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 1.3 2003/11/03 19:31:36 eirikn 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() {
  50     char **dflags;
  51
  52         fprintf(stderr, "usage: cron [-s] [-o] [-x debugflag[,...]]\n");
  53         fprintf(stderr, "\ndebugflags: ");
  54
  55         for(dflags = DebugFlagNames; *dflags; dflags++) {
  56                 fprintf(stderr, "%s ", *dflags);
  57         }
  58         fprintf(stderr, "\n");
  59
  60         exit(ERROR_EXIT);
  61 }
  62
  63
  64 int
  65 main(argc, argv)
  66         int     argc;
  67         char    *argv[];
  68 {
  69         cron_db database;
  70
  71         ProgramName = argv[0];
  72
  73 #if defined(BSD)
  74         setlinebuf(stdout);
  75         setlinebuf(stderr);
  76 #endif
  77
  78         parse_args(argc, argv);
  79
  80 #ifdef USE_SIGCHLD
  81         (void) signal(SIGCHLD, sigchld_handler);
  82 #else
  83         (void) signal(SIGCLD, SIG_IGN);
  84 #endif
  85         (void) signal(SIGHUP, sighup_handler);
  86
  87         acquire_daemonlock(0);
  88         set_cron_uid();
  89         set_cron_cwd();
  90
  91 #if defined(POSIX)
  92         setenv("PATH", _PATH_DEFPATH, 1);
  93 #endif
  94
  95         /* if there are no debug flags turned on, fork as a daemon should.
  96          */
  97 # if DEBUGGING
  98         if (DebugFlags) {
  99 # else
 100         if (0) {
 101 # endif
 102                 (void) fprintf(stderr, "[%d] cron started\n", getpid());
 103         } else {
 104                 if (daemon(1, 0) == -1) {
 105                         log_it("CRON",getpid(),"DEATH","can't become daemon");
 106                         exit(0);
 107                 }
 108         }
 109
 110         acquire_daemonlock(0);
 111         database.head = NULL;
 112         database.tail = NULL;
 113         database.mtime = (time_t) 0;
 114         load_database(&database);
 115         run_reboot_jobs(&database);
 116         cron_sync();
 117         while (TRUE) {
 118 # if DEBUGGING
 119             /* if (!(DebugFlags & DTEST)) */
 120 # endif /*DEBUGGING*/
 121                         cron_sleep(&database);
 122
 123                 load_database(&database);
 124
 125                 /* do this iteration
 126                  */
 127                 cron_tick(&database);
 128
 129                 /* sleep 1 minute
 130                  */
 131                 TargetTime += 60;
 132         }
 133 }
 134
 135
 136 static void
 137 run_reboot_jobs(db)
 138         cron_db *db;
 139 {
 140         register user           *u;
 141         register entry          *e;
 142
 143         for (u = db->head;  u != NULL;  u = u->next) {
 144                 for (e = u->crontab;  e != NULL;  e = e->next) {
 145                         if (e->flags & WHEN_REBOOT) {
 146                                 job_add(e, u);
 147                         }
 148                 }
 149         }
 150         (void) job_runqueue();
 151 }
 152
 153
 154 static void
 155 cron_tick(db)
 156         cron_db *db;
 157 {
 158         static struct tm        lasttm;
 159         static time_t   diff = 0, /* time difference in seconds from the last offset change */
 160                 difflimit = 0; /* end point for the time zone correction */
 161         struct tm       otztm; /* time in the old time zone */
 162         int             otzminute, otzhour, otzdom, otzmonth, otzdow;
 163         register struct tm      *tm = localtime(&TargetTime);
 164         register int            minute, hour, dom, month, dow;
 165         register user           *u;
 166         register entry          *e;
 167
 168         /* make 0-based values out of these so we can use them as indicies
 169          */
 170         minute = tm->tm_min -FIRST_MINUTE;
 171         hour = tm->tm_hour -FIRST_HOUR;
 172         dom = tm->tm_mday -FIRST_DOM;
 173         month = tm->tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 174         dow = tm->tm_wday -FIRST_DOW;
 175
 176         Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d)\n",
 177                 getpid(), minute, hour, dom, month, dow))
 178
 179         if (dst_enabled && last_time != 0
 180         && TargetTime > last_time /* exclude stepping back */
 181         && tm->tm_gmtoff != lasttm.tm_gmtoff ) {
 182
 183                 diff = tm->tm_gmtoff - lasttm.tm_gmtoff;
 184
 185                 if ( diff > 0 ) { /* ST->DST */
 186                         /* mark jobs for an earlier run */
 187                         difflimit = TargetTime + diff;
 188                         for (u = db->head;  u != NULL;  u = u->next) {
 189                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 190                                         e->flags &= ~NOT_UNTIL;
 191                                         if ( e->lastrun >= TargetTime )
 192                                                 e->lastrun = 0;
 193                                         /* not include the ends of hourly ranges */
 194                                         if ( e->lastrun < TargetTime - 3600 )
 195                                                 e->flags |= RUN_AT;
 196                                         else
 197                                                 e->flags &= ~RUN_AT;
 198                                 }
 199                         }
