title: GetTokenInformation() first call. What for?
body: <p>Looking at MSDN documentaion for <a href="http://msdn.microsoft.com/en-us/library/aa446671.aspx" rel="nofollow noreferrer">GetTokenInformation()</a> and the <a href="http://msdn.microsoft.com/en-us/library/aa446670(v=VS.85).aspx" rel="nofollow noreferrer">Getting the Logon SID</a> example, GetTokenInformation() needs to be called twice. The first call is to get the buffer size.</p>
  
  <p>So, buffer size of what? Just say I use TokenUser as its second parameter, I see that the dwReturnLength returned by first call is not the size of TOKEN_USER structure.</p>
  
  <p>Thanks in advance</p>