1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (C) 1993-1998 by Andrey A. Chernov, Moscow, Russia.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29/*
30 * Andrey A. Chernov   <ache@astral.msk.su>    Dec 20 1993
31 *
32 * Fix kernel time value if machine run wall CMOS clock
33 * (and /etc/wall_cmos_clock file present)
34 * using zoneinfo rules or direct TZ environment variable set.
35 * Use Joerg Wunsch idea for seconds accurate offset calculation
36 * with Garrett Wollman and Bruce Evans fixes.
37 *
38 */
39#include <stdio.h>
40#include <signal.h>
41#include <stdlib.h>
42#include <unistd.h>
43#include <syslog.h>
44#include <sys/time.h>
45#include <sys/param.h>
46#include <machine/cpu.h>
47#include <sys/sysctl.h>
48
49#include "pathnames.h"
50
51/*#define DEBUG*/
52
53#define True (1)
54#define False (0)
55#define Unknown (-1)
56
57#define REPORT_PERIOD (30*60)
58
59static void fake(int);
60static void usage(void) __dead2;
61
62static void
63fake(int unused __unused)
64{
65
66	/* Do nothing. */
67}
68
69int
70main(int argc, char *argv[])
71{
72	struct tm local;
73	struct timeval tv, *stv;
74	struct timezone tz, *stz;
75	int kern_offset, wall_clock, disrtcset;
76	size_t len;
77	/* Avoid time_t here, can be unsigned long or worse */
78	long offset, localsec, diff;
79	time_t initial_sec, final_sec;
80	int ch;
81	int initial_isdst = -1, final_isdst;
82	int need_restore = False, sleep_mode = False, looping,
83	    init = Unknown;
84	sigset_t mask, emask;
85
86	while ((ch = getopt(argc, argv, "ais")) != -1)
87		switch((char)ch) {
88		case 'i':               /* initial call, save offset */
89			if (init != Unknown)
90				usage();
91			init = True;
92			break;
93		case 'a':               /* adjustment call, use saved offset */
94			if (init != Unknown)
95				usage();
96			init = False;
97			break;
98		case 's':
99			sleep_mode = True;
100			break;
101		default:
102			usage();
103		}
104	if (init == Unknown)
105		usage();
106
107	if (access(_PATH_CLOCK, F_OK) != 0)
108		return 0;
109
110	if (init)
111		sleep_mode = True;
112
113	sigemptyset(&mask);
114	sigemptyset(&emask);
115	sigaddset(&mask, SIGTERM);
116
117	openlog("adjkerntz", LOG_PID|LOG_PERROR, LOG_DAEMON);
118
119	(void) signal(SIGHUP, SIG_IGN);
120
121	if (init && daemon(0,
122#ifdef DEBUG
123	    1
124#else
125	    0
126#endif
127	    )) {
128		syslog(LOG_ERR, "daemon: %m");
129		return 1;
130	}
131
132again:
133	(void) sigprocmask(SIG_BLOCK, &mask, NULL);
134	(void) signal(SIGTERM, fake);
135
136	diff = 0;
137	stv = NULL;
138	stz = NULL;
139	looping = False;
140
141	wall_clock = (access(_PATH_CLOCK, F_OK) == 0);
142	if (init && !sleep_mode) {
143		init = False;
144		if (!wall_clock)
145			return 0;
146	}
147
148	tzset();
149
150	len = sizeof(kern_offset);
151	if (sysctlbyname("machdep.adjkerntz", &kern_offset, &len, NULL, 0) == -1) {
152		syslog(LOG_ERR, "sysctl(\"machdep.adjkerntz\"): %m");
153		return 1;
154	}
155
156/****** Critical section, do all things as fast as possible ******/
157
158	/* get local CMOS clock and possible kernel offset */
159	if (gettimeofday(&tv, &tz)) {
160		syslog(LOG_ERR, "gettimeofday: %m");
161		return 1;
162	}
163
164	/* get the actual local timezone difference */
165	initial_sec = tv.tv_sec;
166
167recalculate:
168	local = *localtime(&initial_sec);
169	if (diff == 0)
170		initial_isdst = local.tm_isdst;
171	local.tm_isdst = initial_isdst;
172
173	/* calculate local CMOS diff from GMT */
174
175	localsec = mktime(&local);
176	if (localsec == -1) {
177		/*
178		 * XXX user can only control local time, and it is
179		 * unacceptable to fail here for init.  2:30 am in the
180		 * middle of the nonexistent hour means 3:30 am.
181		 */
182		if (!sleep_mode) {
183			syslog(LOG_WARNING,
184			"Warning: nonexistent local time, try to run later.");
185			syslog(LOG_WARNING, "Giving up.");
186			return 1;
187		}
188		syslog(LOG_WARNING,
189			"Warning: nonexistent local time.");
190		syslog(LOG_WARNING, "Will retry after %d minutes.",
191			REPORT_PERIOD / 60);
192		(void) signal(SIGTERM, SIG_DFL);
193		(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
194		(void) sleep(REPORT_PERIOD);
195		goto again;
196	}
197	offset = -local.tm_gmtoff;
198#ifdef DEBUG
199	fprintf(stderr, "Initial offset: %ld secs\n", offset);
200#endif
201
202	/* correct the kerneltime for this diffs */
203	/* subtract kernel offset, if present, old offset too */
204
205	diff = offset - tz.tz_minuteswest * 60 - kern_offset;
206
207	if (diff != 0) {
208#ifdef DEBUG
209		fprintf(stderr, "Initial diff: %ld secs\n", diff);
210#endif
211		/* Yet one step for final time */
212
213		final_sec = initial_sec + diff;
214
215		/* get the actual local timezone difference */
216		local = *localtime(&final_sec);
217		final_isdst = diff < 0 ? initial_isdst : local.tm_isdst;
218		if (diff > 0 && initial_isdst != final_isdst) {
219			if (looping)
220				goto bad_final;
221			looping = True;
222			initial_isdst = final_isdst;
223			goto recalculate;
224		}
225		local.tm_isdst =  final_isdst;
226
227		localsec = mktime(&local);
228		if (localsec == -1) {
229		bad_final:
230			/*
231			 * XXX as above.  The user has even less control,
232			 * but perhaps we never get here.
