fopen vs CreateFile Driver Access issue

NTDEV
1

Hi All,

I’m trying to create a driver for a device that our group created and have
run into a bit of snag that I was hoping you could help with. I’ve got it
setup so that we can open our device using CreateFile however when we try to
access the same device using fopen all we get is a Perission Denied error
message. I’ve tried a couple of variants of how I setup the IoCreateDevice
or IoCreateDeviceSecure but can’t figure out what my problem is. Again your
help is greatly appreciated in solving the odd problem.

Thanks,

–
Paul Ryan
xxxxx@gmail.com

2

If CreateFile works while fopen does not (which eventually just calls CreateFile underneath the covers anyways), this has nothing to do with security on the device object. You need to step into fopen and the CRT (you get the src as a part of VS) and see what the differences in parameters being passed to createfile are.

d

From: xxxxx@lists.osr.com [mailto:xxxxx@lists.osr.com] On Behalf Of Paul Ryan
Sent: Wednesday, April 30, 2008 6:11 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] fopen vs CreateFile Driver Access issue

Hi All,

I’m trying to create a driver for a device that our group created and have run into a bit of snag that I was hoping you could help with. I’ve got it setup so that we can open our device using CreateFile however when we try to access the same device using fopen all we get is a Perission Denied error message. I’ve tried a couple of variants of how I setup the IoCreateDevice or IoCreateDeviceSecure but can’t figure out what my problem is. Again your help is greatly appreciated in solving the odd problem.

Thanks,

–
Paul Ryan
xxxxx@gmail.commailto:xxxxx — NTDEV is sponsored by OSR For our schedule of WDF, WDM, debugging and other seminars visit: http://www.osr.com/seminars To unsubscribe, visit the List Server section of OSR Online at http://www.osronline.com/page.cfm?name=ListServer</mailto:xxxxx>

3

Or, if you don’t have the source of your runtime, Sysinternals’ Process Monitor can capture the CreateFile flags for you too.

-Stephen Cleary

4

Thanks guys I’ll give those a try.

On Wed, Apr 30, 2008 at 11:23 AM, wrote:

> Or, if you don’t have the source of your runtime, Sysinternals’ Process
> Monitor can capture the CreateFile flags for you too.
>
> -Stephen Cleary
>
> —
> NTDEV is sponsored by OSR
>
> For our schedule of WDF, WDM, debugging and other seminars visit:
> http://www.osr.com/seminars
>
> To unsubscribe, visit the List Server section of OSR Online at
> http://www.osronline.com/page.cfm?name=ListServer
>

–
Paul Ryan
xxxxx@gmail.com