The CDetectDotNet class detects whether the .NET Framework is
installed on a machine and also retrieves the list of Framework versions
currently installed. Not unpredictably, it's an unmanaged C++ class with zero
dependency on anything .NET related - it would have been utterly worthless if it
required the .NET framework to run. I believe the class would be pretty useful in installer
applications, that might need to detect whether the target machine has .NET
installed and if so, whether a specific version is available. One important
thing to keep in mind is that the .NET versions retrieved represent CLR versions
(along with the matching BCL), and may not necessarily mean that the
corresponding SDKs are present; the distinction to be observed here is that
between the full SDK and the .NET runtime.
Add DetectDotNet.h and DetectDotNet.cpp to your project.
#include "DetectDotNet.h" // . . . CDetectDotNet detect; vector<string> CLRVersions; cout << "Is .NET present : " << (detect.IsDotNetPresent() ? "Yes" : "No") << endl; TCHAR szPath[300]; cout << "Root Path : " << (detect.GetInstallRootPath(szPath, 299) ? szPath : "") << endl; cout << "Number of CLRs detected : " << (int)detect.EnumerateCLRVersions(CLRVersions) << endl; cout << "CLR versions available :-" << endl; for(vector<string>::iterator it = CLRVersions.begin(); it < CLRVersions.end(); it++) { cout << *it << endl; } cout << "Press any key..." << endl; getch();
Is .NET present : Yes Root Path : C:\WINDOWS\Microsoft.NET\Framework\ Number of CLRs detected : 2 CLR versions available :- 2.0.50215 1.1.4322 Press any key...
CDetectDotNet();Constructs a CDetectDotNet object.
bool IsDotNetPresent();Detects if .NET is present on a system.
Returns true if .NET is detected on the system and false
otherwise.
bool GetInstallRootPath(TCHAR* szRootPath, DWORD dwBufferSize);Retrieves the root installation path of the .NET Framework
szRootPath - The .NET root installation path is returned in
szRootPath.dwBufferSize - Specifies the length of szRootPath.Returns true if successful and false otherwise.
size_t EnumerateCLRVersions(vector<string>& CLRVersions);Enumerates the list of active CLR versions in the system.
CLRVersions - This will contain the list of CLR versions
detected on the system.Returns the count of CLR versions detected.
The extremely simple technique I use to detect whether the .NET Framework is
present on the system is to LoadLibrary "mscoree.dll" and if that
succeeds, I also do a GetProcAddress for "GetCORVersion"
which takes care of scenarios where the OS version comes with a placeholder DLL.
I also cache the result (in the class constructor), so that subsequent calls
need not repeat the LoadLibrary/GetProcAddress calls.
bool CDetectDotNet::IsDotNetPresent() { return m_bDotNetPresent; }
bool CDetectDotNet::IsDotNetPresentInternal() { bool bRet = false; //Attempt to LoadLibrary "mscoree.dll" (the CLR EE shim) HMODULE hModule = LoadLibrary(_T("mscoree")); if(hModule) { //Okay - that worked, but just to ensure that this is //not a placeholder DLL shipped with some earlier OS versions, //we attempt to GetProcAddress "GetCORVersion". bRet = (GetProcAddress(hModule, "GetCORVersion") != NULL); FreeLibrary(hModule); } return bRet; }
Here's the mechanism I use to enumerate the available CLR versions on a system.
GetRequestedRuntimeInfo to query the presence of the CLR
versions detected in the previous step. Surprisingly, the pwszVersion
parameter that GetRequestedRuntimeInfo takes is actually the
directory name within the .NET root path where a specific CLR version
exists. Thus, if you rename the default folder name (usually something like
"v2.0.50215") to something else, GetRequestedRuntimeInfo will
still succeed.GetRequestedRuntimeInfo has succeeded, we still need
to get the version string (to take care of situations where someone has
renamed the folder name). To do this I simply look for mscorlib.dll
within that folder and extract its file version, and you can be sure that
any successful implementation of the framework will definitely have an
mscorlib.dll in its installation folder.Note - You'll find GetRequestedRuntimeInfo in
mscoree.h. Here's what I have in the version that comes with VS.NET 2005
Beta 2.
