xref: /dragonfly/sbin/adjkerntz/adjkerntz.c (revision ed36d35d) 
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  * @(#)Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia. All rights reserved.
27  * $FreeBSD: src/sbin/adjkerntz/adjkerntz.c,v 1.25.2.1 2001/07/30 10:38:04 dd Exp $
28  * $DragonFly: src/sbin/adjkerntz/adjkerntz.c,v 1.6 2005/11/06 12:03:15 swildner Exp $
29  */
30 
31 /*
32  * Andrey A. Chernov   <ache@astral.msk.su>    Dec 20 1993
33  *
34  * Fix kernel time value if machine run wall CMOS clock
35  * (and /etc/wall_cmos_clock file present)
36  * using zoneinfo rules or direct TZ environment variable set.
37  * Use Joerg Wunsch idea for seconds accurate offset calculation
38  * with Garrett Wollman and Bruce Evans fixes.
39  *
40  */
41 #include <stdio.h>
42 #include <signal.h>
43 #include <stdlib.h>
44 #include <unistd.h>
45 #include <syslog.h>
46 #include <sys/time.h>
47 #include <sys/param.h>
48 #include <machine/cpu.h>
49 #include <sys/sysctl.h>
50 
51 #include "pathnames.h"
52 
53 /*#define DEBUG*/
54 
55 #define True (1)
56 #define False (0)
57 #define Unknown (-1)
58 
59 #define REPORT_PERIOD (30*60)
60 
61 static void fake(int);
62 static void usage(void);
63 
64 static void
65 fake(int unused __unused)
66 {
67 
68 	/* Do nothing. */
69 }
70 
71 int
72 main(int argc, 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 	signal(SIGHUP, SIG_IGN);
123 
124 	if (init && daemon(0, 1)) {
125 		syslog(LOG_ERR, "daemon: %m");
126 		return 1;
127 	}
128 
129 again:
130 	sigprocmask(SIG_BLOCK, &mask, NULL);
131 	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 
164 recalculate:
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 		signal(SIGTERM, SIG_DFL);
190 		sigprocmask(SIG_UNBLOCK, &mask, NULL);
191 		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 			signal(SIGTERM, SIG_DFL);
242 			sigprocmask(SIG_UNBLOCK, &mask, NULL);
243 			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, 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 		sigsuspend(&emask);
363 		goto again;
364 	}
365 
366 	return 0;
367 }
368 
369 static void
370 usage(void)
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