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  * $FreeBSD: src/usr.sbin/cron/cron/cron.c,v 1.9.2.2 2001/05/28 23:37:26 babkin Exp $
  18  * $DragonFly: src/usr.sbin/cron/cron/cron.c,v 1.8 2006/03/18 20:29:50 dillon Exp $
  19  */
  20
  21 #define MAIN_PROGRAM
  22
  23
  24 #include "cron.h"
  25 #include <sys/signal.h>
  26 #if SYS_TIME_H
  27 # include <sys/time.h>
  28 #else
  29 # include <time.h>
  30 #endif
  31
  32
  33 static  void    usage(void),
  34                 run_reboot_jobs(cron_db *),
  35                 cron_tick(cron_db *),
  36                 cron_sync(void),
  37                 cron_sleep(cron_db *),
  38                 cron_clean(cron_db *),
  39 #ifdef USE_SIGCHLD
  40                 sigchld_handler(int),
  41 #endif
  42                 sighup_handler(int),
  43                 parse_args(int c, char *v[]);
  44
  45 static time_t   last_time = 0;
  46 static int      dst_enabled = 0;
  47
  48 static void
  49 usage(void)
  50 {
  51     char **dflags;
  52
  53         fprintf(stderr, "usage: cron [-j jitter] [-J rootjitter] "
  54                         "[-s] [-o] [-x debugflag[,...]]\n");
  55
  56         for(dflags = DebugFlagNames; *dflags; dflags++) {
  57                 fprintf(stderr, "%s ", *dflags);
  58         }
  59         fprintf(stderr, "\n");
  60
  61         exit(ERROR_EXIT);
  62 }
  63
  64
  65 int
  66 main(int argc, char **argv)
  67 {
  68         cron_db database;
  69
  70         ProgramName = argv[0];
  71
  72 #if defined(BSD)
  73         setlinebuf(stdout);
  74         setlinebuf(stderr);
  75 #endif
  76
  77         parse_args(argc, argv);
  78
  79 #ifdef USE_SIGCHLD
  80         signal(SIGCHLD, sigchld_handler);
  81 #else
  82         signal(SIGCLD, SIG_IGN);
  83 #endif
  84         signal(SIGHUP, sighup_handler);
  85
  86         acquire_daemonlock(0);
  87         set_cron_uid();
  88         set_cron_cwd();
  89
  90 #if defined(POSIX)
  91         if (setenv("PATH", _PATH_DEFPATH, 1) == -1) {
  92                 log_it("CRON", getpid(), "DEATH",
  93                        "setenv: cannot set PATH");
  94                 exit(0);
  95         }
  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                 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(cron_db *db)
 141 {
 142         user *u;
 143         entry *e;
 144
 145         for (u = db->head;  u != NULL;  u = u->next) {
 146                 for (e = u->crontab;  e != NULL;  e = e->next) {
 147                         if (e->flags & WHEN_REBOOT) {
 148                                 job_add(e, u);
 149                         }
 150                 }
 151         }
 152         job_runqueue();
 153 }
 154
 155
 156 static void
 157 cron_tick(cron_db *db)
 158 {
 159         static struct tm lasttm;
 160         static time_t diff;      /* delta time from the last offset change */
 161         static time_t difflimit; /* end point for the time zone correction */
 162         struct tm otztm; /* time in the old time zone */
 163         int otzminute, otzhour, otzdom, otzmonth, otzdow;
 164         struct tm *tm;
 165         int minute, hour, dom, month, dow;
 166         user *u;
 167         entry *e;
 168
 169         tm = localtime(&TargetTime);
 170         /* make 0-based values out of these so we can use them as indicies
 171          */
 172         minute = tm->tm_min -FIRST_MINUTE;
 173         hour = tm->tm_hour -FIRST_HOUR;
 174         dom = tm->tm_mday -FIRST_DOM;
 175         month = tm->tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 176         dow = tm->tm_wday -FIRST_DOW;
 177
 178         Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d)\n",
 179                 getpid(), minute, hour, dom, month, dow))
 180
 181         if (dst_enabled && last_time != 0
 182         && TargetTime > last_time /* exclude stepping back */
 183         && tm->tm_gmtoff != lasttm.tm_gmtoff ) {
 184
 185                 diff = tm->tm_gmtoff - lasttm.tm_gmtoff;
 186
 187                 if ( diff > 0 ) { /* ST->DST */
 188                         /* mark jobs for an earlier run */
 189                         difflimit = TargetTime + diff;
 190                         for (u = db->head;  u != NULL;  u = u->next) {
 191                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 192                                         e->flags &= ~NOT_UNTIL;
 193                                         if ( e->lastrun >= TargetTime )
 194                                                 e->lastrun = 0;
 195                                         /* not include the ends of hourly ranges */
 196                                         if ( e->lastrun < TargetTime - 3600 )
 197                                                 e->flags |= RUN_AT;
 198                                         else
 199                                                 e->flags &= ~RUN_AT;
 200                                 }
 201                         }
 202                 } else { /* diff < 0 : DST->ST */
 203                         /* mark jobs for skipping */
 204                         difflimit = TargetTime - diff;
