adjkerntz.c revision 158516 
1/*
2 * Copyright (C) 1993-1998 by Andrey A. Chernov, Moscow, Russia.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#if 0
28#ifndef lint
29static const char copyright[] =
30"@(#)Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia.\n\
31 All rights reserved.\n";
32#endif /* not lint */
33#endif
34#include <sys/cdefs.h>
35__FBSDID("$FreeBSD: head/sbin/adjkerntz/adjkerntz.c 158516 2006-05-13 11:58:58Z pjd $");
36
37/*
38 * Andrey A. Chernov   <ache@astral.msk.su>    Dec 20 1993
39 *
40 * Fix kernel time value if machine run wall CMOS clock
41 * (and /etc/wall_cmos_clock file present)
42 * using zoneinfo rules or direct TZ environment variable set.
43 * Use Joerg Wunsch idea for seconds accurate offset calculation
44 * with Garrett Wollman and Bruce Evans fixes.
45 *
46 */
47#include <stdio.h>
48#include <signal.h>
49#include <stdlib.h>
50#include <unistd.h>
51#include <syslog.h>
52#include <sys/time.h>
53#include <sys/param.h>
54#include <machine/cpu.h>
55#include <sys/sysctl.h>
56
57#include "pathnames.h"
58
59/*#define DEBUG*/
60
61#define True (1)
62#define False (0)
63#define Unknown (-1)
64
65#define REPORT_PERIOD (30*60)
66
67static void fake(int);
68static void usage(void);
69
70static void
71fake(int unused __unused)
72{
73
74	/* Do nothing. */
75}
76
77int
78main(int argc, char *argv[])
79{
80	struct tm local;
81	struct timeval tv, *stv;
82	struct timezone tz, *stz;
83	int kern_offset, wall_clock, disrtcset;
84	size_t len;
85	/* Avoid time_t here, can be unsigned long or worse */
86	long offset, localsec, diff;
87	time_t initial_sec, final_sec;
88	int ch;
89	int initial_isdst = -1, final_isdst;
90	int need_restore = False, sleep_mode = False, looping,
91	    init = Unknown;
92	sigset_t mask, emask;
93
94	while ((ch = getopt(argc, argv, "ais")) != -1)
95		switch((char)ch) {
96		case 'i':               /* initial call, save offset */
97			if (init != Unknown)
98				usage();
99			init = True;
100			break;
101		case 'a':               /* adjustment call, use saved offset */
102			if (init != Unknown)
103				usage();
104			init = False;
105			break;
106		case 's':
107			sleep_mode = True;
108			break;
109		default:
110			usage();
111		}
112	if (init == Unknown)
113		usage();
114
115	if (access(_PATH_CLOCK, F_OK) != 0)
116		return 0;
117
118	if (init)
119		sleep_mode = True;
120
121	sigemptyset(&mask);
122	sigemptyset(&emask);
123	sigaddset(&mask, SIGTERM);
124
125	openlog("adjkerntz", LOG_PID|LOG_PERROR, LOG_DAEMON);
126
127	(void) signal(SIGHUP, SIG_IGN);
128
129	if (init && daemon(0, 1)) {
130		syslog(LOG_ERR, "daemon: %m");
131		return 1;
132	}
133
134again:
135	(void) sigprocmask(SIG_BLOCK, &mask, NULL);
136	(void) signal(SIGTERM, fake);
137
138	diff = 0;
139	stv = NULL;
140	stz = NULL;
141	looping = False;
142
143	wall_clock = (access(_PATH_CLOCK, F_OK) == 0);
144	if (init && !sleep_mode) {
145		init = False;
146		if (!wall_clock)
147			return 0;
148	}
149
150	tzset();
151
152	len = sizeof(kern_offset);
153	if (sysctlbyname("machdep.adjkerntz", &kern_offset, &len, NULL, 0) == -1) {
154		syslog(LOG_ERR, "sysctl(\"machdep.adjkerntz\"): %m");
155		return 1;
156	}
157
158/****** Critical section, do all things as fast as possible ******/
159
160	/* get local CMOS clock and possible kernel offset */
161	if (gettimeofday(&tv, &tz)) {
162		syslog(LOG_ERR, "gettimeofday: %m");
163		return 1;
164	}
165
166	/* get the actual local timezone difference */
167	initial_sec = tv.tv_sec;
168
169recalculate:
170	local = *localtime(&initial_sec);
171	if (diff == 0)
172		initial_isdst = local.tm_isdst;
173	local.tm_isdst = initial_isdst;
174
175	/* calculate local CMOS diff from GMT */
176
177	localsec = mktime(&local);
178	if (localsec == -1) {
179		/*
180		 * XXX user can only control local time, and it is
181		 * unacceptable to fail here for init.  2:30 am in the
182		 * middle of the nonexistent hour means 3:30 am.
