adjkerntz.c revision 4048 
1/*
2 * Copyright (C) 1993 by Andrew 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 by Andrew A. Chernov, Moscow, Russia.\n\
30 All rights reserved.\n";
31#endif /* not lint */
32
33/*
34 * Andrew 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 <stdlib.h>
45#include <unistd.h>
46#include <syslog.h>
47#include <sys/stat.h>
48#include <sys/time.h>
49#include <sys/param.h>
50#include <machine/cpu.h>
51#include <sys/sysctl.h>
52
53#include "pathnames.h"
54
55#define REPORT_PERIOD (30*60)
56
57int main(argc, argv)
58	int argc;
59	char **argv;
60{
61	struct tm local, utc;
62	struct timeval tv, *stv;
63	struct timezone tz, *stz;
64	int kern_offset;
65	size_t len;
66	int mib[2];
67	/* Avoid time_t here, can be unsigned long or worse */
68	long offset, utcsec, localsec, diff;
69	time_t initial_sec, final_sec;
70	int init = 1, nonex1 = 0, nonex2 = 0;
71	int disrtcset, need_restore = 0;
72
73	if (argc != 1) {
74		fprintf(stderr, "Usage:\tadjkerntz\n");
75		return 2;
76	}
77
78	if (access(_PATH_CLOCK, F_OK))
79		return 0;
80
81	if (daemon(0, 0)) {
82		perror("daemon");
83		return 1;
84	}
85
86	openlog("adjkerntz", LOG_PID, LOG_DAEMON);
87
88	/* Spy on timezone changes with 1sec accurancy */
89	for (;;sleep(1)) {
90
91/****** Critical section, do all things as fast as possible ******/
92
93		/* get local CMOS clock and possible kernel offset */
94		if (gettimeofday(&tv, &tz)) {
95			syslog(LOG_ERR, "gettimeofday: %m");
96			return 1;
97		}
98
99		/* get the actual local timezone difference */
100		initial_sec = tv.tv_sec;
101		local = *localtime(&initial_sec);
102		utc = *gmtime(&initial_sec);
103		utc.tm_isdst = local.tm_isdst; /* Use current timezone for mktime(), */
104					       /* because it assumed local time */
105
106		/* calculate local CMOS diff from GMT */
107
108		utcsec = mktime(&utc);
109		localsec = mktime(&local);
110		if (utcsec == -1 || localsec == -1) {
111			/*
112			 * XXX user can only control local time, and it is
113			 * unacceptable to fail here for init.  2:30 am in the
114			 * middle of the nonexistent hour means 3:30 am.
115			 */
116			if (!(nonex1++ % REPORT_PERIOD)) {
117				if (nonex1 > 1)
118					nonex1 = 0;
119				syslog(LOG_WARNING,
120				"Nonexistent local time -- retry each second");
121			}
122			continue;
123		}
124		offset = utcsec - localsec;
125
126		mib[0] = CTL_MACHDEP;
127		mib[1] = CPU_ADJKERNTZ;
128		len = sizeof(kern_offset);
129		if (sysctl(mib, 2, &kern_offset, &len, NULL, 0) == -1) {
130			syslog(LOG_ERR, "sysctl(get_offset): %m");
131			return 1;
132		}
133
134		/* correct the kerneltime for this diffs */
135		/* subtract kernel offset, if present, old offset too */
136
137		diff = offset - tz.tz_minuteswest * 60 - kern_offset;
138
139		if (diff != 0) {
140
141			/* Yet one step for final time */
142
143			final_sec = tv.tv_sec + diff;
144
145			/* get the actual local timezone difference */
146			local = *localtime(&final_sec);
147			utc = *gmtime(&final_sec);
148			utc.tm_isdst = local.tm_isdst; /* Use current timezone for mktime(), */
149						       /* because it assumed local time */
150
151			utcsec = mktime(&utc);
152			localsec = mktime(&local);
153			if (utcsec == -1 || localsec == -1) {
154				/*
155				 * XXX as above.  The user has even less control,
156				 * but perhaps we never get here.
157				 */
158				if (!(nonex2++ % REPORT_PERIOD)) {
159					if (nonex2 > 1)
160						nonex2 = 0;
161					syslog(LOG_WARNING,
162			"Nonexistent (final) local time -- retry each second");
163				}
164				continue;
165			}
166			offset = utcsec - localsec;
167
168			/* correct the kerneltime for this diffs */
169			/* subtract kernel offset, if present, old offset too */
170
171			diff = offset - tz.tz_minuteswest * 60 - kern_offset;
172
173			if (diff != 0) {
174				tv.tv_sec += diff;
175				tv.tv_usec = 0;       /* we are restarting here... */
176				stv = &tv;
177			}
178			else
179				stv = NULL;
180		}
181		else
182			stv = NULL;
183
184		if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
185			tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
186			stz = &tz;
187		}
188		else
189			stz = NULL;
190
191		if (stz != NULL || stv != NULL) {
192			if (init && stv != NULL) {
193				mib[0] = CTL_MACHDEP;
194				mib[1] = CPU_DISRTCSET;
195				len = sizeof(disrtcset);
196				if (sysctl(mib, 2, &disrtcset, &len, NULL, 0) == -1) {
197					syslog(LOG_ERR, "sysctl(get_disrtcset): %m");
198					return 1;
199				}
200				if (disrtcset == 0) {
201					disrtcset = 1;
202					need_restore = 1;
203					if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
204						syslog(LOG_ERR, "sysctl(set_disrtcset): %m");
205						return 1;
206					}
207				}
208			}
209			/* stz means that kernel zone shifted */
210			/* clock needs adjustment even if !init */
211			if ((init || stz != NULL) && settimeofday(stv, stz)) {
212				syslog(LOG_ERR, "settimeofday: %m");
213				return 1;
214			}
215		}
216
217		if (kern_offset != offset) {
218			kern_offset = offset;
219			mib[0] = CTL_MACHDEP;
220			mib[1] = CPU_ADJKERNTZ;
221			len = sizeof(kern_offset);
222			if (sysctl(mib, 2, NULL, NULL, &kern_offset, len) == -1) {
223				syslog(LOG_ERR, "sysctl(update_offset): %m");
224				return 1;
225			}
226		}
227
228		if (need_restore) {
229			need_restore = 0;
230			disrtcset = 0;
231			if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
232				syslog(LOG_ERR, "sysctl(restore_disrtcset): %m");
233				return 1;
234			}
235		}
236
237/****** End of critical section ******/
238
239		init = 0;
240	}
241	return 1;
242}
243