newfileops_on_fork_test.c revision 298490 
1/*-
2 * Copyright (c) 2009 Robert N. M. Watson
3 * All rights reserved.
4 *
5 * This software was developed at the University of Cambridge Computer
6 * Laboratory with support from a grant from Google, Inc.
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 * $FreeBSD: stable/10/tests/sys/file/newfileops_on_fork_test.c 298490 2016-04-22 21:30:42Z ngie $
30 */
31
32/*
33 * When a multi-threaded application calls fork(2) from one thread while
34 * another thread is blocked in accept(2), we prefer that the file descriptor
35 * to be returned by accept(2) not appear in the child process.  Test this by
36 * creating a thread blocked in accept(2), then forking a child and seeing if
37 * the fd it would have returned is defined in the child or not.
38 */
39
40#include <sys/socket.h>
41#include <sys/wait.h>
42
43#include <netinet/in.h>
44
45#include <err.h>
46#include <errno.h>
47#include <pthread.h>
48#include <signal.h>
49#include <stdlib.h>
50#include <string.h>
51#include <unistd.h>
52
53#define	PORT	9000
54
55static int listen_fd;
56
57static void *
58do_accept(__unused void *arg)
59{
60	int accept_fd;
61
62	accept_fd = accept(listen_fd, NULL, NULL);
63	if (accept_fd < 0)
64		err(-1, "accept");
65
66	return (NULL);
67}
68
69static void
70do_fork(void)
71{
72	int pid;
73
74	pid = fork();
75	if (pid < 0)
76		err(-1, "fork");
77	if (pid > 0) {
78		waitpid(pid, NULL, 0);
79		exit(0);
80	}
81
82	/*
83	 * We will call ftruncate(2) on the next available file descriptor,
84	 * listen_fd+1, and get back EBADF if it's not a valid descriptor,
85	 * and EINVAL if it is.  This (currently) works fine in practice.
86	 */
87	if (ftruncate(listen_fd + 1, 0 < 0)) {
88		if (errno == EBADF)
89			exit(0);
90		else if (errno == EINVAL)
91			errx(-1, "file descriptor still open in child");
92		else
93			err(-1, "unexpected error");
94	} else
95		errx(-1, "ftruncate succeeded");
96}
97
98int
99main(__unused int argc, __unused char *argv[])
100{
101	struct sockaddr_in sin;
102	pthread_t accept_thread;
103
104	listen_fd = socket(PF_INET, SOCK_STREAM, 0);
105	if (listen_fd < 0)
106		err(-1, "socket");
107	bzero(&sin, sizeof(sin));
108	sin.sin_family = AF_INET;
109	sin.sin_len = sizeof(sin);
110	sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
111	sin.sin_port = htons(PORT);
112	if (bind(listen_fd, (struct sockaddr *)&sin, sizeof(sin)) < 0)
113		err(-1, "bind");
114	if (listen(listen_fd, -1) <0)
115		err(-1, "listen");
116	if (pthread_create(&accept_thread, NULL, do_accept, NULL) != 0)
117		err(-1, "pthread_create");
118	sleep(1);	/* Easier than using a CV. */
119	do_fork();
120	exit(0);
121}
122