LogonUserW logon fails for a non-ascii username - c++

Question

I have C++ code that tries to authenticate a local user to windows:
BOOL result = ::LogonUserW(localAdminUserName_.c_str(), L".", localAdminPassword_.c_str(),
LOGON32_LOGON_NETWORK, LOGON32_PROVIDER_DEFAULT);
This works fine for ASCII character-set based usernames.
But doesn't work for a user named, say userああ
If I print the variable localAdminUserName_ in the log, It's printing the username just fine.
Is .c_str() messing it up somehow?
Should I encode the username/password in someway before making this API call?
The following console application I made to test this scenario, is working fine!
_declspec(dllimport)
BOOL
__stdcall
LogonUserW(
__in LPCWSTR lpszUsername,
__in_opt LPCWSTR lpszDomain,
__in LPCWSTR lpszPassword,
__in DWORD dwLogonType,
__in DWORD dwLogonProvider,
__deref_out PHANDLE phToken
);
int _tmain(int argc, _TCHAR* argv[])
{
HANDLE hToken = NULL;
BOOL returnValue = LogonUserW(
L"userああ",
L".",
L"pa$$w0rd",
LOGON32_LOGON_NETWORK,
LOGON32_PROVIDER_DEFAULT,
&hToken);
if (returnValue == false) {
std::cout<<"Error!";
} else {
std::cout<<"Success!";
}
return 0;
}

Answer 1

Problem got solved after the original string is converted to multi byte string and then used the MultiByteToWideChar method in windows.h to convert it to wide char:
//convert the credentials to a multi-byte string first
std::string MbLocalAdminUserName = MbString(localAdminUserName_.c_str());
std::string MbLocalAdminPassowrd = MbString(localAdminPassowrd_.c_str());
//convert this multi-byte format to wide char that windows is expecting
//username
int len_MbLocalAdminUserName = MultiByteToWideChar(CP_UTF8, 0, MbLocalAdminUserName.c_str() , -1, NULL, 0);
wchar_t* WcLocalAdminUserName = new wchar_t[len_MbLocalAdminUserName + 1];
MultiByteToWideChar(CP_UTF8, 0, MbLocalAdminUserName.c_str(), -1, WcLocalAdminUserName, len_MbLocalAdminUserName + 1);
//password
int len_MbLocalAdminPassowrd = MultiByteToWideChar(CP_UTF8, 0, MbLocalAdminPassowrd.c_str() , -1, NULL, 0);
wchar_t* WcLocalAdminPassowrd = new wchar_t[len_MbLocalAdminPassowrd + 1];
MultiByteToWideChar(CP_UTF8, 0, MbLocalAdminPassowrd.c_str(), -1, WcLocalAdminPassowrd, len_MbLocalAdminPassowrd + 1);
BOOL result = ::LogonUser(WcLocalAdminUserName, L".", WcLocalAdminPassowrd,
LOGON32_LOGON_NETWORK, LOGON32_PROVIDER_DEFAULT, &hToken);
delete[] WcLocalAdminUserName;
delete[] WcLocalAdminPassowrd;
Where MbString is :
MbString::MbString(const wchar_t* src)
: buf_(0) {
const size_t count = 1 + sizeof(wchar_t) * wcslen(src);
buf_ = new char[count];
// The 3rd parameter specifies the size of multi-bytes string buffer.
wcstombs(buf_, src, count);
}