Eject USB device via C#

Question

I was looking for a short way to eject USB-devices via C#-code, so I coded a little class myself, yet it simply doesn't work. Since there's no popup that says "Lock success!" I assume that the problem relies within the "LockVolume"-function, but I don't know where.

Does anybody see the mistake I made?

class USBEject
{
    [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    private static extern IntPtr CreateFile(
         string lpFileName,
         uint dwDesiredAccess,
         uint dwShareMode,
         IntPtr SecurityAttributes,
         uint dwCreationDisposition,
         uint dwFlagsAndAttributes,
         IntPtr hTemplateFile
    );

    [DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
    private static extern bool DeviceIoControl(
        IntPtr hDevice, 
        uint dwIoControlCode,
        IntPtr lpInBuffer, 
        uint nInBufferSize,
        IntPtr lpOutBuffer, 
        uint nOutBufferSize,
        out uint lpBytesReturned, 
        IntPtr lpOverlapped
    );

    [DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
    private static extern bool DeviceIoControl(
        IntPtr hDevice, 
        uint dwIoControlCode,
        byte[] lpInBuffer, 
        uint nInBufferSize,
        IntPtr lpOutBuffer, 
        uint nOutBufferSize,
        out uint lpBytesReturned, 
        IntPtr lpOverlapped
    );

    [DllImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool CloseHandle(IntPtr hObject);

    private IntPtr handle = IntPtr.Zero;

    const int GENERIC_READ = 0x80000000;
    const int GENERIC_WRITE = 0x40000000;
    const int FILE_SHARE_READ = 0x1;
    const int FILE_SHARE_WRITE = 0x2;
    const int FSCTL_LOCK_VOLUME = 0x00090018;
    const int FSCTL_DISMOUNT_VOLUME = 0x00090020;
    const int IOCTL_STORAGE_EJECT_MEDIA = 0x2D4808;
    const int IOCTL_STORAGE_MEDIA_REMOVAL = 0x002D4804;

    /// <summary>
    /// Constructor for the USBEject class
    /// </summary>
    /// <param name="driveLetter">This should be the drive letter. Format: F:/, C:/..</param>

    public USBEject(string driveLetter)
    {
        string filename = @"\\.\" + driveLetter[0] + ":";
        handle = CreateFile(filename, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, IntPtr.Zero, 0x3, 0, IntPtr.Zero);
    }

    public bool Eject()
    {
        if (LockVolume(handle) && DismountVolume(handle))
        {
            PreventRemovalOfVolume(handle, false);
            return AutoEjectVolume(handle);
        }

        return false;
    }

    private bool LockVolume(IntPtr handle)
    {
        uint byteReturned;

        for (int i = 0; i < 10; i++)
        {
            if (DeviceIoControl(handle, FSCTL_LOCK_VOLUME, IntPtr.Zero, 0, IntPtr.Zero, 0, out byteReturned, IntPtr.Zero))
            {
                System.Windows.Forms.MessageBox.Show("Lock success!");
                return true;
            }
            Thread.Sleep(500);
        }
        return false;
    }

    private bool PreventRemovalOfVolume(IntPtr handle, bool prevent)
    {
        byte[] buf = new byte[1];
        uint retVal;

        buf[0] = (prevent) ? (byte)1 : (byte)0;
        return DeviceIoControl(handle, IOCTL_STORAGE_MEDIA_REMOVAL, buf, 1, IntPtr.Zero, 0, out retVal, IntPtr.Zero);
    }

    private bool DismountVolume(IntPtr handle)
    {
        uint byteReturned;
        return DeviceIoControl(handle, FSCTL_DISMOUNT_VOLUME, IntPtr.Zero, 0, IntPtr.Zero, 0, out byteReturned, IntPtr.Zero);
    }

    private bool AutoEjectVolume(IntPtr handle)
    {
        uint byteReturned;
        return DeviceIoControl(handle, IOCTL_STORAGE_EJECT_MEDIA, IntPtr.Zero, 0, IntPtr.Zero, 0, out byteReturned, IntPtr.Zero);
    }

    private bool CloseVolume(IntPtr handle)
    {
        return CloseHandle(handle);
    }
}

Answer 1

Changed just a little bit your code and it goes as follows:

    [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    private static extern IntPtr CreateFile(
     string lpFileName,
     uint dwDesiredAccess,
     uint dwShareMode,
     IntPtr SecurityAttributes,
     uint dwCreationDisposition,
     uint dwFlagsAndAttributes,
     IntPtr hTemplateFile
);

    [DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
    private static extern bool DeviceIoControl(
        IntPtr hDevice,
        uint dwIoControlCode,
        IntPtr lpInBuffer,
        uint nInBufferSize,
        IntPtr lpOutBuffer,
        uint nOutBufferSize,
        out uint lpBytesReturned,
        IntPtr lpOverlapped
    );

