Programming: How to prevent shutdown using VB?

Dwarf said:

I've asked for more help. :)

Thanks for your help! :)

Dwarf said:

Can you post the code so that we can have a look at it. Parts may need to be rewritten and reorganised.

This is for my i-cafe software

WindowsStar said:

How about this?

Code:

 
Public Sub Handler_SessionEnding(ByVal sender As Object, ByVal e As Microsoft.Win32.SessionEndingEventArgs) 
        If e.Reason = Microsoft.Win32.SessionEndReasons.Logoff Then 
            MessageBox.Show("User is logging off") 
        ElseIf e.Reason = Microsoft.Win32.SessionEndReasons.SystemShutdown Then 
            MessageBox.Show("System is shutting down") 
        End If 
    End Sub 
 
 Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load 
        AddHandler Microsoft.Win32.SystemEvents.SessionEnding, AddressOf Handler_SessionEnding 
    End Sub

or

SystemEvents.SessionEnding Event (Microsoft.Win32)

or a quick google:

Code:

' Original Code
' Created by E.Spencer - This code is public domain.
' Routines for running an app as an NT service.
'
' modified/rehashed by G.Crisp
' code modified to just detect and cancel windows shutdown - only a few unused bits deleted
'
'orginal code available from
'http://www.ilook.fsnet.co.uk/vb/vbntserv.htm
'
Public Const GWL_WNDPROC = (-4)
Public Const WM_ENDSESSION = &H16
Public Const WM_QUERYENDSESSION = &H11
Public WndProc As Long
Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hwnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
' exiting from windows
'-------------------------------------------------------
Public Declare Function ExitWindowsEx Lib "user32.dll" (ByVal uFlags As Long, ByVal dwReserved As Long) As Long
'EWX_FORCE = 4 Force any applications to quit instead of prompting the user to close them.
'EWX_LOGOFF = 0 Log off the network.
'EWX_POWEROFF = 8 Shut down the system and, if possible, turn the computer off.
'EWX_REBOOT = 2 Perform a full reboot of the system.
'EWX_SHUTDOWN = 1
'call this from your form
Public Sub Hook(Lwnd As Long)
Dim uProcess As Long
WndProc = SetWindowLong(Lwnd, GWL_WNDPROC, AddressOf WindowProc)
End Sub
Public Function WindowProc(ByVal hw As Long, ByVal uMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
If uMsg = WM_QUERYENDSESSION Then
   'MsgBox "hw:" + CStr(hw) + " uMsg:" + CStr(uMsg) + " wParam:" + CStr(wParam)
   WindowProc = False 'send don't shut down
   'run code do what you want, then call ExitWindowsEx etc up to you
   Exit Function
ElseIf uMsg = WM_ENDSESSION Then
   'MsgBox "hw:" + CStr(hw) + " uMsg:" + CStr(uMsg) + " wParam:" + CStr(wParam)
   WindowProc = False
   'run code
   Exit Function
End If
WindowProc = CallWindowProc(WndProc, hw, uMsg, wParam, lParam)
End FunctionForm

Form

Code:

Private Sub Form_Load()
Hook (Me.hwnd)
End Sub

I have tested it, but the result still same with my previous code. Windows screen dialog still appear when we try to shutdown. And your code make my another code freeze if mouse pointer in hover of my form.