Implement pthread_atfork in libthr. This is mostly from deichen's

work in libpthread.

Submitted by: Dan Nelson <dnelson@allantgroup.com>

lib/libthr/thread/Makefile.inc

@@ -4,6 +4,7 @@
 .PATH: ${.CURDIR}/thread
 
 SRCS+= \
+	thr_atfork.c \
 	thr_attr.c \
 	thr_autoinit.c \
 	thr_barrier.c \

lib/libthr/thread/thr_atfork.c

@@ -0,0 +1,60 @@
+/*
+ * 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.
+ *
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <errno.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <sys/queue.h>
+
+#include "thr_private.h"
+
+__weak_reference(_pthread_atfork, pthread_atfork);
+
+int
+_pthread_atfork(void (*prepare)(void), void (*parent)(void),
+    void (*child)(void))
+{
+	struct pthread_atfork *af;
+
+	if (_thread_initial == NULL)
+		_thread_init();
+
+	if ((af = malloc(sizeof(struct pthread_atfork))) == NULL)
+		return (ENOMEM);
+
+	af->prepare = prepare;
+	af->parent = parent;
+	af->child = child;
+	_pthread_mutex_lock(&_atfork_mutex);
+	TAILQ_INSERT_TAIL(&_atfork_list, af, qe);
+	_pthread_mutex_unlock(&_atfork_mutex);
+	return (0);
+}
+

lib/libthr/thread/thr_init.c

@@ -334,6 +334,10 @@ _thread_init(void)
 	getcontext(&pthread->ctx);
 	pthread->ctx.uc_stack.ss_sp = pthread->stack;
 	pthread->ctx.uc_stack.ss_size = PTHREAD_STACK_INITIAL;
+
+	/* Initialize the atfork list and mutex */
+	TAILQ_INIT(&_atfork_list);
+	_pthread_mutex_init(&_atfork_mutex, NULL);
 }
 
 /*

lib/libthr/thread/thr_private.h

@@ -269,6 +269,13 @@ struct pthread_cleanup {
 	void			*routine_arg;
 };
 
+struct pthread_atfork {
+	TAILQ_ENTRY(pthread_atfork) qe;
+	void (*prepare)(void);
+	void (*parent)(void);
+	void (*child)(void);
+};
+
 struct pthread_attr {
 	int	sched_policy;
 	int	sched_inherit;
@@ -691,6 +698,9 @@ SCLASS struct pthread *_thread_initial
 ;
 #endif
 
+SCLASS TAILQ_HEAD(atfork_head, pthread_atfork)	_atfork_list;
+SCLASS pthread_mutex_t		_atfork_mutex;
+
 /* Default thread attributes: */
 SCLASS struct pthread_attr pthread_attr_default
 #ifdef GLOBAL_PTHREAD_PRIVATE

lib/libthr/thread/thr_syscalls.c

@@ -90,6 +90,8 @@
 
 #include "thr_private.h"
 
+extern spinlock_t *__malloc_lock;
+
 extern int __creat(const char *, mode_t);
 extern int __sleep(unsigned int);
 extern int __sys_nanosleep(const struct timespec *, struct timespec *);
@@ -174,6 +176,62 @@ _fcntl(int fd, int cmd,...)
 	return ret;
 }
 
+__weak_reference(_fork, fork);
+
+int
+_fork(int fd)
+{
+	int	ret;
+	struct pthread_atfork *af;
+
+	_pthread_mutex_lock(&_atfork_mutex);
+
+	/* Run down atfork prepare handlers. */
+	TAILQ_FOREACH_REVERSE(af, &_atfork_list, atfork_head, qe) {
+		if (af->prepare != NULL)
+			af->prepare();
+	}
+
+ 	/*
+	 * Fork a new process.
+	 * XXX - The correct way to handle __malloc_lock is to have
+	 *	 the threads libraries (or libc) install fork handlers for it
+	 *	 in their initialization routine. We should probably
+	 *	 do that for all the locks in libc.
+	 */
+	if (__isthreaded && __malloc_lock != NULL)
+		_SPINLOCK(__malloc_lock);
+	ret = __sys_fork();
+ 	if (ret == 0) {
+		__isthreaded = 0;
+		if (__malloc_lock != NULL)
+			memset(__malloc_lock, 0, sizeof(spinlock_t));
+		init_tdlist(curthread, 1);
+		init_td_common(curthread, NULL, 1);
+		_mutex_reinit(&_atfork_mutex);
+
+		/* Run down atfork child handlers. */
+		TAILQ_FOREACH(af, &_atfork_list, qe) {
+			if (af->child != NULL)
+				af->child();
+		}
+ 	} else if (ret != -1) {
+		/* Run down atfork parent handlers. */
+		TAILQ_FOREACH(af, &_atfork_list, qe) {
+			if (af->parent != NULL)
+			af->parent();
+		}
+	}
+
+	if (ret != 0) {
+		if (__isthreaded && __malloc_lock != NULL)
+			_SPINUNLOCK(__malloc_lock);
+		_pthread_mutex_unlock(&_atfork_mutex);
+	}
+	return ret;
+}
+
+
 __weak_reference(_fsync, fsync);
 
 int