br />
}<br />

2. Spawned thread

<br />
UINT fnReadMsgFrmNamedpipe(LPVOID pParam)<br />
{	<br />
	I32L	dwResult = SUCCEED;	<br />
	CString strLog( _T("") );<br />
	HANDLE hClientReqPipe = (HANDLE) pParam;<br />
<br />
	OVERLAPPED stClientRecOverLap = {0};<br />
<br />
	stClientRecOverLap.hEvent = CreateEvent( NULL,    // no security attributes<br />
											 TRUE,    // manual reset event<br />
											 FALSE,   // not-signalled<br />
											 NULL );   // no name<br />
<br />
	if( stClientRecOverLap.hEvent == NULL )<br />
	{<br />
		return 0;<br />
	}<br />
	<br />
	HANDLE		hEvents;<br />
	hEvents = stClientRecOverLap.hEvent;<br />
<br />
	DWORD				dwTotalByte, dwRead, dwRet;<br />
<br />
	while ( TRUE )<br />
	{	<br />
		dwTotalByte = 0;<br />
		dwRead = 0;<br />
<br />
		ReadFile( hClientReqPipe, NULL, 0, &dwRead, &stClientRecOverLap );<br />
		dwRet = WaitForSingleObject( hEvents, INFINITE );<br />
		<br />
		if( dwRet != WAIT_OBJECT_0 )<br />
		{<br />
			dwResult = GetLastError();<br />
			break;<br />
		}<br />
		if( !PeekNamedPipe( hClientReqPipe, NULL, 0, NULL, &dwTotalByte, NULL ) )<br />
		{<br />
			dwResult = GetLastError();<br />
			break;<br />
		}<br />
<br />
		// There are messages to read in namedpipe<br />
		if( dwTotalByte > 0 )<br />
		{<br />
			// Allocate memory for the message based on the size from PeekNamedPipe<br />
			char*	pBuffer = new char[ dwTotalByte + 1 ];<br />
			if( !pBuffer )<br />
			{<br />
				continue;				<br />
			}<br />
			::ZeroMemory( pBuffer, dwTotalByte + 1 );<br />
<br />
			ReadFile( hClientReqPipe, pBuffer, dwTotalByte, &dwRead, &stClientRecOverLap );<br />
			dwRet = WaitForSingleObject( stClientRecOverLap.hEvent, 10000 );<br />
			if( dwRet != WAIT_OBJECT_0 )<br />
			{<br />
				dwResult = GetLastError();<br />
				break;<br />
			}<br />
<br />
			delete pBuffer;<br />
			<br />
		}<br />
	}<br />
	<br />
	DisconnectNamedPipe( hClientReqPipe );<br />
	CloseHandle( stClientRecOverLap.hEvent );<br />
	return dwResult;<br />
}<br />

3. Namedpipe Client

<br />
BOOL fnNewConnectNamedPipe(LPCTSTR lpczPipeName)<br />
{<br />
	HANDLE hPipe; <br />
	<br />
	// Try to open a named pipe; wait for it, if necessary. <br />
	while (TRUE)<br />
	{<br />
		hPipe = CreateFile( <br />
				lpczPipeName,   // pipe name <br />
				GENERIC_READ |  // read and write access <br />
				GENERIC_WRITE, <br />
				0,              // no sharing <br />
				NULL,           // default security attributes<br />
				OPEN_EXISTING,  // opens existing pipe <br />
				0,              // default attributes <br />
				NULL);          // no template file <br />
		<br />
		// Break if the pipe handle is valid. <br />
		<br />
		if (hPipe != INVALID_HANDLE_VALUE) <br />
			break; <br />
		<br />
		// Exit if an error other than ERROR_PIPE_BUSY occurs. <br />
		<br />
		if (GetLastError() != ERROR_PIPE_BUSY) <br />
		{<br />
			printf("Could not open pipe"); <br />
			return FALSE;<br />
		}<br />
		<br />
		// All pipe instances are busy, so wait for 20 seconds. 		<br />
		if ( !WaitNamedPipe(lpczPipeName, 20000) ) <br />
		{ <br />
			printf("Could not open pipe"); <br />
			return FALSE;<br />
		} <br />
	} <br />
	<br />
 	DWORD dwBytesWritten = 0;	<br />
	DWORD dwBytesWrite = m_strMsgText.GetLength();<br />
	DWORD dwRet;<br />
<br />
	OVERLAPPED WriteOverLap = {0};<br />
	WriteOverLap.hEvent = CreateEvent(<br />
								NULL,    // no security attributes<br />
								TRUE,    // manual reset event<br />
								FALSE,   // not-signalled<br />
								NULL);   // no name<br />
<br />
	HANDLE	hEvent;<br />
	hEvent = WriteOverLap.hEvent;<br />
	if( !WriteFile(hPipe, m_strMsgText, dwBytesWrite + 1, &dwBytesWritten, &WriteOverLap) )<br />
	{<br />
		if (GetLastError() == ERROR_IO_PENDING)<br />
		{<br />
			dwRet = WaitForSingleObject(WriteOverLap.hEvent, 10000);<br />
			if (dwRet != WAIT_OBJECT_0) // Something not correct happens<br />
			{<br />
				CloseHandle(WriteOverLap.hEvent);<br />
				CloseHandle(hPipe);<br />
				hPipe = NULL;<br />
				return FALSE;<br />
			}<br />
		}<br />
		else <br />
		{<br />
			CloseHandle(WriteOverLap.hEvent); <br />
			CloseHandle(hPipe);<br />
			hPipe = NULL;<br />
			return FALSE;<br />
		}<br />
	}<br />
	<br />
	CloseHandle(WriteOverLap.hEvent); <br />
	CloseHandle(hPipe);<br />
	hPipe = NULL;<br />
<br />
    return TRUE; <br />
}<br />

