diff options
| -rw-r--r-- | sys-utils/hwclock.c | 38 |
1 files changed, 28 insertions, 10 deletions
diff --git a/sys-utils/hwclock.c b/sys-utils/hwclock.c index 395b5c389..5e786a84a 100644 --- a/sys-utils/hwclock.c +++ b/sys-utils/hwclock.c @@ -91,6 +91,11 @@ struct clock_ops *ur; #define FLOOR(arg) ((arg >= 0 ? (int) arg : ((int) arg) - 1)); +/* Maximal clock adjustment in seconds per day. + (adjtime() glibc call has 2145 seconds limit on i386, so it is good enough for us as well, + 43219 is a maximal safe value preventing exact_adjustment overflow.) */ +#define MAX_DRIFT 2145.0 + const char *adj_file_name = NULL; struct adjtime { @@ -1008,6 +1013,7 @@ adjust_drift_factor(struct adjtime *adjtime_p, double adj_days, cal_days; double exp_drift, unc_drift; double factor_adjust; + double drift_factor; /* Adjusted time units per hardware time unit */ atime_per_htime = 1.0 + adjtime_p->drift_factor / sec_per_day; @@ -1033,16 +1039,28 @@ adjust_drift_factor(struct adjtime *adjtime_p, /* Amount to add to previous drift factor */ factor_adjust = unc_drift / cal_days; - if (debug) - printf(_("Clock drifted %.1f seconds in the past " - "%d seconds in spite of a drift factor of " - "%f seconds/day.\n" - "Adjusting drift factor by %f seconds/day\n"), - unc_drift, - (int)(nowtime - adjtime_p->last_calib_time), - adjtime_p->drift_factor, factor_adjust); - - adjtime_p->drift_factor += factor_adjust; + /* New drift factor */ + drift_factor = adjtime_p->drift_factor + factor_adjust; + + if (abs(drift_factor) > MAX_DRIFT) { + if (debug) + printf(_("Clock drift factor was calculated as " + "%f seconds/day.\n" + "It is far too much. Resetting to zero.\n"), + drift_factor); + drift_factor = 0; + } else { + if (debug) + printf(_("Clock drifted %.1f seconds in the past " + "%d seconds in spite of a drift factor of " + "%f seconds/day.\n" + "Adjusting drift factor by %f seconds/day\n"), + unc_drift, + (int)(nowtime - adjtime_p->last_calib_time), + adjtime_p->drift_factor, factor_adjust); + } + + adjtime_p->drift_factor = drift_factor; } adjtime_p->last_calib_time = nowtime; |