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 static void     find_interval_entry(pid_t);
  50
  51 static cron_db  database;
  52 static time_t   last_time = 0;
  53 static int      dst_enabled = 0;
  54 static int      dont_daemonize = 0;
  55 struct pidfh *pfh;
  56
  57 static void
  58 usage() {
  59 #if DEBUGGING
  60     char **dflags;
  61 #endif
  62
  63         fprintf(stderr, "usage: cron [-j jitter] [-J rootjitter] "
  64                         "[-m mailto] [-n] [-s] [-o] [-x debugflag[,...]]\n");
  65 #if DEBUGGING
  66         fprintf(stderr, "\ndebugflags: ");
  67
  68         for(dflags = DebugFlagNames; *dflags; dflags++) {
  69                 fprintf(stderr, "%s ", *dflags);
  70         }
  71         fprintf(stderr, "\n");
  72 #endif
  73
  74         exit(ERROR_EXIT);
  75 }
  76
  77 static void
  78 open_pidfile(void)
  79 {
  80         char    pidfile[MAX_FNAME];
  81         char    buf[MAX_TEMPSTR];
  82         int     otherpid;
  83
  84         (void) snprintf(pidfile, sizeof(pidfile), PIDFILE, PIDDIR);
  85         pfh = pidfile_open(pidfile, 0600, &otherpid);
  86         if (pfh == NULL) {
  87                 if (errno == EEXIST) {
  88                         snprintf(buf, sizeof(buf),
  89                             "cron already running, pid: %d", otherpid);
  90                 } else {
  91                         snprintf(buf, sizeof(buf),
  92                             "can't open or create %s: %s", pidfile,
  93                             strerror(errno));
  94                 }
  95                 log_it("CRON", getpid(), "DEATH", buf);
  96                 errx(ERROR_EXIT, "%s", buf);
  97         }
  98 }
  99
 100 int
 101 main(argc, argv)
 102         int     argc;
 103         char    *argv[];
 104 {
 105         int runnum;
 106         int secres1, secres2;
 107         struct tm *tm;
 108
 109         ProgramName = argv[0];
 110
 111 #if defined(BSD)
 112         setlinebuf(stdout);
 113         setlinebuf(stderr);
 114 #endif
 115
 116         parse_args(argc, argv);
 117
 118 #ifdef USE_SIGCHLD
 119         (void) signal(SIGCHLD, sigchld_handler);
 120 #else
 121         (void) signal(SIGCLD, SIG_IGN);
 122 #endif
 123         (void) signal(SIGHUP, sighup_handler);
 124
 125         open_pidfile();
 126         set_cron_uid();
 127         set_cron_cwd();
 128
 129 #if defined(POSIX)
 130         setenv("PATH", _PATH_DEFPATH, 1);
 131 #endif
 132
 133         /* if there are no debug flags turned on, fork as a daemon should.
 134          */
 135 # if DEBUGGING
 136         if (DebugFlags) {
 137 # else
 138         if (0) {
 139 # endif
 140                 (void) fprintf(stderr, "[%d] cron started\n", getpid());
 141         } else if (dont_daemonize == 0) {
 142                 if (daemon(1, 0) == -1) {
 143                         pidfile_remove(pfh);
 144                         log_it("CRON",getpid(),"DEATH","can't become daemon");
 145                         exit(0);
 146                 }
 147         }
 148
 149         if (madvise(NULL, 0, MADV_PROTECT) != 0)
 150                 log_it("CRON", getpid(), "WARNING", "madvise() failed");
 151
 152         pidfile_write(pfh);
 153         database.head = NULL;
 154         database.tail = NULL;
 155         database.mtime = (time_t) 0;
 156         load_database(&database);
 157         secres1 = secres2 = run_at_secres(&database);
 158         cron_sync(secres1);
 159         run_reboot_jobs(&database);
 160         runnum = 0;
 161         while (TRUE) {
 162 # if DEBUGGING
 163             /* if (!(DebugFlags & DTEST)) */
 164 # endif /*DEBUGGING*/
 165                         cron_sleep(&database, secres1);
 166
 167                 if (secres1 == 0 || runnum % 60 == 0) {
 168                         load_database(&database);
 169                         secres2 = run_at_secres(&database);
 170                         if (secres2 != secres1) {
 171                                 secres1 = secres2;
 172                                 if (secres1 != 0) {
 173                                         runnum = 0;
 174                                 } else {
 175                                         /*
 176                                          * Going from 1 sec to 60 sec res. If we
 177                                          * are already at minute's boundary, so
 178                                          * let it run, otherwise schedule for the
 179                                          * next minute.
