summaryrefslogtreecommitdiffstats
path: root/sbin/adjkerntz/adjkerntz.c
blob: d5e10f87719359dbac3e66b66498fafcfb2cbcea (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
/*
 * Copyright (C) 1993, 1994, 1995 by Andrey A. Chernov, Moscow, Russia.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
char copyright[] =
"@(#)Copyright (C) 1993, 1994, 1995 by Andrey A. Chernov, Moscow, Russia.\n\
 All rights reserved.\n";
#endif /* not lint */

/*
 * Andrey A. Chernov   <ache@astral.msk.su>    Dec 20 1993
 *
 * Fix kernel time value if machine run wall CMOS clock
 * (and /etc/wall_cmos_clock file present)
 * using zoneinfo rules or direct TZ environment variable set.
 * Use Joerg Wunsch idea for seconds accurate offset calculation
 * with Garrett Wollman and Bruce Evans fixes.
 *
 */
#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <syslog.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/param.h>
#include <machine/cpu.h>
#include <sys/sysctl.h>

#include "pathnames.h"

/*#define DEBUG*/
#define REPORT_PERIOD (30*60)

void fake() {}

int main(argc, argv)
	int argc;
	char **argv;
{
	struct tm local, utc;
	struct timeval tv, *stv;
	struct timezone tz, *stz;
	int kern_offset;
	size_t len;
	int mib[2];
	/* Avoid time_t here, can be unsigned long or worse */
	long offset, utcsec, localsec, diff;
	time_t initial_sec, final_sec;
	int ch, init = -1;
	int initial_isdst = -1, final_isdst, looping;
	int disrtcset, need_restore = 0;
	sigset_t mask, emask;

	while ((ch = getopt(argc, argv, "ai")) != EOF)
		switch((char)ch) {
		case 'i':               /* initial call, save offset */
			if (init != -1)
				goto usage;
			init = 1;
			break;
		case 'a':               /* adjustment call, use saved offset */
			if (init != -1)
				goto usage;
			init = 0;
			break;
		default:
		usage:
			fprintf(stderr, "Usage:\n\
\tadjkerntz -i\t(initial call from /etc/rc)\n\
\tadjkerntz -a\t(adjustment call from crontab)\n");
  			return 2;
		}
	if (init == -1)
		goto usage;
  
	if (access(_PATH_CLOCK, F_OK))
		return 0;

	sigemptyset(&mask);
	sigemptyset(&emask);
	sigaddset(&mask, SIGTERM);

	openlog("adjkerntz", LOG_PID|LOG_PERROR, LOG_DAEMON);

	(void) signal(SIGHUP, SIG_IGN);

	if (init && daemon(0, 1)) {
		syslog(LOG_ERR, "daemon: %m");
		return 1;
	}

again:

	(void) sigprocmask(SIG_BLOCK, &mask, NULL);
	(void) signal(SIGTERM, fake);

	diff = 0;
	stv = NULL;
	stz = NULL;
	looping = 0;

	mib[0] = CTL_MACHDEP;
	mib[1] = CPU_ADJKERNTZ;
	len = sizeof(kern_offset);
	if (sysctl(mib, 2, &kern_offset, &len, NULL, 0) == -1) {
		syslog(LOG_ERR, "sysctl(get_offset): %m");
		return 1;
	}

/****** Critical section, do all things as fast as possible ******/

	/* get local CMOS clock and possible kernel offset */
	if (gettimeofday(&tv, &tz)) {
		syslog(LOG_ERR, "gettimeofday: %m");
		return 1;
	}

	/* get the actual local timezone difference */
	initial_sec = tv.tv_sec;

recalculate:
	local = *localtime(&initial_sec);
	if (diff == 0)
		initial_isdst = local.tm_isdst;
	utc = *gmtime(&initial_sec);
	local.tm_isdst = utc.tm_isdst = initial_isdst;

	/* calculate local CMOS diff from GMT */

	utcsec = mktime(&utc);
	localsec = mktime(&local);
	if (utcsec == -1 || localsec == -1) {
		/*
		 * XXX user can only control local time, and it is
		 * unacceptable to fail here for init.  2:30 am in the
		 * middle of the nonexistent hour means 3:30 am.
		 */
		syslog(LOG_WARNING,
		"Nonexistent local time -- will retry after %d secs", REPORT_PERIOD);
		(void) signal(SIGTERM, SIG_DFL);
		(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
		(void) sleep(REPORT_PERIOD);
		goto again;
	}
	offset = utcsec - localsec;
#ifdef DEBUG
	fprintf(stderr, "Initial offset: %ld secs\n", offset);
#endif