Re: Namedpipe

Mark Salsbery18-Jul-07 6:19

Mark Salsbery

18-Jul-07 6:19

Have you tried putting a breakpoint (or several) in the thread proc and watching what is
happening?

The debugger is your friend!

Mark

Mark Salsbery
Microsoft MVP - Visual C++

"Great job team! Head back to base for debriefing and cocktails."

Re: Namedpipe

charian092018-Jul-07 14:57

charian0920

18-Jul-07 14:57

hi mark,

yup I already did that ...
the funny thing is that the spawned thread is terminating when I run it with breakpoints
and when I put messageboxes.

What happens after OnInitDialog()?

rp_suman17-Jul-07 22:41

rp_suman

17-Jul-07 22:41

After OnInitDialog()of Dialog-based applications, how the dialog is getting the message from Windows. Is the dialog polling or by wake up?
Best Regards,
Suman

Re: What happens after OnInitDialog()?

Cedric Moonen17-Jul-07 22:49

Cedric Moonen

17-Jul-07 22:49

AFAIK, the application waits until a message is received. So, no CPU time is consumed during this wait (not like if you were actively polling).

Cédric Moonen
Software developer

Charting control [v1.2]

Re: What happens after OnInitDialog()?

Nibu babu thomas18-Jul-07 1:15

Nibu babu thomas

18-Jul-07 1:15

rp_suman wrote:
After OnInitDialog()of Dialog-based applications, how the dialog is getting the message from Windows. Is the dialog polling or by wake up?

If it's a modal dialog then DoModal has a message loop for processing messages, and if it's a non modal dialog box then m_pMainWnd of CWinApp class helps in doing that. CWinApp::Run function has a message loop that processes messages on m_pMainWnd and this is the reason my we have to set m_pMainWnd in InitInstance member function of CWinApp derived class.

Nibu thomas
A Developer

Code must be written to be read, not by the compiler, but by another human being.

http:\\nibuthomas.wordpress.com

Modifying the Windows Explorer Statusbar

Toadflakz_UK17-Jul-07 22:14

Toadflakz_UK

17-Jul-07 22:14

Right, so I would like to put a custom control into the status bar in Windows Explorer while my namespace extension is showing, much like you would if you were writing your own MFC/ATL/WTL-based program.

However, all I've managed to find anywhere are articles on how to do it in your own MFC/ATL/WTL-based program or how to use IShellBrowser::SetStatusTextSB.

Is what I want to do possible?

How to make first dialog iitself in a dialog based application Modeless

robshere17-Jul-07 20:52

robshere

17-Jul-07 20:52

Hai All,

I'm creating a dialog based application.I want the first dialog that gets created from Inintinstance of App to be a modeless one.My problem is that if i use create() i've to declare the dialog object,with a scope in the entire application(ie, on heap).If I declare it in the demo2.h.I've tried so but getting erors when I'm trying to declare an object of app say myapp.

Please suggest me where I went wrong.Also please tell me is it possible to have the first window in an application to be a modless one.If so pls tell me the way to do that.

Thanks in advance
Robs here

Re: How to make first dialog iitself in a dialog based application Modeless

Arman S.17-Jul-07 21:35

Arman S.

17-Jul-07 21:35

What is your puropse of doing that? Making the dialog [from a dialog-based app] be modeless is meaningless unless you specify the aim.

Anyway, if you look at the InitInstance method, you will see that this method will not return until CMyDlg::DoModal returns. Note that the application will exit if the InitInstance exits in a dialog based app. So if your dlg were modeless you'd not do much for him as the app would exit just after the dlg displayed.

Still you may simulate smth like what you want. The code in InitInstance might look like so;

CMyDlg *pDlg = new CMyDlg();
pDlg->Create(CMyDlg::IDD, NULL);
// you may use CWnd::GetDesktopWindow() instead of NULL if it make sense

pDlg->ShowWindow(SW_SHOW);

CWinThread::Run();

// Here CWinThread::Run enters a message loop and thus will prevent the app exit instantly.

The only remaining point was to exit the app when the dialog closed. So you should have PostQuitMessage inside CMyDlg::PostNcDestroy;

PostQuitMessage(0);
delete this;

Once again, these all are note a good practice...

