Where did MAPISVC.INF go?

[This is now documented here: http://msdn.microsoft.com/en-us/library/bb820993.aspx]

There's a KB article (http://support.microsoft.com/kb/229700) that discusses how to use FGetComponentPath to find MAPISVC.INF. It has two major problems:

• It doesn't work well in most non-English locales
• It doesn't work at all with Outlook 2007

The code below corrects both problems. Here's why:

Non-English

I'll admit - I never fully understood this before. The documentation for FGetComponentPath indicates the szQualifier should be "(t)he MSIApplicationLCID or MSIOfficeLCID subkey described in Setting Up the MSI Keys for Your MAPI DLL." I must have skimmed over that comment hundreds of times before it sunk in. It means to go get those keys and pass what's in them to FGetComponentPath! This will allow FGetComponentPath to use the data in those keys to help locate where the localized copy of the component (MAPI) was installed. If szQualifier is left out, it will try to find the installed component using the system's default user LCID, then the system's default LCID, then a hard coded value of 1033 (English-US). This is why the code in the article would work in English locales but not elsewhere.

Outlook 2007

Here, again, it pays to read the documentation for FGetComponentPath (something I'm guilty of not doing). It says szComponent should be "(t)he MSIComponentID reg key described in Mapi32.dll Stub Registry Settings." The code in the article ignored this and instead passed "{473FF9A0-D659-11D1-A4B2-006008AF820E}", which was the component ID of MAPISVC.INF on Outlook 2000. This worked fine when the article was written, and continued to work up through Outlook 2003. However, Outlook 2007 no longer installs MAPISVC.INF (though it will use it if it finds it), so this component ID stops working. The fix is to pass "{FF1D0740-D227-11D1-A4B0-006008AF820E}", which is the component ID of MAPI that you'd get if you read the MSIComponentID key. In the code below, I hard coded this ID, but it would be better to try and read it from the registry first and only fall back to the hard coded string on failure.

This code should work with all versions of Outlook, but I've only tested it with Outlook 2003 and 2007.

// HrGetRegMultiSZValueA
// Get a REG_MULTI_SZ registry value - allocating memory using new to hold it.
void HrGetRegMultiSZValueA(
   IN HKEY hKey, // the key.
   IN LPCSTR lpszValue, // value name in key.
   OUT LPVOID* lppData) // where to put the data.
{
   *lppData = NULL;
   DWORD dwKeyType = NULL;      
   DWORD cb = NULL;
   LONG lRet = 0;
   
   // Get its size
   lRet = RegQueryValueExA(
      hKey,
      lpszValue,
      NULL,
      &dwKeyType,
      NULL,
      &cb);

   if (ERROR_SUCCESS == lRet && cb && REG_MULTI_SZ == dwKeyType)
   {
      *lppData = new BYTE[cb];
      
      if (*lppData)
      {
         // Get the current value
         lRet = RegQueryValueExA(
            hKey, 
            lpszValue, 
            NULL, 
            &dwKeyType, 
            (unsigned char*)*lppData, 
            &cb);
         
         if (ERROR_SUCCESS != lRet)
         {
            delete[] *lppData;
            *lppData = NULL;
         }
      }
   }
}

typedef BOOL (STDAPICALLTYPE FGETCOMPONENTPATH)
(LPSTR szComponent,
 LPSTR szQualifier,
 LPSTR szDllPath,
 DWORD cchBufferSize,
 BOOL fInstall);
typedef FGETCOMPONENTPATH FAR * LPFGETCOMPONENTPATH; 

///////////////////////////////////////////////////////////////////////////////
// Function name   : GetMAPISVCPath
// Description       : This will get the correct path to the MAPISVC.INF file.
// Return type      : void 
// Argument         : LPSTR szMAPIDir - Buffer to hold the path to the MAPISVC file.
//                    ULONG cchMAPIDir - size of the buffer
void GetMAPISVCPath(LPSTR szMAPIDir, ULONG cchMAPIDir)
{
   HRESULT hRes = S_OK;
   UINT uiRet = 0;
   LONG lRet = 0;
   BOOL bRet = true;
   
   szMAPIDir[0] = '\0'; // Terminate String at pos 0 (safer if we fail below)
   
   CHAR szSystemDir[MAX_PATH+1] = {0};
   