 180                                          */
 181                                         tm = localtime(&TargetTime);
 182                                         if (tm->tm_sec > 0)  {
 183                                                 cron_sync(secres2);
 184                                                 continue;
 185                                         }
 186                                 }
 187                         }
 188                 }
 189
 190                 /* do this iteration
 191                  */
 192                 cron_tick(&database, secres1);
 193
 194                 /* sleep 1 or 60 seconds
 195                  */
 196                 TargetTime += (secres1 != 0) ? 1 : 60;
 197                 runnum += 1;
 198         }
 199 }
 200
 201
 202 static void
 203 run_reboot_jobs(db)
 204         cron_db *db;
 205 {
 206         register user           *u;
 207         register entry          *e;
 208
 209         for (u = db->head;  u != NULL;  u = u->next) {
 210                 for (e = u->crontab;  e != NULL;  e = e->next) {
 211                         if (e->flags & WHEN_REBOOT) {
 212                                 job_add(e, u);
 213                         }
 214                         if (e->flags & INTERVAL) {
 215                                 e->lastexit = TargetTime;
 216                         }
 217                 }
 218         }
 219         (void) job_runqueue();
 220 }
 221
 222
 223 static void
 224 cron_tick(cron_db *db, int secres)
 225 {
 226         static struct tm        lasttm;
 227         static time_t   diff = 0, /* time difference in seconds from the last offset change */
 228                 difflimit = 0; /* end point for the time zone correction */
 229         struct tm       otztm; /* time in the old time zone */
 230         int             otzsecond, otzminute, otzhour, otzdom, otzmonth, otzdow;
 231         register struct tm      *tm = localtime(&TargetTime);
 232         register int            second, minute, hour, dom, month, dow;
 233         register user           *u;
 234         register entry          *e;
 235
 236         /* make 0-based values out of these so we can use them as indices
 237          */
 238         second = (secres == 0) ? 0 : tm->tm_sec -FIRST_SECOND;
 239         minute = tm->tm_min -FIRST_MINUTE;
 240         hour = tm->tm_hour -FIRST_HOUR;
 241         dom = tm->tm_mday -FIRST_DOM;
 242         month = tm->tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 243         dow = tm->tm_wday -FIRST_DOW;
 244
 245         Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d,%d)\n",
 246                 getpid(), second, minute, hour, dom, month, dow))
 247
 248         if (dst_enabled && last_time != 0
 249         && TargetTime > last_time /* exclude stepping back */
 250         && tm->tm_gmtoff != lasttm.tm_gmtoff ) {
 251
 252                 diff = tm->tm_gmtoff - lasttm.tm_gmtoff;
 253
 254                 if ( diff > 0 ) { /* ST->DST */
 255                         /* mark jobs for an earlier run */
 256                         difflimit = TargetTime + diff;
 257                         for (u = db->head;  u != NULL;  u = u->next) {
 258                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 259                                         e->flags &= ~NOT_UNTIL;
 260                                         if ( e->lastrun >= TargetTime )
 261                                                 e->lastrun = 0;
 262                                         /* not include the ends of hourly ranges */
 263                                         if ( e->lastrun < TargetTime - 3600 )
 264                                                 e->flags |= RUN_AT;
 265                                         else
 266                                                 e->flags &= ~RUN_AT;
 267                                 }
 268                         }
 269                 } else { /* diff < 0 : DST->ST */
 270                         /* mark jobs for skipping */
 271                         difflimit = TargetTime - diff;
 272                         for (u = db->head;  u != NULL;  u = u->next) {
 273                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 274                                         e->flags |= NOT_UNTIL;
 275                                         e->flags &= ~RUN_AT;
 276                                 }
 277                         }
 278                 }
 279         }
 280
 281         if (diff != 0) {
 282                 /* if the time was reset of the end of special zone is reached */
 283                 if (last_time == 0 || TargetTime >= difflimit) {
 284                         /* disable the TZ switch checks */
 285                         diff = 0;
 286                         difflimit = 0;
 287                         for (u = db->head;  u != NULL;  u = u->next) {
