Win32 API function to programmatically enable/disable device

Question

I am writing a small C# app to disable a device (my laptop touchpad) whenever another mouse device is detected, and enable the touchpad again if a mouse is not detected. I am not even able to disable the touchpad in device manager (it is running on the default mouse class driver).

I am getting into device driver development so I thought maybe I could write a little filter driver that would just accept IOCTLs to enable and disable passing mouse event messages up the device stack, and get messages from user mode via a raw PDO. However, I asked that question and somebody has suggested that I can do this in usermode via the SetupDi.. functions. That would be really good, because this raw PDO communication method is a PITA to work with.

I have only used SetupDiGetClassDevs before, and there are so many of them, can someone with more experience with this part of the Win32 API just tell me quickly what one I should call to stop/disable a mouse device or its interface or if there is something somewhere in the dark corners of the framework that will do this (maybe in WMI?).

Update (24/9/09) I figured out how to do this with a filter driver and posted how I did it on my original question. I still want to know if it is possible to enable or disable devices directly from Win32 and if so, how - so I will leave this question open.

Answer 1

You can enable/disable devices from Win32 (and hence from C# via P/Invoke) using the SetupDi APIs but not all devices are "disable-able" in this way.

The problem you'll run into trying to disable your touchpad from Win32 (or WMI or any other API which calls down into the SetupDi* family of functions) is that the default mouse driver which is in most laptops with a touchpad ("PS/2 compatible mouse") doesn't support being disabled using SetupDi API's. I suspect this may be because actual old mice using PS/2 connectors can't be hot-detached without hosing the hardware.

To verify that you can't disable, go into Device Manager and right-click on your mouse driver. If you see a disable option, you can use SetupDi to disable it. If no disable option, you're out of luck... welcome to IOCTL-land!

If you do see a disable option, then the code below (ported to C# from a VB sample I found here) should let you disable and re-enable the device.

Here's the code to call the library:

    public static void EnableMouse(bool enable)
    {
        // every type of device has a hard-coded GUID, this is the one for mice
        Guid mouseGuid = new Guid("{4d36e96f-e325-11ce-bfc1-08002be10318}");

        // get this from the properties dialog box of this device in Device Manager
        string instancePath = @"ACPI\PNP0F03\4&3688D3F&0";

        DeviceHelper.SetDeviceEnabled(mouseGuid, instancePath, enable);
    }

Here's the library itself, adapted from here.

using System;
using System.Text;
using System.Collections.Generic;
using DisableDevice;
using System.Runtime.InteropServices;
using System.ComponentModel;
using Microsoft.Win32.SafeHandles;
using System.Security;
using System.Runtime.ConstrainedExecution;
using System.Management;

namespace DisableDevice
{

    [Flags()]
    internal enum SetupDiGetClassDevsFlags
    {
        Default = 1,
        Present = 2,
        AllClasses = 4,
        Profile = 8,
        DeviceInterface = (int)0x10
    }

    internal enum DiFunction
    {
        SelectDevice = 1,
        InstallDevice = 2,
        AssignResources = 3,
        Properties = 4,
        Remove = 5,
        FirstTimeSetup = 6,
        FoundDevice = 7,
        SelectClassDrivers = 8,
        ValidateClassDrivers = 9,
        InstallClassDrivers = (int)0xa,
        CalcDiskSpace = (int)0xb,
        DestroyPrivateData = (int)0xc,
        ValidateDriver = (int)0xd,
        Detect = (int)0xf,
        InstallWizard = (int)0x10,
        DestroyWizardData = (int)0x11,
        PropertyChange = (int)0x12,
        EnableClass = (int)0x13,
        DetectVerify = (int)0x14,
        InstallDeviceFiles = (int)0x15,
        UnRemove = (int)0x16,
        SelectBestCompatDrv = (int)0x17,
        AllowInstall = (int)0x18,
        RegisterDevice = (int)0x19,
        NewDeviceWizardPreSelect = (int)0x1a,
        NewDeviceWizardSelect = (int)0x1b,
        NewDeviceWizardPreAnalyze = (int)0x1c,
        NewDeviceWizardPostAnalyze = (int)0x1d,
        NewDeviceWizardFinishInstall = (int)0x1e,
        Unused1 = (int)0x1f,
        InstallInterfaces = (int)0x20,
        DetectCancel = (int)0x21,
        RegisterCoInstallers = (int)0x22,
        AddPropertyPageAdvanced = (int)0x23,
        AddPropertyPageBasic = (int)0x24,
        Reserved1 = (int)0x25,
        Troubleshooter = (int)0x26,
        PowerMessageWake = (int)0x27,
        AddRemotePropertyPageAdvanced = (int)0x28,
        UpdateDriverUI = (int)0x29,
        Reserved2 = (int)0x30
    }

    internal enum StateChangeAction
    {
        Enable = 1,
        Disable = 2,
        PropChange = 3,
        Start = 4,
        Stop = 5
    }

