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 struct pidfh *pfh;
  53
  54 static void
  55 usage() {
  56 #if DEBUGGING
  57     char **dflags;
  58 #endif
  59
  60         fprintf(stderr, "usage: cron [-j jitter] [-J rootjitter] "
  61                         "[-m mailto] [-s] [-o] [-x debugflag[,...]]\n");
  62 #if DEBUGGING
  63         fprintf(stderr, "\ndebugflags: ");
  64
  65         for(dflags = DebugFlagNames; *dflags; dflags++) {
  66                 fprintf(stderr, "%s ", *dflags);
  67         }
  68         fprintf(stderr, "\n");
  69 #endif
  70
  71         exit(ERROR_EXIT);
  72 }
  73
  74 static void
  75 open_pidfile(void)
  76 {
  77         char    pidfile[MAX_FNAME];
  78         char    buf[MAX_TEMPSTR];
  79         int     otherpid;
  80
  81         (void) snprintf(pidfile, sizeof(pidfile), PIDFILE, PIDDIR);
  82         pfh = pidfile_open(pidfile, 0600, &otherpid);
  83         if (pfh == NULL) {
  84                 if (errno == EEXIST) {
  85                         snprintf(buf, sizeof(buf),
  86                             "cron already running, pid: %d", otherpid);
  87                 } else {
  88                         snprintf(buf, sizeof(buf),
  89                             "can't open or create %s: %s", pidfile,
  90                             strerror(errno));
  91                 }
  92                 log_it("CRON", getpid(), "DEATH", buf);
  93                 errx(ERROR_EXIT, "%s", buf);
  94         }
  95 }
  96
  97 int
  98 main(argc, argv)
  99         int     argc;
 100         char    *argv[];
 101 {
 102         cron_db database;
 103         int runnum;
 104         int secres1, secres2;
 105         struct tm *tm;
 106
 107         ProgramName = argv[0];
 108
 109 #if defined(BSD)
 110         setlinebuf(stdout);
 111         setlinebuf(stderr);
 112 #endif
 113
 114         parse_args(argc, argv);
 115
 116 #ifdef USE_SIGCHLD
 117         (void) signal(SIGCHLD, sigchld_handler);
 118 #else
 119         (void) signal(SIGCLD, SIG_IGN);
 120 #endif
 121         (void) signal(SIGHUP, sighup_handler);
 122
 123         open_pidfile();
 124         set_cron_uid();
 125         set_cron_cwd();
 126
 127 #if defined(POSIX)
 128         setenv("PATH", _PATH_DEFPATH, 1);
 129 #endif
 130
 131         /* if there are no debug flags turned on, fork as a daemon should.
 132          */
 133 # if DEBUGGING
 134         if (DebugFlags) {
 135 # else
 136         if (0) {
 137 # endif
 138                 (void) fprintf(stderr, "[%d] cron started\n", getpid());
 139         } else {
 140                 if (daemon(1, 0) == -1) {
 141                         pidfile_remove(pfh);
 142                         log_it("CRON",getpid(),"DEATH","can't become daemon");
 143                         exit(0);
 144                 }
 145         }
 146
 147         if (madvise(NULL, 0, MADV_PROTECT) != 0)
 148                 log_it("CRON", getpid(), "WARNING", "madvise() failed");
 149
 150         pidfile_write(pfh);
 151         database.head = NULL;
 152         database.tail = NULL;
 153         database.mtime = (time_t) 0;
 154         load_database(&database);
 155         secres1 = secres2 = run_at_secres(&database);
 156         run_reboot_jobs(&database);
 157         cron_sync(secres1);
 158         runnum = 0;
 159         while (TRUE) {
 160 # if DEBUGGING
 161             /* if (!(DebugFlags & DTEST)) */
 162 # endif /*DEBUGGING*/
 163                         cron_sleep(&database, secres1);
 164
 165                 if (secres1 == 0 || runnum % 60 == 0) {
 166                         load_database(&database);
 167                         secres2 = run_at_secres(&database);
 168                         if (secres2 != secres1) {
 169                                 secres1 = secres2;
 170                                 if (secres1 != 0) {
 171                                         runnum = 0;
 172                                 } else {
 173                                         /*
 174                                          * Going from 1 sec to 60 sec res. If we
 175                                          * are already at minute's boundary, so
 176                                          * let it run, otherwise schedule for the
 177                                          * next minute.
