usr.sbin/cron/cron/cron.c

   1 /* Copyright 1988,1990,1993,1994 by Paul Vixie
   2  * All rights reserved
   3  *
   4  * Distribute freely, except: don't remove my name from the source or
   5  * documentation (don't take credit for my work), mark your changes (don't
   6  * get me blamed for your possible bugs), don't alter or remove this
   7  * notice.  May be sold if buildable source is provided to buyer.  No
   8  * warrantee of any kind, express or implied, is included with this
   9  * software; use at your own risk, responsibility for damages (if any) to
  10  * anyone resulting from the use of this software rests entirely with the
  11  * user.
  12  *
  13  * Send bug reports, bug fixes, enhancements, requests, flames, etc., and
  14  * I'll try to keep a version up to date.  I can be reached as follows:
  15  * Paul Vixie          <paul@vix.com>          uunet!decwrl!vixie!paul
  16  */
  17
  18 #if !defined(lint) && !defined(LINT)
  19 static const char rcsid[] =
  20   "$FreeBSD$";
  21 #endif
  22
  23 #define MAIN_PROGRAM
  24
  25
  26 #include "cron.h"
  27 #include <sys/signal.h>
  28 #if SYS_TIME_H
  29 # include <sys/time.h>
  30 #else
  31 # include <time.h>
  32 #endif
  33
  34
  35 static  void    usage __P((void)),
  36                 run_reboot_jobs __P((cron_db *)),
  37                 cron_tick __P((cron_db *)),
  38                 cron_sync __P((void)),
  39                 cron_sleep __P((cron_db *)),
  40                 cron_clean __P((cron_db *)),
  41 #ifdef USE_SIGCHLD
  42                 sigchld_handler __P((int)),
  43 #endif
  44                 sighup_handler __P((int)),
  45                 parse_args __P((int c, char *v[]));
  46
  47 static time_t   last_time = 0;
  48 static int      dst_enabled = 0;
  49
  50 static void
  51 usage() {
  52     char **dflags;
  53
  54         fprintf(stderr, "usage: cron [-j jitter] [-J rootjitter] "
  55                         "[-s] [-o] [-x debugflag[,...]]\n");
  56         fprintf(stderr, "\ndebugflags: ");
  57
  58         for(dflags = DebugFlagNames; *dflags; dflags++) {
  59                 fprintf(stderr, "%s ", *dflags);
  60         }
  61         fprintf(stderr, "\n");
  62
  63         exit(ERROR_EXIT);
  64 }
  65
  66
  67 int
  68 main(argc, argv)
  69         int     argc;
  70         char    *argv[];
  71 {
  72         cron_db database;
  73
  74         ProgramName = argv[0];
  75
  76 #if defined(BSD)
  77         setlinebuf(stdout);
  78         setlinebuf(stderr);
  79 #endif
  80
  81         parse_args(argc, argv);
  82
  83 #ifdef USE_SIGCHLD
  84         (void) signal(SIGCHLD, sigchld_handler);
  85 #else
  86         (void) signal(SIGCLD, SIG_IGN);
  87 #endif
  88         (void) signal(SIGHUP, sighup_handler);
  89
  90         acquire_daemonlock(0);
  91         set_cron_uid();
  92         set_cron_cwd();
  93
  94 #if defined(POSIX)
  95         setenv("PATH", _PATH_DEFPATH, 1);
  96 #endif
  97
  98         /* if there are no debug flags turned on, fork as a daemon should.
