rthread_fork.c revision 1.12 
1/*	$OpenBSD: rthread_fork.c,v 1.12 2015/05/10 18:33:15 guenther Exp $ */
2
3/*
4 * Copyright (c) 2008 Kurt Miller <kurt@openbsd.org>
5 * Copyright (c) 2008 Philip Guenther <guenther@openbsd.org>
6 * Copyright (c) 2003 Daniel Eischen <deischen@freebsd.org>
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Neither the name of the author nor the names of any co-contributors
15 *    may be used to endorse or promote products derived from this software
16 *    without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 * $FreeBSD: /repoman/r/ncvs/src/lib/libc_r/uthread/uthread_atfork.c,v 1.1 2004/12/10 03:36:45 grog Exp $
31 */
32
33#if defined(__ELF__)
34#include <sys/types.h>
35#include <sys/exec_elf.h>
36#pragma weak _DYNAMIC
37#endif
38
39#include <errno.h>
40#include <pthread.h>
41#include <stdlib.h>
42#include <unistd.h>
43#include <signal.h>
44
45#include "thread_private.h"	/* in libc/include */
46
47#include "rthread.h"
48
49pid_t   _thread_sys_fork(void);
50pid_t   _thread_sys_vfork(void);
51pid_t	_dofork(int);
52
53pid_t
54_dofork(int is_vfork)
55{
56	pthread_t me;
57	pid_t (*sys_fork)(void);
58	pid_t newid;
59#if defined(__ELF__)
60	sigset_t nmask, omask;
61#endif
62
63	sys_fork = is_vfork ? &_thread_sys_vfork : &_thread_sys_fork;
64
65	if (!_threads_ready)
66		return sys_fork();
67
68	me = pthread_self();
69
70	/*
71	 * Protect important libc/ld.so critical areas across the fork call.
72	 * dlclose() will grab the atexit lock via __cxa_finalize() so lock
73	 * the dl_lock first. malloc()/free() can grab the arc4 lock so lock
74	 * malloc_lock first. Finally lock the bind_lock last so that any lazy
75	 * binding in the other locking functions can succeed.
76	 */
77
78#if defined(__ELF__)
79	if (_DYNAMIC)
80		_rthread_dl_lock(0);
81#endif
82
83	_thread_atexit_lock();
84	_thread_malloc_lock();
85	_thread_arc4_lock();
86
87#if defined(__ELF__)
88	if (_DYNAMIC) {
89		sigfillset(&nmask);
90		_thread_sys_sigprocmask(SIG_BLOCK, &nmask, &omask);
91		_rthread_bind_lock(0);
92	}
93#endif
94
95	newid = sys_fork();
96
97#if defined(__ELF__)
98	if (_DYNAMIC) {
99		_rthread_bind_lock(1);
100		_thread_sys_sigprocmask(SIG_SETMASK, &omask, NULL);
101	}
102#endif
103
104	_thread_arc4_unlock();
105	_thread_malloc_unlock();
106	_thread_atexit_unlock();
107
108	if (newid == 0) {
109#if defined(__ELF__)
110		/* reinitialize the lock in the child */
111		if (_DYNAMIC)
112			_rthread_dl_lock(2);
113#endif
114		/* update this thread's structure */
115		me->tid = getthrid();
116		me->donesem.lock = _SPINLOCK_UNLOCKED_ASSIGN;
117		me->flags &= ~THREAD_DETACHED;
118		me->flags_lock = _SPINLOCK_UNLOCKED_ASSIGN;
119
120		/* this thread is the initial thread for the new process */
121		me->flags |= THREAD_ORIGINAL;
122
123		/* reinit the thread list */
124		LIST_INIT(&_thread_list);
125		LIST_INSERT_HEAD(&_thread_list, me, threads);
126		_thread_lock = _SPINLOCK_UNLOCKED_ASSIGN;
127
128		/* single threaded now */
129		__isthreaded = 0;
130	}
131#if defined(__ELF__)
132	else if (_DYNAMIC)
133		_rthread_dl_lock(1);
134#endif
135	return newid;
136}
137
138pid_t
139_thread_fork(void)
140{
141	return _dofork(0);
142}
143
144pid_t
145vfork(void)
146{
147	return _dofork(1);
148}
149