    [Flags()]
    internal enum Scopes
    {
        Global = 1,
        ConfigSpecific = 2,
        ConfigGeneral = 4
    }

    internal enum SetupApiError
    {
        NoAssociatedClass = unchecked((int)0xe0000200),
        ClassMismatch = unchecked((int)0xe0000201),
        DuplicateFound = unchecked((int)0xe0000202),
        NoDriverSelected = unchecked((int)0xe0000203),
        KeyDoesNotExist = unchecked((int)0xe0000204),
        InvalidDevinstName = unchecked((int)0xe0000205),
        InvalidClass = unchecked((int)0xe0000206),
        DevinstAlreadyExists = unchecked((int)0xe0000207),
        DevinfoNotRegistered = unchecked((int)0xe0000208),
        InvalidRegProperty = unchecked((int)0xe0000209),
        NoInf = unchecked((int)0xe000020a),
        NoSuchHDevinst = unchecked((int)0xe000020b),
        CantLoadClassIcon = unchecked((int)0xe000020c),
        InvalidClassInstaller = unchecked((int)0xe000020d),
        DiDoDefault = unchecked((int)0xe000020e),
        DiNoFileCopy = unchecked((int)0xe000020f),
        InvalidHwProfile = unchecked((int)0xe0000210),
        NoDeviceSelected = unchecked((int)0xe0000211),
        DevinfolistLocked = unchecked((int)0xe0000212),
        DevinfodataLocked = unchecked((int)0xe0000213),
        DiBadPath = unchecked((int)0xe0000214),
        NoClassInstallParams = unchecked((int)0xe0000215),
        FileQueueLocked = unchecked((int)0xe0000216),
        BadServiceInstallSect = unchecked((int)0xe0000217),
        NoClassDriverList = unchecked((int)0xe0000218),
        NoAssociatedService = unchecked((int)0xe0000219),
        NoDefaultDeviceInterface = unchecked((int)0xe000021a),
        DeviceInterfaceActive = unchecked((int)0xe000021b),
        DeviceInterfaceRemoved = unchecked((int)0xe000021c),
        BadInterfaceInstallSect = unchecked((int)0xe000021d),
        NoSuchInterfaceClass = unchecked((int)0xe000021e),
        InvalidReferenceString = unchecked((int)0xe000021f),
        InvalidMachineName = unchecked((int)0xe0000220),
        RemoteCommFailure = unchecked((int)0xe0000221),
        MachineUnavailable = unchecked((int)0xe0000222),
        NoConfigMgrServices = unchecked((int)0xe0000223),
        InvalidPropPageProvider = unchecked((int)0xe0000224),
        NoSuchDeviceInterface = unchecked((int)0xe0000225),
        DiPostProcessingRequired = unchecked((int)0xe0000226),
        InvalidCOInstaller = unchecked((int)0xe0000227),
        NoCompatDrivers = unchecked((int)0xe0000228),
        NoDeviceIcon = unchecked((int)0xe0000229),
        InvalidInfLogConfig = unchecked((int)0xe000022a),
        DiDontInstall = unchecked((int)0xe000022b),
        InvalidFilterDriver = unchecked((int)0xe000022c),
        NonWindowsNTDriver = unchecked((int)0xe000022d),
        NonWindowsDriver = unchecked((int)0xe000022e),
        NoCatalogForOemInf = unchecked((int)0xe000022f),
        DevInstallQueueNonNative = unchecked((int)0xe0000230),
        NotDisableable = unchecked((int)0xe0000231),
        CantRemoveDevinst = unchecked((int)0xe0000232),
        InvalidTarget = unchecked((int)0xe0000233),
        DriverNonNative = unchecked((int)0xe0000234),
        InWow64 = unchecked((int)0xe0000235),
        SetSystemRestorePoint = unchecked((int)0xe0000236),
        IncorrectlyCopiedInf = unchecked((int)0xe0000237),
        SceDisabled = unchecked((int)0xe0000238),
        UnknownException = unchecked((int)0xe0000239),
        PnpRegistryError = unchecked((int)0xe000023a),
        RemoteRequestUnsupported = unchecked((int)0xe000023b),
        NotAnInstalledOemInf = unchecked((int)0xe000023c),
        InfInUseByDevices = unchecked((int)0xe000023d),
        DiFunctionObsolete = unchecked((int)0xe000023e),
        NoAuthenticodeCatalog = unchecked((int)0xe000023f),
        AuthenticodeDisallowed = unchecked((int)0xe0000240),
        AuthenticodeTrustedPublisher = unchecked((int)0xe0000241),
        AuthenticodeTrustNotEstablished = unchecked((int)0xe0000242),
        AuthenticodePublisherNotTrusted = unchecked((int)0xe0000243),
        SignatureOSAttributeMismatch = unchecked((int)0xe0000244),
        OnlyValidateViaAuthenticode = unchecked((int)0xe0000245)
    }

