adjkerntz.c revision 128683 
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 128683 2004-04-27 14:43:03Z ghelmer $");
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	int mib[2];
86	/* Avoid time_t here, can be unsigned long or worse */
87	long offset, localsec, diff;
88	time_t initial_sec, final_sec;
89	int ch;
90	int initial_isdst = -1, final_isdst;
91	int need_restore = False, sleep_mode = False, looping,
92	    init = Unknown;
93	sigset_t mask, emask;
94
95	while ((ch = getopt(argc, argv, "ais")) != -1)
96		switch((char)ch) {
97		case 'i':               /* initial call, save offset */
98			if (init != Unknown)
99				usage();
100			init = True;
101			break;
102		case 'a':               /* adjustment call, use saved offset */
103			if (init != Unknown)
104				usage();
105			init = False;
106			break;
107		case 's':
108			sleep_mode = True;
109			break;
110		default:
111			usage();
112		}
113	if (init == Unknown)
114		usage();
115
116	if (access(_PATH_CLOCK, F_OK) != 0)
117		return 0;
118
119	if (init)
120		sleep_mode = True;
121
122	sigemptyset(&mask);
123	sigemptyset(&emask);
124	sigaddset(&mask, SIGTERM);
125
126	openlog("adjkerntz", LOG_PID|LOG_PERROR, LOG_DAEMON);
127
128	(void) signal(SIGHUP, SIG_IGN);
129
130	if (init && daemon(0, 1)) {
131		syslog(LOG_ERR, "daemon: %m");
132		return 1;
133	}
134
135again:
136	(void) sigprocmask(SIG_BLOCK, &mask, NULL);
137	(void) signal(SIGTERM, fake);
138
139	diff = 0;
140	stv = NULL;
141	stz = NULL;
142	looping = False;
143
144	wall_clock = (access(_PATH_CLOCK, F_OK) == 0);
145	if (init && !sleep_mode) {
146		init = False;
147		if (!wall_clock)
148			return 0;
149	}
150
151	tzset();
152
153	mib[0] = CTL_MACHDEP;
154	mib[1] = CPU_ADJKERNTZ;
155	len = sizeof(kern_offset);
156	if (sysctl(mib, 2, &kern_offset, &len, NULL, 0) == -1) {
157		syslog(LOG_ERR, "sysctl(get_offset): %m");
158		return 1;
159	}
160
161/****** Critical section, do all things as fast as possible ******/
162
163	/* get local CMOS clock and possible kernel offset */
164	if (gettimeofday(&tv, &tz)) {
165		syslog(LOG_ERR, "gettimeofday: %m");
166		return 1;
167	}
168
169	/* get the actual local timezone difference */
170	initial_sec = tv.tv_sec;
171
172recalculate:
173	local = *localtime(&initial_sec);
174	if (diff == 0)
175		initial_isdst = local.tm_isdst;
176	local.tm_isdst = initial_isdst;
177
178	/* calculate local CMOS diff from GMT */
179
180	localsec = mktime(&local);
181	if (localsec == -1) {
182		/*
183		 * XXX user can only control local time, and it is
184		 * unacceptable to fail here for init.  2:30 am in the
185		 * middle of the nonexistent hour means 3:30 am.
186		 */
187		if (!sleep_mode) {
188			syslog(LOG_WARNING,
189			"Warning: nonexistent local time, try to run later.");
190			syslog(LOG_WARNING, "Giving up.");
191			return 1;
192		}
193		syslog(LOG_WARNING,
194			"Warning: nonexistent local time.");
195		syslog(LOG_WARNING, "Will retry after %d minutes.",
196			REPORT_PERIOD / 60);
197		(void) signal(SIGTERM, SIG_DFL);
198		(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
199		(void) sleep(REPORT_PERIOD);
200		goto again;
201	}
202	offset = -local.tm_gmtoff;
203#ifdef DEBUG
204	fprintf(stderr, "Initial offset: %ld secs\n", offset);
205#endif
206
207	/* correct the kerneltime for this diffs */
208	/* subtract kernel offset, if present, old offset too */
209
210	diff = offset - tz.tz_minuteswest * 60 - kern_offset;
211
212	if (diff != 0) {
213#ifdef DEBUG
214		fprintf(stderr, "Initial diff: %ld secs\n", diff);
215#endif
216		/* Yet one step for final time */
217
218		final_sec = initial_sec + diff;
219
220		/* get the actual local timezone difference */
221		local = *localtime(&final_sec);
222		final_isdst = diff < 0 ? initial_isdst : local.tm_isdst;
223		if (diff > 0 && initial_isdst != final_isdst) {
224			if (looping)
225				goto bad_final;
226			looping = True;
227			initial_isdst = final_isdst;
228			goto recalculate;
229		}
230		local.tm_isdst =  final_isdst;
231
232		localsec = mktime(&local);
233		if (localsec == -1) {
234		bad_final:
235			/*
236			 * XXX as above.  The user has even less control,
237			 * but perhaps we never get here.
