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#include <sys/types.h>
17#include <sys/stat.h>
18#include <fcntl.h>
19#include <errno.h>
20#include <unistd.h>
21
22int main(void)
23{
24	char buf[64];
25	int fd;
26
27	fd = open("/proc/self/wchan", O_RDONLY);
28	if (fd == -1) {
29		if (errno == ENOENT)
30			return 4;
31		return 1;
32	}
33
34	buf[0] = '\0';
35	if (read(fd, buf, sizeof(buf)) != 1)
36		return 1;
37	if (buf[0] != '0')
38		return 1;
39	return 0;
40}