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/mman.h>
  28 #include <sys/signal.h>
  29 #if SYS_TIME_H
  30 # include <sys/time.h>
  31 #else
  32 # include <time.h>
  33 #endif
  34
  35
  36 static  void    usage(void),
  37                 run_reboot_jobs(cron_db *),
  38                 cron_tick(cron_db *, int),
  39                 cron_sync(int),
  40                 cron_sleep(cron_db *, int),
  41                 cron_clean(cron_db *),
  42 #ifdef USE_SIGCHLD
  43                 sigchld_handler(int),
  44 #endif
  45                 sighup_handler(int),
  46                 parse_args(int c, char *v[]);
  47
  48 static int      run_at_secres(cron_db *);
  49
  50 static time_t   last_time = 0;
  51 static int      dst_enabled = 0;
  52 static int      dont_daemonize = 0;
  53 struct pidfh *pfh;
  54
  55 static void
  56 usage() {
  57 #if DEBUGGING
  58     char **dflags;
  59 #endif
  60
  61         fprintf(stderr, "usage: cron [-j jitter] [-J rootjitter] "
  62                         "[-m mailto] [-n] [-s] [-o] [-x debugflag[,...]]\n");
  63 #if DEBUGGING
  64         fprintf(stderr, "\ndebugflags: ");
  65
  66         for(dflags = DebugFlagNames; *dflags; dflags++) {
  67                 fprintf(stderr, "%s ", *dflags);
  68         }
  69         fprintf(stderr, "\n");
  70 #endif
  71
  72         exit(ERROR_EXIT);
  73 }
  74
  75 static void
  76 open_pidfile(void)
  77 {
  78         char    pidfile[MAX_FNAME];
  79         char    buf[MAX_TEMPSTR];
  80         int     otherpid;
  81
  82         (void) snprintf(pidfile, sizeof(pidfile), PIDFILE, PIDDIR);
  83         pfh = pidfile_open(pidfile, 0600, &otherpid);
  84         if (pfh == NULL) {
  85                 if (errno == EEXIST) {
  86                         snprintf(buf, sizeof(buf),
  87                             "cron already running, pid: %d", otherpid);
  88                 } else {
  89                         snprintf(buf, sizeof(buf),
  90                             "can't open or create %s: %s", pidfile,
  91                             strerror(errno));
  92                 }
  93                 log_it("CRON", getpid(), "DEATH", buf);
  94                 errx(ERROR_EXIT, "%s", buf);
  95         }
  96 }
  97
  98 int
  99 main(argc, argv)
 100         int     argc;
 101         char    *argv[];
 102 {
 103         cron_db database;
 104         int runnum;
 105         int secres1, secres2;
 106         struct tm *tm;
 107
 108         ProgramName = argv[0];
 109
 110 #if defined(BSD)
 111         setlinebuf(stdout);
 112         setlinebuf(stderr);
 113 #endif
 114
 115         parse_args(argc, argv);
 116
 117 #ifdef USE_SIGCHLD
 118         (void) signal(SIGCHLD, sigchld_handler);
 119 #else
 120         (void) signal(SIGCLD, SIG_IGN);
 121 #endif
 122         (void) signal(SIGHUP, sighup_handler);
 123
 124         open_pidfile();
 125         set_cron_uid();
 126         set_cron_cwd();
 127
 128 #if defined(POSIX)
 129         setenv("PATH", _PATH_DEFPATH, 1);
 130 #endif
 131
 132         /* if there are no debug flags turned on, fork as a daemon should.
 133          */
 134 # if DEBUGGING
 135         if (DebugFlags) {
 136 # else
 137         if (0) {
 138 # endif
 139                 (void) fprintf(stderr, "[%d] cron started\n", getpid());
 140         } else if (dont_daemonize == 0) {
 141                 if (daemon(1, 0) == -1) {
 142                         pidfile_remove(pfh);
 143                         log_it("CRON",getpid(),"DEATH","can't become daemon");
 144                         exit(0);
 145                 }
 146         }
 147
 148         if (madvise(NULL, 0, MADV_PROTECT) != 0)
 149                 log_it("CRON", getpid(), "WARNING", "madvise() failed");
 150
 151         pidfile_write(pfh);
 152         database.head = NULL;
 153         database.tail = NULL;
 154         database.mtime = (time_t) 0;
 155         load_database(&database);
 156         secres1 = secres2 = run_at_secres(&database);
 157         run_reboot_jobs(&database);
 158         cron_sync(secres1);
 159         runnum = 0;
 160         while (TRUE) {
 161 # if DEBUGGING
 162             /* if (!(DebugFlags & DTEST)) */
 163 # endif /*DEBUGGING*/
 164                         cron_sleep(&database, secres1);
 165
 166                 if (secres1 == 0 || runnum % 60 == 0) {
 167                         load_database(&database);
 168                         secres2 = run_at_secres(&database);
 169                         if (secres2 != secres1) {
 170                                 secres1 = secres2;
 171                                 if (secres1 != 0) {
 172                                         runnum = 0;
 173                                 } else {
 174                                         /*
 175                                          * Going from 1 sec to 60 sec res. If we
 176                                          * are already at minute's boundary, so
 177                                          * let it run, otherwise schedule for the
 178                                          * next minute.
