Using RegisterDeviceNotification in a .NET app

Question

I have seen some examples on how to use RegisterDeviceNotification from the Windows API, but I have not seen any .NET examples. I want to write a C# app that is notified when a new drive appears (specifically through USB, firewire, etc). This app needs to be a Windows service, so I can't use WM_DEVICECHANGE messages without some bad-practice hacking. I'd like to avoid that. Can anyone give me a sample of how to use RegisterDeviceNotification in C#, or at least give me a good alternative to it?

EDIT: Again, this is a Windows service that has no graphical user interface. So the possible duplicate that involves WM notification messages won't work in this situation.

Answer 1

This answer provides relevant code samples to detect USB devices removal or addition:

using System;
using System.Runtime.InteropServices;

internal static class UsbNotification
{
    public const int DbtDevicearrival = 0x8000; // system detected a new device        
    public const int DbtDeviceremovecomplete = 0x8004; // device is gone      
    public const int WmDevicechange = 0x0219; // device change event      
    private const int DbtDevtypDeviceinterface = 5;
    private static readonly Guid GuidDevinterfaceUSBDevice = new Guid("A5DCBF10-6530-11D2-901F-00C04FB951ED"); // USB devices
    private static IntPtr notificationHandle;

    /// <summary>
    /// Registers a window to receive notifications when USB devices are plugged or unplugged.
    /// </summary>
    /// <param name="windowHandle">Handle to the window receiving notifications.</param>
    public static void RegisterUsbDeviceNotification(IntPtr windowHandle)
    {
        DevBroadcastDeviceinterface dbi = new DevBroadcastDeviceinterface
        {
            DeviceType = DbtDevtypDeviceinterface,
            Reserved = 0,
            ClassGuid = GuidDevinterfaceUSBDevice,
            Name = 0
        };

        dbi.Size = Marshal.SizeOf(dbi);
        IntPtr buffer = Marshal.AllocHGlobal(dbi.Size);
        Marshal.StructureToPtr(dbi, buffer, true);

        notificationHandle = RegisterDeviceNotification(windowHandle, buffer, 0);
    }

    /// <summary>
    /// Unregisters the window for USB device notifications
    /// </summary>
    public static void UnregisterUsbDeviceNotification()
    {
        UnregisterDeviceNotification(notificationHandle);
    }

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    private static extern IntPtr RegisterDeviceNotification(IntPtr recipient, IntPtr notificationFilter, int flags);

    [DllImport("user32.dll")]
    private static extern bool UnregisterDeviceNotification(IntPtr handle);

    [StructLayout(LayoutKind.Sequential)]
    private struct DevBroadcastDeviceinterface
    {
        internal int Size;
        internal int DeviceType;
        internal int Reserved;
        internal Guid ClassGuid;
        internal short Name;
    }
}

Usage from a WPF window:

    protected override void OnSourceInitialized(EventArgs e)
    {
        base.OnSourceInitialized(e);

        // Adds the windows message processing hook and registers USB device add/removal notification.
        HwndSource source = HwndSource.FromHwnd(new WindowInteropHelper(this).Handle);
        if (source != null)
        {
            windowHandle = source.Handle;
            source.AddHook(HwndHandler);
            UsbNotification.RegisterUsbDeviceNotification(windowHandle);
        }
    }

    /// <summary>
    /// Method that receives window messages.
    /// </summary>
    private IntPtr HwndHandler(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam, ref bool handled)
    {
        if (msg == UsbNotification.WmDevicechange)
        {
            switch ((int)wparam)
            {
                case UsbNotification.DbtDeviceremovecomplete:
                    Usb_DeviceRemoved(); // this is where you do your magic
                    break;
                case UsbNotification.DbtDevicearrival:
                    Usb_DeviceAdded(); // this is where you do your magic
                    break;
            }
        }

        handled = false;
        return IntPtr.Zero;
    }

Usage from Windows Forms:

public Form1()
{
    InitializeComponent();
    UsbNotification.RegisterUsbDeviceNotification(this.Handle);
}

protected override void WndProc(ref Message m)
{
    base.WndProc(ref m);
        if (m.Msg == UsbNotification.WmDevicechange)
    {
        switch ((int)m.WParam)
        {
            case UsbNotification.DbtDeviceremovecomplete:
                Usb_DeviceRemoved(); // this is where you do your magic
                break;
            case UsbNotification.DbtDevicearrival:
                Usb_DeviceAdded(); // this is where you do your magic
                break;
        }
    }
}