AdjustTokenPrivileges error 6 - handle invalid - c++

Question

Please advise why the AdjustTokenPrivileges function below always returns true, thus giving: "AdjustTokenPrivileges error 6" (ie invalid handle)?
stackoverlow is complaining that I didn't explain this enough
I don't know what else to add. I'm new to c++.
HANDLE hToken;
OpenProcessToken(GetCurrentProcess, TOKEN_ADJUST_PRIVILEGES, &hToken);
SetPrivilege(hToken,L"SeBackupPrivilege",1 );
CloseHandle(hToken);
BOOL SetPrivilege(
HANDLE hToken, // access token handle
LPCTSTR lpszPrivilege, // name of privilege to enable/disable
BOOL bEnablePrivilege // to enable or disable privilege
)
{
TOKEN_PRIVILEGES oldtp; /* old token privileges */
TOKEN_PRIVILEGES tp;
DWORD dwSize = sizeof (TOKEN_PRIVILEGES);
LUID luid;
if ( !LookupPrivilegeValue(
NULL, // lookup privilege on local system
lpszPrivilege, // privilege to lookup
&luid ) ) // receives LUID of privilege
{
printf("LookupPrivilegeValue error: %u\n", GetLastError() );
return FALSE;
}
tp.PrivilegeCount = 1;
tp.Privileges[0].Luid = luid;
if (bEnablePrivilege)
tp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
else
tp.Privileges[0].Attributes = 0;
// Enable the privilege or disable all privileges.
if ( !AdjustTokenPrivileges(
&hToken,
FALSE,
&tp,
sizeof(TOKEN_PRIVILEGES),
(PTOKEN_PRIVILEGES) &oldtp,
(PDWORD) &dwSize) )
{
printf("AdjustTokenPrivileges error: %u\n", GetLastError() ); //Get error 6 here (ie invalid handle)
return FALSE;
}
if (GetLastError() == ERROR_NOT_ALL_ASSIGNED)
{
printf("The token does not have the specified privilege. \n");
return FALSE;
}
return TRUE;
}

Answer 1

You should request for TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY and correctly call the function:
if (!OpenProcessToken(GetCurrentProcess(),
TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, &hToken))
return FALSE;
And please: Always check for valid return values!
For a complete example see also: How to Shut Down the System
And just for reference: Your function SetPrivilege was copied from Enabling and Disabling Privileges in C++

Answer 2

&hToken -> hToken
if ( !AdjustTokenPrivileges(
hToken,
FALSE,
&tp,
sizeof(TOKEN_PRIVILEGES),
(PTOKEN_PRIVILEGES) &oldtp,
(PDWORD) &dwSize) )