 179                                          */
 180                                         tm = localtime(&TargetTime);
 181                                         if (tm->tm_sec > 0)  {
 182                                                 cron_sync(secres2);
 183                                                 continue;
 184                                         }
 185                                 }
 186                         }
 187                 }
 188
 189                 /* do this iteration
 190                  */
 191                 cron_tick(&database, secres1);
 192
 193                 /* sleep 1 or 60 seconds
 194                  */
 195                 TargetTime += (secres1 != 0) ? 1 : 60;
 196                 runnum += 1;
 197         }
 198 }
 199
 200
 201 static void
 202 run_reboot_jobs(db)
 203         cron_db *db;
 204 {
 205         register user           *u;
 206         register entry          *e;
 207
 208         for (u = db->head;  u != NULL;  u = u->next) {
 209                 for (e = u->crontab;  e != NULL;  e = e->next) {
 210                         if (e->flags & WHEN_REBOOT) {
 211                                 job_add(e, u);
 212                         }
 213                 }
 214         }
 215         (void) job_runqueue();
 216 }
 217
 218
 219 static void
 220 cron_tick(cron_db *db, int secres)
 221 {
 222         static struct tm        lasttm;
 223         static time_t   diff = 0, /* time difference in seconds from the last offset change */
 224                 difflimit = 0; /* end point for the time zone correction */
 225         struct tm       otztm; /* time in the old time zone */
 226         int             otzsecond, otzminute, otzhour, otzdom, otzmonth, otzdow;
 227         register struct tm      *tm = localtime(&TargetTime);
 228         register int            second, minute, hour, dom, month, dow;
 229         register user           *u;
 230         register entry          *e;
 231
 232         /* make 0-based values out of these so we can use them as indicies
 233          */
 234         second = (secres == 0) ? 0 : tm->tm_sec -FIRST_SECOND;
 235         minute = tm->tm_min -FIRST_MINUTE;
 236         hour = tm->tm_hour -FIRST_HOUR;
 237         dom = tm->tm_mday -FIRST_DOM;
 238         month = tm->tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 239         dow = tm->tm_wday -FIRST_DOW;
 240
 241         Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d,%d)\n",
 242                 getpid(), second, minute, hour, dom, month, dow))
 243
 244         if (dst_enabled && last_time != 0
 245         && TargetTime > last_time /* exclude stepping back */
 246         && tm->tm_gmtoff != lasttm.tm_gmtoff ) {
 247
 248                 diff = tm->tm_gmtoff - lasttm.tm_gmtoff;
 249
 250                 if ( diff > 0 ) { /* ST->DST */
 251                         /* mark jobs for an earlier run */
 252                         difflimit = TargetTime + diff;
 253                         for (u = db->head;  u != NULL;  u = u->next) {
 254                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 255                                         e->flags &= ~NOT_UNTIL;
 256                                         if ( e->lastrun >= TargetTime )
 257                                                 e->lastrun = 0;
 258                                         /* not include the ends of hourly ranges */
 259                                         if ( e->lastrun < TargetTime - 3600 )
 260                                                 e->flags |= RUN_AT;
 261                                         else
 262                                                 e->flags &= ~RUN_AT;
 263                                 }
 264                         }
 265                 } else { /* diff < 0 : DST->ST */
 266                         /* mark jobs for skipping */
 267                         difflimit = TargetTime - diff;
 268                         for (u = db->head;  u != NULL;  u = u->next) {
 269                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 270                                         e->flags |= NOT_UNTIL;
 271                                         e->flags &= ~RUN_AT;
 272                                 }
 273                         }
 274                 }
 275         }
 276
 277         if (diff != 0) {
 278                 /* if the time was reset of the end of special zone is reached */
 279                 if (last_time == 0 || TargetTime >= difflimit) {
 280                         /* disable the TZ switch checks */
 281                         diff = 0;
 282                         difflimit = 0;
 283                         for (u = db->head;  u != NULL;  u = u->next) {
 284                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 285                                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 286                                 }
 287                         }
 288                 } else {
 289                         /* get the time in the old time zone */
 290                         time_t difftime = TargetTime + tm->tm_gmtoff - diff;
 291                         gmtime_r(&difftime, &otztm);
 292
 293                         /* make 0-based values out of these so we can use them as indicies
 294                          */
 295                         otzsecond = (secres == 0) ? 0 : otztm.tm_sec -FIRST_SECOND;
 296                         otzminute = otztm.tm_min -FIRST_MINUTE;
 297                         otzhour = otztm.tm_hour -FIRST_HOUR;
 298                         otzdom = otztm.tm_mday -FIRST_DOM;
 299                         otzmonth = otztm.tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 300                         otzdow = otztm.tm_wday -FIRST_DOW;
 301                 }
 302         }
 303
 304         /* the dom/dow situation is odd.  '* * 1,15 * Sun' will run on the
 305          * first and fifteenth AND every Sunday;  '* * * * Sun' will run *only*
 306          * on Sundays;  '* * 1,15 * *' will run *only* the 1st and 15th.  this
 307          * is why we keep 'e->dow_star' and 'e->dom_star'.  yes, it's bizarre.
