libc.so can't be unloaded, so move the hidden atexit() and pthread_atfork()

stubs for the executable from crtbegin.o into libc, which lets them be
excluded from static links that don't use them.
For this, drop the normal crt{begin,end}S.o from libc.so: the .init and .fini
sections for libc aren't called at the right times anyway, so it's good that
they're unused.  libc.so just needs __guard_local and the .note.openbsd.ident
section, so add them to stack_protector.c for now (this will be improved)

"good time" deraadt@

1 files changed, 18 insertions, 1 deletions

diff --git a/lib/libc/thread/atfork.c b/lib/libc/thread/atfork.c
index e4ae398df5a..09e1c1cef5d 100644
--- a/lib/libc/thread/atfork.c
+++ b/lib/libc/thread/atfork.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: atfork.c,v 1.1 2015/04/07 01:27:07 guenther Exp $ */
+/*	$OpenBSD: atfork.c,v 1.2 2015/11/10 04:14:03 guenther Exp $ */
 
 /*
  * Copyright (c) 2008 Kurt Miller <kurt@openbsd.org>
@@ -32,10 +32,15 @@
 
 #include <errno.h>
 #include <stdlib.h>
+#include <pthread.h>
 
 #include "thread_private.h"
 #include "atfork.h"
 
+int	_thread_atfork(void (*_prepare)(void), void (*_parent)(void),
+	    void (*_child)(void), void *_dso);
+PROTO_NORMAL(_thread_atfork);
+
 int
 _thread_atfork(void (*prepare)(void), void (*parent)(void),
     void (*child)(void), void *dso)
@@ -54,3 +59,15 @@ _thread_atfork(void (*prepare)(void), void (*parent)(void),
 	_ATFORK_UNLOCK();
 	return (0);
 }
+DEF_STRONG(_thread_atfork);
+
+/*
+ * Copy of pthread_atfork() used by libc and anything staticly linked
+ * into the executable.  This passes NULL for the dso, so the callbacks
+ * are never removed by dlclose()
+ */
+int
+pthread_atfork(void (*prep)(void), void (*parent)(void), void (*child)(void))
+{
+	return (_thread_atfork(prep, parent, child, NULL));
+}