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 1.5 2004/03/10 18:27:26 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 [-s] [-o] [-x debugflag[,...]]\n");
  54         fprintf(stderr, "\ndebugflags: ");
  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         (void) signal(SIGCHLD, sigchld_handler);
  81 #else
  82         (void) signal(SIGCLD, SIG_IGN);
  83 #endif
  84         (void) signal(SIGHUP, sighup_handler);
  85
  86         acquire_daemonlock(0);
  87         set_cron_uid();
  88         set_cron_cwd();
  89
  90 #if defined(POSIX)
  91         setenv("PATH", _PATH_DEFPATH, 1);
  92 #endif
  93
  94         /* if there are no debug flags turned on, fork as a daemon should.
  95          */
  96 # if DEBUGGING
  97         if (DebugFlags) {
  98 # else
  99         if (0) {
 100 # endif
 101                 (void) fprintf(stderr, "[%d] cron started\n", getpid());
 102         } else {
 103                 if (daemon(1, 0) == -1) {
 104                         log_it("CRON",getpid(),"DEATH","can't become daemon");
 105                         exit(0);
 106                 }
 107         }
 108
 109         acquire_daemonlock(0);
 110         database.head = NULL;
 111         database.tail = NULL;
 112         database.mtime = (time_t) 0;
 113         load_database(&database);
 114         run_reboot_jobs(&database);
 115         cron_sync();
 116         while (TRUE) {
 117 # if DEBUGGING
 118             /* if (!(DebugFlags & DTEST)) */
 119 # endif /*DEBUGGING*/
 120                         cron_sleep(&database);
 121
 122                 load_database(&database);
 123
 124                 /* do this iteration
 125                  */
 126                 cron_tick(&database);
 127
 128                 /* sleep 1 minute
 129                  */
 130                 TargetTime += 60;
 131         }
 132 }
 133
 134
 135 static void
 136 run_reboot_jobs(cron_db *db)
 137 {
 138         user *u;
 139         entry *e;
 140
 141         for (u = db->head;  u != NULL;  u = u->next) {
 142                 for (e = u->crontab;  e != NULL;  e = e->next) {
 143                         if (e->flags & WHEN_REBOOT) {
 144                                 job_add(e, u);
 145                         }
 146                 }
 147         }
 148         (void) job_runqueue();
 149 }
 150
 151
 152 static void
 153 cron_tick(cron_db *db)
 154 {
 155         static struct tm lasttm;
 156         static time_t diff;      /* delta time from the last offset change */
 157         static time_t difflimit; /* end point for the time zone correction */
 158         struct tm otztm; /* time in the old time zone */
 159         int otzminute, otzhour, otzdom, otzmonth, otzdow;
 160         struct tm *tm;
 161         int minute, hour, dom, month, dow;
 162         user *u;
 163         entry *e;
 164
 165         tm = localtime(&TargetTime);
 166         /* make 0-based values out of these so we can use them as indicies
 167          */
 168         minute = tm->tm_min -FIRST_MINUTE;
 169         hour = tm->tm_hour -FIRST_HOUR;
 170         dom = tm->tm_mday -FIRST_DOM;
 171         month = tm->tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 172         dow = tm->tm_wday -FIRST_DOW;
 173
 174         Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d)\n",
 175                 getpid(), minute, hour, dom, month, dow))
 176
 177         if (dst_enabled && last_time != 0
 178         && TargetTime > last_time /* exclude stepping back */
 179         && tm->tm_gmtoff != lasttm.tm_gmtoff ) {
 180
 181                 diff = tm->tm_gmtoff - lasttm.tm_gmtoff;
 182
 183                 if ( diff > 0 ) { /* ST->DST */
 184                         /* mark jobs for an earlier run */
 185                         difflimit = TargetTime + diff;
 186                         for (u = db->head;  u != NULL;  u = u->next) {
 187                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 188                                         e->flags &= ~NOT_UNTIL;
 189                                         if ( e->lastrun >= TargetTime )
 190                                                 e->lastrun = 0;
 191                                         /* not include the ends of hourly ranges */
 192                                         if ( e->lastrun < TargetTime - 3600 )
 193                                                 e->flags |= RUN_AT;
 194                                         else
 195                                                 e->flags &= ~RUN_AT;
 196                                 }
 197                         }
 198                 } else { /* diff < 0 : DST->ST */
 199                         /* mark jobs for skipping */
 200                         difflimit = TargetTime - diff;
 201                         for (u = db->head;  u != NULL;  u = u->next) {
 202                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 203                                         e->flags |= NOT_UNTIL;
