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Logoff, Shutdown or Restart via API


This handy module will let you perform end-of-session functions,such as logging off the current user, shutting down or restarting the computer.

Option Explicit

'API constants
Private Const EWX_LOGOFF = 0
Private Const EWX_SHUTDOWN = 1
Private Const EWX_REBOOT = 2
Private Const EWX_FORCE = 4
Private Const TOKEN_ADJUST_PRIVILEGES = &H20
Private Const TOKEN_QUERY = &H8
Private Const SE_PRIVILEGE_ENABLED = &H2
Private Const ANYSIZE_ARRAY = 1
Private Const VER_PLATFORM_WIN32_NT = 2

'API structures
Type OSVERSIONINFO
   dwOSVersionInfoSize As Long
   dwMajorVersion As Long
   dwMinorVersion As Long
   dwBuildNumber As Long
   dwPlatformId As Long
   szCSDVersion As String * 128
End Type

Public Type LUID
   LowPart As Long
   HighPart As Long
End Type

Public Type LUID_AND_ATTRIBUTES
   pLuid As LUID
   Attributes As Long
End Type

Public Type TOKEN_PRIVILEGES
   PrivilegeCount As Long
   Privileges(ANYSIZE_ARRAY) As LUID_AND_ATTRIBUTES
End Type

'API Declarations
Private Declare Function GetCurrentProcess Lib "kernel32.dll" () 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 LookupPrivilegeValue Lib "advapi32.dll" Alias "LookupPrivilegeValueA" (ByVal lpSystemName As String, ByVal lpName As String, lpLuid As LUID) 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 ExitWindowsEx Lib "user32.dll" (ByVal uFlags As Long, ByVal dwReserved As Long) As Long
Private Declare Function GetVersionEx Lib "kernel32.dll" Alias "GetVersionExA" (ByRef lpVersionInformation As OSVERSIONINFO) As Long

'Detect if the program is running under Windows NT
Public Function IsWinNT() As Boolean
   Dim myOS As OSVERSIONINFO

   myOS.dwOSVersionInfoSize = Len(myOS)
   GetVersionEx myOS
   IsWinNT = (myOS.dwPlatformId = VER_PLATFORM_WIN32_NT)
End Function

'set the shut down privilege for the current application
Private Sub EnableShutDown()
   Dim hProc As Long
   Dim hToken As Long
   Dim mLUID As LUID
   Dim mPriv As TOKEN_PRIVILEGES
   Dim mNewPriv As TOKEN_PRIVILEGES

   hProc = GetCurrentProcess()
   OpenProcessToken hProc, TOKEN_ADJUST_PRIVILEGES + TOKEN_QUERY, hToken
   LookupPrivilegeValue "", "SeShutdownPrivilege", mLUID
   mPriv.PrivilegeCount = 1
   mPriv.Privileges(0).Attributes = SE_PRIVILEGE_ENABLED
   mPriv.Privileges(0).pLuid = mLUID
   ' enable shutdown privilege for the current application
   AdjustTokenPrivileges hToken, False, mPriv, 4 + (12 * mPriv.PrivilegeCount), mNewPriv, 4 + (12 * mNewPriv.PrivilegeCount)
End Sub

' Shut Down NT
Public Sub ShutDownNT(Force As Boolean)
   Dim ret As Long
   Dim Flags As Long

   Flags = EWX_SHUTDOWN
   If Force Then Flags = Flags + EWX_FORCE
   If IsWinNT Then EnableShutDown
   ExitWindowsEx Flags, 0
End Sub

'Restart NT
Public Sub RebootNT(Force As Boolean)
   Dim ret As Long
   Dim Flags As Long

   Flags = EWX_REBOOT
   If Force Then Flags = Flags + EWX_FORCE
   If IsWinNT Then EnableShutDown
   ExitWindowsEx Flags, 0
End Sub

'Log off the current user
Public Sub LogOffNT(Force As Boolean)
   Dim ret As Long
   Dim Flags As Long

   Flags = EWX_LOGOFF
   If Force Then Flags = Flags + EWX_FORCE
   ExitWindowsEx Flags, 0
End Sub

About this post

Posted: 2019-08-22
By: AndreaTincani
Viewed: 340 times

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Visual Basic 6

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Special Instructions

This code originally appeared on AndreaVB.com, and has been republished here with the permission of Andrea Tincani.


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