 288                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 289                                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 290                                 }
 291                         }
 292                 } else {
 293                         /* get the time in the old time zone */
 294                         time_t difftime = TargetTime + tm->tm_gmtoff - diff;
 295                         gmtime_r(&difftime, &otztm);
 296
 297                         /* make 0-based values out of these so we can use them as indices
 298                          */
 299                         otzsecond = (secres == 0) ? 0 : otztm.tm_sec -FIRST_SECOND;
 300                         otzminute = otztm.tm_min -FIRST_MINUTE;
 301                         otzhour = otztm.tm_hour -FIRST_HOUR;
 302                         otzdom = otztm.tm_mday -FIRST_DOM;
 303                         otzmonth = otztm.tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 304                         otzdow = otztm.tm_wday -FIRST_DOW;
 305                 }
 306         }
 307
 308         /* the dom/dow situation is odd.  '* * 1,15 * Sun' will run on the
 309          * first and fifteenth AND every Sunday;  '* * * * Sun' will run *only*
 310          * on Sundays;  '* * 1,15 * *' will run *only* the 1st and 15th.  this
 311          * is why we keep 'e->dow_star' and 'e->dom_star'.  yes, it's bizarre.
 312          * like many bizarre things, it's the standard.
 313          */
 314         for (u = db->head;  u != NULL;  u = u->next) {
 315                 for (e = u->crontab;  e != NULL;  e = e->next) {
 316                         Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
 317                                           env_get("LOGNAME", e->envp),
 318                                           e->uid, e->gid, e->cmd))
 319
 320                         if (e->flags & INTERVAL) {
 321                                 if (e->lastexit > 0 &&
 322                                     TargetTime >= e->lastexit + e->interval)
 323                                         job_add(e, u);
 324                                 continue;
 325                         }
 326
 327                         if ( diff != 0 && (e->flags & (RUN_AT|NOT_UNTIL)) ) {
 328                                 if (bit_test(e->second, otzsecond)
 329                                  && bit_test(e->minute, otzminute)
 330                                  && bit_test(e->hour, otzhour)
 331                                  && bit_test(e->month, otzmonth)
 332                                  && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 333                                           ? (bit_test(e->dow,otzdow) && bit_test(e->dom,otzdom))
 334                                           : (bit_test(e->dow,otzdow) || bit_test(e->dom,otzdom))
 335                                         )
 336                                    ) {
 337                                         if ( e->flags & RUN_AT ) {
 338                                                 e->flags &= ~RUN_AT;
 339                                                 e->lastrun = TargetTime;
 340                                                 job_add(e, u);
 341                                                 continue;
 342                                         } else
 343                                                 e->flags &= ~NOT_UNTIL;
 344                                 } else if ( e->flags & NOT_UNTIL )
 345                                         continue;
 346                         }
 347
 348                         if (bit_test(e->second, second)
 349                          && bit_test(e->minute, minute)
 350                          && bit_test(e->hour, hour)
 351                          && bit_test(e->month, month)
 352                          && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 353                               ? (bit_test(e->dow,dow) && bit_test(e->dom,dom))
 354                               : (bit_test(e->dow,dow) || bit_test(e->dom,dom))
 355                             )
 356                            ) {
 357                                 e->flags &= ~RUN_AT;
 358                                 e->lastrun = TargetTime;
 359                                 job_add(e, u);
 360                         }
 361                 }
 362         }
 363
 364         last_time = TargetTime;
 365         lasttm = *tm;
 366 }
 367
 368
 369 /* the task here is to figure out how long it's going to be until :00 of the
 370  * following minute and initialize TargetTime to this value.  TargetTime
 371  * will subsequently slide 60 seconds at a time, with correction applied
 372  * implicitly in cron_sleep().  it would be nice to let cron execute in
 373  * the "current minute" before going to sleep, but by restarting cron you
 374  * could then get it to execute a given minute's jobs more than once.
