[unix-history] / sbin / adjkerntz / adjkerntz.c

/*
 * Copyright (C) 1993 by Andrew 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 DEVELOPERS ``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 by Andrew A. Chernov, Moscow, Russia.\n\
 All rights reserved.\n";
#endif /* not lint */

/*
 * Andrew 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 <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/time.h>

#include "pathnames.h"

char storage[] = _PATH_OFFSET;

int main(argc, argv)
	int argc;
	char **argv;
{
	struct tm local, utc;
	struct timeval tv, *stv;
	struct timezone tz, *stz;
	/* Avoid time_t here, can be unsigned long */
	long offset, oldoffset, utcsec, localsec, diff;
	time_t final_sec;
	int ch, init = -1, verbose = 0;
	FILE *f;

	while ((ch = getopt(argc, argv, "aiv")) != 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;
		case 'v':               /* verbose */
			verbose = 1;
			break;
		default:
		usage:
			fprintf(stderr, "Usage:\n\
\tadjkerntz -i [-v]\t(initial call from /etc/rc)\n\
\tadjkerntz -a [-v]\t(adjustment call from crontab)\n");
			return 2;
		}
	if (init == -1)
		goto usage;

	if (access(_PATH_CLOCK, F_OK))
		return 0;

	/* Restore saved offset */

	if (!init) {
		if ((f = fopen(storage, "r")) == NULL) {
			perror(storage);
			return 1;
		}
		if (fscanf(f, "%ld", &oldoffset) != 1) {
			fprintf(stderr, "Incorrect offset in %s\n", storage);
			return 1;
		}
		(void) fclose(f);
	}
	else
		oldoffset = 0;

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

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

	/* get the actual local timezone difference */
	local = *localtime(&tv.tv_sec);
	utc = *gmtime(&tv.tv_sec);
	utc.tm_isdst = local.tm_isdst; /* Use current timezone for mktime(), */
				       /* because it assumed local time */

	/* calculate local CMOS diff from GMT */

	utcsec = mktime(&utc);
	localsec = mktime(&local);
	if (utcsec == -1 || localsec == -1) {
		fprintf(stderr, "Wrong initial hour to call\n");
		return 1;
	}
	offset = utcsec - localsec;

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

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

	if (diff != 0) {

		/* Yet one step for final time */

		final_sec = tv.tv_sec + diff;

		/* get the actual local timezone difference */
		local = *localtime(&final_sec);
		utc = *gmtime(&final_sec);
		utc.tm_isdst = local.tm_isdst; /* Use current timezone for mktime(), */
					       /* because it assumed local time */

		utcsec = mktime(&utc);
		localsec = mktime(&local);
		if (utcsec == -1 || localsec == -1) {
			fprintf(stderr, "Wrong final hour to call\n");
			return 1;
		}
		offset = utcsec - localsec;

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

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

		if (diff != 0) {
			tv.tv_sec += diff;
			tv.tv_usec = 0;       /* we are restarting here... */
			stv = &tv;
		}
		else
			stv = NULL;
	}
	else
		stv = NULL;

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

	if (stz != NULL || stv != NULL) {
		if (settimeofday(stv, stz)) {
			perror("settimeofday");
			return 1;
		}
	}

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

	if (verbose)
		printf("Calculated zone offset diffs: %ld seconds\n", diff);

	if (offset != oldoffset) {
		(void) umask(022);
		/* Save offset for next calls from crontab */
		if ((f = fopen(storage, "w")) == NULL) {
			perror(storage);
			return 1;
		}
		fprintf(f, "%ld\n", offset);
		if (fclose(f)) {
			perror(storage);
			return 1;
		}
	}