    [DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
    private static extern bool DeviceIoControl(
        IntPtr hDevice,
        uint dwIoControlCode,
        byte[] lpInBuffer,
        uint nInBufferSize,
        IntPtr lpOutBuffer,
        uint nOutBufferSize,
        out uint lpBytesReturned,
        IntPtr lpOverlapped
    );

    [DllImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool CloseHandle(IntPtr hObject);

    private IntPtr handle = IntPtr.Zero;

    const uint GENERIC_READ = 0x80000000;
    const uint GENERIC_WRITE = 0x40000000;
    const int FILE_SHARE_READ = 0x1;
    const int FILE_SHARE_WRITE = 0x2;
    const int FSCTL_LOCK_VOLUME = 0x00090018;
    const int FSCTL_DISMOUNT_VOLUME = 0x00090020;
    const int IOCTL_STORAGE_EJECT_MEDIA = 0x2D4808;
    const int IOCTL_STORAGE_MEDIA_REMOVAL = 0x002D4804;

    /// <summary>
    /// Constructor for the USBEject class
    /// </summary>
    /// <param name="driveLetter">This should be the drive letter. Format: F:/, C:/..</param>

    public IntPtr USBEject(string driveLetter)
    {
        string filename = @"\\.\" + driveLetter[0] + ":";
        return CreateFile(filename, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, IntPtr.Zero, 0x3, 0, IntPtr.Zero);
    }

    public bool Eject(IntPtr handle)
    {
        bool result = false;

        if (LockVolume(handle) && DismountVolume(handle))
        {
            PreventRemovalOfVolume(handle, false);
            result = AutoEjectVolume(handle);
        }
        CloseHandle(handle);
        return result;
    }

    private bool LockVolume(IntPtr handle)
    {
        uint byteReturned;

        for (int i = 0; i < 10; i++)
        {
            if (DeviceIoControl(handle, FSCTL_LOCK_VOLUME, IntPtr.Zero, 0, IntPtr.Zero, 0, out byteReturned, IntPtr.Zero))
            {
                System.Windows.Forms.MessageBox.Show("Lock success!");
                return true;
            }
            Thread.Sleep(500);
        }
        return false;
    }

    private bool PreventRemovalOfVolume(IntPtr handle, bool prevent)
    {
        byte[] buf = new byte[1];
        uint retVal;

        buf[0] = (prevent) ? (byte)1 : (byte)0;
        return DeviceIoControl(handle, IOCTL_STORAGE_MEDIA_REMOVAL, buf, 1, IntPtr.Zero, 0, out retVal, IntPtr.Zero);
    }

    private bool DismountVolume(IntPtr handle)
    {
        uint byteReturned;
        return DeviceIoControl(handle, FSCTL_DISMOUNT_VOLUME, IntPtr.Zero, 0, IntPtr.Zero, 0, out byteReturned, IntPtr.Zero);
    }

    private bool AutoEjectVolume(IntPtr handle)
    {
        uint byteReturned;
        return DeviceIoControl(handle, IOCTL_STORAGE_EJECT_MEDIA, IntPtr.Zero, 0, IntPtr.Zero, 0, out byteReturned, IntPtr.Zero);
    }

    private bool CloseVolume(IntPtr handle)
    {
        return CloseHandle(handle);
    }

So you can use it in two ways:

        handle = USBEject("D:");
        Eject(handle);

or directly:

        Eject(USBEject("D:"));

It works for me on my Windows 10 machine (preview 14291)

Answer 2

Found the answer for my issue by using some of Roger Deep's code for the CreateFile call.

My code to remove a USB drive inside WPF Window:

private void Button_Click_1(object sender, RoutedEventArgs e)
{
    EjectDrive('K');
}
void EjectDrive(char driveLetter)
{
    string path = @"\\.\" + driveLetter + @":";
    IntPtr handle = CreateFile(path, GENERIC_READ | GENERIC_WRITE,
    FILE_SHARE_READ | FILE_SHARE_WRITE, IntPtr.Zero, 0x3, 0, IntPtr.Zero);

    if ((long)handle == -1)
    {
        MessageBox.Show("Unable to open drive " + driveLetter);
        return;
    }

    int dummy = 0;

    DeviceIoControl(handle, IOCTL_STORAGE_EJECT_MEDIA, IntPtr.Zero, 0,
        IntPtr.Zero, 0, ref dummy, IntPtr.Zero);

    CloseHandle(handle);

    MessageBox.Show("OK to remove drive.");
}
[DllImport("kernel32", SetLastError = true)]
private static extern IntPtr CreateFile
    (string filename, uint desiredAccess,
        uint shareMode, IntPtr securityAttributes,
        int creationDisposition, int flagsAndAttributes,
        IntPtr templateFile);
[DllImport("kernel32")]
private static extern int DeviceIoControl
    (IntPtr deviceHandle, uint ioControlCode,
        IntPtr inBuffer, int inBufferSize,
        IntPtr outBuffer, int outBufferSize,
        ref int bytesReturned, IntPtr overlapped);
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool CloseHandle(IntPtr hObject);