 308          * like many bizarre things, it's the standard.
 309          */
 310         for (u = db->head;  u != NULL;  u = u->next) {
 311                 for (e = u->crontab;  e != NULL;  e = e->next) {
 312                         Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
 313                                           env_get("LOGNAME", e->envp),
 314                                           e->uid, e->gid, e->cmd))
 315
 316                         if ( diff != 0 && (e->flags & (RUN_AT|NOT_UNTIL)) ) {
 317                                 if (bit_test(e->second, otzsecond)
 318                                  && bit_test(e->minute, otzminute)
 319                                  && bit_test(e->hour, otzhour)
 320                                  && bit_test(e->month, otzmonth)
 321                                  && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 322                                           ? (bit_test(e->dow,otzdow) && bit_test(e->dom,otzdom))
 323                                           : (bit_test(e->dow,otzdow) || bit_test(e->dom,otzdom))
 324                                         )
 325                                    ) {
 326                                         if ( e->flags & RUN_AT ) {
 327                                                 e->flags &= ~RUN_AT;
 328                                                 e->lastrun = TargetTime;
 329                                                 job_add(e, u);
 330                                                 continue;
 331                                         } else
 332                                                 e->flags &= ~NOT_UNTIL;
 333                                 } else if ( e->flags & NOT_UNTIL )
 334                                         continue;
 335                         }
 336
 337                         if (bit_test(e->second, second)
 338                          && bit_test(e->minute, minute)
 339                          && bit_test(e->hour, hour)
 340                          && bit_test(e->month, month)
 341                          && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 342                               ? (bit_test(e->dow,dow) && bit_test(e->dom,dom))
 343                               : (bit_test(e->dow,dow) || bit_test(e->dom,dom))
 344                             )
 345                            ) {
 346                                 e->flags &= ~RUN_AT;
 347                                 e->lastrun = TargetTime;
 348                                 job_add(e, u);
 349                         }
 350                 }
 351         }
 352
 353         last_time = TargetTime;
 354         lasttm = *tm;
 355 }
 356
 357
 358 /* the task here is to figure out how long it's going to be until :00 of the
 359  * following minute and initialize TargetTime to this value.  TargetTime
 360  * will subsequently slide 60 seconds at a time, with correction applied
 361  * implicitly in cron_sleep().  it would be nice to let cron execute in
 362  * the "current minute" before going to sleep, but by restarting cron you
 363  * could then get it to execute a given minute's jobs more than once.
 364  * instead we have the chance of missing a minute's jobs completely, but
 365  * that's something sysadmin's know to expect what with crashing computers..
 366  */
 367 static void
 368 cron_sync(int secres) {
 369         struct tm *tm;
 370
 371         TargetTime = time((time_t*)0);
 372         if (secres != 0) {
 373                 TargetTime += 1;
 374         } else {
 375                 tm = localtime(&TargetTime);
 376                 TargetTime += (60 - tm->tm_sec);
 377         }
 378 }
 379
 380 static void
 381 timespec_subtract(struct timespec *result, struct timespec *x,
 382     struct timespec *y)
 383 {
 384         *result = *x;
 385         result->tv_sec -= y->tv_sec;
 386         result->tv_nsec -= y->tv_nsec;
 387         if (result->tv_nsec < 0) {
 388                 result->tv_sec--;
 389                 result->tv_nsec += 1000000000;
 390         }
 391 }
 392
 393 static void
 394 cron_sleep(cron_db *db, int secres)
 395 {
 396         int seconds_to_wait;
 397         int rval;
 398         struct timespec ctime, ttime, stime, remtime;
 399
 400         /*
 401          * Loop until we reach the top of the next minute, sleep when possible.
