/* * hwclock.c * * clock.c was written by Charles Hedrick, hedrick@cs.rutgers.edu, Apr 1992 * Modified for clock adjustments - Rob Hooft , Nov 1992 * Improvements by Harald Koenig * and Alan Modra . * * Major rewrite by Bryan Henderson , 96.09.19. * The new program is called hwclock. New features: * * - You can set the hardware clock without also modifying the system * clock. * - You can read and set the clock with finer than 1 second precision. * - When you set the clock, hwclock automatically refigures the drift * rate, based on how far off the clock was before you set it. * * Reshuffled things, added sparc code, and re-added alpha stuff * by David Mosberger * and Jay Estabrook * and Martin Ostermann , aeb@cwi.nl, 990212. * * Fix for Award 2094 bug, Dave Coffin (dcoffin@shore.net) 11/12/98 * Change of local time handling, Stefan Ring * Change of adjtime handling, James P. Rutledge . * * Distributed under GPL */ /* * Explanation of `adjusting' (Rob Hooft): * * The problem with my machine is that its CMOS clock is 10 seconds * per day slow. With this version of clock.c, and my '/etc/rc.local' * reading '/etc/clock -au' instead of '/etc/clock -u -s', this error * is automatically corrected at every boot. * * To do this job, the program reads and writes the file '/etc/adjtime' * to determine the correction, and to save its data. In this file are * three numbers: * * 1) the correction in seconds per day. (So if your clock runs 5 * seconds per day fast, the first number should read -5.0) * 2) the number of seconds since 1/1/1970 the last time the program * was used * 3) the remaining part of a second which was leftover after the last * adjustment * * Installation and use of this program: * * a) create a file '/etc/adjtime' containing as the first and only * line: '0.0 0 0.0' * b) run 'clock -au' or 'clock -a', depending on whether your cmos is * in universal or local time. This updates the second number. * c) set your system time using the 'date' command. * d) update your cmos time using 'clock -wu' or 'clock -w' * e) replace the first number in /etc/adjtime by your correction. * f) put the command 'clock -au' or 'clock -a' in your '/etc/rc.local' */ #include #include #include #include #include #include #include #include #include #include #include #include "c.h" #include "closestream.h" #include "nls.h" #include "optutils.h" #include "pathnames.h" #include "hwclock.h" #include "timeutils.h" #include "env.h" #include "xalloc.h" #include "path.h" #include "strutils.h" #ifdef HAVE_LIBAUDIT #include static int hwaudit_fd = -1; #endif UL_DEBUG_DEFINE_MASK(hwclock); UL_DEBUG_DEFINE_MASKNAMES(hwclock) = UL_DEBUG_EMPTY_MASKNAMES; /* The struct that holds our hardware access routines */ static struct clock_ops *ur; /* 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 struct adjtime { /* * This is information we keep in the adjtime file that tells us how * to do drift corrections. Elements are all straight from the * adjtime file, so see documentation of that file for details. * Exception is , which is an indication that what's in this * structure is not what's in the disk file (because it has been * updated since read from the disk file). */ int dirty; /* line 1 */ double drift_factor; time_t last_adj_time; double not_adjusted; /* line 2 */ time_t last_calib_time; /* * The most recent time that we set the clock from an external * authority (as opposed to just doing a drift adjustment) */ /* line 3 */ enum a_local_utc { UTC = 0, LOCAL, UNKNOWN } local_utc; /* * To which time zone, local or UTC, we most recently set the * hardware clock. */ }; static void hwclock_init_debug(const char *str) { __UL_INIT_DEBUG_FROM_STRING(hwclock, HWCLOCK_DEBUG_, 0, str); DBG(INIT, ul_debug("hwclock debug mask: 0x%04x", hwclock_debug_mask)); DBG(INIT, ul_debug("hwclock version: %s", PACKAGE_STRING)); } /* FOR TESTING ONLY: inject random delays of up to 1000ms */ static void up_to_1000ms_sleep(void) { int usec = random() % 1000000; DBG(RANDOM_SLEEP, ul_debug("sleeping ~%d usec", usec)); xusleep(usec); } /* * time_t to timeval conversion. */ static struct timeval t2tv(time_t timet) { struct timeval rettimeval; rettimeval.tv_sec = timet; rettimeval.tv_usec = 0; return rettimeval; } /* * The difference in seconds between two times in "timeval" format. */ double time_diff(struct timeval subtrahend, struct timeval subtractor) { return (subtrahend.tv_sec - subtractor.tv_sec) + (subtrahend.tv_usec - subtractor.tv_usec) / 1E6; } /* * The time, in "timeval" format, which is seconds after the * time . Of course, may be negative. */ static struct timeval time_inc(struct timeval addend, double increment) { struct timeval newtime; newtime.tv_sec = addend.tv_sec + (int)increment; newtime.tv_usec = addend.tv_usec + (increment - (int)increment) * 1E6; /* * Now adjust it so that the microsecond value is between 0 and 1 * million. */ if (newtime.tv_usec < 0) { newtime.tv_usec += 1E6; newtime.tv_sec -= 1; } else if (newtime.tv_usec >= 1E6) { newtime.tv_usec -= 1E6; newtime.tv_sec += 1; } return newtime; } static int hw_clock_is_utc(const struct hwclock_control *ctl, const struct adjtime adjtime) { int ret; if (ctl->utc) ret = 1; /* --utc explicitly given on command line */ else if (ctl->local_opt) ret = 0; /* --localtime explicitly given */ else /* get info from adjtime file - default is UTC */ ret = (adjtime.local_utc != LOCAL); if (ctl->verbose) printf(_("Assuming hardware clock is kept in %s time.\n"), ret ? _("UTC") : _("local")); return ret; } /* * Read the adjustment parameters out of the /etc/adjtime file. * * Return them as the adjtime structure <*adjtime_p>. Its defaults are * initialized in main(). */ static int read_adjtime(const struct hwclock_control *ctl, struct adjtime *adjtime_p) { FILE *adjfile; char line1[81]; /* String: first line of adjtime file */ char line2[81]; /* String: second line of adjtime file */ char line3[81]; /* String: third line of adjtime file */ if (access(ctl->adj_file_name, R_OK) != 0) return EXIT_SUCCESS; adjfile = fopen(ctl->adj_file_name, "r"); /* open file for reading */ if (adjfile == NULL) { warn(_("cannot open %s"), ctl->adj_file_name); return EXIT_FAILURE; } if (!fgets(line1, sizeof(line1), adjfile)) line1[0] = '\0'; /* In case fgets fails */ if (!fgets(line2, sizeof(line2), adjfile)) line2[0] = '\0'; /* In case fgets fails */ if (!fgets(line3, sizeof(line3), adjfile)) line3[0] = '\0'; /* In case fgets fails */ fclose(adjfile); sscanf(line1, "%lf %ld %lf", &adjtime_p->drift_factor, &adjtime_p->last_adj_time, &adjtime_p->not_adjusted); sscanf(line2, "%ld", &adjtime_p->last_calib_time); if (!strcmp(line3, "UTC\n")) { adjtime_p->local_utc = UTC; } else if (!strcmp(line3, "LOCAL\n")) { adjtime_p->local_utc = LOCAL; } else { adjtime_p->local_utc = UNKNOWN; if (line3[0]) { warnx(_("Warning: unrecognized third line in adjtime file\n" "(Expected: `UTC' or `LOCAL' or nothing.)")); } } if (ctl->verbose) { printf(_ ("Last drift adjustment done at %ld seconds after 1969\n"), (long)adjtime_p->last_adj_time); printf(_("Last calibration done at %ld seconds after 1969\n"), (long)adjtime_p->last_calib_time); printf(_("Hardware clock is on %s time\n"), (adjtime_p->local_utc == LOCAL) ? _("local") : (adjtime_p->local_utc == UTC) ? _("UTC") : _("unknown")); } return EXIT_SUCCESS; } /* * Wait until the falling edge of the Hardware Clock's update flag so that * any time that is read from the clock immediately after we return will be * exact. * * The clock only has 1 second precision, so it gives the exact time only * once per second, right on the falling edge of the update flag. * * We wait (up to one second) either blocked waiting for an rtc device or in * a CPU spin loop. The former is probably not very accurate. * * Return 0 if it worked, nonzero if it didn't. */ static int synchronize_to_clock_tick(const struct hwclock_control *ctl) { int rc; if (ctl->verbose) printf(_("Waiting for clock tick...