Re: Preparing to release 0.9.12

[Timo Teras <timo.teras@iki.fi>]

On Thu, 25 Jul 2013 17:38:51 -0700
Isaac <idunham@lavabit.com> wrote:

> On Thu, Jul 25, 2013 at 07:59:55PM +0300, Timo Teras wrote:
> > On Thu, 25 Jul 2013 12:16:55 -0400
> > Rich Felker <dalias@aerifal.cx> wrote:
> > 
> > > On Thu, Jul 25, 2013 at 10:44:59AM +0300, Timo Teras wrote:
> > > > On Wed, 24 Jul 2013 16:02:21 -0400
> > > > Rich Felker <dalias@aerifal.cx> wrote:
> > > > 
> > > > > The list of changes since 0.9.11 has grown quite large, and
> > > > > although we haven't met some of the roadmap goals for 0.9.12,
> > > > > others that were marked for 0.9.13 have already been
> > > > > finished. So I think it's reasonable to aim to release very
> > > > > soon now. There are still a few pending items I'd like to get
> > > > > committed before the release:
> > > > > 
> > > > > - orc's getaddrinfo fix for AF_UNSPEC with NULL hostname
> > > > > - Andre's ARM memcpy optimizations
> > > > > - New crt1.c code for adding PIE support for more archs
> > > > > - MAYBE the symlink direction issue...
> > > > 
> > > > Since the C++ ABI was fixed, it means that any current native
> > > > musl toolchain will get C++ ABI breakage?
> > > > 
> > > > In this case the symlink direction issue would help with
> > > > smoother transitions. It would be also crucial to start using
> > > > proper SONAME versioning, so we could handle binary upgrades
> > > > smoothly.
> > > 
> > > This would not help. The ABI between the application and musl's
> > > libc.so has not changed since just after the initial public
> > > release, except for some bugs that had arch-specific structures
> > > laid out wrong, etc. -- and in this case, programs built before
> > > the fix were not working at all anyway when using the affected
> > > feature.
> > 
> > The so versioning will not help for C++ related things. The most
> > important use case I had in mind is that, package managers that use
> > soversions for automatic dependencies, can insert proper "require
> > version XXX or later of this .so". That is, if we built with musl
> > X, we can detect that from .so, and record it. And later ensure
> > that musl X-1 will not satisfy the newly built package's
> > dependencies. Especially important when we are introducing new
> > symbols.
>  
> 
> On Debian, there's the "symbols" system; this lists all symbols with
> the version they appeared in, and the tools look through the symbols
> and find the lowest version providing all the symbols.
> 
> But as a standard rule, _added_ symbols _do_ _not_ call for a new
> SONAME, since they do not break the ABI.

Correct.

The usual way is:
soname = <lib-name>.<abiver>
filename = <soname>.<lib-version>

And then have symlink soname -> filename. This would allow side-by-side
installation of different library versions if needed.

But the "symbols" system looks interesting too. If doing that, the
lib-version would be then. A good related read was (explains also the
soname/filename concept):
http://developer.ubuntu.com/packaging/html/libraries.html

While SONAME we want to keep stable, and change only in the unlikely
event of abi breakage. I think it'd be still nice allow easily the
<lib-version> suffix to the generated file.

Thanks,
 Timo