Adding upstream version 2.39.3.upstream/2.39.3

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1693 insertions, 0 deletions

diff --git a/sys-utils/hwclock.c b/sys-utils/hwclock.c
new file mode 100644
index 0000000..2a18443
--- /dev/null
+++ b/sys-utils/hwclock.c
@@ -0,0 +1,1693 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * Since 7a3000f7ba548cf7d74ac77cc63fe8de228a669e (v2.30) hwclock is linked
+ * with parse_date.y from gnullib. This gnulib code is distributed with GPLv3.
+ * Use --disable-hwclock-gplv3 to exclude this code.
+ *
+ *
+ * clock.c was written by Charles Hedrick, hedrick@cs.rutgers.edu, Apr 1992
+ * Modified for clock adjustments - Rob Hooft <hooft@chem.ruu.nl>, Nov 1992
+ * Improvements by Harald Koenig <koenig@nova.tat.physik.uni-tuebingen.de>
+ * and Alan Modra <alan@spri.levels.unisa.edu.au>.
+ *
+ * Major rewrite by Bryan Henderson <bryanh@giraffe-data.com>, 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 <davidm@azstarnet.com>
+ * and Jay Estabrook <jestabro@amt.tay1.dec.com>
+ * and Martin Ostermann <ost@comnets.rwth-aachen.de>, aeb@cwi.nl, 990212.
+ *
+ * Fix for Award 2094 bug, Dave Coffin (dcoffin@shore.net) 11/12/98
+ * Change of local time handling, Stefan Ring <e9725446@stud3.tuwien.ac.at>
+ * Change of adjtime handling, James P. Rutledge <ao112@rgfn.epcc.edu>.
+ *
+ *
+ */
+/*
+ * 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 <errno.h>
+#include <getopt.h>
+#include <limits.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#ifdef HAVE_SYS_SYSCALL_H
+#include <sys/syscall.h>
+#endif
+#include <time.h>
+#include <unistd.h>
+#include <inttypes.h>
+
+#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 <libaudit.h>
+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 const 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 <dirty>, 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 <increment> seconds after the
+ * time <addend>. Of course, <increment> may be negative.
+ */
+static struct timeval time_inc(struct timeval addend, double increment)
+{
+	struct timeval newtime;
+
+	newtime.tv_sec = addend.tv_sec + (time_t)increment;
+	newtime.tv_usec = addend.tv_usec + (increment - (time_t)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 */
+	int64_t last_adj_time;
+	int64_t last_calib_time;
+
+	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);
+
+	if (sscanf(line1, "%lf %"SCNd64" %lf",
+			&adjtime_p->drift_factor,
+			&last_adj_time,
+			&adjtime_p->not_adjusted) != 3)
+		warnx(_("Warning: unrecognized line in adjtime file: %s"), line1);
+
+	if (sscanf(line2, "%"SCNd64, &last_calib_time) != 1)
+		warnx(_("Warning: unrecognized line in adjtime file: %s"), line2);
+
+	adjtime_p->last_adj_time = (time_t)last_adj_time;
+	adjtime_p->last_calib_time = (time_t)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 %"PRId64" seconds after 1969\n"),
+		       (int64_t)adjtime_p->last_adj_time);
+		printf(_("Last calibration done at %"PRId64" seconds after 1969\n"),
+		       (int64_t)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 <tm>. 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 = "
+				 "%"PRId64" seconds since 1969\n"), tm.tm_year + 1900,
+			       tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min,
+			       tm.tm_sec, (int64_t)*systime_p);
+	}
+	return valid;
+}
+
+/*
+ * Read the hardware clock and return the current time via <tm> argument.
+ *
+ * Use the method indicated by <method> 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 = { 0 };
+	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 <newtime>, in local time zone or UTC,
+ * according to <universal>.