 178                                          */
 179                                         tm = localtime(&TargetTime);
 180                                         if (tm->tm_sec > 0)  {
 181                                                 cron_sync(secres2);
 182                                                 continue;
 183                                         }
 184                                 }
 185                         }
 186                 }
 187
 188                 /* do this iteration
 189                  */
 190                 cron_tick(&database, secres1);
 191
 192                 /* sleep 1 or 60 seconds
 193                  */
 194                 TargetTime += (secres1 != 0) ? 1 : 60;
 195                 runnum += 1;
 196         }
 197 }
 198
 199
 200 static void
 201 run_reboot_jobs(db)
 202         cron_db *db;
 203 {
 204         register user           *u;
 205         register entry          *e;
 206
 207         for (u = db->head;  u != NULL;  u = u->next) {
 208                 for (e = u->crontab;  e != NULL;  e = e->next) {
 209                         if (e->flags & WHEN_REBOOT) {
 210                                 job_add(e, u);
 211                         }
 212                 }
 213         }
 214         (void) job_runqueue();
 215 }
 216
 217
 218 static void
 219 cron_tick(cron_db *db, int secres)
 220 {
 221         static struct tm        lasttm;
 222         static time_t   diff = 0, /* time difference in seconds from the last offset change */
 223                 difflimit = 0; /* end point for the time zone correction */
 224         struct tm       otztm; /* time in the old time zone */
 225         int             otzsecond, otzminute, otzhour, otzdom, otzmonth, otzdow;
 226         register struct tm      *tm = localtime(&TargetTime);
 227         register int            second, minute, hour, dom, month, dow;
 228         register user           *u;
 229         register entry          *e;
 230
 231         /* make 0-based values out of these so we can use them as indicies
 232          */
 233         second = (secres == 0) ? 0 : tm->tm_sec -FIRST_SECOND;
 234         minute = tm->tm_min -FIRST_MINUTE;
 235         hour = tm->tm_hour -FIRST_HOUR;
 236         dom = tm->tm_mday -FIRST_DOM;
 237         month = tm->tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 238         dow = tm->tm_wday -FIRST_DOW;
 239
 240         Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d,%d)\n",
 241                 getpid(), second, minute, hour, dom, month, dow))
 242
 243         if (dst_enabled && last_time != 0
 244         && TargetTime > last_time /* exclude stepping back */
 245         && tm->tm_gmtoff != lasttm.tm_gmtoff ) {
 246
 247                 diff = tm->tm_gmtoff - lasttm.tm_gmtoff;
 248
 249                 if ( diff > 0 ) { /* ST->DST */
 250                         /* mark jobs for an earlier run */
 251                         difflimit = TargetTime + diff;
 252                         for (u = db->head;  u != NULL;  u = u->next) {
 253                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 254                                         e->flags &= ~NOT_UNTIL;
 255                                         if ( e->lastrun >= TargetTime )
 256                                                 e->lastrun = 0;
 257                                         /* not include the ends of hourly ranges */
 258                                         if ( e->lastrun < TargetTime - 3600 )
 259                                                 e->flags |= RUN_AT;
 260                                         else
 261                                                 e->flags &= ~RUN_AT;
 262                                 }
 263                         }
 264                 } else { /* diff < 0 : DST->ST */
 265                         /* mark jobs for skipping */
 266                         difflimit = TargetTime - diff;
 267                         for (u = db->head;  u != NULL;  u = u->next) {
 268                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 269                                         e->flags |= NOT_UNTIL;
 270                                         e->flags &= ~RUN_AT;
 271                                 }
 272                         }
 273                 }
 274         }
 275
 276         if (diff != 0) {
 277                 /* if the time was reset of the end of special zone is reached */
 278                 if (last_time == 0 || TargetTime >= difflimit) {
 279                         /* disable the TZ switch checks */
 280                         diff = 0;
 281                         difflimit = 0;
 282                         for (u = db->head;  u != NULL;  u = u->next) {
 283                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 284                                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 285                                 }
 286                         }
 287                 } else {
 288                         /* get the time in the old time zone */
 289                         time_t difftime = TargetTime + tm->tm_gmtoff - diff;
 290                         gmtime_r(&difftime, &otztm);
 291
 292                         /* make 0-based values out of these so we can use them as indicies
 293                          */
 294                         otzsecond = (secres == 0) ? 0 : otztm.tm_sec -FIRST_SECOND;
 295                         otzminute = otztm.tm_min -FIRST_MINUTE;
 296                         otzhour = otztm.tm_hour -FIRST_HOUR;
 297                         otzdom = otztm.tm_mday -FIRST_DOM;
 298                         otzmonth = otztm.tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 299                         otzdow = otztm.tm_wday -FIRST_DOW;
 300                 }
 301         }
 302
 303         /* the dom/dow situation is odd.  '* * 1,15 * Sun' will run on the
 304          * first and fifteenth AND every Sunday;  '* * * * Sun' will run *only*
 305          * on Sundays;  '* * 1,15 * *' will run *only* the 1st and 15th.  this
 306          * is why we keep 'e->dow_star' and 'e->dom_star'.  yes, it's bizarre.
