atexit.c revision 92986 
1245450Sganbold/*-
2245450Sganbold * Copyright (c) 1990, 1993
3245450Sganbold *	The Regents of the University of California.  All rights reserved.
4245450Sganbold *
5245450Sganbold * This code is derived from software contributed to Berkeley by
6245450Sganbold * Chris Torek.
7245450Sganbold *
8245450Sganbold * Redistribution and use in source and binary forms, with or without
9245450Sganbold * modification, are permitted provided that the following conditions
10245450Sganbold * are met:
11246057Sganbold * 1. Redistributions of source code must retain the above copyright
12266277Sian *    notice, this list of conditions and the following disclaimer.
13246342Sganbold * 2. Redistributions in binary form must reproduce the above copyright
14246057Sganbold *    notice, this list of conditions and the following disclaimer in the
15266277Sian *    documentation and/or other materials provided with the distribution.
16266277Sian * 3. All advertising materials mentioning features or use of this software
17266277Sian *    must display the following acknowledgement:
18266277Sian *	This product includes software developed by the University of
19266277Sian *	California, Berkeley and its contributors.
20266274Sian * 4. Neither the name of the University nor the names of its contributors
21245450Sganbold *    may be used to endorse or promote products derived from this software
22278727Sian *    without specific prior written permission.
23278727Sian *
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
37#if defined(LIBC_SCCS) && !defined(lint)
38static char sccsid[] = "@(#)atexit.c	8.2 (Berkeley) 7/3/94";
39#endif /* LIBC_SCCS and not lint */
40#include <sys/cdefs.h>
41__FBSDID("$FreeBSD: head/lib/libc/stdlib/atexit.c 92986 2002-03-22 21:53:29Z obrien $");
42
43#include "namespace.h"
44#include <stddef.h>
45#include <stdlib.h>
46#include <unistd.h>
47#include <pthread.h>
48#include "atexit.h"
49#include "un-namespace.h"
50
51#include "libc_private.h"
52
53static pthread_mutex_t atexit_mutex = PTHREAD_MUTEX_INITIALIZER;
54
55#define _MUTEX_LOCK(x)		if (__isthreaded) _pthread_mutex_lock(x)
56#define _MUTEX_UNLOCK(x)	if (__isthreaded) _pthread_mutex_unlock(x)
57
58struct atexit *__atexit;	/* points to head of LIFO stack */
59
60/*
61 * Register a function to be performed at exit.
62 */
63int
64atexit(fn)
65	void (*fn)();
66{
67	static struct atexit __atexit0;	/* one guaranteed table */
68	struct atexit *p;
69
70	_MUTEX_LOCK(&atexit_mutex);
71	if ((p = __atexit) == NULL)
72		__atexit = p = &__atexit0;
73	else while (p->ind >= ATEXIT_SIZE) {
74		struct atexit *old__atexit;
75		old__atexit = __atexit;
76	        _MUTEX_UNLOCK(&atexit_mutex);
77		if ((p = (struct atexit *)malloc(sizeof(*p))) == NULL)
78			return (-1);
79		_MUTEX_LOCK(&atexit_mutex);
80		if (old__atexit != __atexit) {
81			/* Lost race, retry operation */
82			_MUTEX_UNLOCK(&atexit_mutex);
83			free(p);
84			_MUTEX_LOCK(&atexit_mutex);
85			p = __atexit;
86			continue;
87		}
88		p->ind = 0;
89		p->next = __atexit;
90		__atexit = p;
91	}
92	p->fns[p->ind++] = fn;
93	_MUTEX_UNLOCK(&atexit_mutex);
94	return (0);
95}
96