Creating modal dialog in vc++

[dhanashivam]

Hi All,

I have developed a VC+ dll file which provides a product key for my msi setup file. This VC++ dll work fine together with my setup file. but,

my problem is, i have given a message box inside the dll for showing error message while an invalid key is entered. but the messagebox is not shown as modal dialog. i must want to show this as modal dialog.

in my VC++ method i have passed the MSIHANDLE from the msi file.

how can i change the message as modal dialog?

my code is:

#include "windows.h"
#include "msi.h"
#include "msiquery.h "

extern "C" _declspec(dllex port) UINT __stdcall VerifyPID(MSIHA NDLE hInstall);

TCHAR* GetPIDValue(TCH AR*);

extern "C" UINT __stdcall VerifyPID(MSIHA NDLE hInstall)
{
UINT nRetVal = 0;
UINT uiMsiRc;
TCHAR szPidKey[MAX_PATH];
TCHAR szSourceDir[MAX_PATH];
TCHAR* lpszPidValue;
DWORD dwBuffer;

dwBuffer = sizeof(szSource Dir)/sizeof(TCHAR);

uiMsiRc = MsiGetProperty( hInstall, TEXT("SourceDir "), szSourceDir, &dwBuffer);

if (ERROR_SUCCESS != uiMsiRc)
{
MessageBox(NULL , "Not able to retrieve the SourceDir property. The setup may be corrupt. Please contact Technical Support.", "Setup Error", MB_OK | MB_ICONEXCLAMAT ION);
return 0;
}

lpszPidValue = GetPIDValue(szS ourceDir);

dwBuffer = sizeof(szPidKey )/sizeof(TCHAR);

uiMsiRc = MsiGetProperty( hInstall, TEXT("PIDKEY"), szPidKey, &dwBuffer);

if (ERROR_SUCCESS != uiMsiRc)
{
MessageBox(NULL , "Not able to retrieve PIDKEY property. The setup may be corrupt. Please contact Technical Support.", "Setup Error", MB_OK | MB_ICONEXCLAMAT ION);
return 0;
}

int str = lstrcmp(szPidKe y, lpszPidValue);

if (str == 0)
MsiSetProperty( hInstall, "PIDCHECK", "TRUE");
else
{
MsiSetProperty( hInstall, "PIDCHECK", "FALSE");
MessageBox(NULL ,"Please enter the correct product registration code!", "Invalid Key", MB_OK | MB_ICONINFORMAT ION);
}
return 0;
}

TCHAR* GetPIDValue(TCH AR* lpszSourceDir)
{
return "123-456-789";
}

Please help to resolve it.

Thanks in advance.

Regards,
Dhanasekaran. G

[weaknessforcats]

Your code works for me after I changed it this way:
[code=cpp]
void __stdcall DisplayFromDll( )
{
MessageBox(NULL , TEXT("Not able to retrieve the SourceDir property. The setup may be corrupt. Please contact Technical Support."), TEXT("Setup Error"), MB_OK | MB_ICONEXCLAMAT ION);

}
[/code]

Notice I used the TEXT macro. Otherwise, your code won't compile.

Next, be sure your DLL project has a DEF file that exports the C++ name as a name you can use with GetProcAddress:
[code=cpp]
;BEGIN ADLL.DEF FILE
;This DEF file is required becuase the argument to GetProcAddress( )
;for the function is a C-string and it will never be equal to the
;C++ mangled name for the function
;This DEF file maps the mangled name to a name that can be used with GetProcAddress( )
;Note also: Change project settings in Visual Studio to send the LINK this def file.
;Visual Studio.NET: Project Properties/Linker/Input/Module Definition File/...Path to the def file\Adll.def
LIBRARY ADll
EXPORTS
;Exported Name C++ Mangled Name
DisplayFromDll = ?DisplayFromDll @@YGXXZ
;END DEF FILE
[/code]

Next, be certain to set the path to the DEF file in the linker input project property.

Finally, I called the funciton:
[code=cpp]
//First, load the dll into memory
HMODULE theDll = LoadLibrary(TEX T("C:\\Scratch\ \Instructor\\De bug\\DLLExample .dll"));
if (!theDll)
{
MessageBox(NULL , TEXT("Dll Failed to Load"), TEXT("Fatal Error"), MB_OK | MB_ICONEXCLAMAT ION);
return 1;
}

//Second, get the address of the desried function from the dll
FARPROC addr = GetProcAddress( theDll, "DisplayFromDll ");
if (!addr)
{

//Look up the error in the system errors list
unsigned int what = GetLastError();
if (what == ERROR_PROC_NOT_ FOUND)
{
MessageBox(NULL , TEXT("Function not found in the dll"), TEXT("Fatal Error"), MB_OK | MB_ICONEXCLAMAT ION);

}
return 2;
}
cout << "The function has been located in the dll" << endl;
//Declare a function pointer that can accept the address of the function.
//You will need to know the function prototype to do this.
//Dll function prototypes should be provided by the vendor of the dll
void (__stdcall *DisplayFromDll )();
//Type-cast the address returned from GetProcAddress to the function pointer type
DisplayFromDll = reinterpret_cas t<void (__stdcall *)()> (addr);
//Now use the function pointer to call the function:
DisplayFromDll( );
[/code]