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