 307          * like many bizarre things, it's the standard.
 308          */
 309         for (u = db->head;  u != NULL;  u = u->next) {
 310                 for (e = u->crontab;  e != NULL;  e = e->next) {
 311                         Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
 312                                           env_get("LOGNAME", e->envp),
 313                                           e->uid, e->gid, e->cmd))
 314
 315                         if ( diff != 0 && (e->flags & (RUN_AT|NOT_UNTIL)) ) {
 316                                 if (bit_test(e->second, otzsecond)
 317                                  && bit_test(e->minute, otzminute)
 318                                  && bit_test(e->hour, otzhour)
 319                                  && bit_test(e->month, otzmonth)
 320                                  && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 321                                           ? (bit_test(e->dow,otzdow) && bit_test(e->dom,otzdom))
 322                                           : (bit_test(e->dow,otzdow) || bit_test(e->dom,otzdom))
 323                                         )
 324                                    ) {
 325                                         if ( e->flags & RUN_AT ) {
 326                                                 e->flags &= ~RUN_AT;
 327                                                 e->lastrun = TargetTime;
 328                                                 job_add(e, u);
 329                                                 continue;
 330                                         } else
 331                                                 e->flags &= ~NOT_UNTIL;
 332                                 } else if ( e->flags & NOT_UNTIL )
 333                                         continue;
 334                         }
 335
 336                         if (bit_test(e->second, second)
 337                          && bit_test(e->minute, minute)
 338                          && bit_test(e->hour, hour)
 339                          && bit_test(e->month, month)
 340                          && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 341                               ? (bit_test(e->dow,dow) && bit_test(e->dom,dom))
 342                               : (bit_test(e->dow,dow) || bit_test(e->dom,dom))
 343                             )
 344                            ) {
 345                                 e->flags &= ~RUN_AT;
 346                                 e->lastrun = TargetTime;
 347                                 job_add(e, u);
 348                         }
 349                 }
 350         }
 351
 352         last_time = TargetTime;
 353         lasttm = *tm;
 354 }
 355
 356
 357 /* the task here is to figure out how long it's going to be until :00 of the
 358  * following minute and initialize TargetTime to this value.  TargetTime
 359  * will subsequently slide 60 seconds at a time, with correction applied
 360  * implicitly in cron_sleep().  it would be nice to let cron execute in
 361  * the "current minute" before going to sleep, but by restarting cron you
 362  * could then get it to execute a given minute's jobs more than once.
 363  * instead we have the chance of missing a minute's jobs completely, but
 364  * that's something sysadmin's know to expect what with crashing computers..
 365  */
 366 static void
 367 cron_sync(int secres) {
 368         struct tm *tm;
 369
 370         TargetTime = time((time_t*)0);
 371         if (secres != 0) {
 372                 TargetTime += 1;
 373         } else {
 374                 tm = localtime(&TargetTime);
 375                 TargetTime += (60 - tm->tm_sec);
 376         }
 377 }
 378
 379 static int
 380 timespec_subtract(struct timespec *result, struct timespec *x,
 381     struct timespec *y)
 382 {
 383         time_t nsec;
 384
 385         /* Perform the carry for the later subtraction by updating y. */
 386         if (x->tv_nsec < y->tv_nsec) {
 387                 nsec = (y->tv_nsec - x->tv_nsec) / 10000000 + 1;
 388                 y->tv_nsec -= 1000000000 * nsec;
 389                 y->tv_sec += nsec;
 390         }
 391         if (x->tv_nsec - y->tv_nsec > 1000000000) {
 392                 nsec = (x->tv_nsec - y->tv_nsec) / 1000000000;
 393                 y->tv_nsec += 1000000000 * nsec;
 394                 y->tv_sec -= nsec;
 395         }
 396
 397         /* tv_nsec is certainly positive. */
 398         result->tv_sec = x->tv_sec - y->tv_sec;
 399         result->tv_nsec = x->tv_nsec - y->tv_nsec;
 400
 401         /* Return True if result is negative. */
 402         return (x->tv_sec < y->tv_sec);
 403 }
 404
 405 static void
 406 cron_sleep(cron_db *db, int secres)
 407 {
 408         int seconds_to_wait;
 409         int rval;
 410         struct timespec ctime, ttime, stime, remtime;
 411
 412         /*
 413          * Loop until we reach the top of the next minute, sleep when possible.
