Are there licensing restrictions on handlers?

[Henry Spencer]

>   I would like to write a device handler for a UNIX
> system.  I could look at the source listings of existing
> handlers and modify them.  If I did that, could I:

General principles:  the AT&T source code belongs to AT&T, and must not
be released to people who are not authorized to have it.  This applies
to anything directly derived from it:  modified versions, rewrites based
on copying the original, etc.  If you study it and learn the general
principles of device-driver writing, and then write your own drivers
from first principles (not just re-typing AT&T ones from memory), then
your code is your own.  For the following specific answers, I will
assume a driver derived from AT&T code, since that's what your message
suggests.

> 1) Post the resulting handler to the net?

No.  Many sites on the net are not authorized to have AT&T sources.

> 2) Sell the resulting handler?

Not to people who are not licensed for the original source.

>  3) Give the resulting handler to other sites with 
>     source licenses?

Yes, provided their source licenses cover the specific piece of source.
(E.g. you cannot sell stuff derived from System V to a site that is
licensed only for System III.)

>  4) Give the resulting handler to other sites without
>     source licenses?

No.  Not even if you give just a binary to a binary-only site, because
the binary-only licenses include restrictions about who binary-only sites
can get software from.

>  5) Sell the resulting handler to other sites with
>     source licenses?

Same comments as #3, with the added caveat that if your original source
license is an educational license, you are not supposed to be using it
to make money.  A small fee to cover distribution and paperwork is all
right (AT&T has explicitly said so).

>  6) Sell the resulting handler to other sites without
>     source licenses?

Same comments as #4, plus the caveat from #5.

>   Is there another way to learn how to write handlers other
> than examining the UNIX source code?

Basically, no.  There are bits and pieces of documentation on the subject,
but I'm not sure that any of them is really complete enough to teach you
how to write a driver from scratch.

Beware:  I am not a lawyer.  Consult an expert before doing anything rash.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry