OpenAL & freealut Library Versioning

Hi,

I'm a member of the Debian Games Team, and we're currently taking over
maintenance of the OpenAL package in Debian.  We are preparing an upload
of the latest OpenAL and freealut releases.

One remaining problem is related to library versioning.  Neither version
0.0.8 nor CVS HEAD do specify version information when building with
libtool.  This is a big problem when packaging a library because
applications linked against an older version of the library will break
if new, backwards-incompatible versions are installed.  In Debian, we
really want to ensure smooth upgrades between both libopenal itself as
well as depending packages.  The only way to do this is to introduce
proper library versioning.

In order to avoid breakage, SONAMEs are used in the Linux world.  These
are handled automatically by libtool, as described here[0].  Note that
libtool introduces an own versioning scheme in order to provide a
portable method of defining library versioning, so that you as developer
don't have to care about SONAMEs at all if libtool versioning is used
correctly.  I'm not sure how libtool implements this on Windows, but I
assume that -version-info does nothing there.

This way, if a new version, which is backwards-incompatible will receive
a new SONAME (at least on all platforms which do support such a mechanism),
and thus applications linked against an older version will still be able to
use the old version.  Both versions of a library can coexist peacefully.

The attached patches add support for library versioning to OpenAL and
freealut.  Note that to actually work, the LT_CURRENT, LT_REVISION and
LT_AGE variables will need to be updated when necessary.  For information
on when these need to be changed, see [0].  The patches are against
versions 0.0.8 and 1.0.1 of OpenAL and freealut respectively.

We would really appreciate if you could apply those patches upstream and
keep adjusting the library version-info as necessary.

For the time being, I suggest that OpenAL starts with a SONAME of
libopenal.so.1.  That way we can transition smoothly from our current
OpenAL in Debian, which doesn't have library versioning at all and thus
ends up with a (default) SONAME of libopenal.so.0.

The included patches already set LT_CURRENT=1 for OpenAL, which will
result in the correct SONAME.  LT_CURRENT is set to 0 for freealut, but you may
want to increment it if there are already versions with SONAME libalut.so.0 or
libalut.so.1 for other distributions.

For the Debian Games Team,
Thierry Reding
 
[0]: http://sources.redhat.com/autobook/autobook/autobook_91.html

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