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gpsdate
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gpsdate: Discard gpsd reports when no fix or no satellites used 

We've observed several times that GPS receivers would report a wrong
time/date directly after boot, probably assuming that their RTC is
correct.

Let's wait until the receiver reports it has a fix and reports actual
satellites were used to compute it.
master
Harald Welte 2019-08-17 12:54:24 +02:00
parent cd7b77ef31
commit d59eb51be6
1 changed files with 26 additions and 2 deletions
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28
gpsdate.c
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@ -1,5 +1,5 @@
/* gpsdate - small utility to set system RTC based on gpsd time
* (C) 2013-2015 by sysmocom - s.f.m.c. GmbH, Author: Harald Welte
* (C) 2013-2019 by sysmocom - s.f.m.c. GmbH, Author: Harald Welte
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
@ -35,6 +35,7 @@
#include <string.h>
#include <syslog.h>
#include <getopt.h>
#include <inttypes.h>
#include <sys/time.h>
#include <sys/types.h>
@ -52,6 +53,7 @@ static void callback(struct gps_data_t *gpsdata)
{
struct timeval tv;
time_t time;
char *timestr, *lf;
int rc;
if (!(gpsdata->set & TIME_SET))
@ -62,12 +64,34 @@ static void callback(struct gps_data_t *gpsdata)
tv.tv_usec = 0;
time = tv.tv_sec;
timestr = ctime(&time);
if (!timestr) {
syslog(LOG_ERR, "ctime failed");
timestr = "<unknown>";
}
/* god knows why ctime insists on including a LF at the end */
lf = strchr(timestr, '\n');
if (lf)
*lf = '\0';
syslog(LOG_DEBUG, "%s: gpsdate->set=0x%08"PRIu64"x status=%u sats_used=%u\n",
timestr, gpsdata->set, gpsdata->status, gpsdata->satellites_used);
if (gpsdata->status == 0) {
syslog(LOG_INFO, "%s: discarding; no fix yet\n", timestr);
return;
}
if (gpsdata->satellites_used == 0) {
syslog(LOG_INFO, "%s: discarding; 0 satellites used\n", timestr);
return;
}
rc = settimeofday(&tv, NULL);
gps_close(gpsdata);
if (rc == 0) {
syslog(LOG_NOTICE, "Successfully set RTC time to GPSD time:"
" %s", ctime(&time));
" %s\n", timestr);
closelog();
exit(EXIT_SUCCESS);
} else {