adjkerntz.c revision 35142 
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 *		$Id: adjkerntz.c,v 1.22 1998/03/30 09:29:47 ache Exp $
27 */
28
29#ifndef lint
30char copyright[] =
31"@(#)Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia.\n\
32 All rights reserved.\n";
33#endif /* not lint */
34
35/*
36 * Andrey A. Chernov   <ache@astral.msk.su>    Dec 20 1993
37 *
38 * Fix kernel time value if machine run wall CMOS clock
39 * (and /etc/wall_cmos_clock file present)
40 * using zoneinfo rules or direct TZ environment variable set.
41 * Use Joerg Wunsch idea for seconds accurate offset calculation
42 * with Garrett Wollman and Bruce Evans fixes.
43 *
44 */
45#include <stdio.h>
46#include <signal.h>
47#include <stdlib.h>
48#include <unistd.h>
49#include <syslog.h>
50#include <sys/stat.h>
51#include <sys/time.h>
52#include <sys/param.h>
53#include <machine/cpu.h>
54#include <sys/sysctl.h>
55
56#include "pathnames.h"
57
58/*#define DEBUG*/
59
60#define True (1)
61#define False (0)
62#define Unknown (-1)
63
64#define REPORT_PERIOD (30*60)
65
66static void usage __P((void));
67
68void fake() {}
69
70int main(argc, argv)
71	int argc;
72	char **argv;
73{
74	struct tm local;
75	struct timeval tv, *stv;
76	struct timezone tz, *stz;
77	int kern_offset, wall_clock, disrtcset;
78	size_t len;
79	int mib[2];
80	/* Avoid time_t here, can be unsigned long or worse */
81	long offset, localsec, diff;
82	time_t initial_sec, final_sec;
83	int ch;
84	int initial_isdst = -1, final_isdst;
85	int need_restore = False, sleep_mode = False, looping,
86	    init = Unknown;
87	sigset_t mask, emask;
88
89	while ((ch = getopt(argc, argv, "ais")) != -1)
90		switch((char)ch) {
91		case 'i':               /* initial call, save offset */
92			if (init != Unknown)
93				usage();
94			init = True;
95			break;
96		case 'a':               /* adjustment call, use saved offset */
97			if (init != Unknown)
98				usage();
99			init = False;
100			break;
101		case 's':
102			sleep_mode = True;
103			break;
104		default:
105			usage();
106		}
107	if (init == Unknown)
108		usage();
109
110	if (access(_PATH_CLOCK, F_OK) != 0)
111		return 0;
112
113	if (init)
114		sleep_mode = True;
115
116	sigemptyset(&mask);
117	sigemptyset(&emask);
118	sigaddset(&mask, SIGTERM);
119
120	openlog("adjkerntz", LOG_PID|LOG_PERROR, LOG_DAEMON);
121
122	(void) signal(SIGHUP, SIG_IGN);
123
124	if (init && daemon(0, 1)) {
125		syslog(LOG_ERR, "daemon: %m");
126		return 1;
127	}
128
129again:
130	(void) sigprocmask(SIG_BLOCK, &mask, NULL);
131	(void) signal(SIGTERM, fake);
132
133	diff = 0;
134	stv = NULL;
135	stz = NULL;
136	looping = False;
137
138	wall_clock = (access(_PATH_CLOCK, F_OK) == 0);
139	if (init && !sleep_mode) {
140		init = False;
141		if (!wall_clock)
142			return 0;
143	}
144
145	mib[0] = CTL_MACHDEP;
146	mib[1] = CPU_ADJKERNTZ;
147	len = sizeof(kern_offset);
148	if (sysctl(mib, 2, &kern_offset, &len, NULL, 0) == -1) {
149		syslog(LOG_ERR, "sysctl(get_offset): %m");
150		return 1;
151	}
152
153/****** Critical section, do all things as fast as possible ******/
154
155	/* get local CMOS clock and possible kernel offset */
156	if (gettimeofday(&tv, &tz)) {
157		syslog(LOG_ERR, "gettimeofday: %m");
158		return 1;
159	}
160
161	/* get the actual local timezone difference */
162	initial_sec = tv.tv_sec;
163
164recalculate:
165	local = *localtime(&initial_sec);
166	if (diff == 0)
167		initial_isdst = local.tm_isdst;
168	local.tm_isdst = initial_isdst;
169
170	/* calculate local CMOS diff from GMT */
171
172	localsec = mktime(&local);
173	if (localsec == -1) {
174		/*
175		 * XXX user can only control local time, and it is
176		 * unacceptable to fail here for init.  2:30 am in the
177		 * middle of the nonexistent hour means 3:30 am.
178		 */
179		if (!sleep_mode) {
180			syslog(LOG_WARNING,
181			"Warning: nonexistent local time, try to run later.");
182			syslog(LOG_WARNING, "Giving up.");
183			return 1;
184		}
185		syslog(LOG_WARNING,
186			"Warning: nonexistent local time.");
187		syslog(LOG_WARNING, "Will retry after %d minutes.",
188			REPORT_PERIOD / 60);
189		(void) signal(SIGTERM, SIG_DFL);
190		(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
191		(void) sleep(REPORT_PERIOD);
192		goto again;
193	}
194	offset = -local.tm_gmtoff;
195#ifdef DEBUG
196	fprintf(stderr, "Initial offset: %ld secs\n", offset);
197#endif
198
199	/* correct the kerneltime for this diffs */
200	/* subtract kernel offset, if present, old offset too */
201
202	diff = offset - tz.tz_minuteswest * 60 - kern_offset;
203
204	if (diff != 0) {
205#ifdef DEBUG
206		fprintf(stderr, "Initial diff: %ld secs\n", diff);
207#endif
208		/* Yet one step for final time */
209
210		final_sec = initial_sec + diff;
211
212		/* get the actual local timezone difference */
213		local = *localtime(&final_sec);
214		final_isdst = diff < 0 ? initial_isdst : local.tm_isdst;
215		if (diff > 0 && initial_isdst != final_isdst) {
216			if (looping)
217				goto bad_final;
218			looping = True;
219			initial_isdst = final_isdst;
220			goto recalculate;
221		}
222		local.tm_isdst =  final_isdst;
223
224		localsec = mktime(&local);
225		if (localsec == -1) {
226		bad_final:
227			/*
228			 * XXX as above.  The user has even less control,
229			 * but perhaps we never get here.
