sbin/adjkerntz/adjkerntz.c

   1 /*
   2  * Copyright (C) 1993-1998 by Andrey 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  * @(#)Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia. All rights reserved.
  27  * $FreeBSD: src/sbin/adjkerntz/adjkerntz.c,v 1.25.2.1 2001/07/30 10:38:04 dd Exp $
  28  * $DragonFly: src/sbin/adjkerntz/adjkerntz.c,v 1.6 2005/11/06 12:03:15 swildner Exp $
  29  */
  30
  31 /*
  32  * Andrey A. Chernov   <ache@astral.msk.su>    Dec 20 1993
  33  *
  34  * Fix kernel time value if machine run wall CMOS clock
  35  * (and /etc/wall_cmos_clock file present)
  36  * using zoneinfo rules or direct TZ environment variable set.
  37  * Use Joerg Wunsch idea for seconds accurate offset calculation
  38  * with Garrett Wollman and Bruce Evans fixes.
  39  *
  40  */
  41 #include <stdio.h>
  42 #include <signal.h>
  43 #include <stdlib.h>
  44 #include <unistd.h>
  45 #include <syslog.h>
  46 #include <sys/time.h>
  47 #include <sys/param.h>
  48 #include <machine/cpu.h>
  49 #include <sys/sysctl.h>
  50
  51 #include "pathnames.h"
  52
  53 /*#define DEBUG*/
  54
  55 #define True (1)
  56 #define False (0)
  57 #define Unknown (-1)
  58
  59 #define REPORT_PERIOD (30*60)
  60
  61 static void fake(int);
  62 static void usage(void);
  63
  64 static void
  65 fake(int unused __unused)
  66 {
  67
  68         /* Do nothing. */
  69 }
  70
  71 int
  72 main(int argc, char **argv)
  73 {
  74         struct tm local;
  75         struct timeval tv, *stv;
  76         struct timezone tz, *stz;
  77         int kern_offset, wall_clock, disrtcset;
  78         size_t len;
  79         int mib[2];
  80         /* Avoid time_t here, can be unsigned long or worse */
  81         long offset, localsec, diff;
  82         time_t initial_sec, final_sec;
  83         int ch;
  84         int initial_isdst = -1, final_isdst;
  85         int need_restore = False, sleep_mode = False, looping,
  86             init = Unknown;
  87         sigset_t mask, emask;
  88
  89         while ((ch = getopt(argc, argv, "ais")) != -1)
  90                 switch((char)ch) {
  91                 case 'i':               /* initial call, save offset */
  92                         if (init != Unknown)
  93                                 usage();
  94                         init = True;
  95                         break;
  96                 case 'a':               /* adjustment call, use saved offset */
  97                         if (init != Unknown)
  98                                 usage();
  99                         init = False;
 100                         break;
 101                 case 's':
 102                         sleep_mode = True;
 103                         break;
 104                 default:
 105                         usage();
 106                 }
 107         if (init == Unknown)
 108                 usage();
 109
 110         if (access(_PATH_CLOCK, F_OK) != 0)
 111                 return 0;
 112
 113         if (init)
 114                 sleep_mode = True;
 115
 116         sigemptyset(&mask);
 117         sigemptyset(&emask);
 118         sigaddset(&mask, SIGTERM);
 119
 120         openlog("adjkerntz", LOG_PID|LOG_PERROR, LOG_DAEMON);
 121
 122         signal(SIGHUP, SIG_IGN);
 123
 124         if (init && daemon(0, 1)) {
 125                 syslog(LOG_ERR, "daemon: %m");
 126                 return 1;
 127         }
 128
 129 again:
 130         sigprocmask(SIG_BLOCK, &mask, NULL);
 131         signal(SIGTERM, fake);
 132
 133         diff = 0;
 134         stv = NULL;
 135         stz = NULL;
 136         looping = False;
 137
 138         wall_clock = (access(_PATH_CLOCK, F_OK) == 0);
 139         if (init && !sleep_mode) {
 140                 init = False;
 141                 if (!wall_clock)
 142                         return 0;
 143         }
 144
 145         mib[0] = CTL_MACHDEP;
 146         mib[1] = CPU_ADJKERNTZ;
 147         len = sizeof(kern_offset);
 148         if (sysctl(mib, 2, &kern_offset, &len, NULL, 0) == -1) {
 149                 syslog(LOG_ERR, "sysctl(get_offset): %m");
 150                 return 1;
 151         }
 152
 153 /****** Critical section, do all things as fast as possible ******/
 154
 155         /* get local CMOS clock and possible kernel offset */
 156         if (gettimeofday(&tv, &tz)) {
 157                 syslog(LOG_ERR, "gettimeofday: %m");
 158                 return 1;
 159         }
 160
 161         /* get the actual local timezone difference */
 162         initial_sec = tv.tv_sec;
 163
 164 recalculate:
 165         local = *localtime(&initial_sec);
 166         if (diff == 0)
 167                 initial_isdst = local.tm_isdst;
 168         local.tm_isdst = initial_isdst;
 169
 170         /* calculate local CMOS diff from GMT */
 171
 172         localsec = mktime(&local);
 173         if (localsec == -1) {
 174                 /*
 175                  * XXX user can only control local time, and it is
 176                  * unacceptable to fail here for init.  2:30 am in the
 177                  * middle of the nonexistent hour means 3:30 am.
