adjkerntz.c revision 24359 
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")) != -1)
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	if (init && !sleep_mode) {
136		init = False;
137		if (!wall_clock)
138			return 0;
139	}
140
141	mib[0] = CTL_MACHDEP;
142	mib[1] = CPU_ADJKERNTZ;
143	len = sizeof(kern_offset);
144	if (sysctl(mib, 2, &kern_offset, &len, NULL, 0) == -1) {
145		syslog(LOG_ERR, "sysctl(get_offset): %m");
146		return 1;
147	}
148
149/****** Critical section, do all things as fast as possible ******/
150
151	/* get local CMOS clock and possible kernel offset */
152	if (gettimeofday(&tv, &tz)) {
153		syslog(LOG_ERR, "gettimeofday: %m");
154		return 1;
155	}
156
157	/* get the actual local timezone difference */
158	initial_sec = tv.tv_sec;
159
160recalculate:
161	local = *localtime(&initial_sec);
162	if (diff == 0)
163		initial_isdst = local.tm_isdst;
164	utc = *gmtime(&initial_sec);
165	local.tm_isdst = utc.tm_isdst = initial_isdst;
166
167	/* calculate local CMOS diff from GMT */
168
169	utcsec = mktime(&utc);
170	localsec = mktime(&local);
171	if (utcsec == -1 || localsec == -1) {
172		/*
173		 * XXX user can only control local time, and it is
174		 * unacceptable to fail here for init.  2:30 am in the
175		 * middle of the nonexistent hour means 3:30 am.
176		 */
177		syslog(LOG_WARNING,
178		"Warning: nonexistent %s time.",
179			utcsec == -1 && localsec == -1 ? "UTC time and local" :
180			utcsec == -1 ? "UTC" : "local");
181		if (!sleep_mode) {
182			syslog(LOG_WARNING, "Giving up.");
183			return 1;
184		}
185		syslog(LOG_WARNING, "Will retry after %d minutes.",
186			REPORT_PERIOD / 60);
187		(void) signal(SIGTERM, SIG_DFL);
188		(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
189		(void) sleep(REPORT_PERIOD);
190		goto again;
191	}
192	offset = utcsec - localsec;
193#ifdef DEBUG
194	fprintf(stderr, "Initial offset: %ld secs\n", offset);
195#endif
196
197	/* correct the kerneltime for this diffs */
198	/* subtract kernel offset, if present, old offset too */
199
200	diff = offset - tz.tz_minuteswest * 60 - kern_offset;
201
202	if (diff != 0) {
203#ifdef DEBUG
204		fprintf(stderr, "Initial diff: %ld secs\n", diff);
205#endif
206		/* Yet one step for final time */
207
208		final_sec = initial_sec + diff;
209
210		/* get the actual local timezone difference */
211		local = *localtime(&final_sec);
212		final_isdst = diff < 0 ? initial_isdst : local.tm_isdst;
213		if (diff > 0 && initial_isdst != final_isdst) {
214			if (looping)
215				goto bad_final;
216			looping = True;
217			initial_isdst = final_isdst;
218			goto recalculate;
219		}
220		utc = *gmtime(&final_sec);
221		local.tm_isdst = utc.tm_isdst = final_isdst;
222
223		utcsec = mktime(&utc);
224		localsec = mktime(&local);
225		if (utcsec == -1 || 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			syslog(LOG_WARNING,
232				"Warning: nonexistent final %s time.",
233				utcsec == -1 && localsec == -1 ? "UTC time and local" :
234				utcsec == -1 ? "UTC" : "local");
235			if (!sleep_mode) {
236				syslog(LOG_WARNING, "Giving up.");
237				return 1;
238			}
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 = utcsec - localsec;
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			tv.tv_sec += diff;
261			tv.tv_usec = 0;       /* we are restarting here... */
262			stv = &tv;
263		}
264	}
265
266	if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
267		tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
268		stz = &tz;
269	}
270	if (!wall_clock && stz == NULL)
271		stv = NULL;
272
273	/* if init or UTC clock and offset/date will be changed, */
274	/* disable RTC modification for a while.                      */
275
276	if (   (init && stv != NULL)
277	    || ((init || !wall_clock) && kern_offset != offset)
278	   ) {
279		mib[0] = CTL_MACHDEP;
280		mib[1] = CPU_DISRTCSET;
281		len = sizeof(disrtcset);
282		if (sysctl(mib, 2, &disrtcset, &len, NULL, 0) == -1) {
283			syslog(LOG_ERR, "sysctl(get_disrtcset): %m");
284			return 1;
285		}
286		if (disrtcset == 0) {
287			disrtcset = 1;
288			need_restore = True;
289			if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
290				syslog(LOG_ERR, "sysctl(set_disrtcset): %m");
291				return 1;
292			}
293		}
294	}
295
296	if (   (   (init && (stv != NULL || stz != NULL))
297		|| (stz != NULL && stv == NULL)
298	       )
299	    && settimeofday(stv, stz)
300	   ) {
301		syslog(LOG_ERR, "settimeofday: %m");
302		return 1;
303	}
304
305	/* setting CPU_ADJKERNTZ have a side effect: resettodr(), which */
306	/* can be disabled by CPU_DISRTCSET, so if init or UTC clock    */
307	/* -- don't write RTC, else write RTC.                          */
308
309	if (kern_offset != offset) {
310		kern_offset = offset;
311		mib[0] = CTL_MACHDEP;
312		mib[1] = CPU_ADJKERNTZ;
313		len = sizeof(kern_offset);
314		if (sysctl(mib, 2, NULL, NULL, &kern_offset, len) == -1) {
315			syslog(LOG_ERR, "sysctl(update_offset): %m");
316			return 1;
317		}
318	}
319
320	mib[0] = CTL_MACHDEP;
321	mib[1] = CPU_WALLCLOCK;
322	len = sizeof(wall_clock);
323	if (sysctl(mib, 2, NULL, NULL, &wall_clock, len) == -1) {
324		syslog(LOG_ERR, "sysctl(put_wallclock): %m");
325		return 1;
326	}
327
328	if (need_restore) {
329		need_restore = False;
330		mib[0] = CTL_MACHDEP;
331		mib[1] = CPU_DISRTCSET;
332		disrtcset = 0;
333		len = sizeof(disrtcset);
334		if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
335			syslog(LOG_ERR, "sysctl(restore_disrtcset): %m");
336			return 1;
337		}
338	}
339
340/****** End of critical section ******/
341
342	if (init && wall_clock) {
343		sleep_mode = False;
344		/* wait for signals and acts like -a */
345		(void) sigsuspend(&emask);
346		goto again;
347	}
348
349	return 0;
350}
351