 200                 } else { /* diff < 0 : DST->ST */
 201                         /* mark jobs for skipping */
 202                         difflimit = TargetTime - diff;
 203                         for (u = db->head;  u != NULL;  u = u->next) {
 204                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 205                                         e->flags |= NOT_UNTIL;
 206                                         e->flags &= ~RUN_AT;
 207                                 }
 208                         }
 209                 }
 210         }
 211
 212         if (diff != 0) {
 213                 /* if the time was reset of the end of special zone is reached */
 214                 if (last_time == 0 || TargetTime >= difflimit) {
 215                         /* disable the TZ switch checks */
 216                         diff = 0;
 217                         difflimit = 0;
 218                         for (u = db->head;  u != NULL;  u = u->next) {
 219                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 220                                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 221                                 }
 222                         }
 223                 } else {
 224                         /* get the time in the old time zone */
 225                         time_t difftime = TargetTime + tm->tm_gmtoff - diff;
 226                         gmtime_r(&difftime, &otztm);
 227
 228                         /* make 0-based values out of these so we can use them as indicies
 229                          */
 230                         otzminute = otztm.tm_min -FIRST_MINUTE;
 231                         otzhour = otztm.tm_hour -FIRST_HOUR;
 232                         otzdom = otztm.tm_mday -FIRST_DOM;
 233                         otzmonth = otztm.tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 234                         otzdow = otztm.tm_wday -FIRST_DOW;
 235                 }
 236         }
 237
 238         /* the dom/dow situation is odd.  '* * 1,15 * Sun' will run on the
 239          * first and fifteenth AND every Sunday;  '* * * * Sun' will run *only*
 240          * on Sundays;  '* * 1,15 * *' will run *only* the 1st and 15th.  this
 241          * is why we keep 'e->dow_star' and 'e->dom_star'.  yes, it's bizarre.
 242          * like many bizarre things, it's the standard.
 243          */
 244         for (u = db->head;  u != NULL;  u = u->next) {
 245                 for (e = u->crontab;  e != NULL;  e = e->next) {
 246                         Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
 247                                           env_get("LOGNAME", e->envp),
 248                                           e->uid, e->gid, e->cmd))
 249
 250                         if ( diff != 0 && (e->flags & (RUN_AT|NOT_UNTIL)) ) {
 251                                 if (bit_test(e->minute, otzminute)
 252                                  && bit_test(e->hour, otzhour)
 253                                  && bit_test(e->month, otzmonth)
 254                                  && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 255                                           ? (bit_test(e->dow,otzdow) && bit_test(e->dom,otzdom))
 256                                           : (bit_test(e->dow,otzdow) || bit_test(e->dom,otzdom))
 257                                         )
 258                                    ) {
 259                                         if ( e->flags & RUN_AT ) {
 260                                                 e->flags &= ~RUN_AT;
 261                                                 e->lastrun = TargetTime;
 262                                                 job_add(e, u);
 263                                                 continue;
 264                                         } else
 265                                                 e->flags &= ~NOT_UNTIL;
 266                                 } else if ( e->flags & NOT_UNTIL )
 267                                         continue;
 268                         }
 269
 270                         if (bit_test(e->minute, minute)
 271                          && bit_test(e->hour, hour)
 272                          && bit_test(e->month, month)
 273                          && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 274                               ? (bit_test(e->dow,dow) && bit_test(e->dom,dom))
 275                               : (bit_test(e->dow,dow) || bit_test(e->dom,dom))
 276                             )
 277                            ) {
 278                                 e->flags &= ~RUN_AT;
 279                                 e->lastrun = TargetTime;
 280                                 job_add(e, u);
 281                         }
 282                 }
 283         }
 284
 285         last_time = TargetTime;
 286         lasttm = *tm;
 287 }
 288
 289
 290 /* the task here is to figure out how long it's going to be until :00 of the
 291  * following minute and initialize TargetTime to this value.  TargetTime
 292  * will subsequently slide 60 seconds at a time, with correction applied
 293  * implicitly in cron_sleep().  it would be nice to let cron execute in
 294  * the "current minute" before going to sleep, but by restarting cron you
 295  * could then get it to execute a given minute's jobs more than once.
