[TUHS] Source code abundance?

[Random832]

On Wed, Mar 1, 2017, at 14:29, Steve Nickolas wrote:
> On Wed, 1 Mar 2017, Henry Bent wrote:
> 
> > My understanding is that System V source of any sort is not legal to
> > distribute.  I believe that source exists and has been archived for at
> > least some variants of SVR1, SVR2, SVR3, and SVR4.
> 
> Well, that's probably 95% true...the other 5% is Solaris. ;)

I sometimes wonder how the legality of that worked (a recent complaint
someone made about BSD drivers being incorporated into Linux got me
thinking about it again) - surely there are big chunks of the
opensolaris code that are not *very much* changed from the original
System V code they're based on. Under what theory, then, was Sun the
copyright holder and therefore able to release it under the CDDL?