Path: utzoo!attcan!uunet!snorkelwacker!bloom-beacon!eru!hagbard!sunic!sics.se!nmpbas.nmpcad.se!attila
From: attila@nmpbas.nmpcad.se (Attila Nemeth)
Newsgroups: comp.sys.apollo
Subject: Dynamic linking on Apollo, how?
Message-ID: <1990Oct4.150210.17095@sics.se>
Date: 4 Oct 90 15:02:10 GMT
Sender: news@sics.se
Reply-To: attila@nmpbas.nmpcad.se (Attila Nemeth)
Organization: Swedish Institute of Microelectronics, Kista
Lines: 52

I have an application (interpreter) written under UNIX that
are using dynamic linking. I want to port this application
to BSD4.3 on Apollo.

The application is an extension language interpreter. One of
the features is the possibility to write a module, in let
say C, and then load the module dynamically without
relinking the interpreter.

The interpreter achieves this by using ld -A option (on SUN
and HP), which unfortunately has a different semantics under
Apollo.

The following steps are done in the interpreter to fix
dynamic linking:

1. Call sbrk(0) to find out where the new module is going to
be mapped. Set a pointer to this address.

2. Relink the core interpreter with the new module (ld -A ....)
This gives a new -o file in the filesystem.

3. Open this file (COFF format), and read the header to
find out the size of text, data, and bss. i.e. size = text +
data + bss .

4. Call sbrk(size), then copy text and data of the new file
to the old image (the pointer where to copy is given by step 1)

5. Use the relinked file in the filesystem, and access the symbol
table  (the interpreter needs some initialization routines)

So my question is:

Is it possible to obtain a relinked file in the filesystem
and use its symbol table, i.e. I want to do the steps done
in 3 and 5.

How do you achieve dynamic linking under Apollo, what system
calls are involved? Where is the new symbol table located,
in the KGT?



I would really appreciate if someone could give some help on this.


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Attila Nemeth |  Box 1193      | Electronic Mail:  attila@inmic.se  |
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