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This tip demonstrates how to shutdown, logoff and/or reboot a system. Shutting down a
Windows 9x system is very straightforward - just one API call to ExitWindowsEx is all
that is required. However, under NT it is a little more tricky. By default, no application
processes under Windows NT have the privilege to shut the system down, and the call to
ExitWindowsEx simply fails on calling it. The trick to make it work is to call the API
AdjustTokenPrivileges function to enable the calling process to shut the system down.
Note that under NT the user may not have sufficient system privileges to shut down anyway.
Start a new project in VB. Add a new module, then add the following
code to it:
' To Shutdown Windows:
Private Declare Function ExitWindowsEx Lib "user32" (ByVal uFlags As Long, ByVal dwReserved As Long) As Long
Private Const ENDSESSION_LOGOFF = &H80000000
Public Enum EShutDownTypes
    [_First] = 0
    EWX_LOGOFF = 0
    EWX_SHUTDOWN = 1&
    EWX_REBOOT = 2&
    EWX_FORCE = 4&
    EWX_POWEROFF = 8&
        EWX_FORCEIFHUNG = 10&
' NT5 only
   
    EWX_RESET = EWX_LOGOFF Or EWX_FORCE Or EWX_REBOOT
    [_Last] = &H20& - 1
End Enum
Public Enum EShutDownErrorBaseConstant
    eeSSDErrorBase = vbObjectError Or (1048 + &H210)
End Enum
' To Determine if we are running NT or not:
Private Type OSVERSIONINFO
    dwOSVersionInfoSize As Long
    dwMajorVersion As Long
    dwMinorVersion As Long
    dwBuildNumber As Long
    dwPlatformId As Long
        szCSDVersion As String * 128
' Maintenance string for PSS usage
End Type
Private Declare Function GetVersionEx Lib "kernel32" Alias "GetVersionExA" (lpVersionInformation As OSVERSIONINFO) As Long
Private Const VER_PLATFORM_WIN32_NT = 2
Private Const VER_PLATFORM_WIN32_WINDOWS = 1
Private Const VER_PLATFORM_WIN32s = 0
' To Report API errors:
Private Const FORMAT_MESSAGE_ALLOCATE_BUFFER = &H100
Private Const FORMAT_MESSAGE_ARGUMENT_ARRAY = &H2000
Private Const FORMAT_MESSAGE_FROM_HMODULE = &H800
Private Const FORMAT_MESSAGE_FROM_STRING = &H400
Private Const FORMAT_MESSAGE_FROM_SYSTEM = &H1000
Private Const FORMAT_MESSAGE_IGNORE_INSERTS = &H200
Private Const FORMAT_MESSAGE_MAX_WIDTH_MASK = &HFF
Private Declare Function FormatMessage Lib "kernel32" Alias "FormatMessageA" (ByVal dwFlags As Long, lpSource As Any, ByVal dwMessageId As Long, ByVal dwLanguageId As Long, ByVal lpBuffer As String, ByVal nSize As Long, Arguments As Long) As Long
' ============================================================================================
' NT Only
Private Type LARGE_INTEGER
    LowPart As Long
    HighPart As Long
End Type
Private Type LUID
    LowPart As Long
    HighPart As Long
End Type
Private Type LUID_AND_ATTRIBUTES
    pLuid As LUID
    Attributes As Long
End Type
Private Type TOKEN_PRIVILEGES
    PrivilegeCount As Long
    Privileges(0 To 0) As LUID_AND_ATTRIBUTES
End Type
Private Declare Function GetCurrentProcess Lib "kernel32" () 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 CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function GetTokenInformation Lib "advapi32.dll" (ByVal TokenHandle As Long, TokenInformationClass As Integer, TokenInformation As Any, ByVal TokenInformationLength As Long, ReturnLength As Long) As Long
Private Declare Function AdjustTokenPrivileges Lib "advapi32.dll" (ByVal TokenHandle As Long, ByVal DisableAllPrivileges As Long, NewState As TOKEN_PRIVILEGES, ByVal BufferLength As Long, PreviousState As TOKEN_PRIVILEGES, ReturnLength As Long) As Long
Private Declare Function LookupPrivilegeValue Lib "advapi32.dll" Alias "LookupPrivilegeValueA" (ByVal lpSystemName As String, ByVal lpName As String, lpLuid As LUID) As Long
Private Const SE_SHUTDOWN_NAME = "SeShutdownPrivilege"
Private Const SE_PRIVILEGE_ENABLED = &H2
Private Const READ_CONTROL = &H20000
Private Const STANDARD_RIGHTS_ALL = &H1F0000
Private Const STANDARD_RIGHTS_EXECUTE = (READ_CONTROL)
Private Const STANDARD_RIGHTS_READ = (READ_CONTROL)
Private Const STANDARD_RIGHTS_REQUIRED = &HF0000
Private Const STANDARD_RIGHTS_WRITE = (READ_CONTROL)
Private Const TOKEN_ASSIGN_PRIMARY = &H1
Private Const TOKEN_DUPLICATE = (&H2)
Private Const TOKEN_IMPERSONATE = (&H4)
Private Const TOKEN_QUERY = (&H8)
Private Const TOKEN_QUERY_SOURCE = (&H10)
Private Const TOKEN_ADJUST_PRIVILEGES = (&H20)
Private Const TOKEN_ADJUST_GROUPS = (&H40)
Private Const TOKEN_ADJUST_DEFAULT = (&H80)
Private Const TOKEN_ALL_ACCESS = (STANDARD_RIGHTS_REQUIRED Or _
                        TOKEN_ASSIGN_PRIMARY Or _
                        TOKEN_DUPLICATE Or _
                        TOKEN_IMPERSONATE Or _
                        TOKEN_QUERY Or _
                        TOKEN_QUERY_SOURCE Or _
                        TOKEN_ADJUST_PRIVILEGES Or _
                        TOKEN_ADJUST_GROUPS Or _
                        TOKEN_ADJUST_DEFAULT)
Private Const TOKEN_READ = (STANDARD_RIGHTS_READ Or _
                        TOKEN_QUERY)
Private Const TOKEN_WRITE = (STANDARD_RIGHTS_WRITE Or _
                        TOKEN_ADJUST_PRIVILEGES Or _
                        TOKEN_ADJUST_GROUPS Or _
                        TOKEN_ADJUST_DEFAULT)
Private Const TOKEN_EXECUTE = (STANDARD_RIGHTS_EXECUTE)
Private Const TokenDefaultDacl = 6
Private Const TokenGroups = 2
Private Const TokenImpersonationLevel = 9
Private Const TokenOwner = 4
Private Const TokenPrimaryGroup = 5
Private Const TokenPrivileges = 3
Private Const TokenSource = 7
Private Const TokenStatistics = 10
Private Const TokenType = 8
Private Const TokenUser = 1
' ============================================================================================
Public Function WinError(ByVal lLastDLLError As Long) As String
Dim sBuff As String
Dim lCount As Long
   