233			 */
234			if (!sleep_mode) {
235				syslog(LOG_WARNING,
236					"Warning: nonexistent final local time, try to run later.");
237				syslog(LOG_WARNING, "Giving up.");
238				return 1;
239			}
240			syslog(LOG_WARNING,
241				"Warning: nonexistent final local time.");
242			syslog(LOG_WARNING, "Will retry after %d minutes.",
243				REPORT_PERIOD / 60);
244			(void) signal(SIGTERM, SIG_DFL);
245			(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
246			(void) sleep(REPORT_PERIOD);
247			goto again;
248		}
249		offset = -local.tm_gmtoff;
250#ifdef DEBUG
251		fprintf(stderr, "Final offset: %ld secs\n", offset);
252#endif
253
254		/* correct the kerneltime for this diffs */
255		/* subtract kernel offset, if present, old offset too */
256
257		diff = offset - tz.tz_minuteswest * 60 - kern_offset;
258
259		if (diff != 0) {
260#ifdef DEBUG
261			fprintf(stderr, "Final diff: %ld secs\n", diff);
262#endif
263			/*
264			 * stv is abused as a flag.  The important value
265			 * is in `diff'.
266			 */
267			stv = &tv;
268		}
269	}
270
271	if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
272		tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
273		stz = &tz;
274	}
275	if (!wall_clock && stz == NULL)
276		stv = NULL;
277
278	/* if init or UTC clock and offset/date will be changed, */
279	/* disable RTC modification for a while.                      */
280
281	if (   (init && stv != NULL)
282	    || ((init || !wall_clock) && kern_offset != offset)
283	   ) {
284		len = sizeof(disrtcset);
285		if (sysctlbyname("machdep.disable_rtc_set", &disrtcset, &len, NULL, 0) == -1) {
286			syslog(LOG_ERR, "sysctl(get: \"machdep.disable_rtc_set\"): %m");
287			return 1;
288		}
289		if (disrtcset == 0) {
290			disrtcset = 1;
291			need_restore = True;
292			if (sysctlbyname("machdep.disable_rtc_set", NULL, NULL, &disrtcset, len) == -1) {
293				syslog(LOG_ERR, "sysctl(set: \"machdep.disable_rtc_set\"): %m");
294				return 1;
295			}
296		}
297	}
298
299	if (   (init && (stv != NULL || stz != NULL))
300	    || (stz != NULL && stv == NULL)
301	   ) {
302		if (stv != NULL) {
303			/*
304			 * Get the time again, as close as possible to
305			 * adjusting it, to minimise drift.
306			 * XXX we'd better not fail between here and
307			 * restoring disrtcset, since we don't clean up
308			 * anything.
309			 */
310			(void)gettimeofday(&tv, NULL);
311			tv.tv_sec += diff;
312			stv = &tv;
313		}
314		if (settimeofday(stv, stz)) {
315			syslog(LOG_ERR, "settimeofday: %m");
316			return 1;
317		}
318	}
319
320	/* setting machdep.adjkerntz have a side effect: resettodr(), which */
321	/* can be disabled by machdep.disable_rtc_set, so if init or UTC clock    */
322	/* -- don't write RTC, else write RTC.                          */
323
324	if (kern_offset != offset) {
325		kern_offset = offset;
326		len = sizeof(kern_offset);
327		if (sysctlbyname("machdep.adjkerntz", NULL, NULL, &kern_offset, len) == -1) {
328			syslog(LOG_ERR, "sysctl(set: \"machdep.adjkerntz\"): %m");
329			return 1;
330		}
331	}
332
333	len = sizeof(wall_clock);
334	if (sysctlbyname("machdep.wall_cmos_clock",  NULL, NULL, &wall_clock, len) == -1) {
335		syslog(LOG_ERR, "sysctl(set: \"machdep.wall_cmos_clock\"): %m");
336		return 1;
337	}
338
339	if (need_restore) {
340		need_restore = False;
341		disrtcset = 0;
342		len = sizeof(disrtcset);
343		if (sysctlbyname("machdep.disable_rtc_set", NULL, NULL, &disrtcset, len) == -1) {
344			syslog(LOG_ERR, "sysctl(set: \"machdep.disable_rtc_set\"): %m");
345			return 1;
346		}
347	}
348
349/****** End of critical section ******/
350
351	if (init && wall_clock) {
352		sleep_mode = False;
353		/* wait for signals and acts like -a */
354		(void) sigsuspend(&emask);
355		goto again;
356	}
357
358	return 0;
359}
360
361static void
362usage(void)
363{
364	fprintf(stderr, "%s\n%s\n%s\n%s\n",
365		"usage: adjkerntz -i",
366		"\t\t(initial call from /etc/rc)",
367		"       adjkerntz -a [-s]",
368		"\t\t(adjustment call, -s for sleep/retry mode)");
369	exit(2);
370}
371