GetTokenInformation in Visual Basic 6

Answer 1

There is another question here that seems to have solved the GetTokenInformation call. Copied from the accepted answer:

Call GetTokenInformation(hToken, 1, ByVal 0, 0, lNeeded)
ReDim baBuffer(0 To lNeeded)
...

Answer 2

If you want to use dynamicly sized array for Groups you'll need "custom API call marshaling" code. Basicly couple of CopyMemory's and an array resize

Option Explicit

'--- for OpenProcessToken
Private Const TOKEN_READ                    As Long = &H20008

Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (pTo As Any, uFrom As Any, ByVal lSize As Long)
Private Declare Function GetCurrentProcess Lib "kernel32" () As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function OpenProcessToken Lib "advapi32.dll" (ByVal ProcessHandle As Long, ByVal DesiredAccess As Long, TokenHandle As Long) As Long
Private Declare Function GetTokenInformation Lib "advapi32.dll" (ByVal TokenHandle As Long, ByVal TokenInformationClass As Long, TokenInformation As Any, ByVal TokenInformationLength As Long, ReturnLength As Long) As Long

Private Type SID_AND_ATTRIBUTES
    Sid             As Long
    Attributes      As Long
End Type

Private Type VB_TOKEN_GROUPS
    GroupCount      As Long
    Groups()        As SID_AND_ATTRIBUTES
End Type


Private Sub Command1_Click()
    Dim hProcessID      As Long
    Dim hToken          As Long
    Dim lNeeded         As Long
    Dim baBuffer()      As Byte
    Dim uGroups         As VB_TOKEN_GROUPS

    hProcessID = GetCurrentProcess()
    If hProcessID <> 0 Then
        If OpenProcessToken(hProcessID, TOKEN_READ, hToken) = 1 Then
            Call GetTokenInformation(hToken, 2, ByVal 0, 0, lNeeded)
            ReDim baBuffer(0 To lNeeded)
            '--- enum TokenInformationClass { TokenUser = 1, TokenGroups = 2, ... }
            If GetTokenInformation(hToken, 2, baBuffer(0), UBound(baBuffer), lNeeded) = 1 Then
                Call CopyMemory(uGroups.GroupCount, baBuffer(0), 4)
                ReDim uGroups.Groups(0 To uGroups.GroupCount - 1)
                Call CopyMemory(uGroups.Groups(0), baBuffer(4), uGroups.GroupCount * Len(uGroups.Groups(0)))
            End If
            Call CloseHandle(hToken)
        End If
        Call CloseHandle(hProcessID)
    End If
End Sub