ExamGuru IT/.Net Guru : RegNotifyChangeKeyValue on microsoft.public.dotnet.framework.interop

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RegNotifyChangeKeyValue

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This message was discovered on microsoft.public.dotnet.framework.interop.

TonyC

I have written a C# wapper around RegNotifyChangeKeyValue to handle Registry
change notifications. This works fine, except in Release builds, where I
seem to get spurious notifications. I've probably done womething stupid -
any ideas? The code is based on an MSDN article (If I remember correctly)

Many thanks

Tony

The declarations:

    public enum NotifyFilterFlags
    {
        REG_NOTIFY_CHANGE_NAME = 1,
        REG_NOTIFY_CHANGE_ATTRIBUTES = 2,
        REG_NOTIFY_CHANGE_LAST_SET = 4,
        REG_NOTIFY_CHANGE_SECURITY = 8
    }

    public const int ERROR_KEY_DELETED = 1018;

    [DllImport("advapi32.dll", EntryPoint="RegNotifyChangeKeyValue",
CallingConvention = CallingConvention.Cdecl)]
    static public extern int RegNotifyChangeKeyValue( IntPtr key,
        [MarshalAs(UnmanagedType.Bool)] bool watchsubtree,
        NotifyFilterFlags flags,
        IntPtr notifyEvent,
        [MarshalAs(UnmanagedType.Bool)] bool asynch );

The calling code:

            // handle to reg key
            IntPtr KeyHandle;
            // establish key
            RegistryKey KeyToMonitor = this.m_RootKey.OpenSubKey( this.m_SubKey,
false );
            // get Win32 stuff
            Type regKeyType = typeof( RegistryKey );
            FieldInfo field;
            field = regKeyType.GetField( "hkey", BindingFlags.Instance |
BindingFlags.NonPublic );
            // and the actual win32 handle
            KeyHandle = (IntPtr)field.GetValue(KeyToMonitor);
            int err;
            // call the reg function asynchronously
            err = NativeMethods.RegNotifyChangeKeyValue(KeyHandle,
                true,
                REG_NOTIFY_CHANGE_ATTRIBUTES |
                REG_NOTIFY_CHANGE_LAST_SET |
                REG_NOTIFY_CHANGE_NAME |
                REG_NOTIFY_CHANGE_SECURITY,
                notifyEvent.Handle,
                true );

            if ( err == 0 )
            {
                bool fired = false;
                while ( !fired && !m_bStop )
                {
                    // wait max 1 sec
                    if ( notifyEvent.WaitOne( 1000, false ) )
                    {
                        // fired
                        KeyChanged( this, new EventArgs() );
                        fired = true;
                    }
                }

--
Systems Development Consultant

Reply to this message...

Dot Net Guruias Sjögren

Tony,

[Original message clipped]

The calling convention is wrong, you should use Stdcall (the default).

The MarshalAs attributes are redundant but not incorrect.

[Original message clipped]

This is the most broken part of your code. Reflecting on private
members is evil, don't do it.

Dot Net Guruias

--
Dot Net Guruias Sjögren [MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

Reply to this message...

TonyC

Thanks for this. I changed the calling convention (silly mistake - too much
copy and paste!), but no change.

I re-packed the class slightly, and all the problems vanished (no core code
changes). So, I remain mystified, but now happy!.

Why can't you user Reflection on private members? My class still does this
(and it's documented more than once elsewhere). How else would you solve
that problem?

Regards

Tony

"Dot Net Guruias SjÃ¶gren" wrote:

[Original message clipped]

Reply to this message...

Robert Jordan

Hi Dot Net Guruias,

[Original message clipped]

Why? Even when the assembly is requesting FullTrust?
How will Formatters work in the future w/out this feature?

bye
Rob

Reply to this message...

	System.EventArgs
	System.IntPtr
	System.Reflection.BindingFlags
	System.Reflection.FieldInfo
	System.Runtime.InteropServices.CallingConvention
	System.Runtime.InteropServices.UnmanagedType

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