experiment: process communication depend by registry

/// @file srcProcessCommunicationDependRegistry.cpp 
/// @brief KEY_WOW64_64KEY or KEY_WOW64_32KEY use on RegXX functions
/// @title experiment: process communication depend by registry
/// @reference http://www.codeproject.com/Articles/14200/Registry-Redirector-in-x64-IA64/

#include "stdafx.h"
#include <windows.h>
#include <tchar.h>
#include <string>

#ifndef G_REG_KEY_NAME
#define G_REG_KEY_NAME		_T("SOFTWARE\\LsApp\\Parameter")
#define G_REG_VALUE_NAME	_T("ProcessId")
#endif

DWORD WriteProcessHandleOnX86();
DWORD ReadProcessHandelOnX64();

int _tmain(int argc, _TCHAR* argv[])
{
	LONG lRc = 0;

	lRc = WriteProcessHandleOnX86();
	_tprintf(_T("%s = %d\n"), _T("WriteProcessHandleOnX86"), lRc);

	lRc = ReadProcessHandelOnX64();
	_tprintf(_T("%s = %d\n"), _T("ReadProcessHandelOnX64"), lRc);

	getchar();

	/// run result
	/// run x86 version first
	/**
	On X86 write: szValue = 4660
	WriteProcessHandleOnX86 = 0
	ReadProcessHandelOnX64 = 1
	*/
	/// run x64 version
	/**
	WriteProcessHandleOnX86 = 1
	On X64 Read: szValue = 4660
	ReadProcessHandelOnX64 = 0
	*/

	return 0;
}

DWORD WriteProcessHandleOnX86()
{
	LONG lRc = S_FALSE;
#if _M_IX86
	HKEY hKey = NULL;
	TCHAR szValue[_MAX_PATH];

	::ZeroMemory(szValue, sizeof(szValue));
	lRc = RegOpenKeyEx(HKEY_LOCAL_MACHINE, G_REG_KEY_NAME, NULL, KEY_ALL_ACCESS | KEY_WOW64_64KEY, &hKey);
	if(ERROR_SUCCESS != lRc)
	{	
		/// if key not exist, try to create it
		lRc = RegCreateKeyEx(HKEY_LOCAL_MACHINE,G_REG_KEY_NAME, 0, NULL, 0, KEY_ALL_ACCESS | KEY_WOW64_64KEY, NULL, &hKey, NULL);
	}

	if(ERROR_SUCCESS != lRc)
	{
		goto _WriteProcessHandleOnX86_END;
	}

	_stprintf(szValue, _T("%d"), GetCurrentProcessId());
	_tprintf(_T("%s: %s = %s\n"), _T("On X86 write"), _T("szValue"), szValue);
	RegSetValueEx(hKey, G_REG_VALUE_NAME, 0, REG_SZ,
		(const BYTE*) szValue,
		(_tcslen(szValue) + 1) * sizeof(TCHAR));

_WriteProcessHandleOnX86_END:
	if(hKey)
	{
		RegCloseKey(hKey);
	}

#endif
	return lRc;
}

DWORD ReadProcessHandelOnX64()
{
	LONG lRc = S_FALSE;
#if _M_X64
	HKEY hKey = NULL;
	TCHAR szValue[_MAX_PATH];
	DWORD nLenValue = sizeof(szValue);

	::ZeroMemory(szValue, sizeof(szValue));
	lRc = RegOpenKeyEx(HKEY_LOCAL_MACHINE, G_REG_KEY_NAME, NULL, KEY_ALL_ACCESS | KEY_WOW64_64KEY, &hKey);
	if(ERROR_SUCCESS != lRc)
	{
		/// x86 application write to registry, x64 application read back only
		goto _ReadProcessHandelOnX64_END;
	}

	lRc = RegQueryValueEx(hKey, G_REG_VALUE_NAME, NULL, NULL, (BYTE*)szValue, &nLenValue);
	if(ERROR_SUCCESS == lRc)
	{
		_tprintf(_T("%s: %s = %s\n"), _T("On X64 Read"), _T("szValue"), szValue);
	}

_ReadProcessHandelOnX64_END:
	if(hKey)
	{
		RegCloseKey(hKey);
	}

#endif
	return lRc;
}