 402          */
 403
 404         for (;;) {
 405                 clock_gettime(CLOCK_REALTIME, &ctime);
 406                 ttime.tv_sec = TargetTime;
 407                 ttime.tv_nsec = 0;
 408                 timespec_subtract(&stime, &ttime, &ctime);
 409
 410                 /*
 411                  * If the seconds_to_wait value is insane, jump the cron
 412                  */
 413
 414                 if (stime.tv_sec < -600 || stime.tv_sec > 600) {
 415                         cron_clean(db);
 416                         cron_sync(secres);
 417                         continue;
 418                 }
 419
 420                 seconds_to_wait = (stime.tv_nsec > 0) ? stime.tv_sec + 1 :
 421                     stime.tv_sec;
 422
 423                 Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
 424                         getpid(), (long)TargetTime, seconds_to_wait))
 425
 426                 /*
 427                  * If we've run out of wait time or there are no jobs left
 428                  * to run, break
 429                  */
 430
 431                 if (stime.tv_sec < 0)
 432                         break;
 433                 if (job_runqueue() == 0) {
 434                         Debug(DSCH, ("[%d] sleeping for %d seconds\n",
 435                                 getpid(), seconds_to_wait))
 436
 437                         for (;;) {
 438                                 rval = nanosleep(&stime, &remtime);
 439                                 if (rval == 0 || errno != EINTR)
 440                                         break;
 441                                 stime.tv_sec = remtime.tv_sec;
 442                                 stime.tv_nsec = remtime.tv_nsec;
 443                         }
 444                 }
 445         }
 446 }
 447
 448
 449 /* if the time was changed abruptly, clear the flags related
 450  * to the daylight time switch handling to avoid strange effects
 451  */
 452
 453 static void
 454 cron_clean(db)
 455         cron_db *db;
 456 {
 457         user            *u;
 458         entry           *e;
 459
 460         last_time = 0;
 461
 462         for (u = db->head;  u != NULL;  u = u->next) {
 463                 for (e = u->crontab;  e != NULL;  e = e->next) {
 464                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 465                 }
 466         }
 467 }
 468
 469 #ifdef USE_SIGCHLD
 470 static void
 471 sigchld_handler(int x)
 472 {
 473         WAIT_T          waiter;
 474         PID_T           pid;
 475
 476         for (;;) {
 477 #ifdef POSIX
 478                 pid = waitpid(-1, &waiter, WNOHANG);
 479 #else
 480                 pid = wait3(&waiter, WNOHANG, (struct rusage *)0);
 481 #endif
 482                 switch (pid) {
 483                 case -1:
 484                         Debug(DPROC,
 485                                 ("[%d] sigchld...no children\n", getpid()))
 486                         return;
 487                 case 0:
 488                         Debug(DPROC,
 489                                 ("[%d] sigchld...no dead kids\n", getpid()))
 490                         return;
 491                 default:
 492                         Debug(DPROC,
 493                                 ("[%d] sigchld...pid #%d died, stat=%d\n",
 494                                 getpid(), pid, WEXITSTATUS(waiter)))
 495                 }
 496         }
 497 }
 498 #endif /*USE_SIGCHLD*/
 499
 500
 501 static void
 502 sighup_handler(int x)
 503 {
 504         log_close();
 505 }
 506
 507
 508 static void
 509 parse_args(argc, argv)
 510         int     argc;
 511         char    *argv[];
 512 {
 513         int     argch;
 514         char    *endp;
 515
 516         while ((argch = getopt(argc, argv, "j:J:m:nosx:")) != -1) {
 517                 switch (argch) {
 518                 case 'j':
 519                         Jitter = strtoul(optarg, &endp, 10);
 520                         if (*optarg == '\0' || *endp != '\0' || Jitter > 60)
 521                                 errx(ERROR_EXIT,
 522                                      "bad value for jitter: %s", optarg);
 523                         break;
 524                 case 'J':
 525                         RootJitter = strtoul(optarg, &endp, 10);
 526                         if (*optarg == '\0' || *endp != '\0' || RootJitter > 60)
 527                                 errx(ERROR_EXIT,
 528                                      "bad value for root jitter: %s", optarg);
 529                         break;
 530                 case 'm':
 531                         defmailto = optarg;
 532                         break;
 533                 case 'n':
 534                         dont_daemonize = 1;
 535                         break;
 536                 case 'o':
 537                         dst_enabled = 0;
 538                         break;
 539                 case 's':
 540                         dst_enabled = 1;
 541                         break;
 542                 case 'x':
 543                         if (!set_debug_flags(optarg))
 544                                 usage();
 545                         break;
 546                 default:
 547                         usage();
 548                 }
 549         }
 550 }
 551
 552 static int
 553 run_at_secres(cron_db *db)
 554 {
 555         user *u;
 556         entry *e;
 557
 558         for (u = db->head;  u != NULL;  u = u->next) {
 559                 for (e = u->crontab;  e != NULL;  e = e->next) {
 560                         if ((e->flags & SEC_RES) != 0)
 561                                 return 1;
 562                 }
 563         }
 564         return 0;
 565 }