+ */
+static void
+set_hardware_clock(const struct hwclock_control *ctl, const time_t newtime)
+{
+	struct tm new_broken_time = { 0 };
+	/*
+	 * 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 "
+			 "= %"PRId64" seconds since 1969\n"),
+		       new_broken_time.tm_hour, new_broken_time.tm_min,
+		       new_broken_time.tm_sec, (int64_t)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 %"PRId64".%06"PRId64" - retargeting\n"),
+				       ticksize, (int64_t)nowsystime.tv_sec,
+				       (int64_t)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("%"PRId64".%06"PRId64" < %"PRId64".%06"PRId64" (%.6f)",
+				     (int64_t)nowsystime.tv_sec, (int64_t)nowsystime.tv_usec,
+				     (int64_t)targetsystime.tv_sec,
+				     (int64_t)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 - %"PRId64".%06"PRId64" is too far "
+					 "past %"PRId64".%06"PRId64" (%.6f > %.6f)\n"),
+				       (int64_t)nowsystime.tv_sec,
+				       (int64_t)nowsystime.tv_usec,
+				       (int64_t)targetsystime.tv_sec,
+				       (int64_t)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
+		    + ceil(time_diff(nowsystime, refsystime)
+			    - delay /* don't count this */);
+	if (ctl->verbose)
+		printf(_("%"PRId64".%06"PRId64" is close enough to %"PRId64".%06"PRId64" (%.6f < %.6f)\n"
+			 "Set RTC to %"PRId64" (%"PRId64" + %d; refsystime = %"PRId64".%06"PRId64")\n"),
+		       (int64_t)nowsystime.tv_sec, (int64_t)nowsystime.tv_usec,
+		       (int64_t)targetsystime.tv_sec, (int64_t)targetsystime.tv_usec,
+		       deltavstarget, target_time_tolerance_secs,
+		       (int64_t)newhwtime, (int64_t)sethwtime,
+		       (int)((int64_t)newhwtime - (int64_t)sethwtime),
+		       (int64_t)refsystime.tv_sec, (int64_t)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  | TZ  | PCIL |           | warp_clock |
+ * |   tv    |   tz    | set  | warped | set | set  | firsttime |   locked   |
+ * |---------|---------|---------------|-----|------|-----------|------------|
+ * | pointer | NULL    |  yes |   no   | no  |  no  |     1     |    no      |
+ * | NULL    | ptr2utc |  no  |   no   | yes |  no  |     0     |    yes     |
+ * | NULL    | pointer |  no  |   yes  | 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* & kernel tz   2nd) sets system time |
+ * | hctosys |   UTC     | 1st) locks warp* 2nd) sets tz 3rd) sets system time |
+ * +---------------------------------------------------------------------------+
+ *                         * only on first call after boot
+ *
+ * POSIX 2008 marked TZ in settimeofday() as deprecated. Unfortunately,
+ * different C libraries react to this deprecation in a different way. Since
+ * glibc v2.31 settimeofday() will fail if both args are not NULL, Musl-C
+ * ignores TZ at all, etc. We use __set_time() and __set_timezone() to hide
+ * these portability issues and to keep code readable.