\n")); rc = ur->synchronize_to_clock_tick(ctl); if (ctl->verbose) { if (rc) printf(_("...synchronization failed\n")); else printf(_("...got clock tick\n")); } return rc; } /* * Convert a time in broken down format (hours, minutes, etc.) into standard * unix time (seconds into epoch). Return it as *systime_p. * * The broken down time is argument . This broken down time is either * in local time zone or UTC, depending on value of logical argument * "universal". True means it is in UTC. * * If the argument contains values that do not constitute a valid time, and * mktime() recognizes this, return *valid_p == false and *systime_p * undefined. However, mktime() sometimes goes ahead and computes a * fictional time "as if" the input values were valid, e.g. if they indicate * the 31st day of April, mktime() may compute the time of May 1. In such a * case, we return the same fictional value mktime() does as *systime_p and * return *valid_p == true. */ static int mktime_tz(const struct hwclock_control *ctl, struct tm tm, time_t *systime_p) { int valid; if (ctl->universal) *systime_p = timegm(&tm); else *systime_p = mktime(&tm); if (*systime_p == -1) { /* * This apparently (not specified in mktime() documentation) * means the 'tm' structure does not contain valid values * (however, not containing valid values does _not_ imply * mktime() returns -1). */ valid = 0; if (ctl->verbose) printf(_("Invalid values in hardware clock: " "%4d/%.2d/%.2d %.2d:%.2d:%.2d\n"), tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec); } else { valid = 1; if (ctl->verbose) printf(_ ("Hw clock time : %4d/%.2d/%.2d %.2d:%.2d:%.2d = " "%ld seconds since 1969\n"), tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec, (long)*systime_p); } return valid; } /* * Read the hardware clock and return the current time via argument. * * Use the method indicated by argument to access the hardware * clock. */ static int read_hardware_clock(const struct hwclock_control *ctl, int *valid_p, time_t *systime_p) { struct tm tm; int err; err = ur->read_hardware_clock(ctl, &tm); if (err) return err; if (ctl->verbose) printf(_ ("Time read from Hardware Clock: %4d/%.2d/%.2d %02d:%02d:%02d\n"), tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec); *valid_p = mktime_tz(ctl, tm, systime_p); return 0; } /* * Set the Hardware Clock to the time , in local time zone or UTC, * according to . */ static void set_hardware_clock(const struct hwclock_control *ctl, const time_t newtime) { struct tm new_broken_time; /* * Time to which we will set Hardware Clock, in broken down format, * in the time zone of caller's choice */ if (ctl->universal) gmtime_r(&newtime, &new_broken_time); else localtime_r(&newtime, &new_broken_time); if (ctl->verbose) printf(_("Setting Hardware Clock to %.2d:%.2d:%.2d " "= %ld seconds since 1969\n"), new_broken_time.tm_hour, new_broken_time.tm_min, new_broken_time.tm_sec, (long)newtime); if (!ctl->testing) ur->set_hardware_clock(ctl, &new_broken_time); } static double get_hardware_delay(const struct hwclock_control *ctl) { const char *devpath, *rtcname; char name[128 + 1]; struct path_cxt *pc; int rc; devpath = ur->get_device_path(); if (!devpath) goto unknown; rtcname = strrchr(devpath, '/'); if (!rtcname || !*(rtcname + 1)) goto unknown; rtcname++; pc = ul_new_path("/sys/class/rtc/%s", rtcname); if (!pc) goto unknown; rc = ul_path_scanf(pc, "name", "%128[^\n ]", &name); ul_unref_path(pc); if (rc != 1 || !*name) goto unknown; if (ctl->verbose) printf(_("RTC type: '%s'\n"), name); /* MC146818A-compatible (x86) */ if (strcmp(name, "rtc_cmos") == 0) return 0.5; /* Another HW */ return 0; unknown: /* Let's be backwardly compatible */ return 0.5; } /* * Set the Hardware Clock to the time "sethwtime", in local time zone or * UTC, according to "universal". * * Wait for a fraction of a second so that "sethwtime" is the value of the * Hardware Clock as of system time "refsystime", which is in the past. For * example, if "sethwtime" is 14:03:05 and "refsystime" is 12:10:04.5 and * the current system time is 12:10:06.0: Wait .5 seconds (to make exactly 2 * seconds since "refsystime") and then set the Hardware Clock to 14:03:07, * thus getting a precise and retroactive setting of the clock. The .5 delay is * default on x86, see --delay and get_hardware_delay(). * * (Don't be confused by the fact that the system clock and the Hardware * Clock differ by two hours in the above example. That's just to remind you * that there are two independent time scales here). * * This function ought to be able to accept set times as fractional times. * Idea for future enhancement. */ static void set_hardware_clock_exact(const struct