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To: Poul-Henning Kamp <phk@critter.dk.tfs.com>
cc: Mark Murray <mark@grondar.za>, peter@FreeBSD.ORG, current@FreeBSD.ORG
Subject: Re: Static binaries and dlopen(3) with a new crypt(3) lib. 
In-reply-to: Your message of "Mon, 20 Jan 1997 09:32:30 +0100."
             <11234.853749150@critter.dk.tfs.com> 
References: <11234.853749150@critter.dk.tfs.com> 
Date: Mon, 20 Jan 1997 08:33:00 -0800
From: John Polstra <jdp@polstra.com>
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> >I also want to move the dl* functions out of crt0.o
...
> So you would leave the meat of the code in crt0 and just move the
> public interface to it ?

The meat of the code is already really in the dynamic linker, and
the code in crt0 is just an interface to it.  At program start-up
time, crt0 (with help from the dynamic linker) sets up a struct
containing function pointers pointing to the real implementations
of dlopen, dlclose, dlsym, and dlerror in the dynamic linker.
(That's the required crt0 tie-in that I mentioned.)  The public
interfaces in crt0 just forward the calls through those function
pointers.  For example, this is the dlopen code in crt0:

    void *
    dlopen(name, mode)
    char    *name;
    int     mode;
    {
	    if (ld_entry == NULL)
		    return NULL;

	    return (ld_entry->dlopen)(name, mode);
    }

I want to make "ld_entry" a global symbol in the reserved part of
the namespace ("_ld_entry" or "__ld_entry"), and then move the
interface functions into libc.

John
--
   John Polstra                                       jdp@polstra.com
   John D. Polstra & Co., Inc.                Seattle, Washington USA
   "Self-knowledge is always bad news."                 -- John Barth