+ */
+#define __set_time(_tv)		settimeofday(_tv, NULL)
+
+#ifndef SYS_settimeofday
+# ifdef __NR_settimeofday
+#  define SYS_settimeofday	__NR_settimeofday
+# elif defined(__NR_settimeofday_time32)
+#  define SYS_settimeofday	__NR_settimeofday_time32
+# endif
+#endif
+
+static inline int __set_timezone(const struct timezone *tz)
+{
+#ifdef SYS_settimeofday
+	errno = 0;
+	return syscall(SYS_settimeofday, NULL, tz);
+#else
+	return settimeofday(NULL, tz);
+#endif
+}
+
+static int
+set_system_clock(const struct hwclock_control *ctl,
+		 const struct timeval newtime)
+{
+	struct tm broken = { 0 };
+	int minuteswest;
+	int rc = 0;
+
+	localtime_r(&newtime.tv_sec, &broken);
+	minuteswest = -get_gmtoff(&broken) / 60;
+
+	if (ctl->verbose) {
+		if (ctl->universal) {
+			puts(_("Calling settimeofday(NULL, 0) "
+			       "to lock the warp_clock function."));
+			if (!( ctl->universal && !minuteswest ))
+				printf(_("Calling settimeofday(NULL, %d) "
+					 "to set the kernel timezone.\n"),
+				       minuteswest);
+		} else
+			printf(_("Calling settimeofday(NULL, %d) to warp "
+				 "System time, set PCIL and the kernel tz.\n"),
+			       minuteswest);
+
+		if (ctl->hctosys)
+			printf(_("Calling settimeofday(%"PRId64".%06"PRId64", NULL) "
+				 "to set the System time.\n"),
+			       (int64_t)newtime.tv_sec, (int64_t)newtime.tv_usec);
+	}
+
+	if (!ctl->testing) {
+		const struct timezone tz_utc = { 0 };
+		const struct timezone tz = { minuteswest };
+
+		/* If UTC RTC: lock warp_clock and PCIL */
+		if (ctl->universal)
+			rc = __set_timezone(&tz_utc);
+
+		/* Set kernel tz; if localtime RTC: warp_clock and set PCIL */
+		if (!rc && !( ctl->universal && !minuteswest ))
+			rc = __set_timezone(&tz);
+
+		/* Set the System Clock */
+		if ((!rc || errno == ENOSYS) && ctl->hctosys)
+			rc = __set_time(&newtime);
+
+		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 <nowtime> and before that was
+ * set to the <hclocktime> 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 %"PRId64" second\n",
+			"Time since last adjustment is %"PRId64" seconds\n",
+		       ((int64_t)systime - (int64_t)last_time)),
+		       ((int64_t)systime - (int64_t)last_time));
+		printf(_("Calculated Hardware Clock drift is %"PRId64".%06"PRId64" seconds\n"),
+		       (int64_t)tdrift_p->tv_sec, (int64_t)tdrift_p->tv_usec);
+	}
+}
+
+/*
+ * Write the contents of the <adjtime> 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 %"PRId64" %f\n%"PRId64"\n%s\n",
+		  adjtime->drift_factor,
+		  (int64_t)adjtime->last_adj_time,
+		  adjtime->not_adjusted,
+		  (int64_t)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) {
+		int rc;
+
+		fp = fopen(ctl->adj_file_name, "w");
+		if (fp == NULL) {
+			warn(_("cannot open %s"), ctl->adj_file_name);
+			return EXIT_FAILURE;
+		}
+
+		rc = fputs(content, fp) < 0;
+		rc += close_stream(fp);
+
+		if (rc) {
+			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.
+ *
+ * <hclocktime> is the drift corrected time read from the Hardware Clock.
+ *
+ * <read_time> was the system time when the <hclocktime> 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.
+ *
+ * <universal>: the Hardware Clock is kept in UTC.