 204                                         e->flags &= ~RUN_AT;
 205                                 }
 206                         }
 207                 }
 208         }
 209
 210         if (diff != 0) {
 211                 /* if the time was reset of the end of special zone is reached */
 212                 if (last_time == 0 || TargetTime >= difflimit) {
 213                         /* disable the TZ switch checks */
 214                         diff = 0;
 215                         difflimit = 0;
 216                         for (u = db->head;  u != NULL;  u = u->next) {
 217                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 218                                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 219                                 }
 220                         }
 221                 } else {
 222                         /* get the time in the old time zone */
 223                         time_t difftime = TargetTime + tm->tm_gmtoff - diff;
 224                         gmtime_r(&difftime, &otztm);
 225
 226                         /* make 0-based values out of these so we can use them as indicies
 227                          */
 228                         otzminute = otztm.tm_min -FIRST_MINUTE;
 229                         otzhour = otztm.tm_hour -FIRST_HOUR;
 230                         otzdom = otztm.tm_mday -FIRST_DOM;
 231                         otzmonth = otztm.tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 232                         otzdow = otztm.tm_wday -FIRST_DOW;
 233                 }
 234         }
 235
 236         /* the dom/dow situation is odd.  '* * 1,15 * Sun' will run on the
 237          * first and fifteenth AND every Sunday;  '* * * * Sun' will run *only*
 238          * on Sundays;  '* * 1,15 * *' will run *only* the 1st and 15th.  this
 239          * is why we keep 'e->dow_star' and 'e->dom_star'.  yes, it's bizarre.
 240          * like many bizarre things, it's the standard.
 241          */
 242         for (u = db->head;  u != NULL;  u = u->next) {
 243                 for (e = u->crontab;  e != NULL;  e = e->next) {
 244                         Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
 245                                           env_get("LOGNAME", e->envp),
 246                                           e->uid, e->gid, e->cmd))
 247
 248                         if ( diff != 0 && (e->flags & (RUN_AT|NOT_UNTIL)) ) {
 249                                 if (bit_test(e->minute, otzminute)
 250                                  && bit_test(e->hour, otzhour)
 251                                  && bit_test(e->month, otzmonth)
 252                                  && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 253                                           ? (bit_test(e->dow,otzdow) && bit_test(e->dom,otzdom))
 254                                           : (bit_test(e->dow,otzdow) || bit_test(e->dom,otzdom))
 255                                         )
 256                                    ) {
 257                                         if ( e->flags & RUN_AT ) {
 258                                                 e->flags &= ~RUN_AT;
 259                                                 e->lastrun = TargetTime;
 260                                                 job_add(e, u);
 261                                                 continue;
 262                                         } else
 263                                                 e->flags &= ~NOT_UNTIL;
 264                                 } else if ( e->flags & NOT_UNTIL )
 265                                         continue;
 266                         }
 267
 268                         if (bit_test(e->minute, minute)
 269                          && bit_test(e->hour, hour)
 270                          && bit_test(e->month, month)
 271                          && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 272                               ? (bit_test(e->dow,dow) && bit_test(e->dom,dom))
 273                               : (bit_test(e->dow,dow) || bit_test(e->dom,dom))
 274                             )
 275                            ) {
 276                                 e->flags &= ~RUN_AT;
 277                                 e->lastrun = TargetTime;
 278                                 job_add(e, u);
 279                         }
 280                 }
 281         }
 282
 283         last_time = TargetTime;
 284         lasttm = *tm;
 285 }
 286
 287
 288 /* the task here is to figure out how long it's going to be until :00 of the
 289  * following minute and initialize TargetTime to this value.  TargetTime
 290  * will subsequently slide 60 seconds at a time, with correction applied
 291  * implicitly in cron_sleep().  it would be nice to let cron execute in
 292  * the "current minute" before going to sleep, but by restarting cron you
 293  * could then get it to execute a given minute's jobs more than once.
