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 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 /* 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 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 or worse */ 61 long offset, oldoffset, utcsec, localsec, diff; 62 time_t initial_sec, 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, "Misformatted offset in %s\n", 103 storage); 104 return 1; 105 } 106 (void) fclose(f); 107 } 108 else 109 oldoffset = 0; 110 111 /****** Critical section, do all things as fast as possible ******/ 112 113 /* get local CMOS clock and possible kernel offset */ 114 if (gettimeofday(&tv, &tz)) { 115 perror("gettimeofday"); 116 return 1; 117 } 118 119 /* get the actual local timezone difference */ 120 initial_sec = tv.tv_sec; 121 local = *localtime(&initial_sec); 122 utc = *gmtime(&initial_sec); 123 utc.tm_isdst = local.tm_isdst; /* Use current timezone for mktime(), */ 124 /* because it assumed local time */ 125 126 /* calculate local CMOS diff from GMT */ 127 128 utcsec = mktime(&utc); 129 localsec = mktime(&local); 130 if (utcsec == -1 || localsec == -1) { 131 /* 132 * XXX user can only control local time, and it is 133 * unacceptable to fail here for -i. 2:30 am in the 134 * middle of the nonexistent hour means 3:30 am. 135 */ 136 fprintf(stderr, 137 "Nonexistent local time - try again in an hour\n"); 138 return 1; 139 } 140 offset = utcsec - localsec; 141 142 /* correct the kerneltime for this diffs */ 143 /* subtract kernel offset, if present, old offset too */ 144 145 diff = offset - tz.tz_minuteswest * 60 - oldoffset; 146 147 if (diff != 0) { 148 149 /* Yet one step for final time */ 150 151 final_sec = tv.tv_sec + diff; 152 153 /* get the actual local timezone difference */ 154 local = *localtime(&final_sec); 155 utc = *gmtime(&final_sec); 156 utc.tm_isdst = local.tm_isdst; /* Use current timezone for mktime(), */ 157 /* because it assumed local time */ 158 159 utcsec = mktime(&utc); 160 localsec = mktime(&local); 161 if (utcsec == -1 || localsec == -1) { 162 /* 163 * XXX as above. The user has even less control, 164 * but perhaps we never get here. 165 */ 166 fprintf(stderr, 167 "Nonexistent (final) local time - try again in an hour\n"); 168 return 1; 169 } 170 offset = utcsec - localsec; 171 172 /* correct the kerneltime for this diffs */ 173 /* subtract kernel offset, if present, old offset too */ 174 175 diff = offset - tz.tz_minuteswest * 60 - oldoffset; 176 177 if (diff != 0) { 178 tv.tv_sec += diff; 179 tv.tv_usec = 0; /* we are restarting here... */ 180 stv = &tv; 181 } 182 else 183 stv = NULL; 184 } 185 else 186 stv = NULL; 187 188 if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) { 189 tz.tz_dsttime = tz.tz_minuteswest = 0; /* zone info is garbage */ 190 stz = &tz; 191 } 192 else 193 stz = NULL; 194 195 if (stz != NULL || stv != NULL) { 196 if (settimeofday(stv, stz)) { 197 perror("settimeofday"); 198 return 1; 199 } 200 } 201 202 /****** End of critical section ******/ 203 204 if (verbose) 205 printf("Calculated zone offset difference: %ld seconds\n", 206 diff); 207 208 if (offset != oldoffset) { 209 (void) umask(022); 210 /* Save offset for next calls from crontab */ 211 if ((f = fopen(storage, "w")) == NULL) { 212 perror(storage); 213 return 1; 214 } 215 fprintf(f, "%ld\n", offset); 216 if (fclose(f)) { 217 perror(storage); 218 return 1; 219 } 220 } 221 222 return 0; 223 } 224 225