  99          */
 100 # if DEBUGGING
 101         if (DebugFlags) {
 102 # else
 103         if (0) {
 104 # endif
 105                 (void) fprintf(stderr, "[%d] cron started\n", getpid());
 106         } else {
 107                 if (daemon(1, 0) == -1) {
 108                         log_it("CRON",getpid(),"DEATH","can't become daemon");
 109                         exit(0);
 110                 }
 111         }
 112
 113         acquire_daemonlock(0);
 114         database.head = NULL;
 115         database.tail = NULL;
 116         database.mtime = (time_t) 0;
 117         load_database(&database);
 118         run_reboot_jobs(&database);
 119         cron_sync();
 120         while (TRUE) {
 121 # if DEBUGGING
 122             /* if (!(DebugFlags & DTEST)) */
 123 # endif /*DEBUGGING*/
 124                         cron_sleep(&database);
 125
 126                 load_database(&database);
 127
 128                 /* do this iteration
 129                  */
 130                 cron_tick(&database);
 131
 132                 /* sleep 1 minute
 133                  */
 134                 TargetTime += 60;
 135         }
 136 }
 137
 138
 139 static void
 140 run_reboot_jobs(db)
 141         cron_db *db;
 142 {
 143         register user           *u;
 144         register entry          *e;
 145
 146         for (u = db->head;  u != NULL;  u = u->next) {
 147                 for (e = u->crontab;  e != NULL;  e = e->next) {
 148                         if (e->flags & WHEN_REBOOT) {
 149                                 job_add(e, u);
 150                         }
 151                 }
 152         }
 153         (void) job_runqueue();
 154 }
 155
 156
 157 static void
 158 cron_tick(db)
 159         cron_db *db;
 160 {
 161         static struct tm        lasttm;
 162         static time_t   diff = 0, /* time difference in seconds from the last offset change */
 163                 difflimit = 0; /* end point for the time zone correction */
 164         struct tm       otztm; /* time in the old time zone */
 165         int             otzminute, otzhour, otzdom, otzmonth, otzdow;
 166         register struct tm      *tm = localtime(&TargetTime);
 167         register int            minute, hour, dom, month, dow;
 168         register user           *u;
 169         register entry          *e;
 170
 171         /* make 0-based values out of these so we can use them as indicies
 172          */
 173         minute = tm->tm_min -FIRST_MINUTE;
 174         hour = tm->tm_hour -FIRST_HOUR;
 175         dom = tm->tm_mday -FIRST_DOM;
 176         month = tm->tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 177         dow = tm->tm_wday -FIRST_DOW;
 178
 179         Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d)\n",
 180                 getpid(), minute, hour, dom, month, dow))
 181
 182         if (dst_enabled && last_time != 0
 183         && TargetTime > last_time /* exclude stepping back */
 184         && tm->tm_gmtoff != lasttm.tm_gmtoff ) {
 185
 186                 diff = tm->tm_gmtoff - lasttm.tm_gmtoff;
 187
 188                 if ( diff > 0 ) { /* ST->DST */
 189                         /* mark jobs for an earlier run */
 190                         difflimit = TargetTime + diff;
 191                         for (u = db->head;  u != NULL;  u = u->next) {
 192                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 193                                         e->flags &= ~NOT_UNTIL;
 194                                         if ( e->lastrun >= TargetTime )
 195                                                 e->lastrun = 0;
 196                                         /* not include the ends of hourly ranges */
 197                                         if ( e->lastrun < TargetTime - 3600 )
 198                                                 e->flags |= RUN_AT;
 199                                         else
 200                                                 e->flags &= ~RUN_AT;
 201                                 }
 202                         }
 203                 } else { /* diff < 0 : DST->ST */
 204                         /* mark jobs for skipping */
 205                         difflimit = TargetTime - diff;
 206                         for (u = db->head;  u != NULL;  u = u->next) {
 207                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 208                                         e->flags |= NOT_UNTIL;
 209                                         e->flags &= ~RUN_AT;
 210                                 }
 211                         }
 212                 }
 213         }
 214
 215         if (diff != 0) {
 216                 /* if the time was reset of the end of special zone is reached */
 217                 if (last_time == 0 || TargetTime >= difflimit) {
 218                         /* disable the TZ switch checks */
 219                         diff = 0;
 220                         difflimit = 0;
 221                         for (u = db->head;  u != NULL;  u = u->next) {
 222                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 223                                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 224                                 }
 225                         }
 226                 } else {
 227                         /* get the time in the old time zone */
 228                         time_t difftime = TargetTime + tm->tm_gmtoff - diff;
 229                         gmtime_r(&difftime, &otztm);
 230
 231                         /* make 0-based values out of these so we can use them as indicies
 232                          */
 233                         otzminute = otztm.tm_min -FIRST_MINUTE;
 234                         otzhour = otztm.tm_hour -FIRST_HOUR;
 235                         otzdom = otztm.tm_mday -FIRST_DOM;
 236                         otzmonth = otztm.tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 237                         otzdow = otztm.tm_wday -FIRST_DOW;
 238                 }
 239         }
 240
 241         /* the dom/dow situation is odd.  '* * 1,15 * Sun' will run on the
 242          * first and fifteenth AND every Sunday;  '* * * * Sun' will run *only*
 243          * on Sundays;  '* * 1,15 * *' will run *only* the 1st and 15th.  this
 244          * is why we keep 'e->dow_star' and 'e->dom_star'.  yes, it's bizarre.
