Hello Mike, nice to hear from you!

06.02.97 02:08, you wrote a message to Vitus Jensen:

...
 MB> Sorry, I missed this the first time around.

 VJ>> I found a "Device Driver Programming FAQ" at www.wdi.co.uk
 VJ>> and it states that returning parameter or data length isn't
 VJ>> possible.
 VJ>> So I stick with an header in front of the list.  Sad.

 MB> I'm familiar with that site, but it is hardly comprehensive. What
 MB> is it that you are trying to do?

From my first posting:
-----------------------------------------------
Hello -all-,

an IOCtl call into a driver has to return a variable-length list.  To skip to 
return a header in front of this list (as I have done on previous 
opportunities) I want to update the application's idea of needed/filled data 
buffer length.

From the application's view:

DosDevIOCtl(hd,cat,func,parm,10,&parmlen,data,1000,&datalen)

Driver fills buffer at 'data' and has to update 'datalen' via that 9. 
argument.  Odd but... the Physical Device Driver Reference doesn't say how to 
do it and all the samples ignore this possibility.

My driver is marked as level 2 and I found '10' and '1000' in the request packet.

Someone?
    Vitus
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[...much stuff deleted...]

I'm familiar with device drivers in general and especially OS/2 physical ones.
I'm writing a filter driver to START/STOP SCSI disks when they haven't beed
accessed for some time.  This works very well.

To let the user change timeout values w/o reboot I defined some IOCtls to
get/change the device list.  Application passes a large buffer (ex. room
for 32 devices) and the driver returns how much it has filled.  The usual
design.

Now: how can the filter modifiy parmlen and/or datalen in the above call? 
No DDK sample uses this possibility and the is no documentation. :-(

Could you enlighten me?
    Vitus [Team OS/2 Germany #835]

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