1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2011 David Chisnall
5 * Copyright (c) 2023 Klara, Inc.
6 * All rights reserved.
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 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/types.h>
31
32#include <stdatomic.h>
33#include <stdlib.h>
34
35/**
36 * Linked list of quick exit handlers.  These will be invoked in reverse
37 * order of insertion when quick_exit() is called.  This is simpler than
38 * the atexit() version, because it is not required to support C++
39 * destructors or DSO-specific cleanups.
40 */
41struct quick_exit_handler {
42	struct quick_exit_handler *next;
43	void (*cleanup)(void);
44};
45
46static _Atomic(struct quick_exit_handler *) handlers;
47
48int
49at_quick_exit(void (*func)(void))
50{
51	struct quick_exit_handler *h;
52
53	if ((h = calloc(1, sizeof(*h))) == NULL) {
54		return (-1);
55	}
56	h->cleanup = func;
57	while (!atomic_compare_exchange_strong(&handlers, &h->next, h)) {
58		/* nothing */ ;
59	}
60	return (0);
61}
62
63void
64quick_exit(int status)
65{
66	struct quick_exit_handler *h;
67
68	/*
69	 * XXX: The C++ spec requires us to call std::terminate if there is an
70	 * exception here.
71	 */
72	for (h = atomic_load_explicit(&handlers, memory_order_acquire);
73	     h != NULL; h = h->next) {
74		h->cleanup();
75	}
76	_Exit(status);
77}
78