    [StructLayout(LayoutKind.Sequential)]
    internal struct DeviceInfoData
    {
        public int Size;
        public Guid ClassGuid;
        public int DevInst;
        public IntPtr Reserved;
    }

    [StructLayout(LayoutKind.Sequential)]
    internal struct PropertyChangeParameters
    {
        public int Size;
        // part of header. It's flattened out into 1 structure.
        public DiFunction DiFunction;
        public StateChangeAction StateChange;
        public Scopes Scope;
        public int HwProfile;
    }

    internal class NativeMethods
    {

        private const string setupapi = "setupapi.dll";

        private NativeMethods()
        {
        }

        [DllImport(setupapi, CallingConvention = CallingConvention.Winapi, SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool SetupDiCallClassInstaller(DiFunction installFunction, SafeDeviceInfoSetHandle deviceInfoSet, [In()]
ref DeviceInfoData deviceInfoData);

        [DllImport(setupapi, CallingConvention = CallingConvention.Winapi, SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool SetupDiEnumDeviceInfo(SafeDeviceInfoSetHandle deviceInfoSet, int memberIndex, ref DeviceInfoData deviceInfoData);

        [DllImport(setupapi, CallingConvention = CallingConvention.Winapi, CharSet = CharSet.Unicode, SetLastError = true)]
        public static extern SafeDeviceInfoSetHandle SetupDiGetClassDevs([In()]
ref Guid classGuid, [MarshalAs(UnmanagedType.LPWStr)]
string enumerator, IntPtr hwndParent, SetupDiGetClassDevsFlags flags);

        /*
        [DllImport(setupapi, CallingConvention = CallingConvention.Winapi, CharSet = CharSet.Unicode, SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool SetupDiGetDeviceInstanceId(SafeDeviceInfoSetHandle deviceInfoSet, [In()]
ref DeviceInfoData did, [MarshalAs(UnmanagedType.LPTStr)]
StringBuilder deviceInstanceId, int deviceInstanceIdSize, [Out()]
ref int requiredSize);
        */
        [DllImport("setupapi.dll", SetLastError = true, CharSet = CharSet.Auto)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool SetupDiGetDeviceInstanceId(
           IntPtr DeviceInfoSet,
           ref DeviceInfoData did,
           [MarshalAs(UnmanagedType.LPTStr)] StringBuilder DeviceInstanceId,
           int DeviceInstanceIdSize,
           out int RequiredSize
        );

        [SuppressUnmanagedCodeSecurity()]
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        [DllImport(setupapi, CallingConvention = CallingConvention.Winapi, SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool SetupDiDestroyDeviceInfoList(IntPtr deviceInfoSet);

        [DllImport(setupapi, CallingConvention = CallingConvention.Winapi, SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool SetupDiSetClassInstallParams(SafeDeviceInfoSetHandle deviceInfoSet, [In()]
ref DeviceInfoData deviceInfoData, [In()]
ref PropertyChangeParameters classInstallParams, int classInstallParamsSize);

    }

    internal class SafeDeviceInfoSetHandle : SafeHandleZeroOrMinusOneIsInvalid
    {

        public SafeDeviceInfoSetHandle()
            : base(true)
        {
        }

        protected override bool ReleaseHandle()
        {
            return NativeMethods.SetupDiDestroyDeviceInfoList(this.handle);
        }

