RE: !!! Somebody has an answer ? --> IoCreateNotification Event problem using it between ring0

NTDEV
1

If you create the event in the process context of a user application then
when that application closes the event will, as you observed, be deleted. On
process termination all handles created in that process context are closed.
This is the expected behavior.

You can create the event in the system process context, but then you will
discover that the default security on the object prevents most applications
from accessing the event :frowning:

There exist undocumented nt apis that allow you to create the event in the
kernel with more friendly security, but alas these methods are undocumented.
If you search this mail list you will find out how to do this.

You could open the event twice in the driver: once to create it using the
process context of the first application that accesses your driver, and then
a second time using a system process context. This ought to keep the event
in existance for this system incarnation, or until your driver decides to
close the system handle. It also ought to give the event the default
security from the first application, which is probably what you want.

-----Original Message-----
From: Daniel Simard [mailto:xxxxx@matrox.com]
Sent: Wednesday, January 09, 2002 6:41 AM
To: NT Developers Interest List
Subject: [ntdev] !!! Somebody has an answer ? –>
IoCreateNotificationEvent problem using it between ring0 and ring3

I am creating an event with IoCreateNotificationEvent with the name
L"\BaseNamedObjects\EventX" into my WDM driver at open
time. After that
I
open the event into an MFC App by using OpenEvent(SYNCHRONIZE, FALSE,
“EventX”) and I wait on it. I then do a KePulseEvent into my
driver and
everything works fine into my app (it unblocks). I then close my app
(without closing the event object), and the at that moment
the event is
removed from \BaseNamedObjects directory. If I want to
reopen it from my app it is failing.

I tryed to open it twice into my driver (to simulate a
increment refcount of the event object) and it is not working.

The only workaround I found is to create the event at open
time and to
delete it at close time if the refcount of the driver is 0.
So I will be
recreated everytime someone open the driver.

Is this a bug ? Is there another better workaround ?

thanks

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