#ifndef UNICODE
#define UNICODE
#endif //UNICODE

#ifndef _WIN32_MSI
#define _WIN32_MSI 200
#endif //_WIN32_MSI

#include <stdio.h>
#include <windows.h>
#include <msi.h>
#pragma comment(lib, "msi.lib")

const int cchGUID = 38;

UINT DetermineContextForAllProducts()
{
	WCHAR wszProductCode[cchGUID+1] = {0};
	WCHAR wszAssignmentType[10] = {0};
	DWORD cchAssignmentType = 
			sizeof(wszAssignmentType)/sizeof(wszAssignmentType[0]);
	DWORD dwIndex = 0;

	DWORD cchProductName = MAX_PATH;
	WCHAR* lpProductName = new WCHAR[cchProductName];
	if (!lpProductName)
	{
		return ERROR_OUTOFMEMORY;
	}

	UINT uiStatus = ERROR_SUCCESS;

	// enumerate all visible products
	do
	{
		uiStatus = MsiEnumProducts(dwIndex,
					      wszProductCode);
		if (ERROR_SUCCESS == uiStatus)
		{
			cchAssignmentType = 
				sizeof(wszAssignmentType)/sizeof(wszAssignmentType[0]);
			BOOL fPerMachine = FALSE;
			BOOL fManaged = FALSE;

			// Determine assignment type of product
			// This indicates whether the product
			// instance is per-user or per-machine
			if (ERROR_SUCCESS == 
				MsiGetProductInfo(wszProductCode,INSTALLPROPERTY_ASSIGNMENTTYPE,wszAssignmentType,&cchAssignmentType))
			{
				if (L'1' == wszAssignmentType[0])
					fPerMachine = TRUE;
			}
			else
			{
				// This halts the enumeration and fails. Alternatively the error
				// could be logged and enumeration continued for the
				// remainder of the products
				uiStatus = ERROR_FUNCTION_FAILED;
				break;
			}

			// determine the "managed" status of the product.
			// If fManaged is TRUE, product is installed managed
			// and runs with elevated privileges.
			// If fManaged is FALSE, product installation operations
			// run as the user.
			if (ERROR_SUCCESS != MsiIsProductElevated(wszProductCode,
								         &fManaged))
			{
				// This halts the enumeration and fails. Alternatively the error
				// could be logged and enumeration continued for the
				// remainder of the products
				uiStatus = ERROR_FUNCTION_FAILED;
				break;
			}

			// obtain the user friendly name of the product
			UINT uiReturn = MsiGetProductInfo(wszProductCode,INSTALLPROPERTY_PRODUCTNAME,lpProductName,&cchProductName);
			if (ERROR_MORE_DATA == uiReturn)
			{
				// try again, but with a larger product name buffer
				delete [] lpProductName;

				// returned character count does not include
				// terminating NULL
				++cchProductName;

				lpProductName = new WCHAR[cchProductName];
				if (!lpProductName)
				{
					uiStatus = ERROR_OUTOFMEMORY;
					break;
				}

				uiReturn = MsiGetProductInfo(wszProductCode,INSTALLPROPERTY_PRODUCTNAME,lpProductName,&cchProductName);
			}

			if (ERROR_SUCCESS != uiReturn)
			{
				// This halts the enumeration and fails. Alternatively the error
				// could be logged and enumeration continued for the
				// remainder of the products
				uiStatus = ERROR_FUNCTION_FAILED;
				break;
			}

			// output information
			wprintf(L" Product %s:\n", lpProductName);
			wprintf(L"\t%s\n", wszProductCode);
            			wprintf(L"\tInstalled %s %s\n", 
				fPerMachine ? L"per-machine" : L"per-user",
				fManaged ? L"managed" : L"non-managed");
		}
		dwIndex++;
	}
	while (ERROR_SUCCESS == uiStatus);

	if (lpProductName)
	{
		delete [] lpProductName;
		lpProductName = NULL;
	}

	return (ERROR_NO_MORE_ITEMS == uiStatus) ? ERROR_SUCCESS : uiStatus;
}