calling GetModuleFileNameEx via psapi.dll is not working, but why?

Question

I am using MinGW which does not have full functionality. eg. It has no wchar_t stream support. I've managed to get around that by writing a mini-set of manipulators (the wcusT() in the code below).. but I find I'm getting stymied again with GetModuleFileNameEx. I have not been able to natively run GetModuleFileNameEx() This function is defined in <psapi.h>, but there seems to be nothing for it to link to. That is my no.1 question: Can/does/is MinGW able to run GetModuleFileNameEx? What do I need to do? Am I missing something simple? As a workaround, I've tried to run it indirectly via a call to its dll (psapi.dll) which is in the Windows system32 folder... but something is wrong. I've got another no-go situation. I'd appreciate any comments on the code below .. thanks

int WINAPI WinMain (HINSTANCE hThisInstance, HINSTANCE hPrevInstance, LPSTR lpszArgument, int nCmdShow)
{ /// typedef and load a dll function
  /// ===============================
  typedef DWORD (__stdcall *foo)(HANDLE, HMODULE, LPTSTR, DWORD);
  LPTSTR  ptcPSAPI_DLL = _T("C:\\WINDOWS\\system32\\psapi.dll");
  HMODULE   hPSAPI_DLL = LoadLibrary(ptcPSAPI_DLL);
  if( !hPSAPI_DLL ) 
  { std::cout<<"ERROR: Failed to load "<<wcusT(ptcPSAPI_DLL)<<std::endl;
    return 1;
  }
  foo GetModFnEx=(foo)GetProcAddress(hPSAPI_DLL,
                  #ifdef  UNICODE
                         "GetModuleFileNameExW");
                  #else
                         "GetModuleFileNameExA");
                  #endif

  /// call the dll library function
  /// =============================
  HWND   hWndNPP = FindWindow(_T("Notepad++"),NULL); // the window calass name
  TCHAR  ytcMFqFn[FILENAME_MAX]; // the buffer for the file name
  DWORD  dwBytes = (GetModFnEx)( hWndNPP, NULL, ytcMFqFn, sizeof(ytcMFqFn) );  
  DWORD  dwError = GetLastError();

  std::cout<<wcusT(_T("hWndNPP  "))<<"="<<hWndNPP        <<"="<<std::endl;
  std::cout<<wcusT(_T("ytcMFqFn "))<<"="<<wcusT(ytcMFqFn)<<"="<<std::endl;
  std::cout<<wcusT(_T("dwBytes  "))<<"="<<dwBytes        <<"="<<std::endl;
  std::cout<<wcusT(_T("dwError  "))<<"="<<dwBytes        <<"="<<std::endl;
  return 0;

  // Output ===============
  // SBCS 
  //   hWndNPP  =0x320606=
  //   ytcMFqFn ==
  //   dwBytes  =0=
  //   dwError  =0=
  // UNICODE
  //   h W n d N P P     =0x320606=
  //   y t c M F q F n   =(☻æ|♀ =
  //   d w B y t e s     =0=
  //   d w E r r o r     =0=
  //  ======================

Answer 1

Your calling GetModuleFileNameEx incorrectly

HWND   hWndNPP = FindWindow(_T("Notepad++"),NULL); 
DWORD  dwBytes = (GetModFnEx)( hWndNPP // this is ment to be a process handle, not a HWND
  , NULL, ytcMFqFn, sizeof(ytcMFqFn) );

MSDN doc on GetModuleFileNameEx

you might try getting a process handle using one of the following

::GetWindowThreadProcessId(hWnd, &dwProcessID);
HANDLE hProcess = ::OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, FALSE, dwProcessID);

// also in PSAPI - EnumProcesses will return an array of app process ids
(BOOL(WINAPI *)(DWORD *,DWORD, DWORD *)) GetProcAddress( psapi, "EnumProcesses" );