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Subj:	Re: Building of shared C++ libraries on SunOS 4

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To: help-g++@prep.ai.mit.edu
Date: 14 Mar 92 22:50:00 GMT
Message-Id: <TEEMU.TORMA.92Mar15005000@merc.frend.fi>
Organization: Front End Oy, Espoo, Finland
From: Teemu.Torma@frend.fi
Sender: help-g++-request@prep.ai.mit.edu
References: <TEEMU.TORMA.92Mar13220204@merc.frend.fi>edu
Subject: Re: Building of shared C++ libraries on SunOS 4

In article <TEEMU.TORMA.92Mar13220204@merc.frend.fi> I wrote:

   I played a little bit with libg++ 2.0 and with couple of patches,
   succeeded of making a shared library out of it--at least "Hello
   World" compiles and executes ok.

I was asked how to do it, so here is some information.  Don't bother
unless you know what you are doing.

I did this on Sun SS1, SunOS 4.1.1.  I have patch 100257-03 installed,
and the library did not work with 100257-02 (dlsym did not find
symbols in __do_dynamic_libs).  I have no idea how this works on an
unpatched system.

1)  Only one patch is needed (to src/init.c, see below).  
2)  Compile the library and src/init.c with -fpic, and build a shared
    library using collect2 as the linker.  I removed curses.o and
    CursesW.o to avoid linking with -lcurses.

    E.g. something like this.
	% make CC="gcc -fpic"
		... now libg++.a should exist.
        % mkdir tmp
	% (cd tmp; ar x ../libg++.a; rm __.SYMDEF curses.o CursesW.o)
        % (cd src; gcc -fpic -g -c init.c -o ../tmp/init.o)
	% LIBDIR/ld -assert pure-text -o libg++.so.2.0 tmp/*.o -ldl
	  ^^^^^^^^^ or whatever needed for collect2.

    Collect2 is used to generate ctor/dtor lists for the library, and
    -ldl since the runtime initialization will need it.

3)  Compile src/drt0.c and put it into libg++.sa.2.0.

Now you might want to try a "Hello World" program.  If ldd reports
that is uses libg++.2 and it's text size is only 8k, the library may
even work.

I don't know shared libraries well enough to say if this a really
working library.  I suppose some problems exist, otherwise the
distribution would have rules to make the shared library.

Teemu

===========================================================================
--- src/init.c.~1~	Thu Aug 15 07:13:02 1991
+++ src/init.c	Fri Mar 13 15:36:08 1992
@@ -60,7 +60,7 @@
   off_ptr++;
 
   while( --i >= 0) {
-    fn = (void_fn)(((int)off_ptr) - ((int)(*off_ptr)));
+    fn = (void_fn)((int)(*off_ptr));
     fn();
     off_ptr++;
   }
===========================================================================