Visual Basic 2015 Unleashed

Understanding Permissions

The .NET Framework provides a high-level security mechanism over system resources, so it can happen that you attempt to access, in both reading or writing, directories or files but you do not have the required rights. To prevent your code from failing at runtime, you can check whether you have permissions. When working with files and directories, you need to check the availability of the System.Security.FileIOPermission object. For example, the following code asks the system (Demand method) if it has permissions to read local files:

Click here to view code image

Dim fp As New FileIOPermission(PermissionState.None)fp.AllLocalFiles = FileIOPermissionAccess.ReadTry    fp.Demand()Catch ex As Security.SecurityException    Console.WriteLine("You ...