 205                         for (u = db->head;  u != NULL;  u = u->next) {
 206                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 207                                         e->flags |= NOT_UNTIL;
 208                                         e->flags &= ~RUN_AT;
 209                                 }
 210                         }
 211                 }
 212         }
 213
 214         if (diff != 0) {
 215                 /* if the time was reset of the end of special zone is reached */
 216                 if (last_time == 0 || TargetTime >= difflimit) {
 217                         /* disable the TZ switch checks */
 218                         diff = 0;
 219                         difflimit = 0;
 220                         for (u = db->head;  u != NULL;  u = u->next) {
 221                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 222                                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 223                                 }
 224                         }
 225                 } else {
 226                         /* get the time in the old time zone */
 227                         time_t difftime = TargetTime + tm->tm_gmtoff - diff;
 228                         gmtime_r(&difftime, &otztm);
 229
 230                         /* make 0-based values out of these so we can use them as indicies
 231                          */
 232                         otzminute = otztm.tm_min -FIRST_MINUTE;
 233                         otzhour = otztm.tm_hour -FIRST_HOUR;
 234                         otzdom = otztm.tm_mday -FIRST_DOM;
 235                         otzmonth = otztm.tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 236                         otzdow = otztm.tm_wday -FIRST_DOW;
 237                 }
 238         }
 239
 240         /* the dom/dow situation is odd.  '* * 1,15 * Sun' will run on the
 241          * first and fifteenth AND every Sunday;  '* * * * Sun' will run *only*
 242          * on Sundays;  '* * 1,15 * *' will run *only* the 1st and 15th.  this
 243          * is why we keep 'e->dow_star' and 'e->dom_star'.  yes, it's bizarre.
 244          * like many bizarre things, it's the standard.
 245          */
 246         for (u = db->head;  u != NULL;  u = u->next) {
 247                 for (e = u->crontab;  e != NULL;  e = e->next) {
 248                         Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
 249                                           env_get("LOGNAME", e->envp),
 250                                           e->uid, e->gid, e->cmd))
 251
 252                         if ( diff != 0 && (e->flags & (RUN_AT|NOT_UNTIL)) ) {
 253                                 if (bit_test(e->minute, otzminute)
 254                                  && bit_test(e->hour, otzhour)
 255                                  && bit_test(e->month, otzmonth)
 256                                  && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 257                                           ? (bit_test(e->dow,otzdow) && bit_test(e->dom,otzdom))
 258                                           : (bit_test(e->dow,otzdow) || bit_test(e->dom,otzdom))
 259                                         )
 260                                    ) {
 261                                         if ( e->flags & RUN_AT ) {
 262                                                 e->flags &= ~RUN_AT;
 263                                                 e->lastrun = TargetTime;
 264                                                 job_add(e, u);
 265                                                 continue;
 266                                         } else
 267                                                 e->flags &= ~NOT_UNTIL;
 268                                 } else if ( e->flags & NOT_UNTIL )
 269                                         continue;
 270                         }
 271
 272                         if (bit_test(e->minute, minute)
 273                          && bit_test(e->hour, hour)
 274                          && bit_test(e->month, month)
 275                          && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 276                               ? (bit_test(e->dow,dow) && bit_test(e->dom,dom))
 277                               : (bit_test(e->dow,dow) || bit_test(e->dom,dom))
 278                             )
 279                            ) {
 280                                 e->flags &= ~RUN_AT;
 281                                 e->lastrun = TargetTime;
 282                                 job_add(e, u);
 283                         }
 284                 }
 285         }
 286
 287         last_time = TargetTime;
 288         lasttm = *tm;
 289 }
 290
 291
 292 /* the task here is to figure out how long it's going to be until :00 of the
 293  * following minute and initialize TargetTime to this value.  TargetTime
 294  * will subsequently slide 60 seconds at a time, with correction applied
 295  * implicitly in cron_sleep().  it would be nice to let cron execute in
 296  * the "current minute" before going to sleep, but by restarting cron you
 297  * could then get it to execute a given minute's jobs more than once.
