Attribute VB_Name = "WinVersion"
' WinVers.bas for Visual Basic 6.0
' Module for retrieving the currently running Windows version
' ©2005-2012 Aivosto Oy www.aivosto.com
'
' Originally distributed with Aivosto Visustin flow chart generator.
' Permission is granted to use, modify and compile this code, but not to publish or sell it.

Option Explicit

' Windows versions enumerated
Public Enum EWinVersion
    wvError = 0         '      Error/Unknown Windows version
    wvWin95             ' 4.0  Windows 95
    wvWin98             ' 4.10 Windows 98
    wvWinME             ' 4.90 Windows ME
    wvWinNT351          ' 3.51 Windows NT 3.51 - this should never occur as VB6 doesn't run on this OS
    wvWinNT4            ' 4.0  Windows NT 4.0
    wvWin2000           ' 5.0  Windows 2000
    wvWinXP             ' 5.1  Windows XP
    wvWinServer2003     ' 5.2  Windows Server 2003 (& R2) - also Windows Home Server, WinXP Pro x64 Edition
    wvWinVista          ' 6.0  Windows Vista
    wvWinServer2008     ' 6.0  Windows Server 2008
    wvWin7              ' 6.1  Windows 7
    wvWinServer2008R2   ' 6.1  Windows Server 2008 R2
    wvWin8              ' 6.2  Windows 8
    wvWinServer2012     ' 6.2  Windows Server 2012
    wvNewer             '      A newer Windows version
End Enum

' API structures
Private Type OSVERSIONINFO
        dwOSVersionInfoSize As Long
        dwMajorVersion As Long
        dwMinorVersion As Long
        dwBuildNumber As Long
        dwPlatformId As Long
        szCSDVersion As String * 128
End Type
Private Type OSVERSIONINFOEX
        dwOSVersionInfoSize As Long
        dwMajorVersion As Long
        dwMinorVersion As Long
        dwBuildNumber As Long
        dwPlatformId As Long
        szCSDVersion As String * 128
        
        wServicePackMajor As Integer
        wServicePackMinor As Integer
        wSuiteMask As Integer
        wProductType As Byte
        wReserved As Byte
End Type

' API Declares
' Two declarations: same function but different parameter
Private Declare Function GetVersionEx Lib "kernel32" Alias "GetVersionExA" (lpVersionInformation As OSVERSIONINFO) As Long
Private Declare Function GetVersionEx2 Lib "kernel32" Alias "GetVersionExA" (lpVersionInformation As OSVERSIONINFOEX) As Long

' API constants
Private Const VER_PLATFORM_WIN32_WINDOWS = 1 ' Windows 95/98/ME
Private Const VER_PLATFORM_WIN32_NT = 2      ' Windows NT
Private Const VER_NT_WORKSTATION = 1         ' Workstation
Private Const VER_NT_SERVER = 3              ' Windows Server 2000, 2003, 2008, 2012
Private Const VER_NT_DOMAIN_CONTROLLER = 2   ' Windows Server 2000, 2003, 2008, 2012 (domain controller)

Public Function GetWinVersionEx() As EWinVersion
' Retrieve the current Windows version as an enumerated constant value
' In the case of an error, return wvError

Dim OSVI As OSVERSIONINFO
Dim OSVIEX As OSVERSIONINFOEX
Dim IsServer As Boolean

On Error Resume Next

' Assume error/unknown until Windows version detected
GetWinVersionEx = wvError

' Retrieve version information into OSVI
OSVI.dwOSVersionInfoSize = Len(OSVI)

If GetVersionEx(OSVI) <> 0 Then
    ' Version retrieved
    If OSVI.dwPlatformId = VER_PLATFORM_WIN32_WINDOWS Then
        ' Win95/98/ME detected
        If OSVI.dwMajorVersion = 4 Then
            ' Windows 4.x detected
            Select Case OSVI.dwMinorVersion
                Case 0  ' 4.0  Windows 95
                    GetWinVersionEx = wvWin95
                Case 10 ' 4.10 Windows 98
                    GetWinVersionEx = wvWin98
                Case 90 ' 4.90 Windows ME
                    GetWinVersionEx = wvWinME
            End Select
        End If
    ElseIf OSVI.dwPlatformId = VER_PLATFORM_WIN32_NT Then
        ' WinNT/2000/XP/2003/2008/7/8/Server detected
        Select Case OSVI.dwMajorVersion
            Case 3 ' Windows NT 3.51
                GetWinVersionEx = wvWinNT351
            Case 4 ' Windows NT 4.0
                GetWinVersionEx = wvWinNT4
            Case 5 ' Windows NT 5.x
                Select Case OSVI.dwMinorVersion
                    Case 0 ' 5.0 Windows 2000
                        GetWinVersionEx = wvWin2000
                    Case 1 ' 5.1 Windows XP
                        GetWinVersionEx = wvWinXP
                    Case 2 ' 5.2 Windows Server 2003 (or R2)
                        ' (also Windows Home Server or WinXP Pro x64 Edition)
                        GetWinVersionEx = wvWinServer2003
                    Case Else ' Unknown Windows version
                        GetWinVersionEx = wvNewer
                End Select
            Case 6
                ' Windows 6.x
                ' Determine Server vs. Workstation
                OSVIEX.dwOSVersionInfoSize = Len(OSVIEX)
                If GetVersionEx2(OSVIEX) <> 0 Then
                    Select Case OSVIEX.wProductType
                        Case VER_NT_WORKSTATION ' Workstation
                            IsServer = False
                        Case Else               ' Server or Domain controller
                            IsServer = True
                    End Select
                Else
                    IsServer = False ' Call failed, assume Workstation
                End If
                
                If IsServer Then
                    ' Server or Domain controller
                    Select Case OSVI.dwMinorVersion
                        Case 0 ' 6.0 Windows Server 2008
                            GetWinVersionEx = wvWinServer2008
                        Case 1 ' 6.1 Windows Server 2008 R2
                            GetWinVersionEx = wvWinServer2008R2
                        Case 2 ' 6.2 Windows Server 2012
                            GetWinVersionEx = wvWinServer2012
                        Case Else ' Unknown, newer Windows version
                            GetWinVersionEx = wvNewer
                    End Select
                Else
                    ' Workstation
                    Select Case OSVI.dwMinorVersion
                        Case 0 ' 6.0 Windows Vista
                            GetWinVersionEx = wvWinVista
                        Case 1 ' 6.1 Windows 7
                            GetWinVersionEx = wvWin7
                        Case 2 ' 6.2 Windows 8
                            GetWinVersionEx = wvWin8
                        Case Else ' Unknown, newer Windows version
                            GetWinVersionEx = wvNewer
                    End Select
                End If
            Case Is > 6
                ' Unknown, newer Windows version
                GetWinVersionEx = wvNewer
        End Select
    End If
End If

End Function