 245          * like many bizarre things, it's the standard.
 246          */
 247         for (u = db->head;  u != NULL;  u = u->next) {
 248                 for (e = u->crontab;  e != NULL;  e = e->next) {
 249                         Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
 250                                           env_get("LOGNAME", e->envp),
 251                                           e->uid, e->gid, e->cmd))
 252
 253                         if ( diff != 0 && (e->flags & (RUN_AT|NOT_UNTIL)) ) {
 254                                 if (bit_test(e->minute, otzminute)
 255                                  && bit_test(e->hour, otzhour)
 256                                  && bit_test(e->month, otzmonth)
 257                                  && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 258                                           ? (bit_test(e->dow,otzdow) && bit_test(e->dom,otzdom))
 259                                           : (bit_test(e->dow,otzdow) || bit_test(e->dom,otzdom))
 260                                         )
 261                                    ) {
 262                                         if ( e->flags & RUN_AT ) {
 263                                                 e->flags &= ~RUN_AT;
 264                                                 e->lastrun = TargetTime;
 265                                                 job_add(e, u);
 266                                                 continue;
 267                                         } else
 268                                                 e->flags &= ~NOT_UNTIL;
 269                                 } else if ( e->flags & NOT_UNTIL )
 270                                         continue;
 271                         }
 272
 273                         if (bit_test(e->minute, minute)
 274                          && bit_test(e->hour, hour)
 275                          && bit_test(e->month, month)
 276                          && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 277                               ? (bit_test(e->dow,dow) && bit_test(e->dom,dom))
 278                               : (bit_test(e->dow,dow) || bit_test(e->dom,dom))
 279                             )
 280                            ) {
 281                                 e->flags &= ~RUN_AT;
 282                                 e->lastrun = TargetTime;
 283                                 job_add(e, u);
 284                         }
 285                 }
 286         }
 287
 288         last_time = TargetTime;
 289         lasttm = *tm;
 290 }
 291
 292
 293 /* the task here is to figure out how long it's going to be until :00 of the
 294  * following minute and initialize TargetTime to this value.  TargetTime
 295  * will subsequently slide 60 seconds at a time, with correction applied
 296  * implicitly in cron_sleep().  it would be nice to let cron execute in
 297  * the "current minute" before going to sleep, but by restarting cron you
 298  * could then get it to execute a given minute's jobs more than once.
 299  * instead we have the chance of missing a minute's jobs completely, but
 300  * that's something sysadmin's know to expect what with crashing computers..
 301  */
 302 static void
 303 cron_sync() {
 304         register struct tm      *tm;
 305
 306         TargetTime = time((time_t*)0);
 307         tm = localtime(&TargetTime);
 308         TargetTime += (60 - tm->tm_sec);
 309 }
 310
 311
 312 static void
 313 cron_sleep(db)
 314         cron_db *db;
 315 {
 316         int     seconds_to_wait = 0;
 317
 318         /*
 319          * Loop until we reach the top of the next minute, sleep when possible.
