Re: transitive shared library dependencies and installation

On Sat, 4 Jan 2020, Russ Allbery wrote:

> [email protected] writes:
>> Bob Friesenhahn <[email protected]> writes:
>
>>> That sounds like a great idea.  However, there is a problem that
>>> linking on some systems does depend on already installed libraries (or
>>> will end up using them) and so the libraries need to be installed and
>>> linked in a particular order.
>
>> Do you happen to know which systems these are?  Where are these
>> constraints documented?
>
> It's been a very long time since I've built shared libraries for any
> platform other than Linux, but my distant recollection is that AIX and
> HP-UX encoded the full path to the dynamic library against which a binary
> was linked.  Therefore, if you built an executable against uninstalled
> libraries, the executable would have a reference to the build directory,
> hence the explicit relinking step after installation to pick up the new
> paths.  I seem to recall that we caused an outage for campus AIX systems
> because of this; I'm less sure about HP-UX.
>
> I don't remember whether this also applied to interdependencies between
> shared libraries (or if those platforms even supported encoding
> dependencies in shared libraries; a lot of platforms didn't).  I vaguely
> recall that mutually-dependent shared libraries were actually impossible
> on at least some UNIX platforms, and thus not portable.

The above matches my own memories.  I do not know the current level of 
usage for AIX or HP-UX but expect that they are still used for 
business purposes because at various times they were market leaders 
and offered the type of support that large businesses needed for 
critical systems.

Mutually-dependent shared libraries are to be avoided in any case.

Using Autotools, I do not recall any particular effort involved with 
supporting AIX, HP-UX, or even IRIX in GraphicsMagick builds.

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
Public Key,     http://www.simplesystems.org/users/bfriesen/public-key.txt