 298  * instead we have the chance of missing a minute's jobs completely, but
 299  * that's something sysadmin's know to expect what with crashing computers..
 300  */
 301 static void
 302 cron_sync(void)
 303 {
 304         struct tm *tm;
 305
 306         TargetTime = time(NULL);
 307         tm = localtime(&TargetTime);
 308         TargetTime += (60 - tm->tm_sec);
 309 }
 310
 311
 312 static void
 313 cron_sleep(cron_db *db)
 314 {
 315         int     seconds_to_wait = 0;
 316
 317         /*
 318          * Loop until we reach the top of the next minute, sleep when possible.
 319          */
 320
 321         for (;;) {
 322                 seconds_to_wait = (int) (TargetTime - time(NULL));
 323
 324                 /*
 325                  * If the seconds_to_wait value is insane, jump the cron
 326                  */
 327
 328                 if (seconds_to_wait < -600 || seconds_to_wait > 600) {
 329                         cron_clean(db);
 330                         cron_sync();
 331                         continue;
 332                 }
 333
 334                 Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
 335                         getpid(), (long)TargetTime, seconds_to_wait))
 336
 337                 /*
 338                  * If we've run out of wait time or there are no jobs left
 339                  * to run, break
 340                  */
 341
 342                 if (seconds_to_wait <= 0)
 343                         break;
 344                 if (job_runqueue() == 0) {
 345                         Debug(DSCH, ("[%d] sleeping for %d seconds\n",
 346                                 getpid(), seconds_to_wait))
 347
 348                         sleep(seconds_to_wait);
 349                 }
 350         }
 351 }
 352
 353
 354 /* if the time was changed abruptly, clear the flags related
 355  * to the daylight time switch handling to avoid strange effects
 356  */
 357
 358 static void
 359 cron_clean(cron_db *db)
 360 {
 361         user            *u;
 362         entry           *e;
 363
 364         last_time = 0;
 365
 366         for (u = db->head;  u != NULL;  u = u->next) {
 367                 for (e = u->crontab;  e != NULL;  e = e->next) {
 368                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 369                 }
 370         }
 371 }
 372
 373 #ifdef USE_SIGCHLD
 374 static void
 375 sigchld_handler(int x)
 376 {
 377         WAIT_T          waiter;
 378         PID_T           pid;
 379
 380         for (;;) {
 381 #ifdef POSIX
 382                 pid = waitpid(-1, &waiter, WNOHANG);
 383 #else
 384                 pid = wait3(&waiter, WNOHANG, NULL);
 385 #endif
 386                 switch (pid) {
 387                 case -1:
 388                         Debug(DPROC,
 389                                 ("[%d] sigchld...no children\n", getpid()))
 390                         return;
 391                 case 0:
 392                         Debug(DPROC,
 393                                 ("[%d] sigchld...no dead kids\n", getpid()))
 394                         return;
 395                 default:
 396                         Debug(DPROC,
 397                                 ("[%d] sigchld...pid #%d died, stat=%d\n",
 398                                 getpid(), pid, WEXITSTATUS(waiter)))
 399                 }
 400         }
 401 }
 402 #endif /*USE_SIGCHLD*/
 403
 404
 405 static void
 406 sighup_handler(int x)
 407 {
 408         log_close();
 409 }
 410
 411
 412 static void
 413 parse_args(int argc, char **argv)
 414 {
 415         int     argch;
 416         char    *endp;
 417
 418         while ((argch = getopt(argc, argv, "j:J:osx:")) != -1) {
 419                 switch (argch) {
 420                 case 'j':
 421                         Jitter = strtoul(optarg, &endp, 10);
 422                         if (*optarg == '\0' || *endp != '\0' || Jitter > 60)
 423                                 errx(ERROR_EXIT,
 424                                      "bad value for jitter: %s", optarg);
 425                         break;
 426                 case 'J':
 427                         RootJitter = strtoul(optarg, &endp, 10);
 428                         if (*optarg == '\0' || *endp != '\0' || RootJitter > 60)
 429                                 errx(ERROR_EXIT,
 430                                      "bad value for root jitter: %s", optarg);
 431                         break;
 432                 case 'o':
 433                         dst_enabled = 0;
 434                         break;
 435                 case 's':
 436                         dst_enabled = 1;
 437                         break;
 438                 case 'x':
 439                         if (!set_debug_flags(optarg))
 440                                 usage();
 441                         break;
 442                 default:
 443                         usage();
 444                 }
 445         }
 446 }
 447