' This sample demonstrates the use of the PermissionSet class.
Imports System.Reflection
Imports System.Security.Permissions
Imports System.Security
Imports System.IO
Imports System.Collections

Class [MyClass]

    Public Shared Sub PermissionSetDemo()
        Console.WriteLine("Executing PermissionSetDemo")
        Try
            ' Open a new PermissionSet.
            Dim ps1 As New PermissionSet(PermissionState.None)
            Console.WriteLine("Adding permission to open a file from a file dialog box.")
            ' Add a permission to the permission set.
            ps1.AddPermission(New FileDialogPermission(FileDialogPermissionAccess.Open))
            Console.WriteLine("Demanding permission to open a file.")
            ps1.Demand()
            Console.WriteLine("Demand succeeded.")
            Console.WriteLine("Adding permission to save a file from a file dialog box.")
            ps1.AddPermission(New FileDialogPermission(FileDialogPermissionAccess.Save))
            Console.WriteLine("Demanding permission to open and save a file.")
            ps1.Demand()
            Console.WriteLine("Demand succeeded.")
            Console.WriteLine("Adding permission to read environment variable USERNAME.")
            ps1.AddPermission(New EnvironmentPermission(EnvironmentPermissionAccess.Read, "USERNAME"))
            ps1.Demand()
            Console.WriteLine("Demand succeeded.")
            Console.WriteLine("Adding permission to read environment variable COMPUTERNAME.")
            ps1.AddPermission(New EnvironmentPermission(EnvironmentPermissionAccess.Read, "COMPUTERNAME"))
            ' Demand all the permissions in the set.
            Console.WriteLine("Demand all permissions.")
            ps1.Demand()
            Console.WriteLine("Demand succeeded.")
            ' Display the number of permissions in the set.
            Console.WriteLine("Number of permissions = " & ps1.Count)
            ' Display the value of the IsSynchronized property.
            Console.WriteLine("IsSynchronized property = " & ps1.IsSynchronized)
            ' Display the value of the IsReadOnly property.
            Console.WriteLine("IsReadOnly property = " & ps1.IsReadOnly)
            ' Display the value of the SyncRoot property.
            Console.WriteLine("SyncRoot property = " & CType(ps1.SyncRoot, PermissionSet).ToString())
            ' Display the result of a call to the ContainsNonCodeAccessPermissions method.
            ' Gets a value indicating whether the PermissionSet contains permissions 
            ' that are not derived from CodeAccessPermission.
            ' Returns true if the PermissionSet contains permissions that are not 
            ' derived from CodeAccessPermission; otherwise, false.
            Console.WriteLine("ContainsNonCodeAccessPermissions method returned " & ps1.ContainsNonCodeAccessPermissions())
            Console.WriteLine("Value of the permission set ToString = " & ControlChars.Lf & ps1.ToString())
            Dim ps2 As New PermissionSet(PermissionState.None)
            ' Create a second permission set and compare it to the first permission set.
            ps2.AddPermission(New EnvironmentPermission(EnvironmentPermissionAccess.Read, "USERNAME"))
            ps2.AddPermission(New EnvironmentPermission(EnvironmentPermissionAccess.Write, "COMPUTERNAME"))
            Console.WriteLine("Permissions in first permission set:")
            Dim list As IEnumerator = ps1.GetEnumerator()
            While list.MoveNext()
                Console.WriteLine(list.Current.ToString())
            End While
            Console.WriteLine("Second permission IsSubsetOf first permission = " & ps2.IsSubsetOf(ps1))
            ' Display the intersection of two permission sets.
            Dim ps3 As PermissionSet = ps2.Intersect(ps1)
            Console.WriteLine("The intersection of the first permission set and " & "the second permission set = " & ps3.ToString())
            ' Create a new permission set.
            Dim ps4 As New PermissionSet(PermissionState.None)
            ps4.AddPermission(New FileIOPermission(FileIOPermissionAccess.Read, "C:\Temp\Testfile.txt"))
            ps4.AddPermission(New FileIOPermission(FileIOPermissionAccess.Read Or FileIOPermissionAccess.Write Or FileIOPermissionAccess.Append, "C:\Temp\Testfile.txt"))
            ' Display the union of two permission sets.
            Dim ps5 As PermissionSet = ps3.Union(ps4)
            Console.WriteLine("The union of permission set 3 and permission set 4 = " & ps5.ToString())
            ' Remove FileIOPermission from the permission set.
            ps5.RemovePermission(GetType(FileIOPermission))
            Console.WriteLine("The last permission set after removing FileIOPermission = " & ps5.ToString())
            ' Change the permission set using SetPermission.
            ps5.SetPermission(New EnvironmentPermission(EnvironmentPermissionAccess.AllAccess, "USERNAME"))
            Console.WriteLine("Permission set after SetPermission = " & ps5.ToString())
            ' Display result of ToXml and FromXml operations.
            Dim ps6 As New PermissionSet(PermissionState.None)
            ps6.FromXml(ps5.ToXml())
            Console.WriteLine("Result of ToFromXml = " & ps6.ToString() & ControlChars.Lf)
            ' Display results of PermissionSet.GetEnumerator.
            Dim psEnumerator As IEnumerator = ps1.GetEnumerator()
            While psEnumerator.MoveNext()
                Console.WriteLine(psEnumerator.Current)
            End While
            ' Check for an unrestricted permission set.
            Dim ps7 As New PermissionSet(PermissionState.Unrestricted)
            Console.WriteLine("Permission set is unrestricted = " & ps7.IsUnrestricted())
            ' Create and display a copy of a permission set.
            ps7 = ps5.Copy()
            Console.WriteLine("Result of copy = " & ps7.ToString())
        Catch e As Exception
            Console.WriteLine(e.Message.ToString())
        End Try
    End Sub

    Overloads Shared Sub Main(ByVal args() As String)
        PermissionSetDemo()
    End Sub
End Class