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I've been trying to disable/enable Windows 10 devices immidiately with WPF. There is an answer here but it give me an exception as mentioned in the answer's comments. There also an suggestion for fixing also in the answer's comments but I don't know how to make it work because I'm new to WPF.

Here is the code:

public static class DisableHardware
{
    const uint DIF_PROPERTYCHANGE = 0x12;
    const uint DICS_ENABLE = 1;
    const uint DICS_DISABLE = 2;  // disable device
    const uint DICS_FLAG_GLOBAL = 1; // not profile-specific
    const uint DIGCF_ALLCLASSES = 4;
    const uint DIGCF_PRESENT = 2;
    const uint ERROR_INVALID_DATA = 13;
    const uint ERROR_NO_MORE_ITEMS = 259;
    const uint ERROR_ELEMENT_NOT_FOUND = 1168;

    static DEVPROPKEY DEVPKEY_Device_DeviceDesc;
    static DEVPROPKEY DEVPKEY_Device_HardwareIds;

    [StructLayout(LayoutKind.Sequential)]
    struct SP_CLASSINSTALL_HEADER
    {
        public UInt32 cbSize;
        public UInt32 InstallFunction;
    }

    [StructLayout(LayoutKind.Sequential)]
    struct SP_PROPCHANGE_PARAMS
    {
        public SP_CLASSINSTALL_HEADER ClassInstallHeader;
        public UInt32 StateChange;
        public UInt32 Scope;
        public UInt32 HwProfile;
    }

    [StructLayout(LayoutKind.Sequential)]
    struct SP_DEVINFO_DATA
    {
        public UInt32 cbSize;
        public Guid classGuid;
        public UInt32 devInst;
        public IntPtr reserved;     // CHANGE #1 - was UInt32
    }

    [StructLayout(LayoutKind.Sequential)]
    struct DEVPROPKEY
    {
        public Guid fmtid;
        public UInt32 pid;
    }

    [DllImport("setupapi.dll", SetLastError = true)]
    static extern IntPtr SetupDiGetClassDevsW(
        [In] ref Guid ClassGuid,
        [MarshalAs(UnmanagedType.LPWStr)]
string Enumerator,
        IntPtr parent,
        UInt32 flags);

    [DllImport("setupapi.dll", SetLastError = true)]
    static extern bool SetupDiDestroyDeviceInfoList(IntPtr handle);

    [DllImport("setupapi.dll", SetLastError = true)]
    static extern bool SetupDiEnumDeviceInfo(IntPtr deviceInfoSet,
        UInt32 memberIndex,
        [Out] out SP_DEVINFO_DATA deviceInfoData);

    [DllImport("setupapi.dll", SetLastError = true)]
    static extern bool SetupDiSetClassInstallParams(
        IntPtr deviceInfoSet,
        [In] ref SP_DEVINFO_DATA deviceInfoData,
        [In] ref SP_PROPCHANGE_PARAMS classInstallParams,
        UInt32 ClassInstallParamsSize);

    [DllImport("setupapi.dll", SetLastError = true)]
    static extern bool SetupDiChangeState(
        IntPtr deviceInfoSet,
        [In] ref SP_DEVINFO_DATA deviceInfoData);

    [DllImport("setupapi.dll", SetLastError = true)]
    static extern bool SetupDiGetDevicePropertyW(
            IntPtr deviceInfoSet,
            [In] ref SP_DEVINFO_DATA DeviceInfoData,
            [In] ref DEVPROPKEY propertyKey,
            [Out] out UInt32 propertyType,
            IntPtr propertyBuffer,
            UInt32 propertyBufferSize,
            out UInt32 requiredSize,
            UInt32 flags);

    [DllImport("setupapi.dll", SetLastError = true)]
    static extern bool SetupDiGetDeviceRegistryPropertyW(
      IntPtr DeviceInfoSet,
      [In] ref SP_DEVINFO_DATA  DeviceInfoData,
      UInt32 Property,
      [Out] out UInt32  PropertyRegDataType,
      IntPtr PropertyBuffer,
      UInt32 PropertyBufferSize,
      [In,Out] ref UInt32 RequiredSize
    );

    static DisableHardware()
    {
        DisableHardware.DEVPKEY_Device_DeviceDesc = new DEVPROPKEY();
        DEVPKEY_Device_DeviceDesc.fmtid = new Guid(
                0xa45c254e, 0xdf1c, 0x4efd, 0x80, 0x20, 0x67,
                0xd1, 0x46, 0xa8, 0x50, 0xe0);
        DEVPKEY_Device_DeviceDesc.pid = 2;

        DEVPKEY_Device_HardwareIds = new DEVPROPKEY();
        DEVPKEY_Device_HardwareIds.fmtid = new Guid(
            0xa45c254e, 0xdf1c, 0x4efd, 0x80, 0x20, 0x67,
            0xd1, 0x46, 0xa8, 0x50, 0xe0);
        DEVPKEY_Device_HardwareIds.pid = 3;
    }




    public static void DisableDevice(Func<string, bool> filter, bool disable = true)
    {
        IntPtr info = IntPtr.Zero;
        Guid NullGuid = Guid.Empty;
        try
        {
            info = SetupDiGetClassDevsW(
                ref NullGuid,
                null,
                IntPtr.Zero,
                DIGCF_ALLCLASSES);
            CheckError("SetupDiGetClassDevs");

            SP_DEVINFO_DATA devdata = new SP_DEVINFO_DATA();
            devdata.cbSize = (UInt32)Marshal.SizeOf(devdata);

            // Get first device matching device criterion.
            for (uint i = 0; ; i++)
            {
                SetupDiEnumDeviceInfo(info,
                    i,
                    out devdata);
                // if no items match filter, throw
                if (Marshal.GetLastWin32Error() == ERROR_NO_MORE_ITEMS)
                    CheckError("No device found matching filter.", 0xcffff);
                CheckError("SetupDiEnumDeviceInfo");

                string devicepath = GetStringPropertyForDevice(info,
                                           devdata, 1); // SPDRP_HARDWAREID

                // Uncomment to print name/path
                //Console.WriteLine(GetStringPropertyForDevice(info,
                //                         devdata, DEVPKEY_Device_DeviceDesc));
                //Console.WriteLine("   {0}", devicepath);
                if (devicepath != null && filter(devicepath)) break;

            }

            SP_CLASSINSTALL_HEADER header = new SP_CLASSINSTALL_HEADER();
            header.cbSize = (UInt32)Marshal.SizeOf(header);
            header.InstallFunction = DIF_PROPERTYCHANGE;

            SP_PROPCHANGE_PARAMS propchangeparams = new SP_PROPCHANGE_PARAMS();
            propchangeparams.ClassInstallHeader = header;
            propchangeparams.StateChange = disable ? DICS_DISABLE : DICS_ENABLE;
            propchangeparams.Scope = DICS_FLAG_GLOBAL;
            propchangeparams.HwProfile = 0;

            SetupDiSetClassInstallParams(info,
                ref devdata,
                ref propchangeparams,
                (UInt32)Marshal.SizeOf(propchangeparams));
            CheckError("SetupDiSetClassInstallParams");

            SetupDiChangeState(
                info,
                ref devdata);
            CheckError("SetupDiChangeState");
        }
        finally
        {
            if (info != IntPtr.Zero)
                SetupDiDestroyDeviceInfoList(info);
        }
    }
    private static void CheckError(string message, int lasterror = -1)
    {

        int code = lasterror == -1 ? Marshal.GetLastWin32Error() : lasterror;
        if (code != 0)
            throw new ApplicationException(
                String.Format("Error disabling hardware device (Code {0}): {1}",
                    code, message));
    }

    private static string GetStringPropertyForDevice(IntPtr info, SP_DEVINFO_DATA devdata,
        uint propId)
    {
        uint proptype, outsize;
        IntPtr buffer = IntPtr.Zero;
        try
        {
            uint buflen = 512;
            buffer = Marshal.AllocHGlobal((int)buflen);
            outsize=0;
            // CHANGE #2 - Use this instead of SetupDiGetDeviceProperty 
            SetupDiGetDeviceRegistryPropertyW(
                info,
                ref devdata,
                propId,
                out proptype,
                buffer,
                buflen,
                ref outsize);
            byte[] lbuffer = new byte[outsize];
            Marshal.Copy(buffer, lbuffer, 0, (int)outsize);
            int errcode = Marshal.GetLastWin32Error();
            if (errcode == ERROR_INVALID_DATA) return null;
            CheckError("SetupDiGetDeviceProperty", errcode);
            return Encoding.Unicode.GetString(lbuffer);
        }
        finally
        {
            if (buffer != IntPtr.Zero)
                Marshal.FreeHGlobal(buffer);
        }
    }

}

The suggested fix is:

The problem is that, the function uses a fixed buffer length of 512, which a lot of times is not enough to hold the data. What needs to be done is to first get the size of buffer as follows: if(!SetupDiGetDeviceRegistryPropertyW(info, ref devdata, propId, out proptype, IntPtr.Zero, 0, ref outsize)). Once the size is got, allocate the buffer and call SetupDiGetDeviceRegistryPropertyW again

manaclan
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1 Answers1

2

I haven't messed with this stuff before, but just reading the comment on that other question, it looks like the suggestion is to do this:

private static string GetStringPropertyForDevice(IntPtr info, SP_DEVINFO_DATA devdata, uint propId)
{
    uint proptype, outsize;
    IntPtr buffer = IntPtr.Zero;
    try
    {
        SetupDiGetDeviceRegistryPropertyW(
            info,
            ref devdata,
            propId,
            out proptype,
            IntPtr.Zero,
            0,
            ref outsize);

        uint buflen = outsize;
        buffer = Marshal.AllocHGlobal((int)buflen);
        outsize = 0;
        SetupDiGetDeviceRegistryPropertyW(
            info,
            ref devdata,
            propId,
            out proptype,
            buffer,
            buflen,
            ref outsize);

        byte[] lbuffer = new byte[outsize];
        Marshal.Copy(buffer, lbuffer, 0, (int)outsize);
        int errcode = Marshal.GetLastWin32Error();
        if (errcode == ERROR_INVALID_DATA) return null;
        CheckError("SetupDiGetDeviceProperty", errcode);
        return Encoding.Unicode.GetString(lbuffer);
    }
    finally
    {
        if (buffer != IntPtr.Zero)
            Marshal.FreeHGlobal(buffer);
    }
}

Call SetupDiGetDeviceRegistryPropertyW with no buffer first, just to get the outsize value, then use that as your buffer size. This avoids creating a buffer of arbitrary length which could be exceeded, at the cost of making the call twice.

Again- I haven't tested this or anything, it just seems like what the person writing that comment was intending. Hopefully it works!

Keith Stein
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  • This answer is right. This is a common pattern seen in Windows (and other?) APIs that need to write arbitrary data into a user-supplied buffer. You call the API twice. The first call is made with a null buffer pointer, which tells the function to retrieve only the buffer size that you'll need. You then allocate a buffer of (at least) that size, then call the API again with a non-null buffer pointer. In cases where the size of the data you're requesting is a constant, you can avoid the first call. As long as your buffer is big enough, the call won't fail. – Scott Smith Jul 25 '20 at 22:50