 320          */
 321
 322         for (;;) {
 323                 seconds_to_wait = (int) (TargetTime - time((time_t*)0));
 324
 325                 /*
 326                  * If the seconds_to_wait value is insane, jump the cron
 327                  */
 328
 329                 if (seconds_to_wait < -600 || seconds_to_wait > 600) {
 330                         cron_clean(db);
 331                         cron_sync();
 332                         continue;
 333                 }
 334
 335                 Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
 336                         getpid(), (long)TargetTime, seconds_to_wait))
 337
 338                 /*
 339                  * If we've run out of wait time or there are no jobs left
 340                  * to run, break
 341                  */
 342
 343                 if (seconds_to_wait <= 0)
 344                         break;
 345                 if (job_runqueue() == 0) {
 346                         Debug(DSCH, ("[%d] sleeping for %d seconds\n",
 347                                 getpid(), seconds_to_wait))
 348
 349                         sleep(seconds_to_wait);
 350                 }
 351         }
 352 }
 353
 354
 355 /* if the time was changed abruptly, clear the flags related
 356  * to the daylight time switch handling to avoid strange effects
 357  */
 358
 359 static void
 360 cron_clean(db)
 361         cron_db *db;
 362 {
 363         user            *u;
 364         entry           *e;
 365
 366         last_time = 0;
 367
 368         for (u = db->head;  u != NULL;  u = u->next) {
 369                 for (e = u->crontab;  e != NULL;  e = e->next) {
 370                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 371                 }
 372         }
 373 }
 374
 375 #ifdef USE_SIGCHLD
 376 static void
 377 sigchld_handler(x) {
 378         WAIT_T          waiter;
 379         PID_T           pid;
 380
 381         for (;;) {
 382 #ifdef POSIX
 383                 pid = waitpid(-1, &waiter, WNOHANG);
 384 #else
 385                 pid = wait3(&waiter, WNOHANG, (struct rusage *)0);
 386 #endif
 387                 switch (pid) {
 388                 case -1:
 389                         Debug(DPROC,
 390                                 ("[%d] sigchld...no children\n", getpid()))
 391                         return;
 392                 case 0:
 393                         Debug(DPROC,
 394                                 ("[%d] sigchld...no dead kids\n", getpid()))
 395                         return;
 396                 default:
 397                         Debug(DPROC,
 398                                 ("[%d] sigchld...pid #%d died, stat=%d\n",
 399                                 getpid(), pid, WEXITSTATUS(waiter)))
 400                 }
 401         }
 402 }
 403 #endif /*USE_SIGCHLD*/
 404
 405
 406 static void
 407 sighup_handler(x) {
 408         log_close();
 409 }
 410
 411
 412 static void
 413 parse_args(argc, argv)
 414         int     argc;
 415         char    *argv[];
 416 {
 417         int     argch;
 418         char    *endp;
 419
 420         while ((argch = getopt(argc, argv, "j:J:osx:")) != -1) {
 421                 switch (argch) {
 422                 case 'j':
 423                         Jitter = strtoul(optarg, &endp, 10);
 424                         if (*optarg == '\0' || *endp != '\0' || Jitter > 60)
 425                                 errx(ERROR_EXIT,
 426                                      "bad value for jitter: %s", optarg);
 427                         break;
 428                 case 'J':
 429                         RootJitter = strtoul(optarg, &endp, 10);
 430                         if (*optarg == '\0' || *endp != '\0' || RootJitter > 60)
 431                                 errx(ERROR_EXIT,
 432                                      "bad value for root jitter: %s", optarg);
 433                         break;
 434                 case 'o':
 435                         dst_enabled = 0;
 436                         break;
 437                 case 's':
 438                         dst_enabled = 1;
 439                         break;
 440                 case 'x':
 441                         if (!set_debug_flags(optarg))
 442                                 usage();
 443                         break;
 444                 default:
 445                         usage();
 446                 }
 447         }
 448 }
 449