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To: Walter Hafner <hafner@forwiss.tu-muenchen.de>
cc: freebsd-questions@FreeBSD.ORG
Subject: Re: questions about dlopen() 
In-reply-to: Your message of "30 Jul 1997 11:15:01 +0200."
             <s9nyb6oyk8a.fsf@pccog4.forwiss.tu-muenchen.de> 
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Date: Fri, 01 Aug 1997 02:06:36 +0100
From: Brian Somers <brian@awfulhak.org>
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> The following message is a courtesy copy of an article
> that has been posted as well.
> 
> Hi there!
> 
> I've got a few questions regarding the 'dlopen()' call. I had a look at
> the sources (/usr/src/lib), but didn't find any references to
> dlopen(). The manpage is no help either.

dlopen() is defined in lib/csu/i386/crt0.c, and things get obscure 
from there :-)  Essentially, ld.so fills in the interesting bits.

> Problem: We try to read shared libs into an application at runtime. Our
> application supports various framegrabbers on various hardware (HP, Sun,
> SGI, PC/Linux, PC/FreeBSD ...) and we have to load wrapper-libs that
> provide a consistent user interface at runtime (plus the vendor-specific
> libs of course). That's where 'dlopen()' comes in handy. The following
> code snipplet works on _all_ hard- and software combinations _except_
> FreeBSD 2.2.* (didn't try 2.1.*):
> 
>     #define RTLD_LAZY 1
>     [...]
>     hndl = dlopen(name,RTLD_LAZY); 
>     if (hndl == NULL) 
>       return H_ERR_DLOPEN; 
> 
[.....]

You're right.

If you want to submit some patches against
/usr/src/gnu/usr.bin/ld/rtld/rtld.c (map_object() would need to 
fondle the path passed to it), I'm sure someone would commit them :-)

> -- 
> Walter Hafner_____________________________ hafner@forwiss.tu-muenchen.de
>      <A href=http://www.forwiss.tu-muenchen.de/~hafner/>*CLICK*</A>
>  The best observation I can make is that the BSD Daemon logo is _much_
>  cooler than that Penguin :-)                       (Donald Whiteside)

-- 
Brian <brian@awfulhak.org>, <brian@freebsd.org>
      <http://www.awfulhak.org>
Don't _EVER_ lose your sense of humour....