Regarding Device IOCTL

NTDEV
1

Hi,
Is it possible to use METHOD_DIRECT and METHOD_BUFFERED together for an
IOCTL, mean without any issues. Also is there any problem in using both
in and out buffers for DeviceIoCotrol for same IOCTL. It seems like most
of the time it is uni-direction is there any specific reason for this.
Regards,
Shashi

2

From a practical standpoint, you couldn’t use both METHOD_DIRECT and
METHOD_BUFFERED because the flags to the IOCTL are mutually exclusive (0
and 1).

The output buffer can be used for bi-directional data transfer. But when
doing so, you must check the permissions on the memory yourself for the
direction that you didn’t specify in the IOCTL. For example, if you
specify METHOD_IN_DIRECT in your control code, you will need to manually
verify that you have write access to the entire user buffer.

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com]On Behalf Of Shashidhar
Sent: Tuesday, October 22, 2002 3:33 AM
To: NT Developers Interest List
Subject: [ntdev] Regarding Device IOCTL

Hi,
Is it possible to use METHOD_DIRECT and METHOD_BUFFERED together for an
IOCTL, mean without any issues. Also is there any problem in using both
in and out buffers for DeviceIoCotrol for same IOCTL. It seems like most
of the time it is uni-direction is there any specific reason for this.
Regards,
Shashi

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