+ *
+ * <testing>:  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:   %"PRId64"\n"), (int64_t)set_time);
+			printf(_("Predicted RTC: %"PRId64"\n"), (int64_t)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);
+	}
+
+	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__ */
+
+#ifdef __linux__
+static int
+manipulate_rtc_param(const struct hwclock_control *ctl)
+{
+	if (ctl->param_get_option) {
+		uint64_t id = 0, value = 0;
+
+		if (get_param_rtc(ctl, ctl->param_get_option, &id, &value)) {
+			warnx(_("unable to read the RTC parameter %s"),
+					ctl->param_get_option);
+			return 1;
+		}
+
+		printf(_("The RTC parameter 0x%jx is set to 0x%jx.\n"),
+		       (uintmax_t) id, (uintmax_t) value);
+		return 0;
+
+	} else if (ctl->param_set_option) {
+		if (ctl->testing)
+			return 0;
+
+		return set_param_rtc(ctl, ctl->param_set_option);
+	}
+
+	return 1;
+}
+#endif
+
+static void out_version(void)
+{
+	printf(UTIL_LINUX_VERSION);
+}
+
+static void __attribute__((__noreturn__))
+usage(void)
+{
+#ifdef __linux__
+	const struct hwclock_param *param = get_hwclock_params();
+#endif
+
+	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
+#ifdef __linux__
+	puts(_("     --param-get <param>         display the RTC parameter"));
+	puts(_("     --param-set <param>=<value> set the RTC parameter"));
+#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 <file>                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 <time>               date/time input for --set and --predict"));
+	puts(_("     --delay <sec>               delay used when set new RTC time"));
+#if defined(__linux__) && defined(__alpha__)
+	puts(_("     --epoch <year>              epoch input for --setepoch"));
+#endif
+	puts(_("     --update-drift              update the RTC drift factor"));
+	printf(_(
+	       "     --noadjfile                 do not use %1$s\n"), _PATH_ADJTIME);
+	printf(_(
+	       "     --adjfile <file>            use an alternate file to %1$s\n"), _PATH_ADJTIME);
+	puts(_("     --test                      dry run; implies --verbose"));
+	puts(_(" -v, --verbose                   display more details"));
+
+	fputs(USAGE_SEPARATOR, stdout);
+	printf(USAGE_HELP_OPTIONS(33));
+
+#ifdef __linux__
+	fputs(USAGE_ARGUMENTS, stdout);
+	puts(_(" <param> is either a numeric RTC parameter value or one of these aliases:"));
+
+	while (param->name) {
+		printf(_("   - %1$s: %2$s (0x%3$x)\n"), param->name, param->help, param->id);
+		param++;
+	}
+
+	puts(_("   See Kernel's include/uapi/linux/rtc.h for parameters and values."));
+	fputs(USAGE_ARG_SEPARATOR, stdout);
+	puts(_(" <param> and <value> accept hexadecimal values if prefixed with 0x, otherwise decimal."));
+#endif
+	printf(USAGE_MAN_TAIL("hwclock(8)"));
+	exit(EXIT_SUCCESS);
+}
+
+int main(int argc, char **argv)
+{
+	struct hwclock_control ctl = {
+			.show = 1,		/* default op is show */
+			.rtc_delay = -1.0	/* unspecified */
+	};
+	struct timeval startup_time;
+	struct adjtime adjtime = { 0 };
+	/*
+	 * The time we started up, in seconds into the epoch, including
+	 * fractions.
+	 */
+	time_t set_time = 0;	/* Time to which user said to set Hardware Clock */
+	int rc, c;
+
+	/* Long only options. */
