I had people relate to me, at least once, cases of utterly independent
implementations of a function that were byte for byte the same, as found in
one court case a friend of mine (now deceased) got pulled into. He had to
prove he'd written his code from scratch. But these were pretty simple
functions. I don't know if bmap qualifies ...

How could this happen? I don't know, but the court case that long predated
SCO. The only conclusion I can reach
is that when enough techniques, ideas, mailling lists, discussions, and
documents become part of a shared culture, the code which
people create might be the same. A weird parallel evolution of code.



On Mon, Nov 4, 2024 at 5:09 PM Larry McVoy <lm@mcvoy.com> wrote:

> The thing I never got a reasonable answer to was I found code in BSD that
> was identical to code going back to at least V7.  Find bmap() in the UFS
> code and then find the same in V7.  I might be wrong about V7, might be
> 32V, might be V6.  I don't think it matters, it's the same in all of them.
>
> bmap() is the code that maps a logical block to a phsyical block,
> I'm quite familiar with it because I rewrote it to bmap_write() and
> bmap_read() as part of making UFS do extents:
>
> http://mcvoy.com/lm/papers/SunOS.ufs_clustering.pdf
>
> When all the lawsuits were going on, since I knew that code really well,
> I went off and looked and the BSD code at that time had bit for bit
> identical bmap() implementations.
>
> I never understood why BSD could claim they rewrote everything when they
> clearly had not rewritten that.
>
> I've raised this question before and I just went and looked, bmap() has
> changed.  I'm pretty sure I have Kirk's BSD source releases, if I do,
> I'm 100% sure I can back up what I'm saying.  Not sure I care enough to
> do so, it's all water under the bridge at this point.
> --
> ---
> Larry McVoy           Retired to fishing
> http://www.mcvoy.com/lm/boat
>