Hello,

I just bought an IBM Thinkpad T-42, and found a couple of useless "Web Forward" and "Web Backwards" that I wrote a program to remap to Music Forwards and Music Backwards, something I use much more.  The program sets a keyboard hook with SetWindowsHookEx.  The standalone program set the hook, then popped up a message box, during which everything worked fine.  Once you clicked on the message box, the procedure would unhook and then the program finished.  Great for debugging and testing, now to make something useful...

So I went ahead and modified the program to be a Windows Service.  The actual keyboard hook is in a DLL.  Everything service-wise is working fine (i.e. Starting, Stopping, etc.), but the hook no longer works!  I did not change the code of how the hook was set (into a DLL), so I'm confused why this part no longer works.  The reason I know it doesn't work, is that I have some logging code, and I added a log to the top of the Keyboard Hook function that traps the keys to just say that the function was called... and it never gets called.

Any ideas?

Here's some code (parts taken out that I thought were irrelevant).

First, the DLL with the hook procedure:

[code]
BYTE vk_next = VK_MEDIA_NEXT_TRACK,
       vk_prev = VK_MEDIA_PREV_TRACK;

int WINAPI DllMain(HINSTANCE hInstance, DWORD fdwReason, PVOID pvReserved)
{
      Log("DllMain: called");
      return TRUE;
}

...

LRESULT CALLBACK LowLevelKeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
{
      Log("LowLevelKeyboardProc: Called");
      BOOL bSuppress = FALSE;

...

      return (bSuppress ? TRUE : CallNextHookEx(NULL, nCode, wParam, lParam));
}
[/code]

And then the service:

[code]
#define DLL_LOCATION "ibmremaplib.dll"
#define SERVICE_NAME "IBM Keyboard Remapper"

HOOKPROC hkprcSysMsg;
static HINSTANCE hinstDLL;
static HHOOK hhookSysMsg;
SERVICE_STATUS          ServiceStatus;
SERVICE_STATUS_HANDLE   hStatus;

HHOOK Start();
BOOL Stop();
void GetErrorString(LPVOID lpMsgBuf);
void ServiceMain(int argc, char** argv);
void ControlHandler(DWORD request);

HHOOK Start()
{
      hhookSysMsg = SetWindowsHookEx(WH_KEYBOARD_LL, hkprcSysMsg, hinstDLL, 0);
      return hhookSysMsg;
}

BOOL Stop()
{
      return UnhookWindowsHookEx(hhookSysMsg);
}

int WINAPI WinMain(HINSTANCE hinst, HINSTANCE prevInstance, PSTR pszCmdLine, int iCmdShow)
{
      LPVOID lpMsgBuf = NULL;
      hinstDLL = LoadLibrary((LPCTSTR) DLL_LOCATION);
      if(!hinstDLL)
      {
            GetErrorString(&lpMsgBuf);
            //MessageBox(NULL, (LPTSTR)lpMsgBuf, TEXT("Error1"), 0);
            Log((PTSTR) lpMsgBuf);
            return S_FALSE;
      }
      hkprcSysMsg = (HOOKPROC)GetProcAddress(hinstDLL, "LowLevelKeyboardProc");
      if(!hkprcSysMsg)
      {
            GetErrorString(&lpMsgBuf);
            Log((PTSTR)lpMsgBuf);
            return S_FALSE;
      }
      Log("WinMain: called");
      SERVICE_TABLE_ENTRY ServiceTable[2];
      ServiceTable[0].lpServiceName = SERVICE_NAME;
      ServiceTable[0].lpServiceProc = (LPSERVICE_MAIN_FUNCTION)ServiceMain;

      ServiceTable[1].lpServiceName = NULL;
      ServiceTable[1].lpServiceProc = NULL;
      // Start the control dispatcher thread for our service
      StartServiceCtrlDispatcher(ServiceTable);
      LocalFree(lpMsgBuf);
      return S_OK;
}

void GetErrorString(void *lpMsgBuf)
{
      FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
            NULL,
            GetLastError(),
            MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
            (LPTSTR) lpMsgBuf,
            0,
            NULL
      );
}

void ServiceMain(int argc, char** argv)
{
      ServiceStatus.dwServiceType = SERVICE_WIN32;
      ServiceStatus.dwCurrentState = SERVICE_START_PENDING;
      ServiceStatus.dwControlsAccepted = SERVICE_ACCEPT_STOP | SERVICE_ACCEPT_SHUTDOWN;
      ServiceStatus.dwWin32ExitCode = 0;
      ServiceStatus.dwServiceSpecificExitCode = 0;
      ServiceStatus.dwCheckPoint = 0;
      ServiceStatus.dwWaitHint = 0;

      hStatus = RegisterServiceCtrlHandler(
            SERVICE_NAME,
            (LPHANDLER_FUNCTION)ControlHandler);
      if(hStatus == (SERVICE_STATUS_HANDLE)0)
      {
            // Registering Control Handler failed
            Log(TEXT("Registering Control Handler failed."));
            return;
      }

      // We report the running status to SCM.
      ServiceStatus.dwCurrentState = SERVICE_RUNNING;
      SetServiceStatus (hStatus, &ServiceStatus);

      if(!Start())
      {
            Log(TEXT("ServiceMain: Could not hook!"));
      }
      else
      {
            TCHAR msg[50];
            Log(TEXT("ServiceMain: Started"));
            sprintf(msg, "%0.8X", hhookSysMsg);
            Log(msg);
      }
      while(ServiceStatus.dwCurrentState == SERVICE_RUNNING)
      {
            Sleep(5000);
      }
}

void ControlHandler(DWORD request)
{
      switch(request)
      {
      case SERVICE_CONTROL_STOP:
      case SERVICE_CONTROL_SHUTDOWN:
            if(!Stop())
            {
                  Log(TEXT("ControlHandler: Could not unhook!"));
            }
            else Log(TEXT("ControlHandler: Stopped."));
            ServiceStatus.dwWin32ExitCode = 0;
            ServiceStatus.dwCurrentState = SERVICE_STOPPED;
            SetServiceStatus (hStatus, &ServiceStatus);
            return;
      }

      // Report current status
      SetServiceStatus (hStatus, &ServiceStatus);
}

[/code]

Thanks for any help!
Kevin Grigorenko