STDAPI GetRequestedRuntimeInfo(
LPCWSTR pExe, LPCWSTR pwszVersion, LPCWSTR pConfigurationFile,
DWORD startupFlags, DWORD runtimeInfoFlags,
LPWSTR pDirectory, DWORD dwDirectory, DWORD *dwDirectoryLength,
LPWSTR pVersion, DWORD cchBuffer, DWORD* dwlength);
Here's a screenshot of my .NET installation root folder.
Notice the folder named "renamed", which is actually the installation folder
for "v2.0.50215". The call to GetRequestedRuntimeInfo with
pwszVersion set to "renamed" actually succeeds (possibly because GetRequestedRuntimeInfo
uses a very similar technique to what I do to extract the version). Funnily, the
version string returned by the function in pVersion is the name of
the folder and not the real version string, but this is not a big bother as we
know that there will be an mscorlib.dll in this folder and that its
version string will give us the CLR version contained in the folder.
This is extracted from the registry.
HKEY_LOCAL_MACHINE
SOFTWARE
Microsoft
.NETFramework : InstallRoot (REG_SZ)
bool CDetectDotNet::GetInstallRootPath(TCHAR* szRootPath, DWORD dwBufferSize) { bool bRet = false; if(m_szInstallRootPath) { size_t siz = _tcslen(m_szInstallRootPath); if(dwBufferSize > siz) { _tcsncpy(szRootPath, m_szInstallRootPath, siz); szRootPath[siz] = NULL; bRet = true; } } return bRet; }
bool CDetectDotNet::GetInstallRootPathInternal(TCHAR* szRootPath, DWORD dwBufferSize) { bool bRet = false; TCHAR szRegPath[] = _T("SOFTWARE\\Microsoft\\.NETFramework"); HKEY hKey = NULL; if(RegOpenKeyEx(HKEY_LOCAL_MACHINE, szRegPath, 0, KEY_READ, &hKey) == ERROR_SUCCESS) { DWORD dwSize = dwBufferSize; if(RegQueryValueEx(hKey, _T("InstallRoot"), NULL, NULL, reinterpret_cast<LPBYTE>(szRootPath), &dwSize) == ERROR_SUCCESS) { bRet = (dwSize <= dwBufferSize); } RegCloseKey(hKey); } return bRet; }
string CDetectDotNet::GetVersionFromFolderName(string szFolderName) { string strRet = "<Version could not be extracted from mscorlib>"; TCHAR szRootPath[g_cPathSize]; if(GetInstallRootPath(szRootPath, g_cPathSize)) { USES_CONVERSION; string szFilepath = T2A(szRootPath); szFilepath += (szFolderName + "\\mscorlib.dll"); string s = GetDotNetVersion(A2CT(szFilepath.c_str())); if(s.size() > 0) strRet = s; } return strRet; }
string CDetectDotNet::GetDotNetVersion(LPCTSTR szFolder) { string strRet = _T(""); LPVOID m_lpData = NULL; TCHAR buff[MAX_PATH + 1] = {0}; _tcsncpy(buff, szFolder, MAX_PATH); DWORD dwHandle = 0; DWORD dwVerInfoSize = GetFileVersionInfoSize(buff, &dwHandle); if(dwVerInfoSize != 0) //Success { m_lpData = malloc(dwVerInfoSize); if(GetFileVersionInfo(buff, dwHandle, dwVerInfoSize, m_lpData) == FALSE) { free(m_lpData); m_lpData = NULL; } else { UINT cbTranslate = 0; struct LANGANDCODEPAGE { WORD wLanguage; WORD wCodePage; } *lpTranslate; if(VerQueryValue(m_lpData,_T("\\VarFileInfo\\Translation"), (LPVOID*)&lpTranslate,&cbTranslate)) { int count = (int)(cbTranslate/sizeof(struct LANGANDCODEPAGE)); for(int i=0; i < count; i++ ) { TCHAR SubBlock[128]; HRESULT hr = StringCchPrintf(SubBlock, 127,_T("\\StringFileInfo\\%04x%04x\\%s"), lpTranslate[i].wLanguage, lpTranslate[i].wCodePage,_T("FileVersion")); if(SUCCEEDED(hr)) { UINT dwBytes = 0; TCHAR* lpBuffer; if(VerQueryValue(m_lpData, SubBlock, (LPVOID*)&lpBuffer, &dwBytes)) { USES_CONVERSION; strRet = T2A(lpBuffer); for(unsigned int x = 0, j = 0; j < strRet.size(); j++) { if(strRet[j] == '.') { if(++x == 3) { strRet.erase(j,strRet.size() - j); break; } } } break; } } } } } } return strRet; }