 375  * instead we have the chance of missing a minute's jobs completely, but
 376  * that's something sysadmin's know to expect what with crashing computers..
 377  */
 378 static void
 379 cron_sync(int secres) {
 380         struct tm *tm;
 381
 382         TargetTime = time((time_t*)0);
 383         if (secres != 0) {
 384                 TargetTime += 1;
 385         } else {
 386                 tm = localtime(&TargetTime);
 387                 TargetTime += (60 - tm->tm_sec);
 388         }
 389 }
 390
 391 static void
 392 timespec_subtract(struct timespec *result, struct timespec *x,
 393     struct timespec *y)
 394 {
 395         *result = *x;
 396         result->tv_sec -= y->tv_sec;
 397         result->tv_nsec -= y->tv_nsec;
 398         if (result->tv_nsec < 0) {
 399                 result->tv_sec--;
 400                 result->tv_nsec += 1000000000;
 401         }
 402 }
 403
 404 static void
 405 cron_sleep(cron_db *db, int secres)
 406 {
 407         int seconds_to_wait;
 408         int rval;
 409         struct timespec ctime, ttime, stime, remtime;
 410
 411         /*
 412          * Loop until we reach the top of the next minute, sleep when possible.
 413          */
 414
 415         for (;;) {
 416                 clock_gettime(CLOCK_REALTIME, &ctime);
 417                 ttime.tv_sec = TargetTime;
 418                 ttime.tv_nsec = 0;
 419                 timespec_subtract(&stime, &ttime, &ctime);
 420
 421                 /*
 422                  * If the seconds_to_wait value is insane, jump the cron
 423                  */
 424
 425                 if (stime.tv_sec < -600 || stime.tv_sec > 600) {
 426                         cron_clean(db);
 427                         cron_sync(secres);
 428                         continue;
 429                 }
 430
 431                 seconds_to_wait = (stime.tv_nsec > 0) ? stime.tv_sec + 1 :
 432                     stime.tv_sec;
 433
 434                 Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
 435                         getpid(), (long)TargetTime, seconds_to_wait))
 436
 437                 /*
 438                  * If we've run out of wait time or there are no jobs left
 439                  * to run, break
 440                  */
 441
 442                 if (stime.tv_sec < 0)
 443                         break;
 444                 if (job_runqueue() == 0) {
 445                         Debug(DSCH, ("[%d] sleeping for %d seconds\n",
 446                                 getpid(), seconds_to_wait))
 447
 448                         for (;;) {
 449                                 rval = nanosleep(&stime, &remtime);
 450                                 if (rval == 0 || errno != EINTR)
 451                                         break;
 452                                 stime.tv_sec = remtime.tv_sec;
 453                                 stime.tv_nsec = remtime.tv_nsec;
 454                         }
 455                 }
 456         }
 457 }
 458
 459
 460 /* if the time was changed abruptly, clear the flags related
 461  * to the daylight time switch handling to avoid strange effects
 462  */
 463
 464 static void
 465 cron_clean(db)
 466         cron_db *db;
 467 {
 468         user            *u;
 469         entry           *e;
 470
 471         last_time = 0;
 472
 473         for (u = db->head;  u != NULL;  u = u->next) {
 474                 for (e = u->crontab;  e != NULL;  e = e->next) {
 475                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 476                 }
 477         }
 478 }
 479
 480 #ifdef USE_SIGCHLD
 481 static void
 482 sigchld_handler(int x)
 483 {
 484         WAIT_T          waiter;
 485         PID_T           pid;
 486
 487         for (;;) {
