xref: /dragonfly/sbin/adjkerntz/adjkerntz.c (revision 984263bc) 
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 #ifndef lint
28 static const char copyright[] =
29 "@(#)Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia.\n\
30  All rights reserved.\n";
31 #endif /* not lint */
32 
33 #ifndef lint
34 static const char rcsid[] =
35   "$FreeBSD: src/sbin/adjkerntz/adjkerntz.c,v 1.25.2.1 2001/07/30 10:38:04 dd Exp $";
36 #endif /* not lint */
37 
38 /*
39  * Andrey A. Chernov   <ache@astral.msk.su>    Dec 20 1993
40  *
41  * Fix kernel time value if machine run wall CMOS clock
42  * (and /etc/wall_cmos_clock file present)
43  * using zoneinfo rules or direct TZ environment variable set.
44  * Use Joerg Wunsch idea for seconds accurate offset calculation
45  * with Garrett Wollman and Bruce Evans fixes.
46  *
47  */
48 #include <stdio.h>
49 #include <signal.h>
50 #include <stdlib.h>
51 #include <unistd.h>
52 #include <syslog.h>
53 #include <sys/time.h>
54 #include <sys/param.h>
55 #include <machine/cpu.h>
56 #include <sys/sysctl.h>
57 
58 #include "pathnames.h"
59 
60 /*#define DEBUG*/
61 
62 #define True (1)
63 #define False (0)
64 #define Unknown (-1)
65 
66 #define REPORT_PERIOD (30*60)
67 
68 static void fake __P((int));
69 static void usage __P((void));
70 
71 static void
72 fake(unused)
73 	int unused __unused;
74 {
75 
76 	/* Do nothing. */
77 }
78 
79 int main(argc, argv)
80 	int argc;
81 	char **argv;
82 {
83 	struct tm local;
84 	struct timeval tv, *stv;
85 	struct timezone tz, *stz;
86 	int kern_offset, wall_clock, disrtcset;
87 	size_t len;
88 	int mib[2];
89 	/* Avoid time_t here, can be unsigned long or worse */
90 	long offset, localsec, diff;
91 	time_t initial_sec, final_sec;
92 	int ch;
93 	int initial_isdst = -1, final_isdst;
94 	int need_restore = False, sleep_mode = False, looping,
95 	    init = Unknown;
96 	sigset_t mask, emask;
97 
98 	while ((ch = getopt(argc, argv, "ais")) != -1)
99 		switch((char)ch) {
100 		case 'i':               /* initial call, save offset */
101 			if (init != Unknown)
102 				usage();
103 			init = True;
104 			break;
105 		case 'a':               /* adjustment call, use saved offset */
106 			if (init != Unknown)
107 				usage();
108 			init = False;
109 			break;
110 		case 's':
111 			sleep_mode = True;
112 			break;
113 		default:
114 			usage();
115 		}
116 	if (init == Unknown)
117 		usage();
118 
119 	if (access(_PATH_CLOCK, F_OK) != 0)
120 		return 0;
121 
122 	if (init)
123 		sleep_mode = True;
124 
125 	sigemptyset(&mask);
126 	sigemptyset(&emask);
127 	sigaddset(&mask, SIGTERM);
128 
129 	openlog("adjkerntz", LOG_PID|LOG_PERROR, LOG_DAEMON);
130 
131 	(void) signal(SIGHUP, SIG_IGN);
132 
133 	if (init && daemon(0, 1)) {
134 		syslog(LOG_ERR, "daemon: %m");
135 		return 1;
136 	}
137 
138 again:
139 	(void) sigprocmask(SIG_BLOCK, &mask, NULL);
140 	(void) signal(SIGTERM, fake);
141 
142 	diff = 0;
143 	stv = NULL;
144 	stz = NULL;
145 	looping = False;
146 
147 	wall_clock = (access(_PATH_CLOCK, F_OK) == 0);
148 	if (init && !sleep_mode) {
149 		init = False;
150 		if (!wall_clock)
151 			return 0;
152 	}
153 
154 	mib[0] = CTL_MACHDEP;
155 	mib[1] = CPU_ADJKERNTZ;
156 	len = sizeof(kern_offset);
157 	if (sysctl(mib, 2, &kern_offset, &len, NULL, 0) == -1) {
158 		syslog(LOG_ERR, "sysctl(get_offset): %m");
159 		return 1;
160 	}
161 
162 /****** Critical section, do all things as fast as possible ******/
163 
164 	/* get local CMOS clock and possible kernel offset */
165 	if (gettimeofday(&tv, &tz)) {
166 		syslog(LOG_ERR, "gettimeofday: %m");
167 		return 1;
168 	}
169 
170 	/* get the actual local timezone difference */
171 	initial_sec = tv.tv_sec;
172 
173 recalculate:
174 	local = *localtime(&initial_sec);
175 	if (diff == 0)
176 		initial_isdst = local.tm_isdst;
177 	local.tm_isdst = initial_isdst;
178 
179 	/* calculate local CMOS diff from GMT */
180 
181 	localsec = mktime(&local);
182 	if (localsec == -1) {
183 		/*
184 		 * XXX user can only control local time, and it is
185 		 * unacceptable to fail here for init.  2:30 am in the
186 		 * middle of the nonexistent hour means 3:30 am.
