[lug] library naming conventions, sym links

[Michael Hirsch]

On 7/17/05, D. Stimits <stimits at comcast.net> wrote:
> Chan Kar Heng wrote:
> > hi all,
> >
> > the only implication i can suggest is that an rpm packager has the
> > responsibility to recreate all sym links with every update & can't be
> > lazy with the way rpm prefers it (the latter way).
> >
> > eg:
> >
> > Existing:
> > libSomeLib.so.0.0.0
> > libSomeLib.so.0.0 -> libSomeLib.so.0.0.0
> > libSomeLib.so.0 -> libSomeLib.0.0
> > libSomeLib.so -> libSomeLib.0
> >
> > Introduction of a patch/minor upgrade:
> > libSomeLib.so.0.0.1
> >
> > Update required:
> > rm libSomeLib.so.0.0
> > ln -s libSomeLib.so.0.0.1 libSomeLib.so.0.0
> >
> > All libSomeLib.so.0.0, libSomeLib.so.0 & libSomeLib.so still refer to
> > the new/latest libSomeLib.
> >
> > if on the otherhand:
> >
> > Existing:
> > libSomeLib.so.0.0.0
> > libSomeLib.so.0.0 -> libSomeLib.so.0.0.0
> > libSomeLib.so.0 -> libSomeLib.so.0.0.0
> > libSomeLib.so -> libSomeLib.so.0.0.0
> >
> > Introduction of a patch/minor upgrade:
> > libSomeLib.so.0.0.1
> >
> > Update required:
> > rm libSomeLib.so.0.0 libSomeLib.so.0 libSomeLib.so
> > ln -s libSomeLib.so.0.0.1 libSomeLib.so.0.0
> > # these are also required, else libSomeLib.so.0 & libSomeLib.so breaks.
> > ln -s libSomeLib.so.0.0.1 libSomeLib.so.0
> > ln -s libSomeLib.so.0.0.1 libSomeLib.so
> >
> > i'd assume rpm assumes packagers aren't lazy & always recreates all
> > symlinks..?
> ...
> 
> This is what I'm talking about. If the sym links are chained, then it is
> not possible for a new install to fail to update all of the links,
> because only 1 link matters. When all links point at the hard file, all
> of them must be updated...failure to do so can break things. It isn't
> possible to update the sym links wrong if you only need to update the
> one link in a chain; updating all links requires trusting the packager
> to know what all of the links are, and to deal with them properly. Those
> version numbers lose all meaning when you just point them all at the
> hard file. Some people will disagree, but add in compatibility libs and
> software that depends on old versions, and things change.

True, but I don't think that rpm is directly resposible for updating
the links--that should be done by ldconfig.  The post-install script
for the RPM is responsible for running ldconfig.  ldconfig is the
command that should know how to (re)create the symbolic links.

Michael