1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2022 Jessica Clarke <jrtc27@FreeBSD.org>
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  */
27 
28 #define	KILL_TIMEOUT	10
29 
30 /*
31  * NB: Most of these do not need to be volatile, but a handful are used in
32  * signal handler contexts, so for simplicity we make them all volatile rather
33  * than duplicate the implementation.
34  */
35 struct pipe_barrier {
36 	volatile int		fds[2];
37 };
38 
39 static __inline int
40 pipe_barrier_init(struct pipe_barrier *p)
41 {
42 	int error, fds[2], i;
43 
44 	error = pipe(fds);
45 	if (error != 0)
46 		return (error);
47 
48 	for (i = 0; i < 2; ++i)
49 		p->fds[i] = fds[i];
50 
51 	return (0);
52 }
53 
54 static __inline void
55 pipe_barrier_wait(struct pipe_barrier *p)
56 {
57 	ssize_t ret;
58 	char temp;
59 	int fd;
60 
61 	fd = p->fds[0];
62 	p->fds[0] = -1;
63 	do {
64 		ret = read(fd, &temp, 1);
65 	} while (ret == -1 && errno == EINTR);
66 	close(fd);
67 }
68 
69 static __inline void
70 pipe_barrier_ready(struct pipe_barrier *p)
71 {
72 	int fd;
73 
74 	fd = p->fds[1];
75 	p->fds[1] = -1;
76 	close(fd);
77 }
78 
79 static __inline void
80 pipe_barrier_destroy_impl(struct pipe_barrier *p, int i)
81 {
82 	int fd;
83 
84 	fd = p->fds[i];
85 	if (fd != -1) {
86 		p->fds[i] = -1;
87 		close(fd);
88 	}
89 }
90 
91 static __inline void
92 pipe_barrier_destroy_wait(struct pipe_barrier *p)
93 {
94 	pipe_barrier_destroy_impl(p, 0);
95 }
96 
97 static __inline void
98 pipe_barrier_destroy_ready(struct pipe_barrier *p)
99 {
100 	pipe_barrier_destroy_impl(p, 1);
101 }
102 
103 static __inline void
104 pipe_barrier_destroy(struct pipe_barrier *p)
105 {
106 	pipe_barrier_destroy_wait(p);
107 	pipe_barrier_destroy_ready(p);
108 }
109 
110 void	reproduce_signal_death(int sig);
111