[Sbcl-devel] yet another mach exception handler patch

[Cyrus H. <ch...@bo...>]

Ok, so here's another patch. All tests except exhaust.impure.lisp pass.

Notes:

1. we no longer define USE_MACH_EXCEPTION_HANDLER, but rather define  
a feature :mach-exception-handler. and, come to think of it, my  
customize-target-features.lisp is probably not in the patch, so if  
you want to use this, you need to add that feature to your build,  
preferably via customize-target-features.lisp.

2. the problem with impure tests failing was due to fork not working.  
Well, fork was working, but it was forking a process with only one  
thread, the lisp thread, and no mach exception handling thread. There  
are two possible solutions here, one is to provide an sb-ext type  
function fork-process or some such that wraps forks and starts up the  
mach exception handling thread. the other, and the one I've taken, is  
to modify sb-posix such that fork spawns the mach exception handling  
thread. To do this, I've hacked up the define-call stuff such that it  
can take a c-name argument so the posix fork call becomes (define- 
call "posix-fork" :c-name "fork" ...) or something like that. And I  
made the formerly optional (or rest, I forget which) :largefile  
be :options :largefile. There are certainly other ways to do this,  
but this works. If anyone objects, please speak up.

3. the mach exception stuff generation stuff was cleaned up a little  
and moved into separate functions so that fork could call it

4. the one test that fails, exhaust.impure.lisp, fails when trying to  
push the context on the stack after we've run out of stack. we need  
to figure out how to error out gracefully from stack exhaustion in  
the mach exception handler, but everything else seems to be working,  
so far, although I've only really tried the tests.

5. threads - haven't gone there yet. I think this shouldn't be to  
bad, but we'll see.

So, give it a whirl and let me know how it goes.

Cyrus