187 		 */
188 		if (!sleep_mode) {
189 			syslog(LOG_WARNING,
190 			"Warning: nonexistent local time, try to run later.");
191 			syslog(LOG_WARNING, "Giving up.");
192 			return 1;
193 		}
194 		syslog(LOG_WARNING,
195 			"Warning: nonexistent local time.");
196 		syslog(LOG_WARNING, "Will retry after %d minutes.",
197 			REPORT_PERIOD / 60);
198 		(void) signal(SIGTERM, SIG_DFL);
199 		(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
200 		(void) sleep(REPORT_PERIOD);
201 		goto again;
202 	}
203 	offset = -local.tm_gmtoff;
204 #ifdef DEBUG
205 	fprintf(stderr, "Initial offset: %ld secs\n", offset);
206 #endif
207 
208 	/* correct the kerneltime for this diffs */
209 	/* subtract kernel offset, if present, old offset too */
210 
211 	diff = offset - tz.tz_minuteswest * 60 - kern_offset;
212 
213 	if (diff != 0) {
214 #ifdef DEBUG
215 		fprintf(stderr, "Initial diff: %ld secs\n", diff);
216 #endif
217 		/* Yet one step for final time */
218 
219 		final_sec = initial_sec + diff;
220 
221 		/* get the actual local timezone difference */
222 		local = *localtime(&final_sec);
223 		final_isdst = diff < 0 ? initial_isdst : local.tm_isdst;
224 		if (diff > 0 && initial_isdst != final_isdst) {
225 			if (looping)
226 				goto bad_final;
227 			looping = True;
228 			initial_isdst = final_isdst;
229 			goto recalculate;
230 		}
231 		local.tm_isdst =  final_isdst;
232 
233 		localsec = mktime(&local);
234 		if (localsec == -1) {
235 		bad_final:
236 			/*
237 			 * XXX as above.  The user has even less control,
238 			 * but perhaps we never get here.
239 			 */
240 			if (!sleep_mode) {
241 				syslog(LOG_WARNING,
242 					"Warning: nonexistent final local time, try to run later.");
243 				syslog(LOG_WARNING, "Giving up.");
244 				return 1;
245 			}
246 			syslog(LOG_WARNING,
247 				"Warning: nonexistent final local time.");
248 			syslog(LOG_WARNING, "Will retry after %d minutes.",
249 				REPORT_PERIOD / 60);
250 			(void) signal(SIGTERM, SIG_DFL);
251 			(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
252 			(void) sleep(REPORT_PERIOD);
253 			goto again;
254 		}
255 		offset = -local.tm_gmtoff;
256 #ifdef DEBUG
257 		fprintf(stderr, "Final offset: %ld secs\n", offset);
258 #endif
259 
260 		/* correct the kerneltime for this diffs */
261 		/* subtract kernel offset, if present, old offset too */
262 
263 		diff = offset - tz.tz_minuteswest * 60 - kern_offset;
264 
265 		if (diff != 0) {
266 #ifdef DEBUG
267 			fprintf(stderr, "Final diff: %ld secs\n", diff);
268 #endif
269 			/*
270 			 * stv is abused as a flag.  The important value
271 			 * is in `diff'.
