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Commit	Line	Data
	1	/*-
	2	* Copyright (c) 1990, 1993
	3	* The Regents of the University of California. All rights reserved.
	4	*
	5	* This code is derived from software contributed to Berkeley by
	6	* Chris Torek.
	7	*
	8	* Redistribution and use in source and binary forms, with or without
	9	* modification, are permitted provided that the following conditions
	10	* are met:
	11	* 1. Redistributions of source code must retain the above copyright
	12	* notice, this list of conditions and the following disclaimer.
	13	* 2. Redistributions in binary form must reproduce the above copyright
	14	* notice, this list of conditions and the following disclaimer in the
	15	* documentation and/or other materials provided with the distribution.
	16	* 3. All advertising materials mentioning features or use of this software
	17	* must display the following acknowledgement:
	18	* This product includes software developed by the University of
	19	* California, Berkeley and its contributors.
	20	* 4. Neither the name of the University nor the names of its contributors
	21	* may be used to endorse or promote products derived from this software
	22	* without specific prior written permission.
	23	*
	24	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	25	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	26	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	27	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	28	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	29	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	30	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	31	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	32	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	33	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	34	* SUCH DAMAGE.
	35	*
	36	* $FreeBSD: src/lib/libc/stdlib/atexit.c,v 1.3.6.1 2002/03/10 20:28:40 tegge Exp $
	37	*/
	38
	39	#if defined(LIBC_SCCS) && !defined(lint)
	40	static char sccsid[] = "@(#)atexit.c 8.2 (Berkeley) 7/3/94";
	41	#endif /* LIBC_SCCS and not lint */
	42
	43	#include <stddef.h>
	44	#include <stdlib.h>
	45	#include <unistd.h>
	46	#include "atexit.h"
	47
	48	#include "libc_private.h"
	49	#include "spinlock.h"
	50
	51	static spinlock_t thread_lock = _SPINLOCK_INITIALIZER;
	52
	53	#define THREAD_LOCK() if (__isthreaded) _SPINLOCK(&thread_lock);
	54	#define THREAD_UNLOCK() if (__isthreaded) _SPINUNLOCK(&thread_lock);
	55
	56	struct atexit __atexit; / points to head of LIFO stack */
	57
	58	/*
	59	* Register a function to be performed at exit.
	60	*/
	61	int
	62	atexit(fn)
	63	void (*fn)();
	64	{
	65	static struct atexit __atexit0; /* one guaranteed table */
	66	register struct atexit *p;
	67
	68	THREAD_LOCK();
	69	if ((p = __atexit) == NULL)
	70	__atexit = p = &__atexit0;
	71	else while (p->ind >= ATEXIT_SIZE) {
	72	struct atexit *old__atexit;
	73	old__atexit = __atexit;
	74	THREAD_UNLOCK();
	75	if ((p = (struct atexit )malloc(sizeof(p))) == NULL)
	76	return (-1);
	77	THREAD_LOCK();
	78	if (old__atexit != __atexit) {
	79	/* Lost race, retry operation */
	80	THREAD_UNLOCK();
	81	free(p);
	82	THREAD_LOCK();
	83	p = __atexit;
	84	continue;
	85	}
	86	p->ind = 0;
	87	p->next = __atexit;
	88	__atexit = p;
	89	}
	90	p->fns[p->ind++] = fn;
	91	THREAD_UNLOCK();
	92	return (0);
	93	}