 178                  */
 179                 if (!sleep_mode) {
 180                         syslog(LOG_WARNING,
 181                         "Warning: nonexistent local time, try to run later.");
 182                         syslog(LOG_WARNING, "Giving up.");
 183                         return 1;
 184                 }
 185                 syslog(LOG_WARNING,
 186                         "Warning: nonexistent local time.");
 187                 syslog(LOG_WARNING, "Will retry after %d minutes.",
 188                         REPORT_PERIOD / 60);
 189                 signal(SIGTERM, SIG_DFL);
 190                 sigprocmask(SIG_UNBLOCK, &mask, NULL);
 191                 sleep(REPORT_PERIOD);
 192                 goto again;
 193         }
 194         offset = -local.tm_gmtoff;
 195 #ifdef DEBUG
 196         fprintf(stderr, "Initial offset: %ld secs\n", offset);
 197 #endif
 198
 199         /* correct the kerneltime for this diffs */
 200         /* subtract kernel offset, if present, old offset too */
 201
 202         diff = offset - tz.tz_minuteswest * 60 - kern_offset;
 203
 204         if (diff != 0) {
 205 #ifdef DEBUG
 206                 fprintf(stderr, "Initial diff: %ld secs\n", diff);
 207 #endif
 208                 /* Yet one step for final time */
 209
 210                 final_sec = initial_sec + diff;
 211
 212                 /* get the actual local timezone difference */
 213                 local = *localtime(&final_sec);
 214                 final_isdst = diff < 0 ? initial_isdst : local.tm_isdst;
 215                 if (diff > 0 && initial_isdst != final_isdst) {
 216                         if (looping)
 217                                 goto bad_final;
 218                         looping = True;
 219                         initial_isdst = final_isdst;
 220                         goto recalculate;
 221                 }
 222                 local.tm_isdst =  final_isdst;
 223
 224                 localsec = mktime(&local);
 225                 if (localsec == -1) {
 226                 bad_final:
 227                         /*
 228                          * XXX as above.  The user has even less control,
 229                          * but perhaps we never get here.
 230                          */
 231                         if (!sleep_mode) {
 232                                 syslog(LOG_WARNING,
 233                                         "Warning: nonexistent final local time, try to run later.");
 234                                 syslog(LOG_WARNING, "Giving up.");
 235                                 return 1;
 236                         }
 237                         syslog(LOG_WARNING,
 238                                 "Warning: nonexistent final local time.");
 239                         syslog(LOG_WARNING, "Will retry after %d minutes.",
 240                                 REPORT_PERIOD / 60);
 241                         signal(SIGTERM, SIG_DFL);
 242                         sigprocmask(SIG_UNBLOCK, &mask, NULL);
 243                         sleep(REPORT_PERIOD);
 244                         goto again;
 245                 }
 246                 offset = -local.tm_gmtoff;
 247 #ifdef DEBUG
 248                 fprintf(stderr, "Final offset: %ld secs\n", offset);
 249 #endif
 250
 251                 /* correct the kerneltime for this diffs */
 252                 /* subtract kernel offset, if present, old offset too */
 253
 254                 diff = offset - tz.tz_minuteswest * 60 - kern_offset;
 255
 256                 if (diff != 0) {
 257 #ifdef DEBUG
 258                         fprintf(stderr, "Final diff: %ld secs\n", diff);
 259 #endif
 260                         /*
 261                          * stv is abused as a flag.  The important value
 262                          * is in `diff'.
