Re: predefined macros for various BSD-based systems?

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> I suppose that at least some of the *BSD herd really do predefine some
> of the symbols being attributed to them here, but I would like to see
> something authoritative about which and what.

Documentation follows, but first the summary:

FreeBSD: __FreeBSD__
NetBSD: __NetBSD__
OpenBSD: __OpenBSD__

I believe those #defines also tell you what the release is.
I didn't look into their encoding schemes just now, but can if
you want.

(OS X aka Darwin is harder: they seem to like __APPLE__, but
to determine the OS version the best I can see is
__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__, which is quite
horrid.)

Re BSDi, I have no idea really but based on Google searching
I'd bet on __bsdi__.

Per Wikipedia BSDi was discontinued in 2003 and support ended
in 2004. I submit that anyone still using it is not likely to
be updating their PostgreSQL installation, so +1 from me for
dropping support for it unless a volunteer using it comes
forward.

FYI (and you may know this, but I didn't learn until recently)
GCC will tell you quite easily what #defines are predefined,
and all those platforms use gcc:

$ cc -E -dM - < /dev/null | grep FreeBSD
#define __FreeBSD_cc_version 700003
#define __VERSION__ "4.2.1 20070719 [FreeBSD]"
#define __FreeBSD__ 7

But you wanted something authoritative, so here's what I found:

FreeBSD
=======

http://www.freebsd.org/doc/en/books/porters-handbook/porting-versions.html

"__FreeBSD__ is defined in all versions of FreeBSD."

NetBSD
======

From the NetBSD-1.1 release notes (November, 1995):

"* implement new cpp predefine strategy
define __NetBSD__, ..."

This is still the current behaviour, although the current
release is 5.0.2 from February 2010.

OpenBSD
=======

http://www.openbsd.org/porting.html

"Generic Porting Hints

* __OpenBSD__ should be used sparingly, if at all. Constructs that
look like

#if defined(__NetBSD__) || defined(__FreeBSD__)

are often inappropriate. Don't add blindly __OpenBSD__ to
it. Instead, try to figure out what's going on, and what actual
feature is needed."

Regards,

Giles