Здравствуйте, Sinix, Вы писали:

S>К сожалению, в .Net нет метода GetEffectivePermissions и гугл не знает о готовых решениях.

Может Вы имели в виду GetEffectiveRightsFromAcl? То есть типа этого?

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
        public struct Trustee
        {
            public IntPtr pMultipleTrustee;
            public int MultipleTrusteeOperation;
            public int TrusteeForm;
            public int TrusteeType;
            [MarshalAs(UnmanagedType.LPTStr)]
            public string name;
        }

        [DllImport("advapi32.dll", CharSet = CharSet.Unicode)]
        internal static extern int GetEffectiveRightsFromAclW(
            byte[] pAcl, ref Trustee pTrustee, out uint pAccessMask);


            FileSecurity fss = new FileSecurity(
                "SomeFile.bin", AccessControlSections.Access);
            byte[] rawsd = fss.GetSecurityDescriptorBinaryForm();
            CommonSecurityDescriptor csd 
                = new CommonSecurityDescriptor(true, false, rawsd, 0);
            int aclLen = csd.DiscretionaryAcl.BinaryLength;
            byte[] rawAcl = new byte[aclLen];
            csd.DiscretionaryAcl.GetBinaryForm(rawAcl, 0);
            uint mask;
            Trustee trustee = new Trustee();
            trustee.TrusteeForm = 1;
            trustee.TrusteeType = 1;
            trustee.name = "SomeUser";
            int result = GetEffectiveRightsFromAclW(rawAcl, ref trustee, out mask);
            if (result == 0)
                Console.WriteLine((FileSystemRights)mask);
            else
                Console.WriteLine("Error: {0}", result);