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/*
* 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 15 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;
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 hour to call\n");
return 1;
}
offset = utcsec - localsec;
/* correct the kerneltime for this diffs */
/* subtract kernel offset, if present, old offset too */
diff = oldoffset + tz.tz_minuteswest * 60 - offset;
if (diff != 0) {
tv.tv_sec += diff;
tv.tv_usec = 0; /* we are restarting here... */
stv = &tv;
}
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;
}
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