Re: Compiling daemontools

Laurent,

That sounds like a good point, but I'm not sure what version of Unix you
mean. System III?  I don't think there was a written standard besides
man pages until the System V SVID came out, and I can't remember if that
was in the SVID.  But I agree its always debatable to break old code,
and I've always admired the IBM MVS/zOS compatibility demands. But this
particular old code was probably a hazard. And Linux is relatively new
and old Unix compatibilty seems not to be a goal of Linux. If it were,
they could have taken the BSD4.3 net2 IP stack, the BSD4.4lite VFS
layer, etc and saved themselves a ton of work and many bugs. NFS still
doesn't work well on linux.  Go figure.

Speaking of code and ancient unix, (if you're not interested, don't read
any further) I'm still hoping that SysV.2 and OSF/1 will get
open-sourced for a belated 40th aniversery.  You all might know that BSD
4.3 code was opened by Novell/Caldera, and runs quite nicely on SIMH vax
simulator, as fast or faster than the real thing. But the the 4.3 distro
available now isn't quite pristine from CSRG tape, but appears it was
taken from a running system after being used/configured/etc.  The Open
Group is probably going to make a pristine copy of 4.3BSD src available.
TOG also has a copy of Sys5.2 but for the vax only---someone deleted the
ATT 3b2 directories between 1991 and 1996 or so (I didn't work for TOG
those years--but it was there in 1991).  OSF/1 is still encumbered by
SysV.2 (includes V.2 filesystem code) and probably can't be fully
released until Novell/Caldera gives a green light on SysV.2.  But given
that 4.3BSD is released, I'd think there should be little problem with
releasing SysV.2 if someone asks nicely...

		--Dean

On Tue, 20 Apr 2010, Laurent Bercot wrote:

> > Yes. That is a obsolete method to link in errno.  Multithreaded systems
> > need errno to be thread-specific, and so the interface to errno was
> > changed some time ago. There isn't an extern int errno anymore. The
> > anachronism 'extern errno' shouldn't link on any system, and doesn't on
> > most systems.  But its a common thing found in older code.
> 
>  http://cr.yp.to/docs/unixport.html#errno
> 
>  Single Unix v3 states that #include <errno.h> is the right way to
> declare errno, so future software should indeed conform to that, but
> still, maintaining "extern int errno" compatibility for single-threaded
> programs wasn't hard and breaking it forcefully is a debatable design
> decision from the glibc maintainers.
> 
>  (If only that was their only debatable design decision. :))
> 
> 

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