hwclock_control *ctl, const time_t sethwtime, const struct timeval refsystime) { /* * The Hardware Clock can only be set to any integer time plus one * half second. The integer time is required because there is no * interface to set or get a fractional second. The additional half * second is because the Hardware Clock updates to the following * second precisely 500 ms (not 1 second!) after you release the * divider reset (after setting the new time) - see description of * DV2, DV1, DV0 in Register A in the MC146818A data sheet (and note * that although that document doesn't say so, real-world code seems * to expect that the SET bit in Register B functions the same way). * That means that, e.g., when you set the clock to 1:02:03, it * effectively really sets it to 1:02:03.5, because it will update to * 1:02:04 only half a second later. Our caller passes the desired * integer Hardware Clock time in sethwtime, and the corresponding * system time (which may have a fractional part, and which may or may * not be the same!) in refsystime. In an ideal situation, we would * then apply sethwtime to the Hardware Clock at refsystime+500ms, so * that when the Hardware Clock ticks forward to sethwtime+1s half a * second later at refsystime+1000ms, everything is in sync. So we * spin, waiting for gettimeofday() to return a time at or after that * time (refsystime+500ms) up to a tolerance value, initially 1ms. If * we miss that time due to being preempted for some other process, * then we increase the margin a little bit (initially 1ms, doubling * each time), add 1 second (or more, if needed to get a time that is * in the future) to both the time for which we are waiting and the * time that we will apply to the Hardware Clock, and start waiting * again. * * For example, the caller requests that we set the Hardware Clock to * 1:02:03, with reference time (current system time) = 6:07:08.250. * We want the Hardware Clock to update to 1:02:04 at 6:07:09.250 on * the system clock, and the first such update will occur 0.500 * seconds after we write to the Hardware Clock, so we spin until the * system clock reads 6:07:08.750. If we get there, great, but let's * imagine the system is so heavily loaded that our process is * preempted and by the time we get to run again, the system clock * reads 6:07:11.990. We now want to wait until the next xx:xx:xx.750 * time, which is 6:07:12.750 (4.5 seconds after the reference time), * at which point we will set the Hardware Clock to 1:02:07 (4 seconds * after the originally requested time). If we do that successfully, * then at 6:07:13.250 (5 seconds after the reference time), the * Hardware Clock will update to 1:02:08 (5 seconds after the * originally requested time), and all is well thereafter. */ time_t newhwtime = sethwtime; double target_time_tolerance_secs = 0.001; /* initial value */ double tolerance_incr_secs = 0.001; /* initial value */ double delay; struct timeval rtc_set_delay_tv; struct timeval targetsystime; struct timeval nowsystime; struct timeval prevsystime = refsystime; double deltavstarget; if (ctl->rtc_delay != -1.0) /* --delay specified */ delay = ctl->rtc_delay; else delay = get_hardware_delay(ctl); if (ctl->verbose) printf(_("Using delay: %.6f seconds\n"), delay); rtc_set_delay_tv.tv_sec = 0; rtc_set_delay_tv.tv_usec = delay * 1E6; timeradd(&refsystime, &rtc_set_delay_tv, &targetsystime); while (1) { double ticksize; ON_DBG(RANDOM_SLEEP, up_to_1000ms_sleep()); gettimeofday(&nowsystime, NULL); deltavstarget = time_diff(nowsystime, targetsystime); ticksize = time_diff(nowsystime, prevsystime); prevsystime = nowsystime; if (ticksize < 0) { if (ctl->verbose) printf(_("time jumped backward %.6f seconds " "to %ld.%06ld - retargeting\n"), ticksize, nowsystime.tv_sec, nowsystime.tv_usec); /* The retarget is handled at the end of the loop. */ } else if (deltavstarget < 0) { /* deltavstarget < 0 if current time < target time */ DBG(DELTA_VS_TARGET, ul_debug("%ld.%06ld < %ld.