Check for full trust

Question

How do I check if my code is running in full trust mode? I have seen several suggestions to check for specific permissions using SecurityManager.IsGranted() method, but I specifically want to check for full trust because no specific permission in partial trust mode is enough to use FileSystemWatcher class.

Answer 1

AFAIK, there's only one approach that will work for transparent code (which yours will presumably be under at least 4.0 if it's not fully trusted) in both 3.5 and 4.0: demanding an unrestricted permission set and catching the SecurityException if the demand fails. e.g.:

public static bool RunningWithFullTrust()
{
    bool result;
    try
    {
        (new PermissionSet(PermissionState.Unrestricted)).Demand();
        result = true;
    }
    catch (SecurityException)
    {
        result = false;
    }

    return result;
}

This probably offers no advantage whatsoever over your current approach of catching and ignoring the exception.

For 4.0, there is a new AppDomain.IsFullyTrusted method that would potentially be of use.