 296  * instead we have the chance of missing a minute's jobs completely, but
 297  * that's something sysadmin's know to expect what with crashing computers..
 298  */
 299 static void
 300 cron_sync() {
 301         register struct tm      *tm;
 302
 303         TargetTime = time((time_t*)0);
 304         tm = localtime(&TargetTime);
 305         TargetTime += (60 - tm->tm_sec);
 306 }
 307
 308
 309 static void
 310 cron_sleep(db)
 311         cron_db *db;
 312 {
 313         int     seconds_to_wait = 0;
 314
 315         /*
 316          * Loop until we reach the top of the next minute, sleep when possible.
 317          */
 318
 319         for (;;) {
 320                 seconds_to_wait = (int) (TargetTime - time((time_t*)0));
 321
 322                 /*
 323                  * If the seconds_to_wait value is insane, jump the cron
 324                  */
 325
 326                 if (seconds_to_wait < -600 || seconds_to_wait > 600) {
 327                         cron_clean(db);
 328                         cron_sync();
 329                         continue;
 330                 }
 331
 332                 Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
 333                         getpid(), (long)TargetTime, seconds_to_wait))
 334
 335                 /*
 336                  * If we've run out of wait time or there are no jobs left
 337                  * to run, break
 338                  */
 339
 340                 if (seconds_to_wait <= 0)
 341                         break;
 342                 if (job_runqueue() == 0) {
 343                         Debug(DSCH, ("[%d] sleeping for %d seconds\n",
 344                                 getpid(), seconds_to_wait))
 345
 346                         sleep(seconds_to_wait);
 347                 }
 348         }
 349 }
 350
 351
 352 /* if the time was changed abruptly, clear the flags related
 353  * to the daylight time switch handling to avoid strange effects
 354  */
 355
 356 static void
 357 cron_clean(db)
 358         cron_db *db;
 359 {
 360         user            *u;
 361         entry           *e;
 362
 363         last_time = 0;
 364
 365         for (u = db->head;  u != NULL;  u = u->next) {
 366                 for (e = u->crontab;  e != NULL;  e = e->next) {
 367                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 368                 }
 369         }
 370 }
 371
 372 #ifdef USE_SIGCHLD
 373 static void
 374 sigchld_handler(x) {
 375         WAIT_T          waiter;
 376         PID_T           pid;
 377
 378         for (;;) {
 379 #ifdef POSIX
 380                 pid = waitpid(-1, &waiter, WNOHANG);
 381 #else
 382                 pid = wait3(&waiter, WNOHANG, (struct rusage *)0);
 383 #endif
 384                 switch (pid) {
 385                 case -1:
 386                         Debug(DPROC,
 387                                 ("[%d] sigchld...no children\n", getpid()))
 388                         return;
 389                 case 0:
 390                         Debug(DPROC,
 391                                 ("[%d] sigchld...no dead kids\n", getpid()))
 392                         return;
 393                 default:
 394                         Debug(DPROC,
 395                                 ("[%d] sigchld...pid #%d died, stat=%d\n",
 396                                 getpid(), pid, WEXITSTATUS(waiter)))
 397                 }
 398         }
 399 }
 400 #endif /*USE_SIGCHLD*/
 401
 402
 403 static void
 404 sighup_handler(x) {
 405         log_close();
 406 }
 407
 408
 409 static void
 410 parse_args(argc, argv)
 411         int     argc;
 412         char    *argv[];
 413 {
 414         int     argch;
 415
 416         while ((argch = getopt(argc, argv, "osx:")) != -1) {
 417                 switch (argch) {
 418                 case 'o':
 419                         dst_enabled = 0;
 420                         break;
 421                 case 's':
 422                         dst_enabled = 1;
 423                         break;
 424                 case 'x':
 425                         if (!set_debug_flags(optarg))
 426                                 usage();
 427                         break;
 428                 default:
 429                         usage();
 430                 }
 431         }
 432 }
 433