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 if 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:

If your code has no sufficient permissions, a SecurityException is thrown. Checking for permission is absolutely a best practice and should be applied where possible. In Chapter 46, “Working with Assemblies,” you get some more information about the security model in the .NET Framework.