Earlier uptime determination, which was done with sysinfo(2), had one second resolution, which made time stamps to be rounded unstable way depending on when a dmesg command was executed. In practical terms; the command below was supposed not to differ but it did. $ diff -q <(dmesg --ctime) <(sleep 0.5 ; dmesg --ctime) CC: Kay Sievers <kay@xxxxxxxx> References: https://lkml.org/lkml/2013/6/30/37 Buglink: https://github.com/karelzak/util-linux/issues/24 Signed-off-by: Sami Kerola <kerolasa@xxxxxx> --- sys-utils/dmesg.c | 27 ++++++++++++++------------- 1 file changed, 14 insertions(+), 13 deletions(-) diff --git a/sys-utils/dmesg.c b/sys-utils/dmesg.c index 480c897..c429a82 100644 --- a/sys-utils/dmesg.c +++ b/sys-utils/dmesg.c @@ -145,7 +145,7 @@ struct dmesg_control { struct timeval lasttime; /* last printed timestamp */ struct tm lasttm; /* last localtime */ - time_t boot_time; /* system boot time */ + struct timeval boot_time; /* system boot time */ int action; /* SYSLOG_ACTION_* */ int method; /* DMESG_METHOD_* */ @@ -472,18 +472,19 @@ static int get_syslog_buffer_size(void) return n > 0 ? n : 0; } -static time_t get_boot_time(void) +static void get_boot_time(struct timeval *boot_time) { - struct sysinfo info; - struct timeval tv; + struct timespec hires_uptime; + struct timeval lores_uptime, now; - if (sysinfo(&info) != 0) - warn(_("sysinfo failed")); - else if (gettimeofday(&tv, NULL) != 0) + if (clock_gettime(CLOCK_BOOTTIME, &hires_uptime) != 0) + warn(_("clock_gettime failed")); + else if (gettimeofday(&now, NULL) != 0) warn(_("gettimeofday failed")); - else - return tv.tv_sec -= info.uptime; - return 0; + else { + TIMESPEC_TO_TIMEVAL(&lores_uptime, &hires_uptime); + timersub(&now, &lores_uptime, boot_time); + } } /* @@ -771,7 +772,7 @@ static struct tm *record_localtime(struct dmesg_control *ctl, struct dmesg_record *rec, struct tm *tm) { - time_t t = ctl->boot_time + rec->tv.tv_sec; + time_t t = ctl->boot_time.tv_sec + rec->tv.tv_sec; return localtime_r(&t, tm); } @@ -1338,8 +1339,8 @@ int main(int argc, char *argv[]) usage(stderr); if (is_timefmt(ctl, RELTIME) || is_timefmt(ctl, CTIME) || is_timefmt(ctl, ISO8601)) { - ctl.boot_time = get_boot_time(); - if (!ctl.boot_time) + get_boot_time(&(ctl.boot_time)); + if (ctl.boot_time.tv_sec == 0 && ctl.boot_time.tv_usec == 0) ctl.time_fmt = DMESG_TIMEFTM_NONE; } -- 1.8.3.2 -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
