Filter Manager Control Device I/O Controls

NTFSD
1

Can the filter Manager callback mechanism be used to get Device Controls for
the Control Device Object of the mini filter? I’ve added a stub callback
routine for IRP_MJ_DEVICE_CONTROL & IRP_MJ_INTERNAL_DEVICE_CONTROL but
nothing comes through. I know there in a new comm port model but the front
end app won’t have to change if I continue to us the Control Object model
since it will also need to support OSs without Filter Manager. This will
simplify the front end application.

I saw the post about continuing to use I/O controls with a Control Device
Object when using the Mini Filter (rather then the new comm. port model). Is
there any reason, other then not being able to unload if someone has your
control device object open, to not continue using Control Device Object I/O
controls?

Thanks,

Ken

2

If you want to see operations to a control device object created by your
minifilter, you have to register the old IRP_MJ dispatch routines as
well. Of course, since this will only be used for IO to your control
device object, you can just fill in the operations supported by your
control device object which is usually a much smaller list than all the
IRP_MJ codes. If you are just using it for private IOCTL communication,
all you need is CREATE, DEVICE_CONTROL, CLEANUP and CLOSE.

As Neal said, the main benefit of using the mini-filter communication
port model is that it helps manage unloading. Form a design point of
view, it’s perferable to only have to deal in one model, but having the
cleanest design possible always an option when you have to support
downlevel OSes.

Molly Brown
Microsoft Corporation

This posting is provided “AS IS” with no warranties and confers no
rights.

From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Ken Galipeau
Sent: Tuesday, April 06, 2004 9:41 PM
To: Windows File Systems Devs Interest List
Subject: [ntfsd] Filter Manager Control Device I/O Controls

Can the filter Manager callback mechanism be used to get Device Controls
for the Control Device Object of the mini filter? I’ve added a stub
callback routine for IRP_MJ_DEVICE_CONTROL &
IRP_MJ_INTERNAL_DEVICE_CONTROL but nothing comes through. I know there
in a new comm port model but the front end app won’t have to change if I
continue to us the Control Object model since it will also need to
support OSs without Filter Manager. This will simplify the front end
application.

I saw the post about continuing to use I/O controls with a Control
Device Object when using the Mini Filter (rather then the new comm. port
model). Is there any reason, other then not being able to unload if
someone has your control device object open, to not continue using
Control Device Object I/O controls?

Thanks,

Ken

Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

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