230			 */
231			if (!sleep_mode) {
232				syslog(LOG_WARNING,
233					"Warning: nonexistent final local time, try to run later.");
234				syslog(LOG_WARNING, "Giving up.");
235				return 1;
236			}
237			syslog(LOG_WARNING,
238				"Warning: nonexistent final local time.");
239			syslog(LOG_WARNING, "Will retry after %d minutes.",
240				REPORT_PERIOD / 60);
241			(void) signal(SIGTERM, SIG_DFL);
242			(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
243			(void) sleep(REPORT_PERIOD);
244			goto again;
245		}
246		offset = -local.tm_gmtoff;
247#ifdef DEBUG
248		fprintf(stderr, "Final offset: %ld secs\n", offset);
249#endif
250
251		/* correct the kerneltime for this diffs */
252		/* subtract kernel offset, if present, old offset too */
253
254		diff = offset - tz.tz_minuteswest * 60 - kern_offset;
255
256		if (diff != 0) {
257#ifdef DEBUG
258			fprintf(stderr, "Final diff: %ld secs\n", diff);
259#endif
260			/*
261			 * stv is abused as a flag.  The important value
262			 * is in `diff'.
263			 */
264			stv = &tv;
265		}
266	}
267
268	if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
269		tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
270		stz = &tz;
271	}
272	if (!wall_clock && stz == NULL)
273		stv = NULL;
274
275	/* if init or UTC clock and offset/date will be changed, */
276	/* disable RTC modification for a while.                      */
277
278	if (   (init && stv != NULL)
279	    || ((init || !wall_clock) && kern_offset != offset)
280	   ) {
281		mib[0] = CTL_MACHDEP;
282		mib[1] = CPU_DISRTCSET;
283		len = sizeof(disrtcset);
284		if (sysctl(mib, 2, &disrtcset, &len, NULL, 0) == -1) {
285			syslog(LOG_ERR, "sysctl(get_disrtcset): %m");
286			return 1;
287		}
288		if (disrtcset == 0) {
289			disrtcset = 1;
290			need_restore = True;
291			if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
292				syslog(LOG_ERR, "sysctl(set_disrtcset): %m");
293				return 1;
294			}
295		}
296	}
297
298	if (   (init && (stv != NULL || stz != NULL))
299	    || (stz != NULL && stv == NULL)
300	   ) {
301		if (stv != NULL) {
302			/*
303			 * Get the time again, as close as possible to
304			 * adjusting it, to minimise drift.
305			 * XXX we'd better not fail between here and
306			 * restoring disrtcset, since we don't clean up
307			 * anything.
308			 */
309			if (gettimeofday(&tv, (struct timezone *)NULL)) {
310				syslog(LOG_ERR, "gettimeofday: %m");
311				return 1;
312			}
313			tv.tv_sec += diff;
314			stv = &tv;
315		}
316		if (settimeofday(stv, stz)) {
317			syslog(LOG_ERR, "settimeofday: %m");
318			return 1;
319		}
320	}
321
322	/* setting CPU_ADJKERNTZ have a side effect: resettodr(), which */
323	/* can be disabled by CPU_DISRTCSET, so if init or UTC clock    */
324	/* -- don't write RTC, else write RTC.                          */
325
326	if (kern_offset != offset) {
327		kern_offset = offset;
328		mib[0] = CTL_MACHDEP;
329		mib[1] = CPU_ADJKERNTZ;
330		len = sizeof(kern_offset);
331		if (sysctl(mib, 2, NULL, NULL, &kern_offset, len) == -1) {
332			syslog(LOG_ERR, "sysctl(update_offset): %m");
333			return 1;
334		}
335	}
336
337	mib[0] = CTL_MACHDEP;
338	mib[1] = CPU_WALLCLOCK;
339	len = sizeof(wall_clock);
340	if (sysctl(mib, 2, NULL, NULL, &wall_clock, len) == -1) {
341		syslog(LOG_ERR, "sysctl(put_wallclock): %m");
342		return 1;
343	}
344
345	if (need_restore) {
346		need_restore = False;
347		mib[0] = CTL_MACHDEP;
348		mib[1] = CPU_DISRTCSET;
349		disrtcset = 0;
350		len = sizeof(disrtcset);
351		if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
352			syslog(LOG_ERR, "sysctl(restore_disrtcset): %m");
353			return 1;
354		}
355	}
356
357/****** End of critical section ******/
358
359	if (init && wall_clock) {
360		sleep_mode = False;
361		/* wait for signals and acts like -a */
362		(void) sigsuspend(&emask);
363		goto again;
364	}
365
366	return 0;
367}
368
369static void
370usage()
371{
372	fprintf(stderr, "%s\n%s\n%s\n%s\n",
373		"usage: adjkerntz -i",
374		"\t\t(initial call from /etc/rc)",
375		"       adjkerntz -a [-s]",
376		"\t\t(adjustment call, -s for sleep/retry mode)");
377	exit(2);
378}
379