--
=====
Arman

Re: How to make first dialog iitself in a dialog based application Modeless

Adrian Brutus17-Jul-07 22:08

Adrian Brutus

17-Jul-07 22:08

Hi maybe this can help u

**************************************************************************************

BOOL CDlgMaxApp::InitInstance()
{
// Standard initialization
// If you are not using these features and wish to reduce the size
// of your final executable, you should remove from the following
// the specific initialization routines you do not need.

CDlgTestDlg* pDlg = new CDlgTestDlg;
pDlg->Create( IDD_DLGMAX_DIALOG );
pDlg->ShowWindow( SW_SHOW );
m_pMainWnd = pDlg;

// Since the dialog has been closed, return FALSE so that we exit the
// application, rather than start the application's message pump.
return TRUE;
}

int CDlgMaxApp::ExitInstance()
{
// TODO: Add your specialized code here and/or call the base class
delete m_pMainWnd;
return CWinApp::ExitInstance();
}

int CDlgMaxApp::Run()
{
// TODO: Add your specialized code here and/or call the base class

return CWinApp::Run();
}
**************************************************************************************
InitInstance returns TRUE to start the message pump, if returns FALSE then will not call Run()

Adrian Brutus

Re: How to make first dialog iitself in a dialog based application Modeless

Arman S.17-Jul-07 22:33

Arman S.

17-Jul-07 22:33

Yes, this is even better. I missed to do
m_pMainWnd = pDlg;

The point is that CWinApp::Run doesn't enter a message loop if m_pMainWnd is NULL which is not the case now.

Thanks.

--
=====
Arman

Re: How to make first dialog iitself in a dialog based application Modeless

robshere17-Jul-07 22:15

robshere

17-Jul-07 22:15

Hai Arman Z. Sahakyan ,

Thanks for you reply.I'm new to this GUI part.Correct me if I'm wrong.

My aim is to make onscreen keyboard.For that I need to type in the alphabets and other things to the application ,say,notepad using the onscreen keyboard.this is my aim.Please correct me if my logic don't work.Is there any better way?

Thanks in advance
Robs here

Re: How to make first dialog iitself in a dialog based application Modeless

Arman S.17-Jul-07 22:43

Arman S.

17-Jul-07 22:43

Well, I don't think you need all this stuff about modeless dialogs. You can use ordinary dialog based application (with DoModal). On the other hand, if you want your keyboard to be on the top of all other windows, then use SetWindowPos inside OnInitDialog like so;

SetWindowPos(&CWnd::wndTopMost, x, y, width, height, SWP_SHOWWINDOW);

--
=====
Arman

Re: How to make first dialog iitself in a dialog based application Modeless

robshere17-Jul-07 22:59

robshere

17-Jul-07 22:59

Hai Arman,

My requirment is that I want to create an "ONSCREEN KEYBOARD" application .It should work excatlly like the physical keyboard.For example suppose if we run the "ONSCREEN KEYBOARD" application , now change the focus to an already opened window say notepad the "ONSCREEN KEYBOARD" dialog should not be minimized.It should show as it is inactive but at the same time if the cursor now focused on notepad and again the user clicks soame keys with the mouse on the "ONSCREEN KEYBOARD" application ,the keys pressed (be a,then a should be displayed inside the notepad)should be displayed in the note pad.This is my intention.

Regards
Robs here

Re: How to make first dialog iitself in a dialog based application Modeless

David Crow18-Jul-07 2:49

David Crow

18-Jul-07 2:49

robshere wrote:
For example suppose if we run the "ONSCREEN KEYBOARD" application , now change the focus to an already opened window say notepad the "ONSCREEN KEYBOARD" dialog should not be minimized.It should show as it is inactive but at the same time if the cursor now focused on notepad and again the user clicks soame keys with the mouse on the "ONSCREEN KEYBOARD" application ,the keys pressed (be a,then a should be displayed inside the notepad)should be displayed in the note pad.This is my intention.

And what makes you think a modeless dialog is required for this? A dialog's mode (i.e., modal, modeless) governs how the dialog behaves in relation to its parent window, not windows of other processes.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: How to make first dialog iitself in a dialog based application Modeless

robshere18-Jul-07 3:17

robshere

18-Jul-07 3:17

Hai DavidCrow,

Sorry,my logic was wrong.I got it right now.I want to set the focus from the current application to other application.This is how I'm working on.Thanks for your valuable information and your precious time.I really apprictiate ur kindness for answering me.Any how it gave me very valid informations.

Regards
Robs here

Re: How to make first dialog iitself in a dialog based application Modeless

David Crow18-Jul-07 3:39

David Crow

18-Jul-07 3:39

robshere wrote:
I got it right now.

Glad you got it going.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Convert ActiveX DLL to ActiveX EXE.

Anand Todkar17-Jul-07 20:30

Anand Todkar

17-Jul-07 20:30

Hi,

Can you suggest me if we can convert existing ActiveX DLL( created in Visual Studio 6.0) to ActiveX EXE?

Thanks in Advence. Smile | :)

Thanks,
Anand.

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.