adjkerntz.c revision 882
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 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 49#include "pathnames.h" 50 51char storage[] = _PATH_OFFSET; 52 53int 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; 62 time_t final_sec; 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) { 129 fprintf(stderr, "Wrong initial hour to call\n"); 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 */ 136 137 diff = offset - tz.tz_minuteswest * 60 - oldoffset; 138 139 if (diff != 0) { 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; 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} 210 211