// 必须的头文件;
#include <Windows.h>

// 获取注册表中的.net framwork版本信息;
#define MAX_VALUE_NAME 16383
#define TOTALBYTES    8192
#define BYTEINCREMENT 4096

void GetVersionFromRegistry()
{
	DWORD dwRet = 0;
	HKEY hKeyResult;
	HKEY hSubKeyResult;
	TCHAR szKeyValue[MAX_PATH] = {0};
	TCHAR szKeyName[MAX_PATH] = _T("SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\");
	if ( ERROR_SUCCESS == RegOpenKeyEx(HKEY_LOCAL_MACHINE, szKeyName, 0, KEY_READ, &hKeyResult))
	{
		// 枚举所有子键;
		DWORD dwSubKeyCount = 0;		// number of subkeys;
		DWORD dwSubKeyMaxSize = 0;		// longset subkey size;
		DWORD dwValueCount = 0;			// number of values;
		DWORD dwValueMaxSize = 0;		// longset value name;
		DWORD dwValueDataMaxSize = 0;	// longset value data;
		DWORD dwClassMaxSize = 0;
		DWORD dwClassNameLen = MAX_PATH;
		TCHAR szClassName[MAX_PATH] = _T("");
		DWORD dwSubKeyNameLen = 0;
		TCHAR szSubKeyName[MAX_VALUE_NAME] = _T("");
		DWORD dwValueNameLen = 0;
		TCHAR szValueName[MAX_VALUE_NAME] = _T("");
		DWORD dwSecurityDescriptor = 0;

		
		if ( ERROR_SUCCESS == RegQueryInfoKey(
			hKeyResult,						// Key句柄;
			szClassName,					// Class Name buffer;
			&dwSubKeyNameLen,				// size of class string;
			NULL,							// reserved;
			&dwSubKeyCount,					// number of subkeys;
			&dwSubKeyMaxSize,				// longset subkey size;	
			&dwClassMaxSize,				// longset class string;
			&dwValueCount,					// number of values for this key;
			&dwValueMaxSize,				// longset value name;
			&dwValueDataMaxSize,			// longset value data;
			&dwSecurityDescriptor,			// security descriptor;
			NULL							// last write name;
			) )
		{
			// 遍历所有子键;
			for ( int i = 0; i < dwSubKeyCount; i++ )
			{
				dwSubKeyNameLen = MAX_VALUE_NAME;
				if ( ERROR_SUCCESS == RegEnumKeyEx(hKeyResult, i, szSubKeyName, &dwSubKeyNameLen,NULL, NULL, NULL, NULL) )
				{
					if ( _tcsstr(szSubKeyName, _T("v")) )
					{
						// 查询版本号;
						if ( _tcsicmp(szSubKeyName, _T("v4")) == 0 )
						{
							// 查询Full键Release子键;
							_stprintf(szKeyName, _T("SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\%s\\Full\\"), szSubKeyName);
							if ( ERROR_SUCCESS == RegOpenKeyEx(HKEY_LOCAL_MACHINE, szKeyName, 0, KEY_READ, &hSubKeyResult) )
							{
								DWORD cbData = 0;
								DWORD dwBufferSize = TOTALBYTES;
								cbData = dwBufferSize;
								PPERF_DATA_BLOCK PerfData = (PPERF_DATA_BLOCK) malloc( dwBufferSize );
								dwRet = RegQueryValueEx(hSubKeyResult, _T("Version"), NULL, NULL, (LPBYTE)PerfData, &cbData);
								while ( dwRet == ERROR_MORE_DATA )
								{
									dwBufferSize += BYTEINCREMENT;
									cbData = dwBufferSize;
									PerfData = (PPERF_DATA_BLOCK) realloc( PerfData, dwBufferSize );

									dwRet = RegQueryValueEx( hSubKeyResult,
										TEXT("Version"),
										NULL,
										NULL,
										(LPBYTE) PerfData,
										&cbData );
								}

								// 版本号;4.0.30319
								if ( dwRet == ERROR_SUCCESS )
								{
									memcpy(szKeyValue, PerfData, cbData);
									if ( _tcscmp(szKeyValue,_T("4.0.30319")) >= 0 )
									{
										OutputDebugString(_T("已安装.net framwork:"));
										OutputDebugString(szKeyValue);
										OutputDebugString(_T("\n"));
									}
								}

								if (PerfData)
									free(PerfData);

								// 关闭注册表操作句柄;
								RegCloseKey(hSubKeyResult);
							}
						}
						else
						{// 4.0版本之前,直接获取Version键值;
							_stprintf(szKeyName, _T("SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\%s\\"), szSubKeyName);
							if ( ERROR_SUCCESS == RegOpenKeyEx(HKEY_LOCAL_MACHINE, szKeyName, 0, KEY_READ, &hSubKeyResult) )
							{
								DWORD cbData = 0;
								DWORD dwBufferSize = TOTALBYTES;
								cbData = dwBufferSize;
								PPERF_DATA_BLOCK PerfData = (PPERF_DATA_BLOCK) malloc( dwBufferSize );
								dwRet = RegQueryValueEx(hSubKeyResult, _T("Version"), NULL, NULL, (LPBYTE)PerfData, &cbData);
								while ( dwRet == ERROR_MORE_DATA )
								{
									dwBufferSize += BYTEINCREMENT;
									cbData = dwBufferSize;
									PerfData = (PPERF_DATA_BLOCK) realloc( PerfData, dwBufferSize );

									dwRet = RegQueryValueEx( hSubKeyResult,
										TEXT("Version"),
										NULL,
										NULL,
										(LPBYTE) PerfData,
										&cbData );
								}

								// 版本号;
								if ( dwRet == ERROR_SUCCESS )
								{
									memcpy(szKeyValue, PerfData, cbData);							
									OutputDebugString(_T("已安装.net framwork:"));
									OutputDebugString(szKeyValue);
									OutputDebugString(_T("\n"));
								}

								if (PerfData)
									free(PerfData);

								// 关闭注册表操作句柄;
								RegCloseKey(hSubKeyResult);
							}
						}
					}
				}
			}

#ifdef _QUERY_VALUE_	// 不查询键值;
			for ( int i = 0; i < dwValueCount; i++ )
			{
				dwValueNameLen = MAX_VALUE_NAME;
				szValueName[0] = '\0';
				if ( ERROR_SUCCESS == RegEnumKeyEx(hKeyResult, i, szValueName, &dwValueNameLen, NULL, NULL, NULL, NULL) )
				{
					OutputDebugString(szValueName);
					OutputDebugString(_T("\n"));
				}
			}
#endif
		}

		// 关闭注册表操作句柄;
		RegCloseKey(hKeyResult);
	}
}