svn commit: r216134 - in head: share/man/man9 sys/amd64/include sys/arm/include sys/i386/include sys/ia64/include sys/mips/include sys/pc98/include sys/powerpc/include sys/sparc64/include sys/sun4v...

[Bruce Cran]

On Fri, 3 Dec 2010 15:27:13 +0100
Ivan Voras <ivoras at freebsd.org> wrote:

> I'd say it depends on if the "specific case that hps raised a few
> years ago" sentence part refers to an actual problem; i.e. did it
> happen in practice? If yes, leaving KASSERTs looks like the best
> option.

I've found hps's original email thread, which is at
http://lists.freebsd.org/pipermail/freebsd-hackers/2005-June/012342.html .

The argument for allowing zero-length reads/writes is at
http://lists.freebsd.org/pipermail/freebsd-hackers/2005-June/012348.html .

I suspect the mistake occurred due to a misunderstanding of the API.
NetBSD have documented it in their man page but not added asserts in
the code:

"Functions which take a count of bytes have undefined results if the
specified count is zero."

-- 
Bruce Cran