adjkerntz.c revision 15052 
1/*
2 * Copyright (C) 1993-1996 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
28char copyright[] =
29"@(#)Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia.\n\
30 All rights reserved.\n";
31#endif /* not lint */
32
33/*
34 * Andrey A. Chernov   <ache@astral.msk.su>    Dec 20 1993
35 *
36 * Fix kernel time value if machine run wall CMOS clock
37 * (and /etc/wall_cmos_clock file present)
38 * using zoneinfo rules or direct TZ environment variable set.
39 * Use Joerg Wunsch idea for seconds accurate offset calculation
40 * with Garrett Wollman and Bruce Evans fixes.
41 *
42 */
43#include <stdio.h>
44#include <signal.h>
45#include <stdlib.h>
46#include <unistd.h>
47#include <syslog.h>
48#include <sys/stat.h>
49#include <sys/time.h>
50#include <sys/param.h>
51#include <machine/cpu.h>
52#include <sys/sysctl.h>
53
54#include "pathnames.h"
55
56/*#define DEBUG*/
57
58#define True (1)
59#define False (0)
60#define Unknown (-1)
61
62#define REPORT_PERIOD (30*60)
63
64void fake() {}
65
66int main(argc, argv)
67	int argc;
68	char **argv;
69{
70	struct tm local, utc;
71	struct timeval tv, *stv;
72	struct timezone tz, *stz;
73	int kern_offset, wall_clock, disrtcset;
74	size_t len;
75	int mib[2];
76	/* Avoid time_t here, can be unsigned long or worse */
77	long offset, utcsec, localsec, diff;
78	time_t initial_sec, final_sec;
79	int ch;
80	int initial_isdst = -1, final_isdst;
81	int need_restore = False, sleep_mode = False, looping,
82	    init = Unknown;
83	sigset_t mask, emask;
84
85	while ((ch = getopt(argc, argv, "ais")) != EOF)
86		switch((char)ch) {
87		case 'i':               /* initial call, save offset */
88			if (init != Unknown)
89				goto usage;
90			init = True;
91			break;
92		case 'a':               /* adjustment call, use saved offset */
93			if (init != Unknown)
94				goto usage;
95			init = False;
96			break;
97		case 's':
98			sleep_mode = True;
99			break;
100		default:
101		usage:
102			fprintf(stderr, "Usage:\n\
103\tadjkerntz -i\t\t(initial call from /etc/rc)\n\
104\tadjkerntz -a [-s]\t(adjustment call, -s for sleep/retry mode)\n");
105  			return 2;
106		}
107	if (init == Unknown)
108		goto usage;
109	if (init)
110		sleep_mode = True;
111
112	sigemptyset(&mask);
113	sigemptyset(&emask);
114	sigaddset(&mask, SIGTERM);
115
116	openlog("adjkerntz", LOG_PID|LOG_PERROR, LOG_DAEMON);
117
118	(void) signal(SIGHUP, SIG_IGN);
119
120	if (init && daemon(0, 1)) {
121		syslog(LOG_ERR, "daemon: %m");
122		return 1;
123	}
124
125again:
126	(void) sigprocmask(SIG_BLOCK, &mask, NULL);
127	(void) signal(SIGTERM, fake);
128
129	diff = 0;
130	stv = NULL;
131	stz = NULL;
132	looping = False;
133
134	wall_clock = (access(_PATH_CLOCK, F_OK) == 0);
135
136	mib[0] = CTL_MACHDEP;
137	mib[1] = CPU_ADJKERNTZ;
138	len = sizeof(kern_offset);
139	if (sysctl(mib, 2, &kern_offset, &len, NULL, 0) == -1) {
140		syslog(LOG_ERR, "sysctl(get_offset): %m");
141		return 1;
142	}
143
144/****** Critical section, do all things as fast as possible ******/
145
146	/* get local CMOS clock and possible kernel offset */
147	if (gettimeofday(&tv, &tz)) {
148		syslog(LOG_ERR, "gettimeofday: %m");
149		return 1;
150	}
151
152	/* get the actual local timezone difference */
153	initial_sec = tv.tv_sec;
154
155recalculate:
156	local = *localtime(&initial_sec);
157	if (diff == 0)
158		initial_isdst = local.tm_isdst;
159	utc = *gmtime(&initial_sec);
160	local.tm_isdst = utc.tm_isdst = initial_isdst;
161
162	/* calculate local CMOS diff from GMT */
163
164	utcsec = mktime(&utc);
165	localsec = mktime(&local);
166	if (utcsec == -1 || localsec == -1) {
167		/*
168		 * XXX user can only control local time, and it is
169		 * unacceptable to fail here for init.  2:30 am in the
170		 * middle of the nonexistent hour means 3:30 am.