+	enum {
+		OPT_ADJFILE = CHAR_MAX + 1,
+		OPT_DATE,
+		OPT_DELAY,
+		OPT_DIRECTISA,
+		OPT_EPOCH,
+		OPT_GET,
+		OPT_GETEPOCH,
+		OPT_NOADJFILE,
+		OPT_PARAM_GET,
+		OPT_PARAM_SET,
+		OPT_PREDICT,
+		OPT_SET,
+		OPT_SETEPOCH,
+		OPT_SYSTZ,
+		OPT_TEST,
+		OPT_UPDATE
+	};
+
+	static const struct option longopts[] = {
+		{ "adjust",       no_argument,       NULL, 'a'            },
+		{ "help",         no_argument,       NULL, 'h'            },
+		{ "localtime",    no_argument,       NULL, 'l'            },
+		{ "show",         no_argument,       NULL, 'r'            },
+		{ "hctosys",      no_argument,       NULL, 's'            },
+		{ "utc",          no_argument,       NULL, 'u'            },
+		{ "version",      no_argument,       NULL, 'V'            },
+		{ "systohc",      no_argument,       NULL, 'w'            },
+		{ "debug",        no_argument,       NULL, 'D'            },
+		{ "ul-debug",     required_argument, NULL, 'd'            },
+		{ "verbose",      no_argument,       NULL, 'v'            },
+		{ "set",          no_argument,       NULL, OPT_SET        },
+#if defined(__linux__) && defined(__alpha__)
+		{ "getepoch",     no_argument,       NULL, OPT_GETEPOCH   },
+		{ "setepoch",     no_argument,       NULL, OPT_SETEPOCH   },
+		{ "epoch",        required_argument, NULL, OPT_EPOCH      },
+#endif
+#ifdef __linux__
+		{ "param-get",    required_argument, NULL, OPT_PARAM_GET  },
+		{ "param-set",    required_argument, NULL, OPT_PARAM_SET  },
+#endif
+		{ "noadjfile",    no_argument,       NULL, OPT_NOADJFILE  },
+		{ "directisa",    no_argument,       NULL, OPT_DIRECTISA  },
+		{ "test",         no_argument,       NULL, OPT_TEST       },
+		{ "date",         required_argument, NULL, OPT_DATE       },
+		{ "delay",        required_argument, NULL, OPT_DELAY      },
+#ifdef __linux__
+		{ "rtc",          required_argument, NULL, 'f'            },
+#endif
+		{ "adjfile",      required_argument, NULL, OPT_ADJFILE    },
+		{ "systz",        no_argument,       NULL, OPT_SYSTZ      },
+		{ "predict",      no_argument,       NULL, OPT_PREDICT    },
+		{ "get",          no_argument,       NULL, OPT_GET        },
+		{ "update-drift", no_argument,       NULL, OPT_UPDATE     },
+		{ NULL, 0, NULL, 0 }
+	};
+
+	static const ul_excl_t excl[] = {	/* rows and cols in ASCII order */
+		{ 'a','r','s','w',
+		  OPT_GET, OPT_GETEPOCH, OPT_PREDICT,
+		  OPT_SET, OPT_SETEPOCH, OPT_SYSTZ },
+		{ 'l', 'u' },
+		{ OPT_ADJFILE, OPT_NOADJFILE },
+		{ OPT_NOADJFILE, OPT_UPDATE },
+		{ 0 }
+	};
+	int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT;
+
+	/* Remember what time we were invoked */
+	gettimeofday(&startup_time, NULL);
+
+#ifdef HAVE_LIBAUDIT
+	hwaudit_fd = audit_open();
+	if (hwaudit_fd < 0 && !(errno == EINVAL || errno == EPROTONOSUPPORT ||
+				errno == EAFNOSUPPORT)) {
+		/*
+		 * You get these error codes only when the kernel doesn't
+		 * have audit compiled in.
+		 */
+		warnx(_("Unable to connect to audit system"));
+		return EXIT_FAILURE;
+	}
+#endif
+	setlocale(LC_ALL, "");
+#ifdef LC_NUMERIC
+	/*
+	 * We need LC_CTYPE and LC_TIME and LC_MESSAGES, but must avoid
+	 * LC_NUMERIC since it gives problems when we write to /etc/adjtime.
