Re: predefined macros for various BSD-based systems?

Tom Lane <tgl@sss.pgh.pa.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
whatactual     feature is needed."
 

Regards,

Giles