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Re: Accepted sdl-image1.2 1.2.2-1 (i386 source)



On Mon, Jul 22, 2002 at 10:33:33AM -0500, Christian T. Steigies wrote:
> On Mon, Jul 22, 2002 at 10:28:14AM -0500, Steve Langasek wrote:
> > On Sun, Jul 21, 2002 at 09:24:25PM -0500, Christian T. Steigies wrote:
> > > On Mon, Jul 22, 2002 at 08:08:13AM +0900, Junichi Uekawa wrote:
> > > > cts@debian.org (Christian T. Steigies) immo vero scripsit:
> > > > >    * new upstream version (closes: #150670)
> > > > >    * build-depend on new SDL 1.2.4
> > > > >    * patch acinclude.m4, configure.in
> > > > >    * re-run libtoolize --force --copy; aclocal; patch aclocal.m4 to include
> > > > >      SDL_LIBS_FOR_LIBS, then run automake --foreign; autoconf
> > > > >    * depend on libpng-dev, not on (older) libpng2-dev (closes: #152302)
> > > > > Files: 
> > > > 
> > > > Do you realize that it is bad idea to rebuild against libpng3 
> > > > without changing the soname of your package?

> > > No I didn't, what do you propose?

> > >   If a package keeps the same SONAME, it means that the BINARY COMPATIBILITY
> > >   IS KEPT. 

> > > I did not see any incompatibility (yet), are you sure it is necessary?
> > > But I guess I'll have to revert to png2 and reopen he bug. Changing the
> > > soname would require an sdl-image1.2debian package?

> > > If anybody who knows more about libraries than me is interested in
> > > maintaining sdl-image and sdl-mixer, I'd like to hear from you.

> > Changing SONAMEs because of changes that are NOT part of the library's
> > ABI is messy, and very short-term; you have to repeat the same procedure,
> > for all dependent libraries, every time libpng bumps its soname.

> > A much better long-term solution is the one recently implemented for
> > libdb{2,3,4}: adding support for versioned symbols.  Versioned symbols
> > have been used quite successfully in glibc for years, and they're the
> > optimal solution to enable ANY library to coexist in the same process
> > space with other versions of itself.

> > As mentioned, libdb has recently added support for this -- which means
> > example code is not hard to find.  If the maintainer of the libpng
> > packages is interested in this approach, I'd be happy to help.

> What would be the consequences for sdl-image?

All packages within Debian that link against libpng{2,3} should be
recompiled against a version of the library that has symbol versioning
enabled; until both the library and the application that reference
libpng are recompiled, there is still a good chance that the application
will segfault.  Third-party software that's linked against libpng
therefore also does not benefit until it is recompiled; but such apps
must also be recompiled when libpng2 is phased out, so there's no real
savings from the SONAME approach, IMHO.

So basically, it means you just have to rebuild your packages, without
modification.  Once all packages which depend on libsdl-image1.2 have
also been recompiled, whether against libpng2 or libpng3, you are free
to migrate libsdl-image1.2 to libpng3 at your convenience.

Steve Langasek
postmodern programmer

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