	return 0;
}
Commit	Line	Data
7cb69b29 AC	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 DEVELOPERS ``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	char copyright[] =
	29	"@(#)Copyright (C) 1993 by Andrew A. Chernov, Moscow, Russia.\n\
	30	All rights reserved.\n";
	31	#endif /* not lint */
	32
	33	/*
89703544	34	* Andrew A. Chernov <ache@astral.msk.su> Dec 20 1993
7cb69b29 AC	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
	49	#include "pathnames.h"
	50
	51	char storage[] = _PATH_OFFSET;
	52
	53	int main(argc, argv)
	54	int argc;
	55	char **argv;
	56	{
	57	struct tm local, utc;
	58	struct timeval tv, *stv;
	59	struct timezone tz, *stz;
	60	/* Avoid time_t here, can be unsigned long */
	61	long offset, oldoffset, utcsec, localsec, diff;
89703544	62	time_t final_sec;
7cb69b29 AC	63	int ch, init = -1, verbose = 0;
	64	FILE *f;
	65
	66	while ((ch = getopt(argc, argv, "aiv")) != EOF)
	67	switch((char)ch) {
	68	case 'i': /* initial call, save offset */
	69	if (init != -1)
	70	goto usage;
	71	init = 1;
	72	break;
	73	case 'a': /* adjustment call, use saved offset */
	74	if (init != -1)
	75	goto usage;
	76	init = 0;
	77	break;
	78	case 'v': /* verbose */
	79	verbose = 1;
	80	break;
	81	default:
	82	usage:
	83	fprintf(stderr, "Usage:\n\
	84	\tadjkerntz -i [-v]\t(initial call from /etc/rc)\n\
	85	\tadjkerntz -a [-v]\t(adjustment call from crontab)\n");
	86	return 2;
	87	}
	88	if (init == -1)
	89	goto usage;
	90
	91	if (access(_PATH_CLOCK, F_OK))
	92	return 0;
	93
	94	/* Restore saved offset */
	95
	96	if (!init) {
	97	if ((f = fopen(storage, "r")) == NULL) {
	98	perror(storage);
	99	return 1;
	100	}
	101	if (fscanf(f, "%ld", &oldoffset) != 1) {
	102	fprintf(stderr, "Incorrect offset in %s\n", storage);
	103	return 1;
	104	}
	105	(void) fclose(f);
	106	}
	107	else
	108	oldoffset = 0;
	109
	110	/**** Critical section, do all things as fast as possible ****/
	111
	112	/* get local CMOS clock and possible kernel offset */
	113	if (gettimeofday(&tv, &tz)) {
	114	perror("gettimeofday");
	115	return 1;
	116	}
	117
	118	/* get the actual local timezone difference */
	119	local = *localtime(&tv.tv_sec);
	120	utc = *gmtime(&tv.tv_sec);
	121	utc.tm_isdst = local.tm_isdst; /* Use current timezone for mktime(), */
	122	/* because it assumed local time */
	123
	124	/* calculate local CMOS diff from GMT */
	125
	126	utcsec = mktime(&utc);
127	localsec = mktime(&local);
128	if (utcsec == -1 \|\| localsec == -1) {
89703544	129	fprintf(stderr, "Wrong initial hour to call\n");
7cb69b29 AC	130	return 1;
	131	}
	132	offset = utcsec - localsec;
	133
	134	/* correct the kerneltime for this diffs */
	135	/* subtract kernel offset, if present, old offset too */
	136
89703544 AC	137	diff = offset - tz.tz_minuteswest * 60 - oldoffset;
89703544 AC	138
7cb69b29	139	if (diff != 0) {
89703544 AC	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	fprintf(stderr, "Wrong final hour to call\n");
	155	return 1;
	156	}
	157	offset = utcsec - localsec;
	158
	159	/* correct the kerneltime for this diffs */
	160	/* subtract kernel offset, if present, old offset too */
	161
	162	diff = offset - tz.tz_minuteswest * 60 - oldoffset;
	163
	164	if (diff != 0) {
	165	tv.tv_sec += diff;
	166	tv.tv_usec = 0; /* we are restarting here... */
	167	stv = &tv;
	168	}
	169	else
	170	stv = NULL;
7cb69b29 AC	171	}
	172	else
	173	stv = NULL;
	174
	175	if (tz.tz_dsttime != 0 \|\| tz.tz_minuteswest != 0) {
	176	tz.tz_dsttime = tz.tz_minuteswest = 0; /* zone info is garbage */
	177	stz = &tz;
	178	}
	179	else
	180	stz = NULL;
	181
	182	if (stz != NULL \|\| stv != NULL) {
	183	if (settimeofday(stv, stz)) {
	184	perror("settimeofday");
	185	return 1;
	186	}
	187	}
	188
	189	/**** End of critical section ****/
	190
	191	if (verbose)
	192	printf("Calculated zone offset diffs: %ld seconds\n", diff);
	193
	194	if (offset != oldoffset) {
	195	(void) umask(022);
	196	/* Save offset for next calls from crontab */
	197	if ((f = fopen(storage, "w")) == NULL) {
	198	perror(storage);
	199	return 1;
	200	}
	201	fprintf(f, "%ld\n", offset);
	202	if (fclose(f)) {
	203	perror(storage);
	204	return 1;
	205	}
	206	}
	207
	208	return 0;
	209	}
	210