adjkerntz.c revision 50476 
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#ifndef lint
28static const char copyright[] =
29"@(#)Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia.\n\
30 All rights reserved.\n";
31#endif /* not lint */
32
33#ifndef lint
34static const char rcsid[] =
35  "$FreeBSD: head/sbin/adjkerntz/adjkerntz.c 50476 1999-08-28 00:22:10Z peter $";
36#endif /* not lint */
37
38/*
39 * Andrey A. Chernov   <ache@astral.msk.su>    Dec 20 1993
40 *
41 * Fix kernel time value if machine run wall CMOS clock
42 * (and /etc/wall_cmos_clock file present)
43 * using zoneinfo rules or direct TZ environment variable set.
44 * Use Joerg Wunsch idea for seconds accurate offset calculation
45 * with Garrett Wollman and Bruce Evans fixes.
46 *
47 */
48#include <stdio.h>
49#include <signal.h>
50#include <stdlib.h>
51#include <unistd.h>
52#include <syslog.h>
53#include <sys/time.h>
54#include <sys/param.h>
55#include <machine/cpu.h>
56#include <sys/sysctl.h>
57
58#include "pathnames.h"
59
60/*#define DEBUG*/
61
62#define True (1)
63#define False (0)
64#define Unknown (-1)
65
66#define REPORT_PERIOD (30*60)
67
68static void usage __P((void));
69
70void fake() {}
71
72int main(argc, argv)
73	int argc;
74	char **argv;
75{
76	struct tm local;
77	struct timeval tv, *stv;
78	struct timezone tz, *stz;
79	int kern_offset, wall_clock, disrtcset;
80	size_t len;
81	int mib[2];
82	/* Avoid time_t here, can be unsigned long or worse */
83	long offset, localsec, diff;
84	time_t initial_sec, final_sec;
85	int ch;
86	int initial_isdst = -1, final_isdst;
87	int need_restore = False, sleep_mode = False, looping,
88	    init = Unknown;
89	sigset_t mask, emask;
90
91	while ((ch = getopt(argc, argv, "ais")) != -1)
92		switch((char)ch) {
93		case 'i':               /* initial call, save offset */
94			if (init != Unknown)
95				usage();
96			init = True;
97			break;
98		case 'a':               /* adjustment call, use saved offset */
99			if (init != Unknown)
100				usage();
101			init = False;
102			break;
103		case 's':
104			sleep_mode = True;
105			break;
106		default:
107			usage();
108		}
109	if (init == Unknown)
110		usage();
111
112	if (access(_PATH_CLOCK, F_OK) != 0)
113		return 0;
114
115	if (init)
116		sleep_mode = True;
117
118	sigemptyset(&mask);
119	sigemptyset(&emask);
120	sigaddset(&mask, SIGTERM);
121
122	openlog("adjkerntz", LOG_PID|LOG_PERROR, LOG_DAEMON);
123
124	(void) signal(SIGHUP, SIG_IGN);
125
126	if (init && daemon(0, 1)) {
127		syslog(LOG_ERR, "daemon: %m");
128		return 1;
129	}
130
131again:
132	(void) sigprocmask(SIG_BLOCK, &mask, NULL);
133	(void) signal(SIGTERM, fake);
134
135	diff = 0;
136	stv = NULL;
137	stz = NULL;
138	looping = False;
139
140	wall_clock = (access(_PATH_CLOCK, F_OK) == 0);
141	if (init && !sleep_mode) {
142		init = False;
143		if (!wall_clock)
144			return 0;
145	}
146
147	mib[0] = CTL_MACHDEP;
148	mib[1] = CPU_ADJKERNTZ;
149	len = sizeof(kern_offset);
150	if (sysctl(mib, 2, &kern_offset, &len, NULL, 0) == -1) {
151		syslog(LOG_ERR, "sysctl(get_offset): %m");
152		return 1;
153	}
154
155/****** Critical section, do all things as fast as possible ******/
156
157	/* get local CMOS clock and possible kernel offset */
158	if (gettimeofday(&tv, &tz)) {
159		syslog(LOG_ERR, "gettimeofday: %m");
160		return 1;
161	}
162
163	/* get the actual local timezone difference */
164	initial_sec = tv.tv_sec;
165
166recalculate:
167	local = *localtime(&initial_sec);
168	if (diff == 0)
169		initial_isdst = local.tm_isdst;
170	local.tm_isdst = initial_isdst;
171
172	/* calculate local CMOS diff from GMT */
173
174	localsec = mktime(&local);
175	if (localsec == -1) {
176		/*
177		 * XXX user can only control local time, and it is
178		 * unacceptable to fail here for init.  2:30 am in the
179		 * middle of the nonexistent hour means 3:30 am.
180		 */
181		if (!sleep_mode) {
182			syslog(LOG_WARNING,
183			"Warning: nonexistent local time, try to run later.");
184			syslog(LOG_WARNING, "Giving up.");
185			return 1;
186		}
187		syslog(LOG_WARNING,
188			"Warning: nonexistent local time.");
189		syslog(LOG_WARNING, "Will retry after %d minutes.",
190			REPORT_PERIOD / 60);
191		(void) signal(SIGTERM, SIG_DFL);
192		(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
193		(void) sleep(REPORT_PERIOD);
194		goto again;
195	}
196	offset = -local.tm_gmtoff;
197#ifdef DEBUG
198	fprintf(stderr, "Initial offset: %ld secs\n", offset);
199#endif
200
201	/* correct the kerneltime for this diffs */
202	/* subtract kernel offset, if present, old offset too */
203
204	diff = offset - tz.tz_minuteswest * 60 - kern_offset;
205
206	if (diff != 0) {
207#ifdef DEBUG
208		fprintf(stderr, "Initial diff: %ld secs\n", diff);
209#endif
210		/* Yet one step for final time */
211
212		final_sec = initial_sec + diff;
213
214		/* get the actual local timezone difference */
215		local = *localtime(&final_sec);
216		final_isdst = diff < 0 ? initial_isdst : local.tm_isdst;
217		if (diff > 0 && initial_isdst != final_isdst) {
218			if (looping)
219				goto bad_final;
220			looping = True;
221			initial_isdst = final_isdst;
222			goto recalculate;
223		}
224		local.tm_isdst =  final_isdst;
225
226		localsec = mktime(&local);
227		if (localsec == -1) {
228		bad_final:
229			/*
230			 * XXX as above.  The user has even less control,
231			 * but perhaps we never get here.