    }

    public sealed class DeviceHelper
    {

        private DeviceHelper()
        {
        }

        /// <summary>
        /// Enable or disable a device.
        /// </summary>
        /// <param name="classGuid">The class guid of the device. Available in the device manager.</param>
        /// <param name="instanceId">The device instance id of the device. Available in the device manager.</param>
        /// <param name="enable">True to enable, False to disable.</param>
        /// <remarks>Will throw an exception if the device is not Disableable.</remarks>
        public static void SetDeviceEnabled(Guid classGuid, string instanceId, bool enable)
        {
            SafeDeviceInfoSetHandle diSetHandle = null;
            try
            {
                // Get the handle to a device information set for all devices matching classGuid that are present on the 
                // system.
                diSetHandle = NativeMethods.SetupDiGetClassDevs(ref classGuid, null, IntPtr.Zero, SetupDiGetClassDevsFlags.Present);
                // Get the device information data for each matching device.
                DeviceInfoData[] diData = GetDeviceInfoData(diSetHandle);
                // Find the index of our instance. i.e. the touchpad mouse - I have 3 mice attached...
                int index = GetIndexOfInstance(diSetHandle, diData, instanceId);
                // Disable...
                EnableDevice(diSetHandle, diData[index], enable);
            }
            finally
            {
                if (diSetHandle != null)
                {
                    if (diSetHandle.IsClosed == false)
                    {
                        diSetHandle.Close();
                    }
                    diSetHandle.Dispose();
                }
            }
        }

        private static DeviceInfoData[] GetDeviceInfoData(SafeDeviceInfoSetHandle handle)
        {
            List<DeviceInfoData> data = new List<DeviceInfoData>();
            DeviceInfoData did = new DeviceInfoData();
            int didSize = Marshal.SizeOf(did);
            did.Size = didSize;
            int index = 0;
            while (NativeMethods.SetupDiEnumDeviceInfo(handle, index, ref did))
            {
                data.Add(did);
                index += 1;
                did = new DeviceInfoData();
                did.Size = didSize;
            }
            return data.ToArray();
        }

        // Find the index of the particular DeviceInfoData for the instanceId.
        private static int GetIndexOfInstance(SafeDeviceInfoSetHandle handle, DeviceInfoData[] diData, string instanceId)
        {
            const int ERROR_INSUFFICIENT_BUFFER = 122;
            for (int index = 0; index <= diData.Length - 1; index++)
            {
                StringBuilder sb = new StringBuilder(1);
                int requiredSize = 0;
                bool result = NativeMethods.SetupDiGetDeviceInstanceId(handle.DangerousGetHandle(), ref diData[index], sb, sb.Capacity, out requiredSize);
                if (result == false && Marshal.GetLastWin32Error() == ERROR_INSUFFICIENT_BUFFER)
                {
                    sb.Capacity = requiredSize;
                    result = NativeMethods.SetupDiGetDeviceInstanceId(handle.DangerousGetHandle(), ref diData[index], sb, sb.Capacity, out requiredSize);
                }
                if (result == false)
                    throw new Win32Exception();
                if (instanceId.Equals(sb.ToString()))
                {
                    return index;
                }
            }
            // not found
            return -1;
        }

        // enable/disable...
        private static void EnableDevice(SafeDeviceInfoSetHandle handle, DeviceInfoData diData, bool enable)
        {
            PropertyChangeParameters @params = new PropertyChangeParameters();
            // The size is just the size of the header, but we've flattened the structure.
            // The header comprises the first two fields, both integer.
            @params.Size = 8;
            @params.DiFunction = DiFunction.PropertyChange;
            @params.Scope = Scopes.Global;
            if (enable)
            {
                @params.StateChange = StateChangeAction.Enable;
            }
            else
            {
                @params.StateChange = StateChangeAction.Disable;
            }

            bool result = NativeMethods.SetupDiSetClassInstallParams(handle, ref diData, ref @params, Marshal.SizeOf(@params));
            if (result == false) throw new Win32Exception();
            result = NativeMethods.SetupDiCallClassInstaller(DiFunction.PropertyChange, handle, ref diData);
            if (result == false)
            {
                int err = Marshal.GetLastWin32Error();
                if (err == (int)SetupApiError.NotDisableable)
                    throw new ArgumentException("Device can't be disabled (programmatically or in Device Manager).");
                else if (err >= (int)SetupApiError.NoAssociatedClass && err <= (int)SetupApiError.OnlyValidateViaAuthenticode)
                    throw new Win32Exception("SetupAPI error: " + ((SetupApiError)err).ToString());
                else
                    throw new Win32Exception();
            }
        }
    }
}

Note that when you get an Index-Out-Of-Bounds exception on the line int index = GetIndexOfInstance(diSetHandle, diData, instanceId);, you might have used the wrong classGuid for the device or the wrong instanceId.

Also note that when you run this code on a 64-bit Windows platform, you should target the 64-bit platform when you build your application. Otherwise - i.e. when running your application as a 32-bit process on a 64-bit Windows platform - you will get an SetupAPI error InWow64 (ERROR_IN_WOW64).

When targetting a 64-bit Windows platform, you might also have to make changes to other parts of your application, e.g. when doing pointer arithmetic, in order to prevent overflows.

Answer 2

One way might be to use the Windows Management Instrumentation layer. There seems to be a few device related classes defined in this layer.