 488 #ifdef POSIX
 489                 pid = waitpid(-1, &waiter, WNOHANG);
 490 #else
 491                 pid = wait3(&waiter, WNOHANG, (struct rusage *)0);
 492 #endif
 493                 switch (pid) {
 494                 case -1:
 495                         Debug(DPROC,
 496                                 ("[%d] sigchld...no children\n", getpid()))
 497                         return;
 498                 case 0:
 499                         Debug(DPROC,
 500                                 ("[%d] sigchld...no dead kids\n", getpid()))
 501                         return;
 502                 default:
 503                         find_interval_entry(pid);
 504                         Debug(DPROC,
 505                                 ("[%d] sigchld...pid #%d died, stat=%d\n",
 506                                 getpid(), pid, WEXITSTATUS(waiter)))
 507                 }
 508         }
 509 }
 510 #endif /*USE_SIGCHLD*/
 511
 512
 513 static void
 514 sighup_handler(int x)
 515 {
 516         log_close();
 517 }
 518
 519
 520 static void
 521 parse_args(argc, argv)
 522         int     argc;
 523         char    *argv[];
 524 {
 525         int     argch;
 526         char    *endp;
 527
 528         while ((argch = getopt(argc, argv, "j:J:m:nosx:")) != -1) {
 529                 switch (argch) {
 530                 case 'j':
 531                         Jitter = strtoul(optarg, &endp, 10);
 532                         if (*optarg == '\0' || *endp != '\0' || Jitter > 60)
 533                                 errx(ERROR_EXIT,
 534                                      "bad value for jitter: %s", optarg);
 535                         break;
 536                 case 'J':
 537                         RootJitter = strtoul(optarg, &endp, 10);
 538                         if (*optarg == '\0' || *endp != '\0' || RootJitter > 60)
 539                                 errx(ERROR_EXIT,
 540                                      "bad value for root jitter: %s", optarg);
 541                         break;
 542                 case 'm':
 543                         defmailto = optarg;
 544                         break;
 545                 case 'n':
 546                         dont_daemonize = 1;
 547                         break;
 548                 case 'o':
 549                         dst_enabled = 0;
 550                         break;
 551                 case 's':
 552                         dst_enabled = 1;
 553                         break;
 554                 case 'x':
 555                         if (!set_debug_flags(optarg))
 556                                 usage();
 557                         break;
 558                 default:
 559                         usage();
 560                 }
 561         }
 562 }
 563
 564 static int
 565 run_at_secres(cron_db *db)
 566 {
 567         user *u;
 568         entry *e;
 569
 570         for (u = db->head;  u != NULL;  u = u->next) {
 571                 for (e = u->crontab;  e != NULL;  e = e->next) {
 572                         if ((e->flags & (SEC_RES | INTERVAL)) != 0)
 573                                 return 1;
 574                 }
 575         }
 576         return 0;
 577 }
 578
 579 static void
 580 find_interval_entry(pid_t pid)
 581 {
 582         user *u;
 583         entry *e;
 584
 585         for (u = database.head;  u != NULL;  u = u->next) {
 586                 for (e = u->crontab;  e != NULL;  e = e->next) {
 587                         if ((e->flags & INTERVAL) && e->child == pid) {
 588                                 e->lastexit = time(NULL);
 589                                 e->child = 0;
 590                                 break;
 591                         }
 592                 }
 593         }
 594 }