238			 */
239			if (!sleep_mode) {
240				syslog(LOG_WARNING,
241					"Warning: nonexistent final local time, try to run later.");
242				syslog(LOG_WARNING, "Giving up.");
243				return 1;
244			}
245			syslog(LOG_WARNING,
246				"Warning: nonexistent final local time.");
247			syslog(LOG_WARNING, "Will retry after %d minutes.",
248				REPORT_PERIOD / 60);
249			(void) signal(SIGTERM, SIG_DFL);
250			(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
251			(void) sleep(REPORT_PERIOD);
252			goto again;
253		}
254		offset = -local.tm_gmtoff;
255#ifdef DEBUG
256		fprintf(stderr, "Final offset: %ld secs\n", offset);
257#endif
258
259		/* correct the kerneltime for this diffs */
260		/* subtract kernel offset, if present, old offset too */
261
262		diff = offset - tz.tz_minuteswest * 60 - kern_offset;
263
264		if (diff != 0) {
265#ifdef DEBUG
266			fprintf(stderr, "Final diff: %ld secs\n", diff);
267#endif
268			/*
269			 * stv is abused as a flag.  The important value
270			 * is in `diff'.
271			 */
272			stv = &tv;
273		}
274	}
275
276	if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
277		tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
278		stz = &tz;
279	}
280	if (!wall_clock && stz == NULL)
281		stv = NULL;
282
283	/* if init or UTC clock and offset/date will be changed, */
284	/* disable RTC modification for a while.                      */
285
286	if (   (init && stv != NULL)
287	    || ((init || !wall_clock) && kern_offset != offset)
288	   ) {
289		mib[0] = CTL_MACHDEP;
290		mib[1] = CPU_DISRTCSET;
291		len = sizeof(disrtcset);
292		if (sysctl(mib, 2, &disrtcset, &len, NULL, 0) == -1) {
293			syslog(LOG_ERR, "sysctl(get_disrtcset): %m");
294			return 1;
295		}
296		if (disrtcset == 0) {
297			disrtcset = 1;
298			need_restore = True;
299			if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
300				syslog(LOG_ERR, "sysctl(set_disrtcset): %m");
301				return 1;
302			}
303		}
304	}
305
306	if (   (init && (stv != NULL || stz != NULL))
307	    || (stz != NULL && stv == NULL)
308	   ) {
309		if (stv != NULL) {
310			/*
311			 * Get the time again, as close as possible to
312			 * adjusting it, to minimise drift.
313			 * XXX we'd better not fail between here and
314			 * restoring disrtcset, since we don't clean up
315			 * anything.
316			 */
317			if (gettimeofday(&tv, (struct timezone *)NULL)) {
318				syslog(LOG_ERR, "gettimeofday: %m");
319				return 1;
320			}
321			tv.tv_sec += diff;
322			stv = &tv;
323		}
324		if (settimeofday(stv, stz)) {
325			syslog(LOG_ERR, "settimeofday: %m");
326			return 1;
327		}
328	}
329
330	/* setting CPU_ADJKERNTZ have a side effect: resettodr(), which */
331	/* can be disabled by CPU_DISRTCSET, so if init or UTC clock    */
332	/* -- don't write RTC, else write RTC.                          */
333
334	if (kern_offset != offset) {
335		kern_offset = offset;
336		mib[0] = CTL_MACHDEP;
337		mib[1] = CPU_ADJKERNTZ;
338		len = sizeof(kern_offset);
339		if (sysctl(mib, 2, NULL, NULL, &kern_offset, len) == -1) {
340			syslog(LOG_ERR, "sysctl(update_offset): %m");
341			return 1;
342		}
343	}
344
345	mib[0] = CTL_MACHDEP;
346	mib[1] = CPU_WALLCLOCK;
347	len = sizeof(wall_clock);
348	if (sysctl(mib, 2, NULL, NULL, &wall_clock, len) == -1) {
349		syslog(LOG_ERR, "sysctl(put_wallclock): %m");
350		return 1;
351	}
352
353	if (need_restore) {
354		need_restore = False;
355		mib[0] = CTL_MACHDEP;
356		mib[1] = CPU_DISRTCSET;
357		disrtcset = 0;
358		len = sizeof(disrtcset);
359		if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
360			syslog(LOG_ERR, "sysctl(restore_disrtcset): %m");
361			return 1;
362		}
363	}
364
365/****** End of critical section ******/
366
367	if (init && wall_clock) {
368		sleep_mode = False;
369		/* wait for signals and acts like -a */
370		(void) sigsuspend(&emask);
371		goto again;
372	}
373
374	return 0;
375}
376
377static void
378usage(void)
379{
380	fprintf(stderr, "%s\n%s\n%s\n%s\n",
381		"usage: adjkerntz -i",
382		"\t\t(initial call from /etc/rc)",
383		"       adjkerntz -a [-s]",
384		"\t\t(adjustment call, -s for sleep/retry mode)");
385	exit(2);
386}
387