freebsd-dev/lib/libthr/thread/thr_fork.c
2006-04-04 02:57:49 +00:00

199 lines
6.0 KiB
C

/*
* Copyright (c) 2005 David Xu <davidxu@freebsd.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.
*
* $FreeBSD$
*/
/*
* Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
* 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. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Birrell.
* 4. 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 JOHN BIRRELL 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 "namespace.h"
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <spinlock.h>
#include "un-namespace.h"
#include "libc_private.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 *curthread;
struct pthread_atfork *af;
_thr_check_init();
if ((af = malloc(sizeof(struct pthread_atfork))) == NULL)
return (ENOMEM);
curthread = _get_curthread();
af->prepare = prepare;
af->parent = parent;
af->child = child;
THR_UMTX_LOCK(curthread, &_thr_atfork_lock);
TAILQ_INSERT_TAIL(&_thr_atfork_list, af, qe);
THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock);
return (0);
}
__weak_reference(_fork, fork);
pid_t _fork(void);
pid_t
_fork(void)
{
struct pthread *curthread;
struct pthread_atfork *af;
pid_t ret;
int errsave;
int unlock_malloc;
if (!_thr_is_inited())
return (__sys_fork());
curthread = _get_curthread();
THR_UMTX_LOCK(curthread, &_thr_atfork_lock);
/* Run down atfork prepare handlers. */
TAILQ_FOREACH_REVERSE(af, &_thr_atfork_list, atfork_head, qe) {
if (af->prepare != NULL)
af->prepare();
}
/*
* Try our best to protect memory from being corrupted in
* child process because another thread in malloc code will
* simply be kill by fork().
*/
if (_thr_isthreaded() != 0) {
unlock_malloc = 1;
_malloc_prefork();
} else {
unlock_malloc = 0;
}
/*
* Block all signals until we reach a safe point.
*/
_thr_signal_block(curthread);
/* Fork a new process: */
if ((ret = __sys_fork()) == 0) {
/* Child process */
errsave = errno;
curthread->cancelflags &= ~THR_CANCEL_NEEDED;
/*
* Thread list will be reinitialized, and later we call
* _libpthread_init(), it will add us back to list.
*/
curthread->tlflags &= ~(TLFLAGS_IN_TDLIST | TLFLAGS_DETACHED);
/* child is a new kernel thread. */
thr_self(&curthread->tid);
/* clear other threads locked us. */
_thr_umtx_init(&curthread->lock);
_thr_umtx_init(&_thr_atfork_lock);
_thr_setthreaded(0);
/* reinitialize libc spinlocks. */
_thr_spinlock_init();
_mutex_fork(curthread);
/* reinitalize library. */
_libpthread_init(curthread);
/* Ready to continue, unblock signals. */
_thr_signal_unblock(curthread);
/* Run down atfork child handlers. */
TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
if (af->child != NULL)
af->child();
}
} else {
/* Parent process */
errsave = errno;
/* Ready to continue, unblock signals. */
_thr_signal_unblock(curthread);
if (unlock_malloc)
_malloc_postfork();
/* Run down atfork parent handlers. */
TAILQ_FOREACH(af, &_thr_atfork_list, qe) {
if (af->parent != NULL)
af->parent();
}
THR_UMTX_UNLOCK(curthread, &_thr_atfork_lock);
}
errno = errsave;
/* Return the process ID: */
return (ret);
}