 414          */
 415
 416         for (;;) {
 417                 clock_gettime(CLOCK_REALTIME, &ctime);
 418                 ttime.tv_sec = TargetTime;
 419                 ttime.tv_nsec = 0;
 420                 timespec_subtract(&stime, &ttime, &ctime);
 421
 422                 /*
 423                  * If the seconds_to_wait value is insane, jump the cron
 424                  */
 425
 426                 if (stime.tv_sec < -600 || stime.tv_sec > 600) {
 427                         cron_clean(db);
 428                         cron_sync(secres);
 429                         continue;
 430                 }
 431
 432                 seconds_to_wait = (stime.tv_nsec > 0) ? stime.tv_sec + 1 :
 433                     stime.tv_sec;
 434
 435                 Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
 436                         getpid(), (long)TargetTime, seconds_to_wait))
 437
 438                 /*
 439                  * If we've run out of wait time or there are no jobs left
 440                  * to run, break
 441                  */
 442
 443                 if (stime.tv_sec < 0)
 444                         break;
 445                 if (job_runqueue() == 0) {
 446                         Debug(DSCH, ("[%d] sleeping for %d seconds\n",
 447                                 getpid(), seconds_to_wait))
 448
 449                         for (;;) {
 450                                 rval = nanosleep(&stime, &remtime);
 451                                 if (rval == 0 || errno != EINTR)
 452                                         break;
 453                                 stime.tv_sec = remtime.tv_sec;
 454                                 stime.tv_nsec = remtime.tv_nsec;
 455                         }
 456                 }
 457         }
 458 }
 459
 460
 461 /* if the time was changed abruptly, clear the flags related
 462  * to the daylight time switch handling to avoid strange effects
 463  */
 464
 465 static void
 466 cron_clean(db)
 467         cron_db *db;
 468 {
 469         user            *u;
 470         entry           *e;
 471
 472         last_time = 0;
 473
 474         for (u = db->head;  u != NULL;  u = u->next) {
 475                 for (e = u->crontab;  e != NULL;  e = e->next) {
 476                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 477                 }
 478         }
 479 }
 480
 481 #ifdef USE_SIGCHLD
 482 static void
 483 sigchld_handler(int x)
 484 {
 485         WAIT_T          waiter;
 486         PID_T           pid;
 487
 488         for (;;) {
 489 #ifdef POSIX
 490                 pid = waitpid(-1, &waiter, WNOHANG);
 491 #else
 492                 pid = wait3(&waiter, WNOHANG, (struct rusage *)0);
 493 #endif
 494                 switch (pid) {
 495                 case -1:
 496                         Debug(DPROC,
 497                                 ("[%d] sigchld...no children\n", getpid()))
 498                         return;
 499                 case 0:
 500                         Debug(DPROC,
 501                                 ("[%d] sigchld...no dead kids\n", getpid()))
 502                         return;
 503                 default:
 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:osx:")) != -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 'o':
 546                         dst_enabled = 0;
 547                         break;
 548                 case 's':
 549                         dst_enabled = 1;
 550                         break;
 551                 case 'x':
 552                         if (!set_debug_flags(optarg))
 553                                 usage();
 554                         break;
 555                 default:
 556                         usage();
 557                 }
 558         }
 559 }
 560
 561 static int
 562 run_at_secres(cron_db *db)
 563 {
 564         user *u;
 565         entry *e;
 566
 567         for (u = db->head;  u != NULL;  u = u->next) {
 568                 for (e = u->crontab;  e != NULL;  e = e->next) {
 569                         if ((e->flags & SEC_RES) != 0)
 570                                 return 1;
 571                 }
 572         }
 573         return 0;
 574 }