   
' Return the error message associated with LastDLLError:
    sBuff = String$(256, 0)
    lCount = FormatMessage( _
    FORMAT_MESSAGE_FROM_SYSTEM Or FORMAT_MESSAGE_IGNORE_INSERTS, _
    0, lLastDLLError, 0&, sBuff, Len(sBuff), ByVal 0)
    If lCount Then
    WinError = Left$(sBuff, lCount)
    End If
   
End Function
Public Function IsNT() As Boolean
Static bOnce As Boolean
Static bValue As Boolean
   
' Return whether the system is running NT or not:
    If Not (bOnce) Then
    Dim tVI As OSVERSIONINFO
    tVI.dwOSVersionInfoSize = Len(tVI)
    If (GetVersionEx(tVI) 0) Then
        bValue = (tVI.dwPlatformId = VER_PLATFORM_WIN32_NT)
        bOnce = True
    End If
    End If
    IsNT = bValue
   
End Function
Private Function NTEnableShutDown(ByRef sMsg As String) As Boolean
Dim tLUID As LUID
Dim hProcess As Long
Dim hToken As Long
Dim tTP As TOKEN_PRIVILEGES, tTPOld As TOKEN_PRIVILEGES
Dim lTpOld As Long
Dim lR As Long
   
' Under NT we must enable the SE_SHUTDOWN_NAME privilege in the
   
' process we're trying to shutdown from, otherwise a call to
   
' try to shutdown has no effect!
   