%06ld (%.6f)", nowsystime.tv_sec, nowsystime.tv_usec, targetsystime.tv_sec, targetsystime.tv_usec, deltavstarget)); continue; /* not there yet - keep spinning */ } else if (deltavstarget <= target_time_tolerance_secs) { /* Close enough to the target time; done waiting. */ break; } else /* (deltavstarget > target_time_tolerance_secs) */ { /* * We missed our window. Increase the tolerance and * aim for the next opportunity. */ if (ctl->verbose) printf(_("missed it - %ld.%06ld is too far " "past %ld.%06ld (%.6f > %.6f)\n"), nowsystime.tv_sec, nowsystime.tv_usec, targetsystime.tv_sec, targetsystime.tv_usec, deltavstarget, target_time_tolerance_secs); target_time_tolerance_secs += tolerance_incr_secs; tolerance_incr_secs *= 2; } /* * Aim for the same offset (tv_usec) within the second in * either the current second (if that offset hasn't arrived * yet), or the next second. */ if (nowsystime.tv_usec < targetsystime.tv_usec) targetsystime.tv_sec = nowsystime.tv_sec; else targetsystime.tv_sec = nowsystime.tv_sec + 1; } newhwtime = sethwtime + (int)(time_diff(nowsystime, refsystime) - delay /* don't count this */ + 0.5 /* for rounding */); if (ctl->verbose) printf(_("%ld.%06ld is close enough to %ld.%06ld (%.6f < %.6f)\n" "Set RTC to %ld (%ld + %d; refsystime = %ld.%06ld)\n"), nowsystime.tv_sec, nowsystime.tv_usec, targetsystime.tv_sec, targetsystime.tv_usec, deltavstarget, target_time_tolerance_secs, newhwtime, sethwtime, (int)(newhwtime - sethwtime), refsystime.tv_sec, refsystime.tv_usec); set_hardware_clock(ctl, newhwtime); } static int display_time(struct timeval hwctime) { char buf[ISO_BUFSIZ]; if (strtimeval_iso(&hwctime, ISO_TIMESTAMP_DOT, buf, sizeof(buf))) return EXIT_FAILURE; printf("%s\n", buf); return EXIT_SUCCESS; } /* * Adjusts System time, sets the kernel's timezone and RTC timescale. * * The kernel warp_clock function adjusts the System time according to the * tz.tz_minuteswest argument and sets PCIL (see below). At boot settimeofday(2) * has one-shot access to this function as shown in the table below. * * +-------------------------------------------------------------------+ * | settimeofday(tv, tz) | * |-------------------------------------------------------------------| * | Arguments | System Time | PCIL | | warp_clock | * | tv | tz | set | warped | set | firsttime | locked | * |---------|---------|---------------|------|-----------|------------| * | pointer | NULL | yes | no | no | 1 | no | * | pointer | pointer | yes | no | no | 0 | yes | * | NULL | ptr2utc | no | no | no | 0 | yes | * | NULL | pointer | no | yes | yes | 0 | yes | * +-------------------------------------------------------------------+ * ptr2utc: tz.tz_minuteswest is zero (UTC). * PCIL: persistent_clock_is_local, sets the "11 minute mode" timescale. * firsttime: locks the warp_clock function (initialized to 1 at boot). * * +---------------------------------------------------------------------------+ * | op | RTC scale | settimeofday calls | * |---------|-----------|-----------------------------------------------------| * | systz | Local | 1) warps system time*, sets PCIL* and kernel tz | * | systz | UTC | 1st) locks warp_clock* 2nd) sets kernel tz | * | hctosys | Local | 1st) sets PCIL* 2nd) sets system time and kernel tz | * | hctosys | UTC | 1) sets system time and kernel tz | * +---------------------------------------------------------------------------+ * * only on first call after boot */ static int set_system_clock(const struct hwclock_control *ctl, const struct timeval newtime) { struct tm broken; int minuteswest; int rc = 0; const struct timezone tz_utc = { 0 }; localtime_r(&newtime.tv_sec, &broken); minuteswest = -get_gmtoff(&broken) / 60; if (ctl->verbose) { if (ctl->hctosys && !ctl->universal) printf(_("Calling settimeofday(NULL, %d) to set " "persistent_clock_is_local.\n"), minuteswest); if (ctl->systz && ctl->universal) puts(_("Calling settimeofday(NULL, 0) " "to lock the warp function.")); if (ctl->hctosys) printf(_("Calling settimeofday(%ld.