 294  * instead we have the chance of missing a minute's jobs completely, but
 295  * that's something sysadmin's know to expect what with crashing computers..
 296  */
 297 static void
 298 cron_sync(void)
 299 {
 300         struct tm *tm;
 301
 302         TargetTime = time((time_t*)0);
 303         tm = localtime(&TargetTime);
 304         TargetTime += (60 - tm->tm_sec);
 305 }
 306
 307
 308 static void
 309 cron_sleep(cron_db *db)
 310 {
 311         int     seconds_to_wait = 0;
 312
 313         /*
 314          * Loop until we reach the top of the next minute, sleep when possible.
 315          */
 316
 317         for (;;) {
 318                 seconds_to_wait = (int) (TargetTime - time((time_t*)0));
 319
 320                 /*
 321                  * If the seconds_to_wait value is insane, jump the cron
 322                  */
 323
 324                 if (seconds_to_wait < -600 || seconds_to_wait > 600) {
 325                         cron_clean(db);
 326                         cron_sync();
 327                         continue;
 328                 }
 329
 330                 Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
 331                         getpid(), (long)TargetTime, seconds_to_wait))
 332
 333                 /*
 334                  * If we've run out of wait time or there are no jobs left
 335                  * to run, break
 336                  */
 337
 338                 if (seconds_to_wait <= 0)
 339                         break;
 340                 if (job_runqueue() == 0) {
 341                         Debug(DSCH, ("[%d] sleeping for %d seconds\n",
 342                                 getpid(), seconds_to_wait))
 343
 344                         sleep(seconds_to_wait);
 345                 }
 346         }
 347 }
 348
 349
 350 /* if the time was changed abruptly, clear the flags related
 351  * to the daylight time switch handling to avoid strange effects
 352  */
 353
 354 static void
 355 cron_clean(cron_db *db)
 356 {
 357         user            *u;
 358         entry           *e;
 359
 360         last_time = 0;
 361
 362         for (u = db->head;  u != NULL;  u = u->next) {
 363                 for (e = u->crontab;  e != NULL;  e = e->next) {
 364                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 365                 }
 366         }
 367 }
 368
 369 #ifdef USE_SIGCHLD
 370 static void
 371 sigchld_handler(int x)
 372 {
 373         WAIT_T          waiter;
 374         PID_T           pid;
 375
 376         for (;;) {
 377 #ifdef POSIX
 378                 pid = waitpid(-1, &waiter, WNOHANG);
 379 #else
 380                 pid = wait3(&waiter, WNOHANG, (struct rusage *)0);
 381 #endif
 382                 switch (pid) {
 383                 case -1:
 384                         Debug(DPROC,
 385                                 ("[%d] sigchld...no children\n", getpid()))
 386                         return;
 387                 case 0:
 388                         Debug(DPROC,
 389                                 ("[%d] sigchld...no dead kids\n", getpid()))
 390                         return;
 391                 default:
 392                         Debug(DPROC,
 393                                 ("[%d] sigchld...pid #%d died, stat=%d\n",
 394                                 getpid(), pid, WEXITSTATUS(waiter)))
 395                 }
 396         }
 397 }
 398 #endif /*USE_SIGCHLD*/
 399
 400
 401 static void
 402 sighup_handler(int x)
 403 {
 404         log_close();
 405 }
 406
 407
 408 static void
 409 parse_args(int argc, char **argv)
 410 {
 411         int     argch;
 412
 413         while ((argch = getopt(argc, argv, "osx:")) != -1) {
 414                 switch (argch) {
 415                 case 'o':
 416                         dst_enabled = 0;
 417                         break;
 418                 case 's':
 419                         dst_enabled = 1;
 420                         break;
 421                 case 'x':
 422                         if (!set_debug_flags(optarg))
 423                                 usage();
 424                         break;
 425                 default:
 426                         usage();
 427                 }
 428         }
 429 }
 430