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/* $OpenBSD: watchdogd.c,v 1.16 2023/03/08 04:43:15 guenther Exp $ */
/*
* Copyright (c) 2005 Marc Balmer <mbalmer@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/resource.h>
#include <sys/signal.h>
#include <sys/sysctl.h>
#include <sys/mman.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
volatile sig_atomic_t quit = 0;
__dead void usage(void);
void sighdlr(int);
int main(int, char *[]);
__dead void
usage(void)
{
extern char *__progname;
fprintf(stderr, "usage: %s [-dnq] [-i interval] [-p period]\n",
__progname);
exit(1);
}
void
sighdlr(int signum)
{
quit = 1;
}
int
main(int argc, char *argv[])
{
struct rlimit rlim;
const char *errstr;
size_t len;
u_int interval = 0, period = 30, nperiod;
int ch, trigauto, sauto, speriod;
int quiet = 0, daemonize = 1, retval = 1, do_restore = 1;
int mib[3];
while ((ch = getopt(argc, argv, "di:np:q")) != -1) {
switch (ch) {
case 'd':
daemonize = 0;
break;
case 'i':
interval = (u_int)strtonum(optarg, 1LL, 86400LL,
&errstr);
if (errstr)
errx(1, "interval is %s: %s", errstr, optarg);
break;
case 'n':
do_restore = 0;
break;
case 'p':
period = (u_int)strtonum(optarg, 2LL, 86400LL, &errstr);
if (errstr)
errx(1, "period is %s: %s", errstr, optarg);
break;
case 'q':
quiet = 1;
break;
default:
usage();
}
}
argc -= optind;
argv += optind;
if (argc > 0)
usage();
if (interval == 0 && (interval = period / 3) == 0)
interval = 1;
if (period <= interval)
errx(1, "retrigger interval too long");
/* save kern.watchdog.period and kern.watchdog.auto for restore */
mib[0] = CTL_KERN;
mib[1] = KERN_WATCHDOG;
mib[2] = KERN_WATCHDOG_PERIOD;
len = sizeof(speriod);
if (sysctl(mib, 3, &speriod, &len, &period, sizeof(period)) == -1) {
if (errno == EOPNOTSUPP)
errx(1, "no watchdog timer available");
else
err(1, "can't access kern.watchdog.period");
}
mib[2] = KERN_WATCHDOG_AUTO;
len = sizeof(sauto);
trigauto = 0;
if (sysctl(mib, 3, &sauto, &len, &trigauto, sizeof(trigauto)) == -1)
err(1, "can't access kern.watchdog.auto");
/* Double check the timeout period, some devices change the value */
mib[2] = KERN_WATCHDOG_PERIOD;
len = sizeof(nperiod);
if (sysctl(mib, 3, &nperiod, &len, NULL, 0) == -1) {
warnx("can't read back kern.watchdog.period, "
"restoring original values");
goto restore;
}
if (nperiod != period && !quiet)
warnx("period adjusted to %d by device", nperiod);
if (nperiod <= interval) {
warnx("retrigger interval %d too long, "
"restoring original values", interval);
goto restore;
}
if (daemonize && daemon(0, 0)) {
warn("can't daemonize, restoring original values");
goto restore;
}
/*
* mlockall() below will wire the whole stack up to the limit
* thus we have to reduce stack size to avoid resource abuse
*/
rlim.rlim_cur = 256 * 1024;
rlim.rlim_max = 256 * 1024;
(void)setrlimit(RLIMIT_STACK, &rlim);
(void)mlockall(MCL_CURRENT | MCL_FUTURE);
setpriority(PRIO_PROCESS, getpid(), -5);
signal(SIGTERM, sighdlr);
retval = 0;
while (!quit) {
if (sysctl(mib, 3, NULL, 0, &period, sizeof(period)) == -1)
quit = retval = 1;
sleep(interval);
}
if (do_restore) {
restore: sysctl(mib, 3, NULL, 0, &speriod, sizeof(speriod));
mib[2] = KERN_WATCHDOG_AUTO;
sysctl(mib, 3, NULL, 0, &sauto, sizeof(sauto));
}
return retval;
}
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