Windows System Software -- Consulting, Training, Development -- Unique Expertise, Guaranteed Results

Before Posting...
Please check out the Community Guidelines in the Announcements and Administration Category.

More Info on Driver Writing and Debugging

The free OSR Learning Library has more than 50 articles on a wide variety of topics about writing and debugging device drivers and Minifilters. From introductory level to advanced. All the articles have been recently reviewed and updated, and are written using the clear and definitive style you've come to expect from OSR over the years.

Check out The OSR Learning Library at:

Minifilter FltSendMessage problem

johnhouldingjohnhoulding Member Posts: 28

I have minifilter driver which register IRP_MJ_ACQUIRE_FOR_SECTION_SYNCHRONIZATION PreCallback. In callback routine I send filename to usermode with FltSendMessage and wait Reply message. Then in usermode I open file with CreateFileW read file size then call Sleep(2000) (for testing purpose) and reply message. Like:


It works well but sometimes when I execute program i didnt see filename in usermode? What is problem? Can waiting(Sleep) in usermode make any problem?But as i know FltSendMessage sync operation when I open filename in usermode and reading some of data while this if new program executed it wait in callback routine

Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Upcoming OSR Seminars
OSR has suspended in-person seminars due to the Covid-19 outbreak. But, don't miss your training! Attend via the internet instead!
Kernel Debugging 30 Mar 2020 OSR Seminar Space
Developing Minifilters 15 Jun 2020 LIVE ONLINE
Writing WDF Drivers 22 June 2020 LIVE ONLINE
Internals & Software Drivers 28 Sept 2020 Dulles, VA