Make pthread_atfork() track the DSO that called it like atexit() does,

unregistering callbacks if the DSO is unloaded.  Move the callback
handling from libpthread to libc, though libpthread still overrides the
inner call to handle locking and thread-library reinitialization.
Major version bump for both libc and libpthread.

verification that this fixes various ports ajacoutot@
asm assistance miod@; ok millert@ deraadt@

3 files changed, 81 insertions, 2 deletions

diff --git a/src/lib/libc/include/atfork.h b/src/lib/libc/include/atfork.h
new file mode 100644
index 0000000000..8ec611098c
--- /dev/null
+++ b/src/lib/libc/include/atfork.h
@@ -0,0 +1,44 @@
+/*      $OpenBSD: atfork.h,v 1.1 2015/04/07 01:27:07 guenther Exp $ */
+
+/*
+ * Copyright (c) 2008 Kurt Miller <kurt@openbsd.org>
+ * Copyright (c) 2008 Philip Guenther <guenther@openbsd.org>
+ * Copyright (c) 2003 Daniel Eischen <deischen@freebsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Neither the name of the author nor the names of any co-contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD: /repoman/r/ncvs/src/lib/libc_r/uthread/uthread_atfork.c,v 1.1 2004/12/10 03:36:45 grog Exp $
+ */
+
+#include <sys/queue.h>
+
+struct atfork_fn {
+        TAILQ_ENTRY(atfork_fn) fn_next;
+        void    (*fn_prepare)(void);
+        void    (*fn_parent)(void);
+        void    (*fn_child)(void);
+        void    *fn_dso;
+};
+
+extern TAILQ_HEAD(atfork_listhead, atfork_fn) _atfork_list;
+
diff --git a/src/lib/libc/include/thread_private.h b/src/lib/libc/include/thread_private.h
index 673fb9c6a6..43ebf7d96e 100644
--- a/src/lib/libc/include/thread_private.h
+++ b/src/lib/libc/include/thread_private.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: thread_private.h,v 1.25 2011/10/16 06:29:56 guenther Exp $ */
+/* $OpenBSD: thread_private.h,v 1.26 2015/04/07 01:27:07 guenther Exp $ */
 
 /* PUBLIC DOMAIN: No Rights Reserved. Marco S Hyman <marc@snafu.org> */
 
@@ -160,6 +160,18 @@ void	_thread_atexit_unlock(void);
                                                 _thread_atexit_unlock();\
                                 } while (0)
 
+void    _thread_atfork_lock(void);
+void    _thread_atfork_unlock(void);
+
+#define _ATFORK_LOCK()          do {                                    \
+                                        if (__isthreaded)               \
+                                                _thread_atfork_lock();  \
+                                } while (0)
+#define _ATFORK_UNLOCK()        do {                                    \
+                                        if (__isthreaded)               \
+                                                _thread_atfork_unlock();\
+                                } while (0)
+
 void    _thread_arc4_lock(void);
 void    _thread_arc4_unlock(void);
 
@@ -172,4 +184,9 @@ void	_thread_arc4_unlock(void);
                                                 _thread_arc4_unlock();\
                                 } while (0)
 
+/*
+ * Wrapper for _thread_sys_fork()
+ */
+pid_t   _thread_fork(void);
+
 #endif /* _THREAD_PRIVATE_H_ */
diff --git a/src/lib/libc/stdlib/atexit.c b/src/lib/libc/stdlib/atexit.c
index 6532b382ea..a33080571f 100644
--- a/src/lib/libc/stdlib/atexit.c
+++ b/src/lib/libc/stdlib/atexit.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: atexit.c,v 1.20 2014/07/11 09:51:37 kettenis Exp $ */
+/*      $OpenBSD: atexit.c,v 1.21 2015/04/07 01:27:07 guenther Exp $ */
 /*
  * Copyright (c) 2002 Daniel Hartmeier
  * All rights reserved.
@@ -35,6 +35,7 @@
 #include <string.h>
 #include <unistd.h>
 #include "atexit.h"
+#include "atfork.h"
 #include "thread_private.h"
 
 struct atexit *__atexit;
@@ -161,6 +162,23 @@ restart:
                 __atexit = NULL;
         }
         _ATEXIT_UNLOCK();
+
+        /*
+         * If unloading a DSO, unregister any atfork handlers registered
+         * by it.  Skip the locking if the list is currently empty.
+         */
+        if (dso != NULL && TAILQ_FIRST(&_atfork_list) != NULL) {
+                struct atfork_fn *af, *afnext;
+
+                _ATFORK_LOCK();
+                TAILQ_FOREACH_SAFE(af, &_atfork_list, fn_next, afnext)
+                        if (af->fn_dso == dso) {
+                                TAILQ_REMOVE(&_atfork_list, af, fn_next);
+                                free(af);
+                        }
+                _ATFORK_UNLOCK();
+
+        }
 }
 
 /*