PRB: ExitWindowsEx API Does Not Reboot Windows NT

• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, versions 5.0, 6.0
• Microsoft Visual Basic Standard, Professional, and Enterprise Editions, 32-bit only, for Windows, version 4.0

SYMPTOMS

When you use the ExitWindowsEx API to reboot the system under Windows NT, the machine does not reboot.

CAUSE

In order to programmatically reboot a Windows NT system, the process requires the SE_SHUTDOWN_NAME privilege. By default, Visual Basic applications do not have this privilege and therefore will not reboot the machine.

RESOLUTION

In order to get ExitWindowsEx API to reboot the system under Windows NT, the SE_SHUTDOWN_NAME privilege must be set. The steps below describe how to get the ExitWindowsEx API to work under Windows NT.

Step By Step Example

1. Create a new standard EXE in Visual Basic. Form1 is created by default.



2. View the code for Form1. In the Declarations section, add the following code:

   
         Private Type LUID
            UsedPart As Long
            IgnoredForNowHigh32BitPart As Long
         End Type
   
         Private Type TOKEN_PRIVILEGES
           PrivilegeCount As Long
           TheLuid As LUID
           Attributes As Long
         End Type
   
         Private Const EWX_SHUTDOWN As Long = 1
         Private Const EWX_FORCE As Long = 4
         Private Const EWX_REBOOT = 2
   
         Private Declare Function ExitWindowsEx Lib "user32" (ByVal _
              dwOptions As Long, ByVal dwReserved As Long) As Long
   
         Private Declare Function GetCurrentProcess Lib "kernel32" () As Long
         Private Declare Function OpenProcessToken Lib "advapi32" (ByVal _
            ProcessHandle As Long, _
            ByVal DesiredAccess As Long, TokenHandle As Long) As Long
         Private Declare Function LookupPrivilegeValue Lib "advapi32" _
            Alias "LookupPrivilegeValueA" _
            (ByVal lpSystemName As String, ByVal lpName As String, lpLuid _
            As LUID) As Long
         Private Declare Function AdjustTokenPrivileges Lib "advapi32" _
            (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
    




3. Add a procedure called AdjustToken with the following code:

   
         Private Sub AdjustToken()
            Const TOKEN_ADJUST_PRIVILEGES = &H20
            Const TOKEN_QUERY = &H8
            Const SE_PRIVILEGE_ENABLED = &H2
            Dim hdlProcessHandle As Long
            Dim hdlTokenHandle As Long
            Dim tmpLuid As LUID
            Dim tkp As TOKEN_PRIVILEGES
            Dim tkpNewButIgnored As TOKEN_PRIVILEGES
            Dim lBufferNeeded As Long
   
            hdlProcessHandle = GetCurrentProcess()
            OpenProcessToken hdlProcessHandle, (TOKEN_ADJUST_PRIVILEGES Or _
               TOKEN_QUERY), hdlTokenHandle
   
         ' Get the LUID for shutdown privilege.
            LookupPrivilegeValue "", "SeShutdownPrivilege", tmpLuid
   
            tkp.PrivilegeCount = 1    ' One privilege to set
            tkp.TheLuid = tmpLuid
            tkp.Attributes = SE_PRIVILEGE_ENABLED
   
        ' Enable the shutdown privilege in the access token of this process.
            AdjustTokenPrivileges hdlTokenHandle, False, _
            tkp, Len(tkpNewButIgnored), tkpNewButIgnored, lBufferNeeded
   
        End Sub
    




4. Add a CommandButton to the form. In the Click event, add the following code:

   
         Private Sub Command1_Click()
            AdjustToken
            ExitWindowsEx (EWX_SHUTDOWN Or EWX_FORCE Or EWX_REBOOT), &HFFFF
         End Sub
    




5. Save the project and build an executable. When you run the executable and click the CommandButton the computer will reboot as expected.

STATUS

This behavior is by design.

REFERENCES

For additional information, please see the following articles in the Microsoft Knowledge Base:

Q129637 : HOWTO: Exit Windows from a Visual Basic 4.0 Application

Q142820 : HOWTO: Terminate Windows from a 16-Bit VB Application

Q76981 : VB3: HOWTO: Terminate Windows from a Visual Basic Application

Keywords : kbVBp400 kbVBp500 kbVBp600 kbGrpVB PrgOther kb32bitOnly
Version :
Platform :
Issue type : kbprb