adjkerntz.c revision 4039 
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 <sys/stat.h>
47#include <sys/time.h>
48#include <sys/param.h>
49#include <machine/cpu.h>
50#include <sys/sysctl.h>
51
52#include "pathnames.h"
53
54int main(argc, argv)
55	int argc;
56	char **argv;
57{
58	struct tm local, utc;
59	struct timeval tv, *stv;
60	struct timezone tz, *stz;
61	int kern_offset;
62	size_t len;
63	int mib[2];
64	/* Avoid time_t here, can be unsigned long or worse */
65	long offset, utcsec, localsec, diff;
66	time_t initial_sec, final_sec;
67	int ch, init = -1, verbose = 0;
68	int disrtcset, need_restore = 0;
69
70	while ((ch = getopt(argc, argv, "aiv")) != EOF)
71		switch((char)ch) {
72		case 'i':               /* initial call, save offset */
73			if (init != -1)
74				goto usage;
75			init = 1;
76			break;
77		case 'a':               /* adjustment call, use saved offset */
78			if (init != -1)
79				goto usage;
80			init = 0;
81			break;
82		case 'v':               /* verbose */
83			verbose = 1;
84			break;
85		default:
86		usage:
87			fprintf(stderr, "Usage:\n\
88\tadjkerntz -i [-v]\t(initial call from /etc/rc)\n\
89\tadjkerntz -a [-v]\t(adjustment call from crontab)\n");
90			return 2;
91		}
92	if (init == -1)
93		goto usage;
94
95	if (access(_PATH_CLOCK, F_OK))
96		return 0;
97
98	/* Restore saved offset */
99
100	mib[0] = CTL_MACHDEP;
101	mib[1] = CPU_ADJKERNTZ;
102	len = sizeof(kern_offset);
103	if (sysctl(mib, 2, &kern_offset, &len, NULL, 0) == -1) {
104		perror("sysctl(get_offset)");
105		return 1;
106	}
107
108/****** Critical section, do all things as fast as possible ******/
109
110	/* get local CMOS clock and possible kernel offset */
111	if (gettimeofday(&tv, &tz)) {
112		perror("gettimeofday");
113		return 1;
114	}
115
116	/* get the actual local timezone difference */
117	initial_sec = tv.tv_sec;
118	local = *localtime(&initial_sec);
119	utc = *gmtime(&initial_sec);
120	utc.tm_isdst = local.tm_isdst; /* Use current timezone for mktime(), */
121				       /* because it assumed local time */
122
123	/* calculate local CMOS diff from GMT */
124
125	utcsec = mktime(&utc);
126	localsec = mktime(&local);
127	if (utcsec == -1 || localsec == -1) {
128		/*
129		 * XXX user can only control local time, and it is
130		 * unacceptable to fail here for -i.  2:30 am in the
131		 * middle of the nonexistent hour means 3:30 am.
132		 */
133		fprintf(stderr,
134			"Nonexistent local time - try again in an hour\n");
135		return 1;
136	}
137	offset = utcsec - localsec;
138
139	/* correct the kerneltime for this diffs */
140	/* subtract kernel offset, if present, old offset too */
141
142	diff = offset - tz.tz_minuteswest * 60 - kern_offset;
143
144	if (diff != 0) {
145
146		/* Yet one step for final time */
147
148		final_sec = tv.tv_sec + diff;
149
150		/* get the actual local timezone difference */
151		local = *localtime(&final_sec);
152		utc = *gmtime(&final_sec);
153		utc.tm_isdst = local.tm_isdst; /* Use current timezone for mktime(), */
154					       /* because it assumed local time */
155
156		utcsec = mktime(&utc);
157		localsec = mktime(&local);
158		if (utcsec == -1 || localsec == -1) {
159			/*
160			 * XXX as above.  The user has even less control,
161			 * but perhaps we never get here.
162			 */
163			fprintf(stderr,
164		"Nonexistent (final) local time - try again in an hour\n");
165			return 1;
166		}
167		offset = utcsec - localsec;
168
169		/* correct the kerneltime for this diffs */
170		/* subtract kernel offset, if present, old offset too */
171
172		diff = offset - tz.tz_minuteswest * 60 - kern_offset;
173
174		if (diff != 0) {
175			tv.tv_sec += diff;
176			tv.tv_usec = 0;       /* we are restarting here... */
177			stv = &tv;
178		}
179		else
180			stv = NULL;
181	}
182	else
183		stv = NULL;
184
185	if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
186		tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
187		stz = &tz;
188	}
189	else
190		stz = NULL;
191
192	if (stz != NULL || stv != NULL) {
193		if (init && stv != NULL) {
194			mib[0] = CTL_MACHDEP;
195			mib[1] = CPU_DISRTCSET;
196			len = sizeof(disrtcset);
197			if (sysctl(mib, 2, &disrtcset, &len, NULL, 0) == -1) {
198				perror("sysctl(get_disrtcset)");
199				return 1;
200			}
201			if (disrtcset == 0) {
202				disrtcset = 1;
203				need_restore = 1;
204				if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
205					perror("sysctl(set_disrtcset)");
206					return 1;
207				}
208			}
209		}
210		if ((init || stv == NULL) && settimeofday(stv, stz)) {
211			perror("settimeofday");
212			return 1;
213		}
214	}
215
216	if (kern_offset != offset) {
217		kern_offset = offset;
218		mib[0] = CTL_MACHDEP;
219		mib[1] = CPU_ADJKERNTZ;
220		len = sizeof(kern_offset);
221		if (sysctl(mib, 2, NULL, NULL, &kern_offset, len) == -1) {
222			perror("sysctl(update_offset)");
223			return 1;
224		}
225	}
226
227	if (need_restore) {
228		disrtcset = 0;
229		if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
230			perror("sysctl(restore_disrtcset)");
231			return 1;
232		}
233	}
234
235/****** End of critical section ******/
236
237	if (verbose)
238		printf("Calculated zone offset difference: %ld seconds\n",
239		       diff);
240
241	return 0;
242}
243
244