VB6 - Lock a Directory for Deleting

[CVMichael]

This shows how to lock a Directory so you can't delete it.

Windows will not allow you to delete a folder if a file is in use in that folder. Therefore the solution to locking a directory is simple, create a file, and keep it open, and while the file is open you cannot delete the directory.

But if you open a file with VB's built in functions, when you close the application, VB will automatically close the file pointers also. Therefore we have to use API because if you close the application, the file will still be opened.

Another problem is that if you open a file in that directory, the file will show up in Windows Explorer, and therefore we have to use ADS files.

So, finally, here's the code:
Put put 2 command buttons on the form, named "cmdLock" and "cmdUnlock".
As a sample, this code locks directory "C:\MyDirectory", but you can change it to whatever directory you need.

Option Explicit

Private Const OPEN_ALWAYS = 4
Private Const GENERIC_WRITE = &H40000000

Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" (ByVal lpFileName As String, ByVal dwDesiredAccess As Long, ByVal dwShareMode As Long, ByVal lpSecurityAttributes As Long, ByVal dwCreationDisposition As Long, ByVal dwFlagsAndAttributes As Long, ByVal hTemplateFile As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long

Public Function LockDir(ByVal Path As String) As Long
    LockDir = CreateFile(Path & ":dirlock", GENERIC_WRITE, 0, 0, OPEN_ALWAYS, 0, 0)
End Function

Public Function UnlockDir(ByVal hDir As Long) As Boolean
    UnlockDir = CloseHandle(hDir) <> 0
End Function

Private Sub Form_Load()
    On Error Resume Next
    
    MkDir "C:\MyDirectory"
End Sub

Private Sub cmdLock_Click()
    Dim Ret As Long
    
    Ret = Val(GetSetting(App.EXEName, "DirPointer", "Pointer", -1))
    
    If Ret <> -1 And Ret <> 0 Then
        cmdUnlock_Click
    Else
        Ret = LockDir("C:\MyDirectory")
        
        If Ret <> -1 Then SaveSetting App.EXEName, "DirPointer", "Pointer", Ret
    End If
End Sub

Private Sub cmdUnlock_Click()
    Dim hDir As Long
    
    hDir = Val(GetSetting(App.EXEName, "DirPointer", "Pointer", -1))
    
    If hDir <> -1 And hDir <> 0 Then
        If UnlockDir(hDir) Then SaveSetting App.EXEName, "DirPointer", "Pointer", -1
    End If
End Sub

With this code you can only lock one directory at any time, becase it's saving the file pointer in only one registry location. But you can change the code to store the pointers in a Collection list, and save all the pointers to all the files opened.

Just remember that this code locks a Directory for deleting, not the files in it...