   // Get the system directory path
   // (mapistub.dll and mapi32.dll reside here)
   uiRet = GetSystemDirectoryA(szSystemDir, MAX_PATH);
   if (uiRet > 0)
   {
      CHAR szDLLPath[MAX_PATH+1] = {0};
      
      hRes = StringCchPrintfA(szDLLPath, MAX_PATH+1, "%s\\%s", 
         szSystemDir, "mapistub.dll");
      if (SUCCEEDED(hRes))
      {
         LPFGETCOMPONENTPATH pfnFGetComponentPath = NULL;
         
         HMODULE hmodStub = 0;
         HMODULE hmodMapi32 = 0;
         
         // Load mapistub.dll
         hmodStub = LoadLibraryA(szDLLPath);
         if (hmodStub)
         {   
            // Get the address of FGetComponentPath from the mapistub
            pfnFGetComponentPath = (LPFGETCOMPONENTPATH)GetProcAddress(
               hmodStub, "FGetComponentPath");
         }
         
         // If we didn't get the address of FGetComponentPath
         // try mapi32.dll
         if (!pfnFGetComponentPath)
         {
            hRes = StringCchPrintfA(szDLLPath, MAX_PATH+1, "%s\\%s",
               szSystemDir, "mapi32.dll");
            if (SUCCEEDED(hRes))
            {
               // Load mapi32.dll
               hmodMapi32 = LoadLibraryA(szDLLPath);
               if (hmodMapi32)
               {
                  // Get the address of FGetComponentPath from mapi32
                  pfnFGetComponentPath = (LPFGETCOMPONENTPATH)GetProcAddress(
                     hmodMapi32, "FGetComponentPath");
               }
            }
         }
         if (pfnFGetComponentPath)
         {
            LPSTR szAppLCID = NULL;
            LPSTR szOfficeLCID = NULL;
            HKEY hMicrosoftOutlook = NULL;
            
            lRet = RegOpenKeyEx(
               HKEY_LOCAL_MACHINE,
               _T("Software\\Clients\\Mail\\Microsoft Outlook"),
               NULL,
               KEY_READ,
               &hMicrosoftOutlook);
            
            if (ERROR_SUCCESS == lRet && hMicrosoftOutlook)
            {
               HrGetRegMultiSZValueA(hMicrosoftOutlook, "MSIApplicationLCID", (LPVOID*) &szAppLCID);
               HrGetRegMultiSZValueA(hMicrosoftOutlook, "MSIOfficeLCID", (LPVOID*) &szOfficeLCID);
            }
            
            if (szAppLCID)
            {
               bRet = pfnFGetComponentPath(
                  "{FF1D0740-D227-11D1-A4B0-006008AF820E}", szAppLCID, szMAPIDir, cchMAPIDir, true);
            }
            if ((!bRet || szMAPIDir[0] == _T('\0')) && szOfficeLCID)
            {
               bRet = pfnFGetComponentPath(
                  "{FF1D0740-D227-11D1-A4B0-006008AF820E}", szOfficeLCID, szMAPIDir, cchMAPIDir, true);
            }
            if (!bRet || szMAPIDir[0] == _T('\0'))
            {
               bRet = pfnFGetComponentPath(
                  "{FF1D0740-D227-11D1-A4B0-006008AF820E}", NULL, szMAPIDir, cchMAPIDir, true);
            }
            
            // We got the path to msmapi32.dll - need to strip it
            if (bRet && szMAPIDir[0] != _T('\0'))
            {
               LPSTR lpszSlash = NULL;
               LPSTR lpszCur = szMAPIDir;
               
               for (lpszSlash = lpszCur; *lpszCur; lpszCur = lpszCur++)
               {
                  if (*lpszCur == _T('\\')) lpszSlash = lpszCur;
               }
               *lpszSlash = _T('\0');
            }

            delete[] szOfficeLCID;
            delete[] szAppLCID;
            if (hMicrosoftOutlook) RegCloseKey(hMicrosoftOutlook);      
         }
            
            // If FGetComponentPath returns FALSE or if
            // it returned nothing, or if we never found an
            // address of FGetComponentPath, then
            // just default to the system directory
         if (!bRet || szMAPIDir[0] == '\0')
         {
            hRes = StringCchPrintfA(
               szMAPIDir, cchMAPIDir,"%s", szSystemDir);
         }
         
         if (szMAPIDir[0] != _T('\0'))
         {
            hRes = StringCchPrintfA(
               szMAPIDir, cchMAPIDir, "%s\\%s", szMAPIDir, "MAPISVC.INF");
         }
         
         if (hmodMapi32) FreeLibrary(hmodMapi32);
         if (hmodStub) FreeLibrary(hmodStub);
      }
   }   
}