''' <summary>
''' Checking for directory and file write permissions
''' </summary>
''' <remarks>https://stackoverflow.com/a/22020271</remarks>
Public Class CurrentUserSecurity
    Private ReadOnly _currentUser As WindowsIdentity
    Private ReadOnly _currentPrincipal As WindowsPrincipal
 
    Public Sub New()
        _currentUser = WindowsIdentity.GetCurrent()
        _currentPrincipal = New WindowsPrincipal(WindowsIdentity.GetCurrent())
    End Sub
 
    Public Function HasAccess(directory As IO.DirectoryInfo, right As _
      Security.AccessControl.FileSystemRights) As Boolean
        ' Get the collection of authorization rules that apply to the directory.
        Try
            Dim acl As Security.AccessControl.AuthorizationRuleCollection = _
              directory.GetAccessControl().GetAccessRules(True, True, GetType( _
              SecurityIdentifier))
            Return HasFileOrDirectoryAccess(right, acl)
        Catch UAEx As UnauthorizedAccessException
            Return False
        End Try
    End Function
 
    Public Function HasAccess(file As IO.FileInfo, right As _
      Security.AccessControl.FileSystemRights) As Boolean
        ' Get the collection of authorization rules that apply to the file.
        Try
            Dim acl As Security.AccessControl.AuthorizationRuleCollection = _
              file.GetAccessControl().GetAccessRules(True, True, GetType( _
              SecurityIdentifier))
            Return HasFileOrDirectoryAccess(right, acl)
        Catch UAEx As UnauthorizedAccessException
            Return False
        End Try
 
    End Function
 
    Private Function HasFileOrDirectoryAccess(right As _
      Security.AccessControl.FileSystemRights, acl As _
      Security.AccessControl.AuthorizationRuleCollection) As Boolean
        Dim allow As Boolean = False
        Dim inheritedAllow As Boolean = False
        Dim inheritedDeny As Boolean = False
 
        For i As Integer = 0 To acl.Count - 1
            Dim currentRule As Security.AccessControl.FileSystemAccessRule = _
              DirectCast(acl(i), Security.AccessControl.FileSystemAccessRule)
            ' If the current rule applies to the current user.
            If _currentUser.User.Equals(currentRule.IdentityReference) OrElse _
              _currentPrincipal.IsInRole(DirectCast( _
              currentRule.IdentityReference, SecurityIdentifier)) Then
 
                If currentRule.AccessControlType.Equals( _
                  Security.AccessControl.AccessControlType.Deny) Then
                    If (currentRule.FileSystemRights And right) = right Then
                        If currentRule.IsInherited Then
                            inheritedDeny = True
                        Else
                            ' Non inherited "deny" takes overall precedence.
                            Return False
                        End If
                    End If
                ElseIf currentRule.AccessControlType.Equals( _
                  Security.AccessControl.AccessControlType.Allow) Then
                    If (currentRule.FileSystemRights And right) = right Then
                        If currentRule.IsInherited Then
                            inheritedAllow = True
                        Else
                            allow = True
                        End If
                    End If
                End If
            End If
        Next
 
        If allow Then
            ' Non inherited "allow" takes precedence over inherited rules.
            Return True
        End If
        Return inheritedAllow AndAlso Not inheritedDeny
    End Function
 
End Class

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) _
  Handles Button1.Click
 
    Dim sPath As String = "F:\Temp"
 
    If IO.Directory.Exists(sPath) Then
        Dim CUS As New CurrentUserSecurity
        Dim test As Boolean = CUS.HasAccess(New IO.DirectoryInfo(sPath), _
          Security.AccessControl.FileSystemRights.Write)
        MessageBox.Show($"Sie {If(test, "haben", "haben KEIN")} Schreibzugriff" & _
        "auf {sPath}.")
    Else
        MessageBox.Show($"Kann {sPath} nich finden.")
    End If
 
End Sub