232			 */
233			if (!sleep_mode) {
234				syslog(LOG_WARNING,
235					"Warning: nonexistent final local time, try to run later.");
236				syslog(LOG_WARNING, "Giving up.");
237				return 1;
238			}
239			syslog(LOG_WARNING,
240				"Warning: nonexistent final local time.");
241			syslog(LOG_WARNING, "Will retry after %d minutes.",
242				REPORT_PERIOD / 60);
243			(void) signal(SIGTERM, SIG_DFL);
244			(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
245			(void) sleep(REPORT_PERIOD);
246			goto again;
247		}
248		offset = -local.tm_gmtoff;
249#ifdef DEBUG
250		fprintf(stderr, "Final offset: %ld secs\n", offset);
251#endif
252
253		/* correct the kerneltime for this diffs */
254		/* subtract kernel offset, if present, old offset too */
255
256		diff = offset - tz.tz_minuteswest * 60 - kern_offset;
257
258		if (diff != 0) {
259#ifdef DEBUG
260			fprintf(stderr, "Final diff: %ld secs\n", diff);
261#endif
262			/*
263			 * stv is abused as a flag.  The important value
264			 * is in `diff'.
265			 */
266			stv = &tv;
267		}
268	}
269
270	if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
271		tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
272		stz = &tz;
273	}
274	if (!wall_clock && stz == NULL)
275		stv = NULL;
276
277	/* if init or UTC clock and offset/date will be changed, */
278	/* disable RTC modification for a while.                      */
279
280	if (   (init && stv != NULL)
281	    || ((init || !wall_clock) && kern_offset != offset)
282	   ) {
283		mib[0] = CTL_MACHDEP;
284		mib[1] = CPU_DISRTCSET;
285		len = sizeof(disrtcset);
286		if (sysctl(mib, 2, &disrtcset, &len, NULL, 0) == -1) {
287			syslog(LOG_ERR, "sysctl(get_disrtcset): %m");
288			return 1;
289		}
290		if (disrtcset == 0) {
291			disrtcset = 1;
292			need_restore = True;
293			if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
294				syslog(LOG_ERR, "sysctl(set_disrtcset): %m");
295				return 1;
296			}
297		}
298	}
299
300	if (   (init && (stv != NULL || stz != NULL))
301	    || (stz != NULL && stv == NULL)
302	   ) {
303		if (stv != NULL) {
304			/*
305			 * Get the time again, as close as possible to
306			 * adjusting it, to minimise drift.
307			 * XXX we'd better not fail between here and
308			 * restoring disrtcset, since we don't clean up
309			 * anything.
310			 */
311			if (gettimeofday(&tv, (struct timezone *)NULL)) {
312				syslog(LOG_ERR, "gettimeofday: %m");
313				return 1;
314			}
315			tv.tv_sec += diff;
316			stv = &tv;
317		}
318		if (settimeofday(stv, stz)) {
319			syslog(LOG_ERR, "settimeofday: %m");
320			return 1;
321		}
322	}
323
324	/* setting CPU_ADJKERNTZ have a side effect: resettodr(), which */
325	/* can be disabled by CPU_DISRTCSET, so if init or UTC clock    */
326	/* -- don't write RTC, else write RTC.                          */
327
328	if (kern_offset != offset) {
329		kern_offset = offset;
330		mib[0] = CTL_MACHDEP;
331		mib[1] = CPU_ADJKERNTZ;
332		len = sizeof(kern_offset);
333		if (sysctl(mib, 2, NULL, NULL, &kern_offset, len) == -1) {
334			syslog(LOG_ERR, "sysctl(update_offset): %m");
335			return 1;
336		}
337	}
338
339	mib[0] = CTL_MACHDEP;
340	mib[1] = CPU_WALLCLOCK;
341	len = sizeof(wall_clock);
342	if (sysctl(mib, 2, NULL, NULL, &wall_clock, len) == -1) {
343		syslog(LOG_ERR, "sysctl(put_wallclock): %m");
344		return 1;
345	}
346
347	if (need_restore) {
348		need_restore = False;
349		mib[0] = CTL_MACHDEP;
350		mib[1] = CPU_DISRTCSET;
351		disrtcset = 0;
352		len = sizeof(disrtcset);
353		if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
354			syslog(LOG_ERR, "sysctl(restore_disrtcset): %m");
355			return 1;
356		}
357	}
358
359/****** End of critical section ******/
360
361	if (init && wall_clock) {
362		sleep_mode = False;
363		/* wait for signals and acts like -a */
364		(void) sigsuspend(&emask);
365		goto again;
366	}
367
368	return 0;
369}
370
371static void
372usage()
373{
374	fprintf(stderr, "%s\n%s\n%s\n%s\n",
375		"usage: adjkerntz -i",
376		"\t\t(initial call from /etc/rc)",
377		"       adjkerntz -a [-s]",
378		"\t\t(adjustment call, -s for sleep/retry mode)");
379	exit(2);
380}
381