Initial import from FreeBSD RELENG_4:
[dragonfly.git] / lib / libc / stdlib / atexit.c
CommitLineData
984263bc
MD
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)
40static 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
51static 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
56struct atexit *__atexit; /* points to head of LIFO stack */
57
58/*
59 * Register a function to be performed at exit.
60 */
61int
62atexit(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}