' Find the LUID of the Shutdown privilege token:
    lR = LookupPrivilegeValue(vbNullString, SE_SHUTDOWN_NAME, tLUID)
   
   
' If we get it:
    If (lR 0) Then
               
   
' Get the current process handle:
    hProcess = GetCurrentProcess()
    If (hProcess 0) Then
       
' Open the token for adjusting and querying (if we can - user may not have rights):
        lR = OpenProcessToken(hProcess, TOKEN_ADJUST_PRIVILEGES Or TOKEN_QUERY, hToken)
        If (lR 0) Then
                   
           
' Ok we can now adjust the shutdown priviledges:
            With tTP
                .PrivilegeCount = 1
                With .Privileges(0)
                .Attributes = SE_PRIVILEGE_ENABLED
                .pLuid.HighPart = tLUID.HighPart
                .pLuid.LowPart = tLUID.LowPart
                End With
            End With
           
           
' Now allow this process to shutdown the system:
            lR = AdjustTokenPrivileges(hToken, 0, tTP, Len(tTP), tTPOld, lTpOld)
           
            If (lR 0) Then
                NTEnableShutDown = True
            Else
                Err.Raise eeSSDErrorBase + 6, App.EXEName & ".mShutDown", "Can't enable shutdown: You do not have the privileges to shutdown this system. [" & WinError(Err.LastDllError) & "]"
            End If
           
           
' Remember to close the handle when finished with it:
            CloseHandle hToken
        Else
            Err.Raise eeSSDErrorBase + 6, App.EXEName & ".mShutDown", "Can't enable shutdown: You do not have the privileges to shutdown this system. [" & WinError(Err.LastDllError) & "]"
        End If
    Else
        Err.Raise eeSSDErrorBase + 5, App.EXEName & ".mShutDown", "Can't enable shutdown: Can't determine the current process. [" & WinError(Err.LastDllError) & "]"
    End If
    Else
    Err.Raise eeSSDErrorBase + 4, App.EXEName & ".mShutDown", "Can't enable shutdown: Can't find the SE_SHUTDOWN_NAME privilege value. [" & WinError(Err.LastDllError) & "]"
    End If
End Function
Public Function ShutdownSystem( _
    Optional ByVal eType As EShutDownTypes = EWX_RESET _
    ) As Boolean
Dim lR As Long
Dim sMsg As String
   
' Validate shutdown type:
    If (eType EShutDownTypes.[_Last]) Then
    Err.Raise eeSSDErrorBase + 7, App.EXEName & ".mShutDown", "Invalid parameter to ShutdownSystem: " & eType, vbInformation
    Exit Function
    End If
   
' Make sure we have enabled the privilege to shutdown
   
' for this process if we're running NT:
    If (IsNT) Then
    If Not (NTEnableShutDown(sMsg)) Then
        Exit Function
    End If
    End If
   
' This is the code to shut down
    lR = ExitWindowsEx(eType, &HFFFFFFFF)
    If (lR = 0) Then
    Err.Raise eeSSDErrorBase + 3, App.EXEName & ".mShutDown", "ShutdownSystem failed: " & WinError(Err.LastDllError)
    Else
   
' Remember that shutdown will proceed on another
   
' thread to this one, so code may continue to
   
' execute after this.
    ShutdownSystem = True
End If
End Function
To try out a shutdown, add a Command button to the project's form and then paste in
the following code. Note you should save your work before running it, because the
shutdown will kill VB without asking you to save any changes! Clicking on the Command
button will cause the system to shutdown and reboot.
Private Sub Command1_Click()
   
' Don't do this unless you've saved the code!
    If (MsgBox("Are you sure you want to shutdown?", vbYesNo Or vbQuestion) = vbYes) Then
    ShutdownSystem
End If
End Sub
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