+	 *  - gqueri@mail.dotcom.fr
+	 */
+	setlocale(LC_NUMERIC, "C");
+#endif
+	bindtextdomain(PACKAGE, LOCALEDIR);
+	textdomain(PACKAGE);
+	close_stdout_atexit();
+
+	while ((c = getopt_long(argc, argv,
+				"hvVDd:alrsuwf:", longopts, NULL)) != -1) {
+
+		err_exclusive_options(c, longopts, excl, excl_st);
+
+		switch (c) {
+		case 'D':
+			warnx(_("use --verbose, --debug has been deprecated."));
+			break;
+		case 'v':
+			ctl.verbose = 1;
+			break;
+		case 'd':
+			hwclock_init_debug(optarg);
+			break;
+		case 'a':
+			ctl.adjust = 1;
+			ctl.show = 0;
+			ctl.hwaudit_on = 1;
+			break;
+		case 'l':
+			ctl.local_opt = 1;	/* --localtime */
+			break;
+		case 'r':
+			ctl.show = 1;
+			break;
+		case 's':
+			ctl.hctosys = 1;
+			ctl.show = 0;
+			ctl.hwaudit_on = 1;
+			break;
+		case 'u':
+			ctl.utc = 1;
+			break;
+		case 'w':
+			ctl.systohc = 1;
+			ctl.show = 0;
+			ctl.hwaudit_on = 1;
+			break;
+		case OPT_SET:
+			ctl.set = 1;
+			ctl.show = 0;
+			ctl.hwaudit_on = 1;
+			break;
+#if defined(__linux__) && defined(__alpha__)
+		case OPT_GETEPOCH:
+			ctl.getepoch = 1;
+			ctl.show = 0;
+			break;
+		case OPT_SETEPOCH:
+			ctl.setepoch = 1;
+			ctl.show = 0;
+			ctl.hwaudit_on = 1;
+			break;
+		case OPT_EPOCH:
+			ctl.epoch_option = optarg;	/* --epoch */
+			break;
+#endif
+#ifdef __linux__
+		case OPT_PARAM_GET:
+			ctl.param_get_option = optarg;
+			ctl.show = 0;
+			break;
+		case OPT_PARAM_SET:
+			ctl.param_set_option = optarg;
+			ctl.show = 0;
+			ctl.hwaudit_on = 1;
+			break;
+#endif
+		case OPT_NOADJFILE:
+			ctl.noadjfile = 1;
+			break;
+		case OPT_DIRECTISA:
+			ctl.directisa = 1;
+			break;
+		case OPT_TEST:
+			ctl.testing = 1;	/* --test */
+			ctl.verbose = 1;
+			break;
+		case OPT_DATE:
+			ctl.date_opt = optarg;	/* --date */
+			break;
+		case OPT_DELAY:
+			ctl.rtc_delay = strtod_or_err(optarg, "invalid --delay argument");
+			break;
+		case OPT_ADJFILE:
+			ctl.adj_file_name = optarg;	/* --adjfile */
+			break;
+		case OPT_SYSTZ:
+			ctl.systz = 1;		/* --systz */
+			ctl.show = 0;
+			ctl.hwaudit_on = 1;
+			break;
+		case OPT_PREDICT:
+			ctl.predict = 1;	/* --predict */
+			ctl.show = 0;
+			break;
+		case OPT_GET:
+			ctl.get = 1;		/* --get */
+			ctl.show = 0;
+			break;
+		case OPT_UPDATE:
+			ctl.update = 1;		/* --update-drift */
+			break;
+#ifdef __linux__
+		case 'f':
+			ctl.rtc_dev_name = optarg;	/* --rtc */
+			break;
+#endif
+
+		case 'V':			/* --version */
+			print_version(EXIT_SUCCESS);
+		case 'h':			/* --help */
+			usage();
+		default:
+			errtryhelp(EXIT_FAILURE);
+		}
+	}
+
+	if (argc -= optind) {
+		warnx(_("%d too many arguments given"), argc);
+		errtryhelp(EXIT_FAILURE);
+	}
+
+	if (!ctl.adj_file_name)
+		ctl.adj_file_name = _PATH_ADJTIME;
+
+	if (ctl.update && !ctl.set && !ctl.systohc) {
+		warnx(_("--update-drift requires --set or --systohc"));
+		exit(EXIT_FAILURE);
+	}
+