	/* correct the kerneltime for this diffs */
	/* subtract kernel offset, if present, old offset too */

	diff = offset - tz.tz_minuteswest * 60 - kern_offset;

	if (diff != 0) {
#ifdef DEBUG
		fprintf(stderr, "Initial diff: %ld secs\n", diff);
#endif
		/* Yet one step for final time */

		final_sec = initial_sec + diff;

		/* get the actual local timezone difference */
		local = *localtime(&final_sec);
		final_isdst = diff < 0 ? initial_isdst : local.tm_isdst;
		if (diff > 0 && initial_isdst != final_isdst) {
			if (looping)
				goto bad_final;
			looping++;
			initial_isdst = final_isdst;
			goto recalculate;
		}
		utc = *gmtime(&final_sec);
		local.tm_isdst = utc.tm_isdst = final_isdst;

		utcsec = mktime(&utc);
		localsec = mktime(&local);
		if (utcsec == -1 || localsec == -1) {
		bad_final:
			/*
			 * XXX as above.  The user has even less control,
			 * but perhaps we never get here.
			 */
			syslog(LOG_WARNING,
		"Nonexistent (final) local time -- will retry after %d secs", REPORT_PERIOD);
			(void) signal(SIGTERM, SIG_DFL);
			(void) sigprocmask(SIG_UNBLOCK, &mask, NULL);
			(void) sleep(REPORT_PERIOD);
			goto again;
		}
		offset = utcsec - localsec;
#ifdef DEBUG
		fprintf(stderr, "Final offset: %ld secs\n", offset);
#endif

		/* correct the kerneltime for this diffs */
		/* subtract kernel offset, if present, old offset too */

		diff = offset - tz.tz_minuteswest * 60 - kern_offset;

		if (diff != 0) {
#ifdef DEBUG
			fprintf(stderr, "Final diff: %ld secs\n", diff);
#endif
			tv.tv_sec += diff;
			tv.tv_usec = 0;       /* we are restarting here... */
			stv = &tv;
		}
	}

	if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
		tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
		stz = &tz;
	}

	/* if init and something will be changed, don't touch RTC at all */
	if (init && (stv != NULL || kern_offset != offset)) {
		mib[0] = CTL_MACHDEP;
		mib[1] = CPU_DISRTCSET;
		len = sizeof(disrtcset);
		if (sysctl(mib, 2, &disrtcset, &len, NULL, 0) == -1) {
			syslog(LOG_ERR, "sysctl(get_disrtcset): %m");
			return 1;
		}
		if (disrtcset == 0) {
			disrtcset = 1;
			need_restore = 1;
			if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
				syslog(LOG_ERR, "sysctl(set_disrtcset): %m");
				return 1;
			}
		}
	}

	if ((   (init && (stv != NULL || stz != NULL))
	     || (stz != NULL && stv == NULL)
	    )
	    && settimeofday(stv, stz)
	   ) {
		syslog(LOG_ERR, "settimeofday: %m");
		return 1;
	}

	/* init: don't write RTC, !init: write RTC */
	if (kern_offset != offset) {
		kern_offset = offset;
		mib[0] = CTL_MACHDEP;
		mib[1] = CPU_ADJKERNTZ;
		len = sizeof(kern_offset);
		if (sysctl(mib, 2, NULL, NULL, &kern_offset, len) == -1) {
			syslog(LOG_ERR, "sysctl(update_offset): %m");
			return 1;
		}
	}

	if (need_restore) {
		need_restore = 0;
		mib[0] = CTL_MACHDEP;
		mib[1] = CPU_DISRTCSET;
		disrtcset = 0;
		len = sizeof(disrtcset);
		if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
			syslog(LOG_ERR, "sysctl(restore_disrtcset): %m");
			return 1;
		}
	}

/****** End of critical section ******/

	if (init) {
		init = 0;
		/* wait for signals and acts like -a */
		(void) sigsuspend(&emask);
		goto again;
	}

	return 0;
}
OpenPOWER on IntegriCloud