Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!rice!sun-spots-request
From: auspex!guy@uunet.uu.net (Guy Harris)
Newsgroups: comp.sys.sun
Subject: Re: Dynamic linking on SunOS 4.x
Keywords: SunOS
Message-ID: <6005@brazos.Rice.edu>
Date: 22 Mar 90 19:15:25 GMT
Sender: news@rice.edu
Organization: Sun-Spots
Lines: 39
Approved: Sun-Spots@rice.edu
X-Refs:  Original: v9n96
X-Sun-Spots-Digest: Volume 9, Issue 93, message 3

>What mechanisms do I have available to me under SunOS for this?

It depends on what version of SunOS you're talking about.

If you're talking about 4.0[.x], you don't have a lot; you'd have to roll
your own, and I don't think you'll be able to get much help from the
run-time loader.  (Rob, do you have more cheerful news for him?)

If you're talking about 4.1, you have:

"dlopen()", which takes the name of a ".so" file as an argument, maps that
".so" file into your address space and links it in to your program, and
returns a "handle" to it; and get back a "handle" on it;

"dlsym()", which takes a "handle" from "dlopen()" and a character string
which is the name of a function in the ".so" file referred to by the
handle, and returns a pointer to the function that you can use to call it
(after converting it from "void *" to the appropriate function type);

"dlclose()", which takes a handle from "dlopen()" and decrements the
reference count on the ".so" file, unmapping it if it goes to zero;

and one other function whose name I can't remember.

(If you're talking about System V Release 4, you will have those same four
functions, at least on 99 44/100% of the platforms it's on.)

Unfortunately, none of this helps you if you don't have 4.1, and it's not
released yet, so neither you nor most other people have it....

>I thought shared libraries (.so) were the answer, but I have been unable
>to create a shared library.  There seems to be no documentation on
>*creating* a shared library, only documentation on using one after it
>exists.

Again, not that it'd help a lot in your current situation, but check out
the "Shared Libraries" section of the "Programming Utilities and
Libraries" part of the SunOS 4.0[.x] documentation - it discusses, among
other things, how to build a shared library.