Handling PnP WM_DEVICECHANGE messages from a DLL

NTDEV
1

Sorry this question isn’t exactly a device driver one, but it is related.

We are writing a WDM driver for a USB device under Windows 2K. Along with the driver we are writing a DLL for user applications to call. In the DLL, we want to provide a callback function to notify the application when a USB device has been added or removed. However to register for PnP notification we need to supply a window handle or a service handle, neither of which weI have. My questions are:

Can our DLL create a thread, which creates a window to handle the WD_DEVICECHANGE message?
Is there a better way to do this?
Is there any way to do this?
Is there a better forum to ask these questions?

Larry

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2

Hello ,

HLC> We are writing a WDM driver for a USB device under Windows 2K. Along with the driver we are writing a DLL for user applications to call. In the DLL, we want to provide a callback function to
HLC> notify the application when a USB device has been added or removed. However to register for PnP notification we need to supply a window handle or a service handle, neither of which weI have.
HLC> My questions are:

HLC> Can our DLL create a thread, which creates a window to handle the WD_DEVICECHANGE message?

I have had the same problem (writing a generic solution for PnP
notication) and my solution was a new window. I have created my own
window for WM_DEVICECHANGE notification messages.
This works not for console based programs and services.

I don’t now why this notification is not avail with normal call back
function.

elli

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3

to register for PnP notification we need to supply a window handle or a
service handle, neither
of which weI have. My questions are:

Can our DLL create a thread, which creates a window to handle the
WD_DEVICECHANGE

Creating hidden windows is simple :slight_smile: For instance, COM uses ones.
Since window is owned by the thread which must process its message loop,
creating a thread seems to be a good idea too.
Send WM_QUIT to the window during the shutdown procedure. The thread will
call WndProc, which must destroy the window and then the thread itself.

Max

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4

Hello,

Here is some code that may be of help … It may need a small amount of
tweaking since i deleted and added some blocks of code without
compilation, so please take it with a pinch of salt. It should help form
a basis for what you need to do.

#define hidden_win “hidden”

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam,
LPARAM lParam)
{
switch (message)
{
case WM_CREATE :
return 0;

case WM_DESTROY :
PostQuitMessage(0);
return 0;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}

DWORD _RegisterHiddenWindowClass(HINSTANCE hInstance)
{
WNDCLASS wndclass;

wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = WndProc;
wndclass.cbClsExtra = 16;
wndclass.cbWndExtra = 16;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndclass.hbrBackground = NULL;
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = hidden_win;
if (RegisterClass (&wndclass) == 0)
return FALSE;

return TRUE;
}
DWORD WINAPI _Worker(PVOID pData)
{
MSG msg;
HWND hWnd;

// Create tool window with no caption so that it does not show
up in the task mgr or in the task bar
hWnd = CreateWindowEx(WS_EX_TOOLWINDOW, hidden_win, NULL,
WS_POPUP,
0, 0, 0, 0, NULL,
NULL, GetModuleHandle(NULL), NULL);

if (hWnd == NULL)
ExitThread(0);

// Pass the hWnd back to the creator
(HWND *)*pData = hWnd;

// Go into a message loop …
while (GetMessage (&msg, NULL, 0, 0))
{
TranslateMessage (&msg);
DispatchMessage (&msg);
}

return 0;
}

// You could use the functions like so …

// Some other thread …
{
DWORD hThread, dwThreadId;
HWND hHiddenWindow;

_RegisterHiddenWindowClass(GetModuleHandle(NULL));

hThread = CreateThread(NULL, 0, _Worker, &hHiddenWindow, 0,
&dwThreadId);
if (hThread == NULL)
HANDLEREG(&rCode, ERR_INVALID_INIT);

// Want to close the window
if (hHiddenWindow != NULL)
SendMessage(hHiddenWindow, WM_QUIT, 0, 0);

// Continue …

}

Regards

  • asit

-----Original Message-----
From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
Sent: Tuesday, July 31, 2001 11:50 AM
To: NT Developers Interest List
Subject: [ntdev] Re: Handling PnP WM_DEVICECHANGE messages from a DLL

to register for PnP notification we need to supply a window handle or a
service handle, neither
of which weI have. My questions are:

Can our DLL create a thread, which creates a window to handle the
WD_DEVICECHANGE

Creating hidden windows is simple :slight_smile: For instance, COM uses ones.
Since window is owned by the thread which must process its message loop,
creating a thread seems to be a good idea too.
Send WM_QUIT to the window during the shutdown procedure. The thread
will
call WndProc, which must destroy the window and then the thread itself.

Max

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