272 			 */
273 			stv = &tv;
274 		}
275 	}
276 
277 	if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
278 		tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
279 		stz = &tz;
280 	}
281 	if (!wall_clock && stz == NULL)
282 		stv = NULL;
283 
284 	/* if init or UTC clock and offset/date will be changed, */
285 	/* disable RTC modification for a while.                      */
286 
287 	if (   (init && stv != NULL)
288 	    || ((init || !wall_clock) && kern_offset != offset)
289 	   ) {
290 		mib[0] = CTL_MACHDEP;
291 		mib[1] = CPU_DISRTCSET;
292 		len = sizeof(disrtcset);
293 		if (sysctl(mib, 2, &disrtcset, &len, NULL, 0) == -1) {
294 			syslog(LOG_ERR, "sysctl(get_disrtcset): %m");
295 			return 1;
296 		}
297 		if (disrtcset == 0) {
298 			disrtcset = 1;
299 			need_restore = True;
300 			if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
301 				syslog(LOG_ERR, "sysctl(set_disrtcset): %m");
302 				return 1;
303 			}
304 		}
305 	}
306 
307 	if (   (init && (stv != NULL || stz != NULL))
308 	    || (stz != NULL && stv == NULL)
309 	   ) {
310 		if (stv != NULL) {
311 			/*
312 			 * Get the time again, as close as possible to
313 			 * adjusting it, to minimise drift.
314 			 * XXX we'd better not fail between here and
315 			 * restoring disrtcset, since we don't clean up
316 			 * anything.
317 			 */
318 			if (gettimeofday(&tv, (struct timezone *)NULL)) {
319 				syslog(LOG_ERR, "gettimeofday: %m");
320 				return 1;
321 			}
322 			tv.tv_sec += diff;
323 			stv = &tv;
324 		}
325 		if (settimeofday(stv, stz)) {
326 			syslog(LOG_ERR, "settimeofday: %m");
327 			return 1;
328 		}
329 	}
330 
331 	/* setting CPU_ADJKERNTZ have a side effect: resettodr(), which */
332 	/* can be disabled by CPU_DISRTCSET, so if init or UTC clock    */
333 	/* -- don't write RTC, else write RTC.                          */
334 
335 	if (kern_offset != offset) {
336 		kern_offset = offset;
337 		mib[0] = CTL_MACHDEP;
338 		mib[1] = CPU_ADJKERNTZ;
339 		len = sizeof(kern_offset);
340 		if (sysctl(mib, 2, NULL, NULL, &kern_offset, len) == -1) {
341 			syslog(LOG_ERR, "sysctl(update_offset): %m");
342 			return 1;
343 		}
344 	}
345 
346 	mib[0] = CTL_MACHDEP;
347 	mib[1] = CPU_WALLCLOCK;
348 	len = sizeof(wall_clock);
349 	if (sysctl(mib, 2, NULL, NULL, &wall_clock, len) == -1) {
350 		syslog(LOG_ERR, "sysctl(put_wallclock): %m");
351 		return 1;
352 	}
353 
354 	if (need_restore) {
355 		need_restore = False;
356 		mib[0] = CTL_MACHDEP;
357 		mib[1] = CPU_DISRTCSET;
358 		disrtcset = 0;
359 		len = sizeof(disrtcset);
360 		if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
361 			syslog(LOG_ERR, "sysctl(restore_disrtcset): %m");
362 			return 1;
363 		}
364 	}
365 
366 /****** End of critical section ******/
367 
368 	if (init && wall_clock) {
369 		sleep_mode = False;
370 		/* wait for signals and acts like -a */
371 		(void) sigsuspend(&emask);
372 		goto again;
373 	}
374 
375 	return 0;
376 }
377 
378 static void
379 usage()
380 {
381 	fprintf(stderr, "%s\n%s\n%s\n%s\n",
382 		"usage: adjkerntz -i",
383 		"\t\t(initial call from /etc/rc)",
384 		"       adjkerntz -a [-s]",
385 		"\t\t(adjustment call, -s for sleep/retry mode)");
386 	exit(2);
387 }
388