1 /* $OpenBSD: rthread_fork.c,v 1.10 2013/11/29 16:27:40 guenther Exp $ */ 2 3 /* 4 * Copyright (c) 2008 Kurt Miller <kurt@openbsd.org> 5 * Copyright (c) 2008 Philip Guenther <guenther@gmail.com> 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 49 struct rthread_atfork { 50 TAILQ_ENTRY(rthread_atfork) next; 51 void (*prepare)(void); 52 void (*parent)(void); 53 void (*child)(void); 54 }; 55 56 static TAILQ_HEAD(atfork_listhead, rthread_atfork) _atfork_list = 57 TAILQ_HEAD_INITIALIZER(_atfork_list); 58 59 static struct _spinlock _atfork_lock = _SPINLOCK_UNLOCKED; 60 61 pid_t _thread_sys_fork(void); 62 pid_t _thread_sys_vfork(void); 63 pid_t _dofork(int); 64 65 pid_t 66 _dofork(int is_vfork) 67 { 68 pthread_t me; 69 pid_t (*sys_fork)(void); 70 pid_t newid; 71 #if defined(__ELF__) 72 sigset_t nmask, omask; 73 #endif 74 75 sys_fork = is_vfork ? &_thread_sys_vfork : &_thread_sys_fork; 76 77 if (!_threads_ready) 78 return sys_fork(); 79 80 me = pthread_self(); 81 82 /* 83 * Protect important libc/ld.so critical areas across the fork call. 84 * dlclose() will grab the atexit lock via __cxa_finalize() so lock 85 * the dl_lock first. malloc()/free() can grab the arc4 lock so lock 86 * malloc_lock first. Finally lock the bind_lock last so that any lazy 87 * binding in the other locking functions can succeed. 88 */ 89 90 #if defined(__ELF__) 91 if (_DYNAMIC) 92 _rthread_dl_lock(0); 93 #endif 94 95 _thread_atexit_lock(); 96 _thread_malloc_lock(); 97 _thread_arc4_lock(); 98 99 #if defined(__ELF__) 100 if (_DYNAMIC) { 101 sigfillset(&nmask); 102 _thread_sys_sigprocmask(SIG_BLOCK, &nmask, &omask); 103 _rthread_bind_lock(0); 104 } 105 #endif 106 107 newid = sys_fork(); 108 109 #if defined(__ELF__) 110 if (_DYNAMIC) { 111 _rthread_bind_lock(1); 112 _thread_sys_sigprocmask(SIG_SETMASK, &omask, NULL); 113 } 114 #endif 115 116 _thread_arc4_unlock(); 117 _thread_malloc_unlock(); 118 _thread_atexit_unlock(); 119 120 #if defined(__ELF__) 121 if (_DYNAMIC) 122 _rthread_dl_lock(1); 123 #endif 124 125 if (newid == 0) { 126 /* update this thread's structure */ 127 me->tid = getthrid(); 128 me->donesem.lock = _SPINLOCK_UNLOCKED_ASSIGN; 129 me->flags &= ~THREAD_DETACHED; 130 me->flags_lock = _SPINLOCK_UNLOCKED_ASSIGN; 131 132 /* this thread is the initial thread for the new process */ 133 me->flags |= THREAD_ORIGINAL; 134 135 /* reinit the thread list */ 136 LIST_INIT(&_thread_list); 137 LIST_INSERT_HEAD(&_thread_list, me, threads); 138 _thread_lock = _SPINLOCK_UNLOCKED_ASSIGN; 139 140 /* single threaded now */ 141 __isthreaded = 0; 142 } 143 return newid; 144 } 145 146 pid_t 147 fork(void) 148 { 149 struct rthread_atfork *p; 150 pid_t newid; 151 152 _spinlock(&_atfork_lock); 153 TAILQ_FOREACH_REVERSE(p, &_atfork_list, atfork_listhead, next) 154 if (p->prepare) 155 p->prepare(); 156 newid = _dofork(0); 157 if (newid == 0) { 158 TAILQ_FOREACH(p, &_atfork_list, next) 159 if (p->child) 160 p->child(); 161 } else { 162 TAILQ_FOREACH(p, &_atfork_list, next) 163 if (p->parent) 164 p->parent(); 165 } 166 _spinunlock(&_atfork_lock); 167 return newid; 168 } 169 170 pid_t 171 vfork(void) 172 { 173 return _dofork(1); 174 } 175 176 int 177 pthread_atfork(void (*prepare)(void), void (*parent)(void), 178 void (*child)(void)) 179 { 180 struct rthread_atfork *af; 181 182 if ((af = malloc(sizeof *af)) == NULL) 183 return (ENOMEM); 184 185 af->prepare = prepare; 186 af->parent = parent; 187 af->child = child; 188 _spinlock(&_atfork_lock); 189 TAILQ_INSERT_TAIL(&_atfork_list, af, next); 190 _spinunlock(&_atfork_lock); 191 return (0); 192 } 193