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/* $OpenBSD: rthread_fork.c,v 1.3 2009/11/27 19:42:24 guenther Exp $ */
/*
* Copyright (c) 2008 Kurt Miller <kurt@openbsd.org>
* Copyright (c) 2008 Philip Guenther <guenther@gmail.com>
* 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/param.h>
#include <machine/spinlock.h>
#include <errno.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include "thread_private.h" /* in libc/include */
#include "rthread.h"
struct rthread_atfork {
TAILQ_ENTRY(rthread_atfork) next;
void (*prepare)(void);
void (*parent)(void);
void (*child)(void);
};
static TAILQ_HEAD(atfork_listhead, rthread_atfork) _atfork_list =
TAILQ_HEAD_INITIALIZER(_atfork_list);
static _spinlock_lock_t _atfork_lock = _SPINLOCK_UNLOCKED;
pid_t _thread_sys_fork(void);
pid_t _thread_sys_vfork(void);
pid_t _dofork(int);
pid_t
_dofork(int is_vfork)
{
pthread_t me;
pid_t (*sys_fork)(void);
pid_t newid;
sys_fork = is_vfork ? &_thread_sys_vfork : &_thread_sys_fork;
if (!_threads_ready)
return sys_fork();
me = pthread_self();
/*
* Protect important libc/ld.so critical areas across the fork call.
* dlclose() will grab the atexit lock via __cxa_finalize() so lock
* the dl_lock first. malloc()/free() can grab the arc4 lock so lock
* malloc_lock first. Finally lock the bind_lock last so that any lazy
* binding in the other locking functions can succeed.
*/
#if defined(__ELF__) && defined(PIC)
_rthread_dl_lock(0);
#endif
_thread_atexit_lock();
_thread_malloc_lock();
_thread_arc4_lock();
#if defined(__ELF__) && defined(PIC)
_rthread_bind_lock(0);
#endif
newid = sys_fork();
#if defined(__ELF__) && defined(PIC)
_rthread_bind_lock(1);
#endif
_thread_arc4_unlock();
_thread_malloc_unlock();
_thread_atexit_unlock();
#if defined(__ELF__) && defined(PIC)
_rthread_dl_lock(1);
#endif
if (newid == 0) {
/* update this thread's structure */
me->tid = getthrid();
me->donesem.lock = _SPINLOCK_UNLOCKED;
me->flags &= ~THREAD_DETACHED;
me->flags_lock = _SPINLOCK_UNLOCKED;
/* this thread is the initial thread for the new process */
_initial_thread = *me;
/* reinit the thread list */
LIST_INIT(&_thread_list);
LIST_INSERT_HEAD(&_thread_list, &_initial_thread, threads);
_thread_lock = _SPINLOCK_UNLOCKED;
/* single threaded now */
__isthreaded = 0;
}
return newid;
}
pid_t
fork(void)
{
struct rthread_atfork *p;
pid_t newid;
_spinlock(&_atfork_lock);
TAILQ_FOREACH_REVERSE(p, &_atfork_list, atfork_listhead, next)
if (p->prepare)
p->prepare();
newid = _dofork(0);
if (newid == 0) {
TAILQ_FOREACH(p, &_atfork_list, next)
if (p->child)
p->child();
} else {
TAILQ_FOREACH(p, &_atfork_list, next)
if (p->parent)
p->parent();
}
_spinunlock(&_atfork_lock);
return newid;
}
pid_t
vfork(void)
{
return _dofork(1);
}
int
pthread_atfork(void (*prepare)(void), void (*parent)(void),
void (*child)(void))
{
struct rthread_atfork *af;
if ((af = malloc(sizeof *af)) == NULL)
return (ENOMEM);
af->prepare = prepare;
af->parent = parent;
af->child = child;
_spinlock(&_atfork_lock);
TAILQ_INSERT_TAIL(&_atfork_list, af, next);
_spinunlock(&_atfork_lock);
return (0);
}
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