Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!convex!usenet
From: tchrist@convex.COM (Tom Christiansen)
Newsgroups: comp.unix.wizards
Subject: Re: Loading and Executing Object Code at Runtime
Message-ID: <1991Feb15.173024.15506@convex.com>
Date: 15 Feb 91 17:30:24 GMT
References: <1991Feb13.212704.7016@cec1.wustl.edu> <437@bria>
Sender: usenet@convex.com (news access account)
Reply-To: tchrist@convex.COM (Tom Christiansen)
Organization: CONVEX Software Development, Richardson, TX
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Nntp-Posting-Host: pixel.convex.com

From the keyboard of uunet!bria!mike:
:If you're trying to do what it looks like you're trying to do, the answer
:is "you can't get there from here."  You would have open the object file,
:load the function within the context of the current process (a real trick),
:allocate the core for data, stack, and bbs, push the stack frame, and
:jump to the address of this arbitrary function.  Just ain't no way you
:can be doin' this in user mode.

Never say never.  It certainly is on some architectures.  Just malloc or
mmap in some pages as RWX, then load the position-independently compiled
functions in there from disk, and call through a function pointer.  There
are also overlay schemes available -- that's what I used to do on Z80
machines.  You could also use overlays on PDP-11's.

--tom
--
Tom Christiansen		tchrist@convex.com	convex!tchrist
 "All things are possible, but not all expedient."  (in life, UNIX, and perl)