Clean-up

Refined error handling

DerpingDrivers/App.xaml.cs

@@ -16,7 +16,8 @@ namespace DerpingDrivers
                 "Release",
                 0);
 
-            // This is a big ugly but catches cases where invoked without the app.config
+            // This is a bit ugly but catches cases where invoked without the app.config
+            // will lead to a silent crash because of missing methods etc.
             if (netRelease < 394254)
             {
                 MessageBox.Show(

DerpingDrivers/DerpingDrivers.csproj

@@ -111,6 +111,7 @@
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
     </ApplicationDefinition>
+    <Compile Include="Exceptions\NtQuerySystemInformationException.cs" />
     <Compile Include="Util\CodeIntegrityHelper.cs" />
     <Compile Include="Util\OsUpgradeDetection.cs" />
     <Compile Include="Util\OSVersionInfo.cs" />

DerpingDrivers/Exceptions/NtQuerySystemInformationException.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Runtime.Serialization;
+
+namespace DerpingDrivers.Exceptions
+{
+    public class NtQuerySystemInformationException : Exception
+    {
+        public NtQuerySystemInformationException()
+        {
+        }
+
+        public NtQuerySystemInformationException(string message) : base(message)
+        {
+        }
+
+        public NtQuerySystemInformationException(string message, Exception innerException) : base(message, innerException)
+        {
+        }
+
+        protected NtQuerySystemInformationException(SerializationInfo info, StreamingContext context) : base(info, context)
+        {
+        }
+    }
+}

DerpingDrivers/Util/CodeIntegrityHelper.cs

@@ -1,25 +1,15 @@
-using PInvoke;
+using System;
-using System;
 using System.Runtime.InteropServices;
+using DerpingDrivers.Exceptions;
+using PInvoke;
 
 namespace DerpingDrivers.Util
 {
     public static class CodeIntegrityHelper
     {
-        [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+        /// <summary>
-        private delegate Int32 NtQuerySystemInformation(
+        ///     Determines if the system is currently in TESTSIGNING mode.
-            UInt32 SystemInformationClass,
+        /// </summary>
-            IntPtr SystemInformation,
-            UInt32 SystemInformationLength,
-            out UInt32 ReturnLength);
-
-        [StructLayout(LayoutKind.Sequential)]
-        private struct SYSTEM_CODEINTEGRITY_INFORMATION
-        {
-            public UInt32 Length;
-            public UInt32 CodeIntegrityOptions;
-        };
-
         public static bool IsTestSignEnabled
         {
             get
@@ -47,9 +37,15 @@ namespace DerpingDrivers.Util
                         out _
                     );
 
+                    var error = Kernel32.GetLastError();
+
+                    if (status != 0)
+                        throw new NtQuerySystemInformationException(
+                            $"NtQuerySystemInformation failed with status {error}");
+
                     integrity = Marshal.PtrToStructure<SYSTEM_CODEINTEGRITY_INFORMATION>(pIntegrity);
 
-                    return ((integrity.CodeIntegrityOptions & /* CODEINTEGRITY_OPTION_TESTSIGN */ 0x02) != 0);
+                    return (integrity.CodeIntegrityOptions & /* CODEINTEGRITY_OPTION_TESTSIGN */ 0x02) != 0;
                 }
                 finally
                 {
@@ -57,5 +53,23 @@ namespace DerpingDrivers.Util
                 }
             }
         }
+
+        #region Native
+
+        [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+        private delegate int NtQuerySystemInformation(
+            uint SystemInformationClass,
+            IntPtr SystemInformation,
+            uint SystemInformationLength,
+            out uint ReturnLength);
+
+        [StructLayout(LayoutKind.Sequential)]
+        private struct SYSTEM_CODEINTEGRITY_INFORMATION
+        {
+            public uint Length;
+            public uint CodeIntegrityOptions;
+        }
+
+        #endregion
     }
 }

DerpingDrivers/Util/OSVersionInfo.cs

@@ -594,6 +594,7 @@ namespace DerpingDrivers.Util
                     var majorVersion = osVersion.Version.Major;
                     var minorVersion = osVersion.Version.Minor;
 
+                    // TODO: deprecate this. Use a proper manifest. Always.
                     if (majorVersion == 6 && minorVersion == 2)
                     {
                         //The registry read workaround is by Scott Vickery. Thanks a lot for the help!

DerpingDrivers/Util/OsUpgradeDetection.cs

@@ -9,6 +9,9 @@ namespace DerpingDrivers.Util
     /// </summary>
     public class OsUpgradeDetection
     {
+        /// <summary>
+        ///     Gets whether the system has been in-place upgraded.
+        /// </summary>
         public static bool IsGrandfathered
         {
             get
@@ -39,7 +42,6 @@ namespace DerpingDrivers.Util
                                     return true;
                                 }
 
-                                // TODO: untested but should work
                                 if (productName.StartsWith("Windows 8", StringComparison.InvariantCultureIgnoreCase))
                                 {
                                     return true;

DerpingDrivers/Util/UEFIHelper.cs

@@ -13,10 +13,10 @@ namespace DerpingDrivers.Util
         {
             get
             {
-                var val = Convert.ToInt32(Registry.GetValue(
+                var val = (int) Registry.GetValue(
                     @"HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecureBoot\State",
                     "UEFISecureBootEnabled",
-                    0));
+                    0);
 
                 return val > 0;
             }
@@ -30,20 +30,24 @@ namespace DerpingDrivers.Util
         {
             get
             {
+                // The arguments submitted are dummy values; GetLastError will
+                // report ERROR_INVALID_FUNCTION on Legacy BIOS systems.
                 GetFirmwareEnvironmentVariable(
                     string.Empty,
                     "{00000000-0000-0000-0000-000000000000}",
                     IntPtr.Zero, 0);
 
-                var error = Marshal.GetLastWin32Error();
+                return Marshal.GetLastWin32Error() != 0x01; // ERROR_INVALID_FUNCTION
+            }
+        }
 
-                return error != 0x01; // ERROR_INVALID_FUNCTION
+        #region Native
-            }
-        }
 
         [DllImport("kernel32.dll", EntryPoint = "GetFirmwareEnvironmentVariableW", SetLastError = true,
             CharSet = CharSet.Unicode, ExactSpelling = true)]
         private static extern uint GetFirmwareEnvironmentVariable(string lpName, string lpGuid, IntPtr pBuffer,
             uint nSize);
+
+        #endregion
     }
 }