183		 */
184		if (!sleep_mode) {
185			syslog(LOG_WARNING,
186			"Warning: nonexistent local time, try to run later.");
187			syslog(LOG_WARNING, "Giving up.");
188			return 1;
189		}
190		syslog(LOG_WARNING,
191			"Warning: nonexistent local time.");
192		syslog(LOG_WARNING, "Will retry after %d minutes.",
193			REPORT_PERIOD / 60);
194		(void) signal(SIGTERM, SIG_DFL);
195		(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
196		(void) sleep(REPORT_PERIOD);
197		goto again;
198	}
199	offset = -local.tm_gmtoff;
200#ifdef DEBUG
201	fprintf(stderr, "Initial offset: %ld secs\n", offset);
202#endif
203
204	/* correct the kerneltime for this diffs */
205	/* subtract kernel offset, if present, old offset too */
206
207	diff = offset - tz.tz_minuteswest * 60 - kern_offset;
208
209	if (diff != 0) {
210#ifdef DEBUG
211		fprintf(stderr, "Initial diff: %ld secs\n", diff);
212#endif
213		/* Yet one step for final time */
214
215		final_sec = initial_sec + diff;
216
217		/* get the actual local timezone difference */
218		local = *localtime(&final_sec);
219		final_isdst = diff < 0 ? initial_isdst : local.tm_isdst;
220		if (diff > 0 && initial_isdst != final_isdst) {
221			if (looping)
222				goto bad_final;
223			looping = True;
224			initial_isdst = final_isdst;
225			goto recalculate;
226		}
227		local.tm_isdst =  final_isdst;
228
229		localsec = mktime(&local);
230		if (localsec == -1) {
231		bad_final:
232			/*
233			 * XXX as above.  The user has even less control,
234			 * but perhaps we never get here.
235			 */
236			if (!sleep_mode) {
237				syslog(LOG_WARNING,
238					"Warning: nonexistent final local time, try to run later.");
239				syslog(LOG_WARNING, "Giving up.");
240				return 1;
241			}
242			syslog(LOG_WARNING,
243				"Warning: nonexistent final local time.");
244			syslog(LOG_WARNING, "Will retry after %d minutes.",
245				REPORT_PERIOD / 60);
246			(void) signal(SIGTERM, SIG_DFL);
247			(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
248			(void) sleep(REPORT_PERIOD);
249			goto again;
250		}
251		offset = -local.tm_gmtoff;
252#ifdef DEBUG
253		fprintf(stderr, "Final offset: %ld secs\n", offset);
254#endif
255
256		/* correct the kerneltime for this diffs */
257		/* subtract kernel offset, if present, old offset too */
258
259		diff = offset - tz.tz_minuteswest * 60 - kern_offset;
260
261		if (diff != 0) {
262#ifdef DEBUG
263			fprintf(stderr, "Final diff: %ld secs\n", diff);
264#endif
265			/*
266			 * stv is abused as a flag.  The important value
267			 * is in `diff'.