%06ld, %d)\n"), newtime.tv_sec, newtime.tv_usec, minuteswest); else { printf(_("Calling settimeofday(NULL, %d) "), minuteswest); if (ctl->universal) puts(_("to set the kernel timezone.")); else puts(_("to warp System time.")); } } if (!ctl->testing) { const struct timezone tz = { minuteswest }; if (ctl->hctosys && !ctl->universal) /* set PCIL */ rc = settimeofday(NULL, &tz); if (ctl->systz && ctl->universal) /* lock warp_clock */ rc = settimeofday(NULL, &tz_utc); if (!rc && ctl->hctosys) rc = settimeofday(&newtime, &tz); else if (!rc) rc = settimeofday(NULL, &tz); if (rc) { warn(_("settimeofday() failed")); return EXIT_FAILURE; } } return EXIT_SUCCESS; } /* * Refresh the last calibrated and last adjusted timestamps in <*adjtime_p> * to facilitate future drift calculations based on this set point. * * With the --update-drift option: * Update the drift factor in <*adjtime_p> based on the fact that the * Hardware Clock was just calibrated to and before that was * set to the time scale. */ static void adjust_drift_factor(const struct hwclock_control *ctl, struct adjtime *adjtime_p, const struct timeval nowtime, const struct timeval hclocktime) { if (!ctl->update) { if (ctl->verbose) printf(_("Not adjusting drift factor because the " "--update-drift option was not used.\n")); } else if (adjtime_p->last_calib_time == 0) { if (ctl->verbose) printf(_("Not adjusting drift factor because last " "calibration time is zero,\n" "so history is bad and calibration startover " "is necessary.\n")); } else if ((hclocktime.tv_sec - adjtime_p->last_calib_time) < 4 * 60 * 60) { if (ctl->verbose) printf(_("Not adjusting drift factor because it has " "been less than four hours since the last " "calibration.\n")); } else { /* * At adjustment time we drift correct the hardware clock * according to the contents of the adjtime file and refresh * its last adjusted timestamp. * * At calibration time we set the Hardware Clock and refresh * both timestamps in <*adjtime_p>. * * Here, with the --update-drift option, we also update the * drift factor in <*adjtime_p>. * * Let us do computation in doubles. (Floats almost suffice, * but 195 days + 1 second equals 195 days in floats.) */ const double sec_per_day = 24.0 * 60.0 * 60.0; double factor_adjust; double drift_factor; struct timeval last_calib; last_calib = t2tv(adjtime_p->last_calib_time); /* * Correction to apply to the current drift factor. * * Simplified: uncorrected_drift / days_since_calibration. * * hclocktime is fully corrected with the current drift factor. * Its difference from nowtime is the missed drift correction. */ factor_adjust = time_diff(nowtime, hclocktime) / (time_diff(nowtime, last_calib) / sec_per_day); drift_factor = adjtime_p->drift_factor + factor_adjust; if (fabs(drift_factor) > MAX_DRIFT) { if (ctl->verbose) 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 (ctl->verbose) printf(_("Clock drifted %f seconds in the past " "%f seconds\nin spite of a drift factor of " "%f seconds/day.\n" "Adjusting drift factor by %f seconds/day\n"), time_diff(nowtime, hclocktime), time_diff(nowtime, last_calib), adjtime_p->drift_factor, factor_adjust); } adjtime_p->drift_factor = drift_factor; } adjtime_p->last_calib_time = nowtime.tv_sec; adjtime_p->last_adj_time = nowtime.tv_sec; adjtime_p->not_adjusted = 0; adjtime_p->dirty = 1; } /* * Calculate the drift correction currently needed for the * Hardware Clock based on the last time it was adjusted, * and the current drift factor, as stored in the adjtime file. * * The total drift adjustment needed is stored at tdrift_p. * */ static void calculate_adjustment(const struct hwclock_control *ctl, const double factor, const time_t last_time, const double not_adjusted, const time_t systime, struct timeval *tdrift_p) { double exact_adjustment; exact_adjustment = ((double)(systime - last_time)) * factor / (24 * 60 * 60) + not_adjusted; tdrift_p->tv_sec = (time_t) floor(exact_adjustment); tdrift_p->tv_usec = (exact_adjustment - (double)tdrift_p->tv_sec) * 1E6; if (ctl->verbose) { printf(P_("Time since last adjustment is %ld second\n", "Time since last adjustment is %ld seconds\n", (systime - last_time)), (systime - last_time)); printf(_("Calculated Hardware Clock drift is %ld.