 263                          */
 264                         stv = &tv;
 265                 }
 266         }
 267
 268         if (tz.tz_dsttime != 0 || tz.tz_minuteswest != 0) {
 269                 tz.tz_dsttime = tz.tz_minuteswest = 0;  /* zone info is garbage */
 270                 stz = &tz;
 271         }
 272         if (!wall_clock && stz == NULL)
 273                 stv = NULL;
 274
 275         /* if init or UTC clock and offset/date will be changed, */
 276         /* disable RTC modification for a while.                      */
 277
 278         if (   (init && stv != NULL)
 279             || ((init || !wall_clock) && kern_offset != offset)
 280            ) {
 281                 mib[0] = CTL_MACHDEP;
 282                 mib[1] = CPU_DISRTCSET;
 283                 len = sizeof(disrtcset);
 284                 if (sysctl(mib, 2, &disrtcset, &len, NULL, 0) == -1) {
 285                         syslog(LOG_ERR, "sysctl(get_disrtcset): %m");
 286                         return 1;
 287                 }
 288                 if (disrtcset == 0) {
 289                         disrtcset = 1;
 290                         need_restore = True;
 291                         if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
 292                                 syslog(LOG_ERR, "sysctl(set_disrtcset): %m");
 293                                 return 1;
 294                         }
 295                 }
 296         }
 297
 298         if (   (init && (stv != NULL || stz != NULL))
 299             || (stz != NULL && stv == NULL)
 300            ) {
 301                 if (stv != NULL) {
 302                         /*
 303                          * Get the time again, as close as possible to
 304                          * adjusting it, to minimise drift.
 305                          * XXX we'd better not fail between here and
 306                          * restoring disrtcset, since we don't clean up
 307                          * anything.
 308                          */
 309                         if (gettimeofday(&tv, (struct timezone *)NULL)) {
 310                                 syslog(LOG_ERR, "gettimeofday: %m");
 311                                 return 1;
 312                         }
 313                         tv.tv_sec += diff;
 314                         stv = &tv;
 315                 }
 316                 if (settimeofday(stv, stz)) {
 317                         syslog(LOG_ERR, "settimeofday: %m");
 318                         return 1;
 319                 }
 320         }
 321
 322         /* setting CPU_ADJKERNTZ have a side effect: resettodr(), which */
 323         /* can be disabled by CPU_DISRTCSET, so if init or UTC clock    */
 324         /* -- don't write RTC, else write RTC.                          */
 325
 326         if (kern_offset != offset) {
 327                 kern_offset = offset;
 328                 mib[0] = CTL_MACHDEP;
 329                 mib[1] = CPU_ADJKERNTZ;
 330                 len = sizeof(kern_offset);
 331                 if (sysctl(mib, 2, NULL, NULL, &kern_offset, len) == -1) {
 332                         syslog(LOG_ERR, "sysctl(update_offset): %m");
 333                         return 1;
 334                 }
 335         }
 336
 337         mib[0] = CTL_MACHDEP;
 338         mib[1] = CPU_WALLCLOCK;
 339         len = sizeof(wall_clock);
 340         if (sysctl(mib, 2, NULL, NULL, &wall_clock, len) == -1) {
 341                 syslog(LOG_ERR, "sysctl(put_wallclock): %m");
 342                 return 1;
 343         }
 344
 345         if (need_restore) {
 346                 need_restore = False;
 347                 mib[0] = CTL_MACHDEP;
 348                 mib[1] = CPU_DISRTCSET;
 349                 disrtcset = 0;
 350                 len = sizeof(disrtcset);
 351                 if (sysctl(mib, 2, NULL, NULL, &disrtcset, len) == -1) {
 352                         syslog(LOG_ERR, "sysctl(restore_disrtcset): %m");
 353                         return 1;
 354                 }
 355         }
 356
 357 /****** End of critical section ******/
 358
 359         if (init && wall_clock) {
 360                 sleep_mode = False;
 361                 /* wait for signals and acts like -a */
 362                 sigsuspend(&emask);
 363                 goto again;
 364         }
 365
 366         return 0;
 367 }
 368
 369 static void
 370 usage(void)
 371 {
 372         fprintf(stderr, "%s\n%s\n%s\n%s\n",
 373                 "usage: adjkerntz -i",
 374                 "\t\t(initial call from /etc/rc)",
 375                 "       adjkerntz -a [-s]",
 376                 "\t\t(adjustment call, -s for sleep/retry mode)");
 377         exit(2);
 378 }