1/*
2 * Copyright (c) 2015 Cedric Hnyda <chnyda@suse.com>
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of
7 * the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it would be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write the Free Software Foundation,
16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
17 */
18
19/*
20* Description:
21* Write the current process in argv[1]
22*/
23
24#include <stdio.h>
25#include <sys/time.h>
26#include <sys/types.h>
27#include <unistd.h>
28#include <signal.h>
29#include <stdlib.h>
30#include <string.h>
31
32static void sig_handler(int signo)
33{
34	_exit(0);
35}
36
37int main(int argc, char **argv)
38{
39	FILE *f;
40	struct sigaction sa;
41
42	if (argc != 2) {
43		fprintf(stderr, "Usage: %s /cgroup/.../tasks\n", argv[0]);
44		return 1;
45	}
46
47	f = fopen(argv[1], "a");
48	if (!f) {
49		perror("fopen failed");
50		return 1;
51	}
52
53	fprintf(f, "%i\n", getpid());
54	fclose(f);
55
56	memset(&sa, 0, sizeof(sa));
57	sigemptyset(&sa.sa_mask);
58	sa.sa_handler = sig_handler;
59
60	if (sigaction(SIGVTALRM, &sa, NULL)) {
61		perror("sigaction failed");
62		return 1;
63	}
64
65	struct itimerval it = {.it_value = {.tv_sec = 0, .tv_usec = 10000}};
66
67	setitimer(ITIMER_VIRTUAL, &it, NULL);
68	for (;;);
69	return 0;
70}
71