SCO UNIX *double* device driver

[Hendrik Vermooten]

SCO Xenix/UNIX, PC type hardware.

In short, the problem is the following:

I need to "channel" all I/O going to and from a device, through my own
handler routine (this routine itself uses hardware to do its job).

Examples of this application : Disk Mirroring, Disk Encryption, UNIX
disk I/O monitoring, maybe even compression.

A picture tells a thousand words:

NORMAL DISK        ==============                ==============
 INPUT &     <---- | MY DEVICE  | <------------- | ACTUAL     |
 OUTPUT      ----> | & DRIVER   | -------------> | DISK DRV   |
                   ==============                ==============

All normal disk I/O must go through MYDRIVER software that uses
hardware to do it's job (so must itself be a device driver?) to the
STANDARD disk device driver.

I don't want to change the disk device driver, because I don't want to
have to support all the different types of disks out there!

At first this seemed like a perfect application for STREAMS, but I
cannot find enough documentation to clearly indicate that what I need
to do is possible using STREAMS.

-----------------------------------------------------------------------
Jaco Oosthuyzen, ZEUS systems    TEL +27 12 64-5507, FAX +27 12 64-8382
Bang: ..!uunet!ddsw1!olsa99!zeusa!jaco     or        jaco at zeusa.UUCP
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-- 
-------- Opinions expressed here are my own when not inebriated ----------
Hendrik Vermooten, ZEUS software    TEL +27 12 64-5507, FAX +27 12 64-8382
Bang: ..!uunet!ddsw1!olsa99!zeusa!hendrik     or        hendrik at zeusa.UUCP
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