bool CDetectDotNet::CheckForSpecificCLRVersionInternal(LPCWSTR pszVersion) { bool bRet = false; if( m_bDotNetPresent ) { UINT prevErrMode = SetErrorMode(SEM_FAILCRITICALERRORS); HMODULE hModule = LoadLibrary(_T("mscoree")); if(hModule) { FPGetRequestedRuntimeInfo pGetRequestedRuntimeInfo = reinterpret_cast<FPGetRequestedRuntimeInfo>( GetProcAddress(hModule, "GetRequestedRuntimeInfo")); if(pGetRequestedRuntimeInfo) { LPWSTR dirBuff = NULL; DWORD dwDir = 0; LPWSTR verBuff = NULL; DWORD dwVer = 0; pGetRequestedRuntimeInfo(NULL, pszVersion, NULL,0,0, dirBuff, dwDir, &dwDir, verBuff, dwVer, &dwVer); dirBuff = new WCHAR[dwDir + 1]; verBuff = new WCHAR[dwVer + 1]; HRESULT hr = pGetRequestedRuntimeInfo(NULL, pszVersion, NULL,0,0,dirBuff, dwDir, &dwDir,verBuff, dwVer, &dwVer); bRet = (hr == S_OK); delete[] verBuff; delete[] dirBuff; } FreeLibrary(hModule); } SetErrorMode(prevErrMode); } return bRet; }
size_t CDetectDotNet::EnumerateCLRVersions(vector<string>& CLRVersions) { CLRVersions.clear(); USES_CONVERSION; vector<string> PossibleCLRVersions; EnumeratePossibleCLRVersionsInternal(PossibleCLRVersions); for(vector<string>::iterator it = PossibleCLRVersions.begin(); it < PossibleCLRVersions.end(); it++) { if(CheckForSpecificCLRVersionInternal(A2CW((*it).c_str()))) { CLRVersions.push_back(GetVersionFromFolderName(*it)); } } return CLRVersions.size(); }
size_t CDetectDotNet::EnumeratePossibleCLRVersionsInternal(
vector<string>& PossibleCLRVersions)
{
PossibleCLRVersions.clear();
if(m_bDotNetPresent)
{
TCHAR szRootBuff[g_cPathSize];
if(GetInstallRootPath(szRootBuff, g_cPathSize))
{
WIN32_FIND_DATA finddata = {0};
_tcsncat(szRootBuff, _T("*"), 1);
HANDLE hFind = FindFirstFile(szRootBuff, &finddata);
if(hFind != INVALID_HANDLE_VALUE)
{
do
{
if( finddata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY )
{
PossibleCLRVersions.push_back(finddata.cFileName);
}
}while(FindNextFile(hFind, &finddata));
FindClose(hFind);
}
}
}
return PossibleCLRVersions.size();
}
I haven't tested this code out on every Windows or .NET version out there, so I cannot guarantee that it will work correctly all the time. But if it does not work for you, please let me know of it through the forum, and if you post an accurate problem description, I'll make efforts to implement a fix or a work-around. But you need to tell me, because if I don't know that a bug exists, I am not going to be able to fix it. Enjoy!
IsDotNetPresent to initialize m_bDotNetPresent when I
should have been calling IsDotNetPresentInternal)IsDotNetPresent and GetInstallRootPath
internally (so the actual detection code is executed only once - in the constructor)GetRequestedRuntimeInfo to check for a
specific CLR version.IsDotNetPresent to verify that the
mscoree.dll that LoadLibrary successfully loaded is not a placeholder
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