171		 */
172		syslog(LOG_WARNING,
173		"Warning: nonexistent %s time.",
174			utcsec == -1 && localsec == -1 ? "UTC time and local" :
175			utcsec == -1 ? "UTC" : "local");
176		if (!sleep_mode) {
177			syslog(LOG_WARNING, "Giving up.");
178			return 1;
179		}
180		syslog(LOG_WARNING, "Will retry after %d minutes.",
181			REPORT_PERIOD / 60);
182		(void) signal(SIGTERM, SIG_DFL);
183		(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
184		(void) sleep(REPORT_PERIOD);
185		goto again;
186	}
187	offset = utcsec - localsec;
188#ifdef DEBUG
189	fprintf(stderr, "Initial offset: %ld secs\n", offset);
190#endif
191
192	/* correct the kerneltime for this diffs */
193	/* subtract kernel offset, if present, old offset too */
194
195	diff = offset - tz.tz_minuteswest * 60 - kern_offset;
196
197	if (diff != 0) {
198#ifdef DEBUG
199		fprintf(stderr, "Initial diff: %ld secs\n", diff);
200#endif
201		/* Yet one step for final time */
202
203		final_sec = initial_sec + diff;
204
205		/* get the actual local timezone difference */
206		local = *localtime(&final_sec);
207		final_isdst = diff < 0 ? initial_isdst : local.tm_isdst;
208		if (diff > 0 && initial_isdst != final_isdst) {
209			if (looping)
210				goto bad_final;
211			looping = True;
212			initial_isdst = final_isdst;
213			goto recalculate;
214		}
215		utc = *gmtime(&final_sec);
216		local.tm_isdst = utc.tm_isdst = final_isdst;
217
218		utcsec = mktime(&utc);
219		localsec = mktime(&local);
220		if (utcsec == -1 || localsec == -1) {
221		bad_final:
222			/*
223			 * XXX as above.  The user has even less control,
224			 * but perhaps we never get here.
225			 */
226			syslog(LOG_WARNING,
227				"Warning: nonexistent final %s time.",
228				utcsec == -1 && localsec == -1 ? "UTC time and local" :
229				utcsec == -1 ? "UTC" : "local");
230			if (!sleep_mode) {
231				syslog(LOG_WARNING, "Giving up.");
232				return 1;
233			}
234			syslog(LOG_WARNING, "Will retry after %d minutes.",
235				REPORT_PERIOD / 60);
236			(void) signal(SIGTERM, SIG_DFL);
237			(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
238			(void) sleep(REPORT_PERIOD);
239			goto again;
240		}
241		offset = utcsec - localsec;
242#ifdef DEBUG
243		fprintf(stderr, "Final offset: %ld secs\n", offset);
244#endif
245
246		/* correct the kerneltime for this diffs */
247		/* subtract kernel offset, if present, old offset too */
248
249		diff = offset - tz.tz_minuteswest * 60 - kern_offset;
250
251		if (diff != 0) {
252#ifdef DEBUG
253			fprintf(stderr, "Final diff: %ld secs\n", diff);
254#endif
255			tv.tv_sec += diff;
256			tv.tv_usec = 0;       /* we are restarting here... */
257			stv = &tv;
258		}
259	}
260
261	if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
262		tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
263		stz = &tz;
264	}
265	if (!wall_clock && stz == NULL)
266		stv = NULL;
267
268	/* if init or UTC clock and offset/date will be changed, */
269	/* disable RTC modification for a while.                      */
270
271	if (   (init && stv != NULL)
272	    || ((init || !wall_clock) && kern_offset != offset)
273	   ) {
274		mib[0] = CTL_MACHDEP;
275		mib[1] = CPU_DISRTCSET;
276		len = sizeof(disrtcset);
277		if (sysctl(mib, 2, &disrtcset, &len, NULL, 0) == -1) {
278			syslog(LOG_ERR, "sysctl(get_disrtcset): %m");
279			return 1;
280		}
281		if (disrtcset == 0) {
282			disrtcset = 1;
283			need_restore = True;
284			if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
285				syslog(LOG_ERR, "sysctl(set_disrtcset): %m");
286				return 1;
287			}
288		}
289	}
290
291	if (   (   (init && (stv != NULL || stz != NULL))
292		|| (stz != NULL && stv == NULL)
293	       )
294	    && settimeofday(stv, stz)
295	   ) {
296		syslog(LOG_ERR, "settimeofday: %m");
297		return 1;
298	}
299
300	/* setting CPU_ADJKERNTZ have a side effect: resettodr(), which */
301	/* can be disabled by CPU_DISRTCSET, so if init or UTC clock    */
302	/* -- don't write RTC, else write RTC.                          */
303
304	if (kern_offset != offset) {
305		kern_offset = offset;
306		mib[0] = CTL_MACHDEP;
307		mib[1] = CPU_ADJKERNTZ;
308		len = sizeof(kern_offset);
309		if (sysctl(mib, 2, NULL, NULL, &kern_offset, len) == -1) {
310			syslog(LOG_ERR, "sysctl(update_offset): %m");
311			return 1;
312		}
313	}
314
315	mib[0] = CTL_MACHDEP;
316	mib[1] = CPU_WALLCLOCK;
317	len = sizeof(wall_clock);
318	if (sysctl(mib, 2, NULL, NULL, &wall_clock, len) == -1) {
319		syslog(LOG_ERR, "sysctl(put_wallclock): %m");
320		return 1;
321	}
322
323	if (need_restore) {
324		need_restore = False;
325		mib[0] = CTL_MACHDEP;
326		mib[1] = CPU_DISRTCSET;
327		disrtcset = 0;
328		len = sizeof(disrtcset);
329		if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
330			syslog(LOG_ERR, "sysctl(restore_disrtcset): %m");
331			return 1;
332		}
333	}
334
335/****** End of critical section ******/
336
337	if (init && wall_clock) {
338		init = False;
339		/* wait for signals and acts like -a */
340		(void) sigsuspend(&emask);
341		goto again;
342	}
343
344	return 0;
345}
346