1/*
 2 * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
 3 *
 4 * Permission to use, copy, modify, and distribute this software for any
 5 * purpose with or without fee is hereby granted, provided that the above
 6 * copyright notice and this permission notice appear in all copies.
 7 *
 8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16/* Test that /proc/loadavg correctly reports last pid in pid namespace. */
17#define _GNU_SOURCE
18#include <errno.h>
19#include <sched.h>
20#include <sys/types.h>
21#include <sys/stat.h>
22#include <fcntl.h>
23#include <unistd.h>
24#include <sys/wait.h>
25
26int main(void)
27{
28	pid_t pid;
29	int wstatus;
30
31	if (unshare(CLONE_NEWPID) == -1) {
32		if (errno == ENOSYS || errno == EPERM)
33			return 4;
34		return 1;
35	}
36
37	pid = fork();
38	if (pid == -1)
39		return 1;
40	if (pid == 0) {
41		char buf[128], *p;
42		int fd;
43		ssize_t rv;
44
45		fd = open("/proc/loadavg" , O_RDONLY);
46		if (fd == -1)
47			return 1;
48		rv = read(fd, buf, sizeof(buf));
49		if (rv < 3)
50			return 1;
51		p = buf + rv;
52
53		/* pid 1 */
54		if (!(p[-3] == ' ' && p[-2] == '1' && p[-1] == '\n'))
55			return 1;
56
57		pid = fork();
58		if (pid == -1)
59			return 1;
60		if (pid == 0)
61			return 0;
62		if (waitpid(pid, NULL, 0) == -1)
63			return 1;
64
65		lseek(fd, 0, SEEK_SET);
66		rv = read(fd, buf, sizeof(buf));
67		if (rv < 3)
68			return 1;
69		p = buf + rv;
70
71		/* pid 2 */
72		if (!(p[-3] == ' ' && p[-2] == '2' && p[-1] == '\n'))
73			return 1;
74
75		return 0;
76	}
77
78	if (waitpid(pid, &wstatus, 0) == -1)
79		return 1;
80	if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) == 0)
81		return 0;
82	return 1;
83}