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/* ntpshmmon.c -- monitor the inner end of an ntpshmwrite.connection
*
* This file is Copyright (c) 2010 by the GPSD project
* SPDX-License-Identifier: BSD-2-clause
*
*/
/* sys/ipc.h needs _XOPEN_SOURCE, 500 means X/Open 1995 */
#define _XOPEN_SOURCE 500
#include <stdio.h>
#include <string.h> /* for memset() */
#include <stdlib.h>
#include <getopt.h>
#include <limits.h>
#include <unistd.h>
#include "gps.h" /* for safe_atof() */
#include "gpsd_config.h"
#include "ntpshm.h"
#include "revision.h"
#include "timespec.h"
#define NTPSEGMENTS 256 /* NTPx for x any byte */
static struct shmTime *segments[NTPSEGMENTS + 1];
int main(int argc, char **argv)
{
int option;
int i;
bool killall = false;
bool verbose = false;
int nsamples = INT_MAX;
time_t timeout = (time_t)0, starttime = time(NULL);
/* a copy of all old segments */
struct shm_stat_t shm_stat_old[NTPSEGMENTS + 1];;
memset( shm_stat_old, 0 ,sizeof( shm_stat_old));
while ((option = getopt(argc, argv, "hn:st:vV")) != -1) {
switch (option) {
case 'n':
nsamples = atoi(optarg);
break;
case 's':
killall = true;
break;
case 't':
timeout = (time_t)atoi(optarg);
break;
case 'v':
verbose = true;
break;
case 'V':
(void)fprintf(stderr, "%s: version %s (revision %s)\n",
argv[0], VERSION, REVISION);
exit(EXIT_SUCCESS);
case 'h':
(void)fprintf(
stderr,
"usage: ntpshmmon [-s] [-n max] [-t timeout] [-v] [-h] [-V]\n"
" -h print this help\n"
" -n nsamples exit after nsamples\n"
" -s remove SHMs and exit\n"
" -t nseconds exit after nseconds\n"
" -v be verbose\n"
" -V print version and exit\n"
);
exit(EXIT_SUCCESS);
default:
/* no option, just go and do it */
break;
}
}
/* grab all segments, keep the non-null ones */
for (i = 0; i < NTPSEGMENTS; i++) {
segments[i] = shm_get(i, false, true);
if (verbose && segments[i] != NULL)
(void)fprintf(stderr, "unit %d opened\n", i);
}
if (killall) {
struct shmTime **pp;
for (pp = segments; pp < segments + NTPSEGMENTS; pp++)
if (*pp != NULL)
(void)shmdt((void *)(*pp));
exit(EXIT_SUCCESS);
}
/*
* We want line buffering even if stdout is going to a file. This
* is a (possibly futile) attempt to avoid writing an incomplete
* line on interrupt.
*/
setvbuf(stdout, NULL, _IOLBF, 0);
(void)printf("ntpshmmon version 1\n");
(void)printf("# Name Seen@ Clock Real L Prec\n");
do {
/* the current segment */
struct shm_stat_t shm_stat;
struct timespec delay;
for (i = 0; i < NTPSEGMENTS; i++) {
long long diff; /* 32 bit long is too short for a timespec */
enum segstat_t status = ntp_read(segments[i], &shm_stat, false);
if (verbose)
(void)fprintf(stderr, "unit %d status %d\n", i, status);
switch(status) {
case OK:
/* ntpd can slew the clock at 120% real time
* so do not lock out slightly short cycles
* use 50% of cycle time as lock out limit.
* ignore that system time may jump. */
diff = timespec_diff_ns(shm_stat.tvr, shm_stat_old[i].tvr);
if ( 0 == diff) {
/* no change in tvr */
break;
}
diff = timespec_diff_ns(shm_stat.tvt, shm_stat_old[i].tvt);
if ( 0 == diff) {
/* no change in tvt */
break;
}
/* time stamp it */
clock_gettime(CLOCK_REALTIME, &shm_stat.tvc);
printf("sample %s %ld.%09ld %ld.%09ld %ld.%09ld %d %3d\n",
ntp_name(i),
(long)shm_stat.tvc.tv_sec, shm_stat.tvc.tv_nsec,
(long)shm_stat.tvr.tv_sec, shm_stat.tvr.tv_nsec,
(long)shm_stat.tvt.tv_sec, shm_stat.tvt.tv_nsec,
shm_stat.leap, shm_stat.precision);
--nsamples;
/* save the new time stamp */
shm_stat_old[i] = shm_stat; /* structure copy */
break;
case NO_SEGMENT:
break;
case NOT_READY:
/* do nothing, data not ready, wait another cycle */
break;
case BAD_MODE:
(void)fprintf(stderr,
"ntpshmmon: unknown mode %d on segment %s\n",
shm_stat.status, ntp_name(i));
break;
case CLASH:
/* do nothing, data is corrupt, wait another cycle */
break;
default:
(void)fprintf(stderr,
"ntpshmmon: unknown status %d on segment %s\n",
status, ntp_name(i));
break;
}
}
/* all segments now checked */
/*
* Even on a 1 Hz PPS, a sleep(1) may end up
* being sleep(1.1) and missing a beat. Since
* we're ignoring duplicates via timestamp, polling
* at fast intervals should not be a problem
*
* PPS is not always one pulse per second.
* the Garmin GPS 18x-5Hz outputs 5 pulses per second.
* That is a 200 millSec cycle, minimum 20 milliSec duration
* we will wait 1 milliSec out of caution
*
* and, of course, nanosleep() may sleep a lot longer than we ask...
*/
if ( timeout ) {
/* do not read time unless it matters */
if ( time(NULL) > (starttime + timeout ) ) {
/* time to exit */
break;
}
}
/* wait 1,000 uSec */
delay.tv_sec = 0;
delay.tv_nsec = 1000000L;
nanosleep(&delay, NULL);
} while ( 0 < nsamples );
exit(EXIT_SUCCESS);
}
/* end */
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