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From: stachour@umn-cs.UUCP
Newsgroups: comp.arch,comp.unix.wizards,comp.os.misc
Subject: Re: Shared libraries (Was: Re: Big Programs Hurt Performance)
Message-ID: <2208@umn-cs.UUCP>
Date: Mon, 28-Sep-87 22:36:20 EDT
Article-I.D.: umn-cs.2208
Posted: Mon Sep 28 22:36:20 1987
Date-Received: Fri, 2-Oct-87 02:17:55 EDT
References: <6886@eddie.MIT.EDU) <2501@xanth.UUCP> <2067@sfsup.UUCP>, <8650@utzoo.UUCP>
Organization: University of Minnesota, Minneapolis
Lines: 24
Xref: utgpu comp.arch:2291 comp.unix.wizards:4271 comp.os.misc:241
Summary: shared-lib search-paths and referencing-dir

In article <8650@utzoo.UUCP>, henry@utzoo.UUCP (Henry Spencer) writes:
> > ... What do I do on a shared
> > library system when scanf changes out from under me and breaks my program?
> 
> Whisper the magic phrase:  "search paths".  There is no *inherent* reason
> why you can't keep multiple versions around and have some way to say "run
> this program with the old library, please".

That's why Multics has had search-paths since day-1.  That's also why it
has the phrase "-referencing_dir" in its rules, so that programs pointed
at an old version of a dynamically-linked shared library thereby
getting the first of a set of routines from that particular version
of the library will get the rest of the set that match.

(Multics also has done up-referencing and down-referenceing of data,
argument-interogation, compatible-incompatible replacements,
system_library_obsolete, and other ways to handle multiple versions
of a program, but that's another 20-year old story that few read,
because it works so well no-one needs to read or change the code.)



Paul Stachour                 Why don't computer people seem to know
Stachour@HI-Multics.arpa      Computer History? It isn't like there
stachour at umn-cs.equ        is 1000 or even 50 years of it!