%06ld seconds\n"), tdrift_p->tv_sec, tdrift_p->tv_usec); } } /* * Write the contents of the structure to its disk file. * * But if the contents are clean (unchanged since read from disk), don't * bother. */ static int save_adjtime(const struct hwclock_control *ctl, const struct adjtime *adjtime) { char *content; /* Stuff to write to disk file */ FILE *fp; xasprintf(&content, "%f %ld %f\n%ld\n%s\n", adjtime->drift_factor, adjtime->last_adj_time, adjtime->not_adjusted, adjtime->last_calib_time, (adjtime->local_utc == LOCAL) ? "LOCAL" : "UTC"); if (ctl->verbose){ printf(_("New %s data:\n%s"), ctl->adj_file_name, content); } if (!ctl->testing) { fp = fopen(ctl->adj_file_name, "w"); if (fp == NULL) { warn(_("cannot open %s"), ctl->adj_file_name); return EXIT_FAILURE; } else if (fputs(content, fp) < 0 || close_stream(fp) != 0) { warn(_("cannot update %s"), ctl->adj_file_name); return EXIT_FAILURE; } } return EXIT_SUCCESS; } /* * Do the adjustment requested, by 1) setting the Hardware Clock (if * necessary), and 2) updating the last-adjusted time in the adjtime * structure. * * Do not update anything if the Hardware Clock does not currently present a * valid time. * * is the drift corrected time read from the Hardware Clock. * * was the system time when the was read, which due * to computational delay could be a short time ago. It is used to define a * trigger point for setting the Hardware Clock. The fractional part of the * Hardware clock set time is subtracted from read_time to 'refer back', or * delay, the trigger point. Fractional parts must be accounted for in this * way, because the Hardware Clock can only be set to a whole second. * * : the Hardware Clock is kept in UTC. * * : We are running in test mode (no updating of clock). * */ static void do_adjustment(const struct hwclock_control *ctl, struct adjtime *adjtime_p, const struct timeval hclocktime, const struct timeval read_time) { if (adjtime_p->last_adj_time == 0) { if (ctl->verbose) printf(_("Not setting clock because last adjustment time is zero, " "so history is bad.\n")); } else if (fabs(adjtime_p->drift_factor) > MAX_DRIFT) { if (ctl->verbose) printf(_("Not setting clock because drift factor %f is far too high.\n"), adjtime_p->drift_factor); } else { set_hardware_clock_exact(ctl, hclocktime.tv_sec, time_inc(read_time, -(hclocktime.tv_usec / 1E6))); adjtime_p->last_adj_time = hclocktime.tv_sec; adjtime_p->not_adjusted = 0; adjtime_p->dirty = 1; } } static void determine_clock_access_method(const struct hwclock_control *ctl) { ur = NULL; #ifdef USE_HWCLOCK_CMOS if (ctl->directisa) ur = probe_for_cmos_clock(); #endif #ifdef __linux__ if (!ur) ur = probe_for_rtc_clock(ctl); #endif if (ur) { if (ctl->verbose) puts(ur->interface_name); } else { if (ctl->verbose) printf(_("No usable clock interface found.\n")); warnx(_("Cannot access the Hardware Clock via " "any known method.")); if (!ctl->verbose) warnx(_("Use the --verbose option to see the " "details of our search for an access " "method.")); hwclock_exit(ctl, EXIT_FAILURE); } } /* Do all the normal work of hwclock - read, set clock, etc. */ static int manipulate_clock(const struct hwclock_control *ctl, const time_t set_time, const struct timeval startup_time, struct adjtime *adjtime) { /* The time at which we read the Hardware Clock */ struct timeval read_time = { 0 }; /* * The Hardware Clock gives us a valid time, or at * least something close enough to fool mktime(). */ int hclock_valid = 0; /* * Tick synchronized time read from the Hardware Clock and * then drift corrected for all operations except --show. */ struct timeval hclocktime = { 0 }; /* * hclocktime correlated to startup_time. That is, what drift * corrected Hardware Clock time would have been at start up. */ struct timeval startup_hclocktime = { 0 }; /* Total Hardware Clock drift correction needed. */ struct timeval tdrift = { 0 }; if ((ctl->set || ctl->systohc || ctl->adjust) && (adjtime->local_utc == UTC) != ctl->universal) { adjtime->local_utc = ctl->universal ? UTC : LOCAL; adjtime->dirty = 1; } /* * Negate the drift correction, because we want to 'predict' a * Hardware Clock time that includes drift. */ if (ctl->predict) { hclocktime = t2tv(set_time); calculate_adjustment(ctl, adjtime->drift_factor, adjtime->last_adj_time, adjtime->not_adjusted, hclocktime.tv_sec, &tdrift); hclocktime = time_inc(hclocktime, (double) -(tdrift.tv_sec + tdrift.tv_usec / 1E6)); if (ctl->verbose) { printf(_ ("Target date: %ld\n"), set_time); printf(_ ("Predicted RTC: %ld\n"), hclocktime.tv_sec); } return display_time(hclocktime); } if (ctl->systz) return set_system_clock(ctl, startup_time); if (ur->get_permissions()) return EXIT_FAILURE; /* * Read and drift correct RTC time; except for RTC set functions * without the --update-drift option because: 1) it's not needed; * 2) it enables setting a corrupted RTC without reading it first; * 3) it significantly reduces system shutdown time. */ if ( ! ((ctl->set || ctl->systohc) && !ctl->update)) { /* * Timing critical - do not change the order of, or put * anything between the follow three statements. * Synchronization failure MUST exit, because all drift * operations are invalid without it. */ if (synchronize_to_clock_tick(ctl)) return EXIT_FAILURE; read_hardware_clock(ctl, &hclock_valid, &hclocktime.tv_sec); gettimeofday(&read_time, NULL); if (!hclock_valid) { warnx(_("RTC read returned an invalid value.")); return EXIT_FAILURE; } /* * Calculate and apply drift correction to the Hardware Clock * time for everything except --show */ calculate_adjustment(ctl, adjtime->drift_factor, adjtime->last_adj_time, adjtime->not_adjusted, hclocktime.tv_sec, &tdrift); if (!ctl->show) hclocktime = time_inc(tdrift, hclocktime.tv_sec); startup_hclocktime = time_inc(hclocktime, time_diff(startup_time, read_time)); } if (ctl->show || ctl->get) { return display_time(startup_hclocktime); } else if (ctl->set) { set_hardware_clock_exact(ctl, set_time, startup_time); if (!ctl->noadjfile) adjust_drift_factor(ctl, adjtime, t2tv(set_time), startup_hclocktime); } else if (ctl->adjust) { if (tdrift.tv_sec > 0 || tdrift.tv_sec < -1) do_adjustment(ctl, adjtime, hclocktime, read_time); else printf(_("Needed adjustment is less than one second, " "so not setting clock.\n")); } else if (ctl->systohc) { struct timeval nowtime, reftime; /* * We can only set_hardware_clock_exact to a * whole seconds time, so we set it with * reference to the most recent whole * seconds time. */ gettimeofday(&nowtime, NULL); reftime.tv_sec = nowtime.tv_sec; reftime.tv_usec = 0; set_hardware_clock_exact(ctl, (time_t) reftime.tv_sec, reftime); if (!ctl->noadjfile) adjust_drift_factor(ctl, adjtime, nowtime, hclocktime); } else if (ctl->hctosys) { return set_system_clock(ctl, hclocktime); } if (!ctl->noadjfile && adjtime->dirty) return save_adjtime(ctl, adjtime); return EXIT_SUCCESS; } /** * Get or set the kernel RTC driver's epoch on Alpha machines. * ISA machines are hard coded for 1900. */ #if defined(__linux__) && defined(__alpha__) static void manipulate_epoch(const struct hwclock_control *ctl) { if (ctl->getepoch) { unsigned long epoch; if (get_epoch_rtc(ctl, &epoch)) warnx(_("unable to read the RTC epoch.")); else printf(_("The RTC epoch is set to %lu.\n"), epoch); } else if (ctl->setepoch) { if (!ctl->epoch_option) warnx(_("--epoch is required for --setepoch.")); else if (!ctl->testing) if (set_epoch_rtc(ctl)) warnx(_("unable to set the RTC epoch.")); } } #endif /* __linux__ __alpha__ */ static void out_version(void) { printf(UTIL_LINUX_VERSION); } static void __attribute__((__noreturn__)) usage(void) { fputs(USAGE_HEADER, stdout); printf(_(" %s [function] [option...]\n"), program_invocation_short_name); fputs(USAGE_SEPARATOR, stdout); puts(_("Time clocks utility.")); fputs(USAGE_FUNCTIONS, stdout); puts(_(" -r, --show display the RTC time")); puts(_(" --get display drift corrected RTC time")); puts(_(" --set set the RTC according to --date")); puts(_(" -s, --hctosys set the system time from the RTC")); puts(_(" -w, --systohc set the RTC from the system time")); puts(_(" --systz send timescale configurations to the kernel")); puts(_(" -a, --adjust adjust the RTC to account for systematic drift")); #if defined(__linux__) && defined(__alpha__) puts(_(" --getepoch display the RTC epoch")); puts(_(" --setepoch set the RTC epoch according to --epoch")); #endif puts(_(" --predict predict the drifted RTC time according to --date")); fputs(USAGE_OPTIONS, stdout); puts(_(" -u, --utc the RTC timescale is UTC")); puts(_(" -l, --localtime the RTC timescale is Local")); #ifdef __linux__ printf(_( " -f, --rtc use an alternate file to %1$s\n"), _PATH_RTC_DEV); #endif printf(_( " --directisa use the ISA bus instead of %1$s access\n"), _PATH_RTC_DEV); puts(_(" --date