+	if (ctl.noadjfile && !ctl.utc && !ctl.local_opt) {
+		warnx(_("With --noadjfile, you must specify "
+			"either --utc or --localtime"));
+		exit(EXIT_FAILURE);
+	}
+
+	if (ctl.set || ctl.predict) {
+		if (!ctl.date_opt) {
+			warnx(_("--date is required for --set or --predict"));
+			exit(EXIT_FAILURE);
+		}
+#ifdef USE_HWCLOCK_GPLv3_DATETIME
+		/* date(1) compatible GPLv3 parser */
+		struct timespec when = { 0 };
+
+		if (parse_date(&when, ctl.date_opt, NULL))
+			set_time = when.tv_sec;
+#else
+		/* minimalistic GPLv2 based parser */
+		usec_t usec;
+
+		if (parse_timestamp(ctl.date_opt, &usec) == 0)
+			set_time = (time_t) (usec / 1000000);
+#endif
+		else {
+			warnx(_("invalid date '%s'"), ctl.date_opt);
+			exit(EXIT_FAILURE);
+		}
+	}
+
+#ifdef __linux__
+	if (ctl.param_get_option || ctl.param_set_option) {
+		if (manipulate_rtc_param(&ctl))
+			hwclock_exit(&ctl, EXIT_FAILURE);
+
+		hwclock_exit(&ctl, EXIT_SUCCESS);
+	}
+#endif
+
+#if defined(__linux__) && defined(__alpha__)
+	if (ctl.getepoch || ctl.setepoch) {
+		manipulate_epoch(&ctl);
+		hwclock_exit(&ctl, EXIT_SUCCESS);
+	}
+#endif
+
+	if (ctl.verbose) {
+		out_version();
+		printf(_("System Time: %"PRId64".%06"PRId64"\n"),
+		       (int64_t)startup_time.tv_sec, (int64_t)startup_time.tv_usec);
+	}
+
+	if (!ctl.systz && !ctl.predict)
+		determine_clock_access_method(&ctl);
+
+	if (!ctl.noadjfile && !(ctl.systz && (ctl.utc || ctl.local_opt))) {
+		if ((rc = read_adjtime(&ctl, &adjtime)) != 0)
+			hwclock_exit(&ctl, rc);
+	} else
+		/* Avoid writing adjtime file if we don't have to. */
+		adjtime.dirty = 0;
+
+	ctl.universal = hw_clock_is_utc(&ctl, &adjtime);
+	rc = manipulate_clock(&ctl, set_time, startup_time, &adjtime);
+	if (ctl.testing)
+		puts(_("Test mode: nothing was changed."));
+	hwclock_exit(&ctl, rc);
+	return rc;		/* Not reached */
+}
+
+void
+hwclock_exit(const struct hwclock_control *ctl
+#ifndef HAVE_LIBAUDIT
+	     __attribute__((__unused__))
+#endif
+	     , int status)
+{
+#ifdef HAVE_LIBAUDIT
+	if (ctl->hwaudit_on && !ctl->testing) {
+		audit_log_user_message(hwaudit_fd, AUDIT_USYS_CONFIG,
+				       "op=change-system-time", NULL, NULL, NULL,
+				       status == EXIT_SUCCESS ? 1  : 0);
+	}
+	close(hwaudit_fd);
+#endif
+	exit(status);
+}
+
+/*
+ * History of this program:
+ *
+ * 98.08.12 BJH Version 2.4
+ *
+ * Don't use century byte from Hardware Clock. Add comments telling why.
+ *
+ * 98.06.20 BJH Version 2.3.
+ *
+ * Make --hctosys set the kernel timezone from TZ environment variable
+ * and/or /usr/lib/zoneinfo. From Klaus Ripke (klaus@ripke.com).
+ *
+ * 98.03.05 BJH. Version 2.2.
+ *
+ * Add --getepoch and --setepoch.
+ *
+ * Fix some word length things so it works on Alpha.
+ *
+ * Make it work when /dev/rtc doesn't have the interrupt functions. In this
+ * case, busywait for the top of a second instead of blocking and waiting
+ * for the update complete interrupt.
