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: src/usr.sbin/cron/cron/cron.c,v 1.9.2.2 2001/05/28 23:37:26 babkin Exp $";
  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
  50 static void
  51 usage() {
  52     char **dflags;
  53
  54         fprintf(stderr, "usage: cron [-s] [-o] [-x debugflag[,...]]\n");
  55         fprintf(stderr, "\ndebugflags: ");
  56
  57         for(dflags = DebugFlagNames; *dflags; dflags++) {
  58                 fprintf(stderr, "%s ", *dflags);
  59         }
  60         fprintf(stderr, "\n");
  61
  62         exit(ERROR_EXIT);
  63 }
  64
  65
  66 int
  67 main(argc, argv)
  68         int     argc;
  69         char    *argv[];
  70 {
  71         cron_db database;
  72
  73         ProgramName = argv[0];
  74
  75 #if defined(BSD)
  76         setlinebuf(stdout);
  77         setlinebuf(stderr);
  78 #endif
  79
  80         parse_args(argc, argv);
  81
  82 #ifdef USE_SIGCHLD
  83         (void) signal(SIGCHLD, sigchld_handler);
  84 #else
  85         (void) signal(SIGCLD, SIG_IGN);
  86 #endif
  87         (void) signal(SIGHUP, sighup_handler);
  88
  89         acquire_daemonlock(0);
  90         set_cron_uid();
  91         set_cron_cwd();
  92
  93 #if defined(POSIX)
  94         setenv("PATH", _PATH_DEFPATH, 1);
  95 #endif
  96
  97         /* if there are no debug flags turned on, fork as a daemon should.
  98          */
  99 # if DEBUGGING
 100         if (DebugFlags) {
 101 # else
 102         if (0) {
 103 # endif
 104                 (void) fprintf(stderr, "[%d] cron started\n", getpid());
 105         } else {
 106                 if (daemon(1, 0) == -1) {
 107                         log_it("CRON",getpid(),"DEATH","can't become daemon");
 108                         exit(0);
 109                 }
 110         }
 111
 112         acquire_daemonlock(0);
 113         database.head = NULL;
 114         database.tail = NULL;
 115         database.mtime = (time_t) 0;
 116         load_database(&database);
 117         run_reboot_jobs(&database);
 118         cron_sync();
 119         while (TRUE) {
 120 # if DEBUGGING
 121             /* if (!(DebugFlags & DTEST)) */
 122 # endif /*DEBUGGING*/
 123                         cron_sleep(&database);
 124
 125                 load_database(&database);
 126
 127                 /* do this iteration
 128                  */
 129                 cron_tick(&database);
 130
 131                 /* sleep 1 minute
 132                  */
 133                 TargetTime += 60;
 134         }
 135 }
 136
 137
 138 static void
 139 run_reboot_jobs(db)
 140         cron_db *db;
 141 {
 142         register user           *u;
 143         register 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         (void) job_runqueue();
 153 }
 154
 155
 156 static void
 157 cron_tick(db)
 158         cron_db *db;
 159 {
 160         static struct tm        lasttm;
 161         static time_t   diff = 0, /* time difference in seconds from the last offset change */
 162                 difflimit = 0; /* end point for the time zone correction */
 163         struct tm       otztm; /* time in the old time zone */
 164         int             otzminute, otzhour, otzdom, otzmonth, otzdow;
 165         register struct tm      *tm = localtime(&TargetTime);
 166         register int            minute, hour, dom, month, dow;
 167         register user           *u;
 168         register entry          *e;
 169
 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() {
 303         register struct tm      *tm;
 304
 305         TargetTime = time((time_t*)0);
 306         tm = localtime(&TargetTime);
 307         TargetTime += (60 - tm->tm_sec);
 308 }
 309
 310
 311 static void
 312 cron_sleep(db)
 313         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((time_t*)0));
 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(db)
 360         cron_db *db;
 361 {
 362         user            *u;
 363         entry           *e;
 364
 365         last_time = 0;
 366
 367         for (u = db->head;  u != NULL;  u = u->next) {
 368                 for (e = u->crontab;  e != NULL;  e = e->next) {
 369                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 370                 }
 371         }
 372 }
 373
 374 #ifdef USE_SIGCHLD
 375 static void
 376 sigchld_handler(x) {
 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, (struct rusage *)0);
 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(x) {
 407         log_close();
 408 }
 409
 410
 411 static void
 412 parse_args(argc, argv)
 413         int     argc;
 414         char    *argv[];
 415 {
 416         int     argch;
 417
 418         while ((argch = getopt(argc, argv, "osx:")) != -1) {
 419                 switch (argch) {
 420                 case 'o':
 421                         dst_enabled = 0;
 422                         break;
 423                 case 's':
 424                         dst_enabled = 1;
 425                         break;
 426                 case 'x':
 427                         if (!set_debug_flags(optarg))
 428                                 usage();
 429                         break;
 430                 default:
 431                         usage();
 432                 }
 433         }
 434 }
 435