268			 */
269			stv = &tv;
270		}
271	}
272
273	if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
274		tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
275		stz = &tz;
276	}
277	if (!wall_clock && stz == NULL)
278		stv = NULL;
279
280	/* if init or UTC clock and offset/date will be changed, */
281	/* disable RTC modification for a while.                      */
282
283	if (   (init && stv != NULL)
284	    || ((init || !wall_clock) && kern_offset != offset)
285	   ) {
286		len = sizeof(disrtcset);
287		if (sysctlbyname("machdep.disable_rtc_set", &disrtcset, &len, NULL, 0) == -1) {
288			syslog(LOG_ERR, "sysctl(get: \"machdep.disable_rtc_set\"): %m");
289			return 1;
290		}
291		if (disrtcset == 0) {
292			disrtcset = 1;
293			need_restore = True;
294			if (sysctlbyname("machdep.disable_rtc_set", NULL, NULL, &disrtcset, len) == -1) {
295				syslog(LOG_ERR, "sysctl(set: \"machdep.disable_rtc_set\"): %m");
296				return 1;
297			}
298		}
299	}
300
301	if (   (init && (stv != NULL || stz != NULL))
302	    || (stz != NULL && stv == NULL)
303	   ) {
304		if (stv != NULL) {
305			/*
306			 * Get the time again, as close as possible to
307			 * adjusting it, to minimise drift.
308			 * XXX we'd better not fail between here and
309			 * restoring disrtcset, since we don't clean up
310			 * anything.
311			 */
312			if (gettimeofday(&tv, (struct timezone *)NULL)) {
313				syslog(LOG_ERR, "gettimeofday: %m");
314				return 1;
315			}
316			tv.tv_sec += diff;
317			stv = &tv;
318		}
319		if (settimeofday(stv, stz)) {
320			syslog(LOG_ERR, "settimeofday: %m");
321			return 1;
322		}
323	}
324
325	/* setting machdep.adjkerntz have a side effect: resettodr(), which */
326	/* can be disabled by machdep.disable_rtc_set, so if init or UTC clock    */
327	/* -- don't write RTC, else write RTC.                          */
328
329	if (kern_offset != offset) {
330		kern_offset = offset;
331		len = sizeof(kern_offset);
332		if (sysctlbyname("machdep.adjkerntz", NULL, NULL, &kern_offset, len) == -1) {
333			syslog(LOG_ERR, "sysctl(set: \"machdep.adjkerntz\"): %m");
334			return 1;
335		}
336	}
337
338	len = sizeof(wall_clock);
339	if (sysctlbyname("machdep.wall_cmos_clock",  NULL, NULL, &wall_clock, len) == -1) {
340		syslog(LOG_ERR, "sysctl(set: \"machdep.wall_cmos_clock\"): %m");
341		return 1;
342	}
343
344	if (need_restore) {
345		need_restore = False;
346		disrtcset = 0;
347		len = sizeof(disrtcset);
348		if (sysctlbyname("machdep.disable_rtc_set", NULL, NULL, &disrtcset, len) == -1) {
349			syslog(LOG_ERR, "sysctl(set: \"machdep.disable_rtc_set\"): %m");
350			return 1;
351		}
352	}
353
354/****** End of critical section ******/
355
356	if (init && wall_clock) {
357		sleep_mode = False;
358		/* wait for signals and acts like -a */
359		(void) sigsuspend(&emask);
360		goto again;
361	}
362
363	return 0;
364}
365
366static void
367usage(void)
368{
369	fprintf(stderr, "%s\n%s\n%s\n%s\n",
370		"usage: adjkerntz -i",
371		"\t\t(initial call from /etc/rc)",
372		"       adjkerntz -a [-s]",
373		"\t\t(adjustment call, -s for sleep/retry mode)");
374	exit(2);
375}
376