IRP_MJ_DEVICE_CONTROL of filter driver on the top of usbprint.sys

NTDEV
1

Hi all,

I develop the upper filter driver on the top of usbprint.sys.
And for Irp of IRP_MJ_DEVICE_CONTROL the filter driver will return the
original device id string without calling the lower driver. But the user
mode application can not get the length of the returned string. It’s zero.
Of course, I set the length in Irp->IoStatus.Information and STATUS_SUCCESS
in Irp->IoStatus. The returned string is stored in
Irp->AssociatedIrp.SystemBuffer. What should I do more ?

inaba
2/28/2002