+ *
+ * Fix a bunch of bugs too numerous to mention.
+ *
+ * 97.06.01: BJH. Version 2.1. Read and write the century byte (Byte 50) of
+ * the ISA Hardware Clock when using direct ISA I/O. Problem discovered by
+ * job (jei@iclnl.icl.nl).
+ *
+ * Use the rtc clock access method in preference to the KDGHWCLK method.
+ * Problem discovered by Andreas Schwab <schwab@LS5.informatik.uni-dortmund.de>.
+ *
+ * November 1996: Version 2.0.1. Modifications by Nicolai Langfeldt
+ * (janl@math.uio.no) to make it compile on linux 1.2 machines as well as
+ * more recent versions of the kernel. Introduced the NO_CLOCK access method
+ * and wrote feature test code to detect absence of rtc headers.
+ *
+ ***************************************************************************
+ * Maintenance notes
+ *
+ * To compile this, you must use GNU compiler optimization (-O option) in
+ * order to make the "extern inline" functions from asm/io.h (inb(), etc.)
+ * compile. If you don't optimize, which means the compiler will generate no
+ * inline functions, the references to these functions in this program will
+ * be compiled as external references. Since you probably won't be linking
+ * with any functions by these names, you will have unresolved external
+ * references when you link.
+ *
+ * Here's some info on how we must deal with the time that elapses while
+ * this program runs: There are two major delays as we run:
+ *
+ *	1) Waiting up to 1 second for a transition of the Hardware Clock so
+ *	   we are synchronized to the Hardware Clock.
+ *	2) Running the "date" program to interpret the value of our --date
+ *	   option.
+ *
+ * Reading the /etc/adjtime file is the next biggest source of delay and
+ * uncertainty.
+ *
+ * The user wants to know what time it was at the moment they invoked us, not
+ * some arbitrary time later. And in setting the clock, they are giving us the
+ * time at the moment we are invoked, so if we set the clock some time
+ * later, we have to add some time to that.
+ *
+ * So we check the system time as soon as we start up, then run "date" and
+ * do file I/O if necessary, then wait to synchronize with a Hardware Clock
+ * edge, then check the system time again to see how much time we spent. We
+ * immediately read the clock then and (if appropriate) report that time,
+ * and additionally, the delay we measured.
+ *
+ * If we're setting the clock to a time given by the user, we wait some more
+ * so that the total delay is an integral number of seconds, then set the
+ * Hardware Clock to the time the user requested plus that integral number
+ * of seconds. N.B. The Hardware Clock can only be set in integral seconds.
+ *
+ * If we're setting the clock to the system clock value, we wait for the
+ * system clock to reach the top of a second, and then set the Hardware
+ * Clock to the system clock's value.
+ *
+ * Here's an interesting point about setting the Hardware Clock:  On my
+ * machine, when you set it, it sets to that precise time. But one can
+ * imagine another clock whose update oscillator marches on a steady one
+ * second period, so updating the clock between any two oscillator ticks is
+ * the same as updating it right at the earlier tick. To avoid any
+ * complications that might cause, we set the clock as soon as possible
+ * after an oscillator tick.
+ *
+ * About synchronizing to the Hardware Clock when reading the time: The
+ * precision of the Hardware Clock counters themselves is one second. You
+ * can't read the counters and find out that is 12:01:02.5. But if you
+ * consider the location in time of the counter's ticks as part of its
+ * value, then its precision is as infinite as time is continuous! What I'm
+ * saying is this: To find out the _exact_ time in the hardware clock, we
+ * wait until the next clock tick (the next time the second counter changes)
+ * and measure how long we had to wait. We then read the value of the clock
+ * counters and subtract the wait time and we know precisely what time it
+ * was when we set out to query the time.
+ *
+ * hwclock uses this method, and considers the Hardware Clock to have
+ * infinite precision.
+ */