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/mman.h>
  28 #include <sys/signal.h>
  29 #if SYS_TIME_H
  30 # include <sys/time.h>
  31 #else
  32 # include <time.h>
  33 #endif
  34
  35
  36 static  void    usage(void),
  37                 run_reboot_jobs(cron_db *),
  38                 cron_tick(cron_db *),
  39                 cron_sync(void),
  40                 cron_sleep(cron_db *),
  41                 cron_clean(cron_db *),
  42 #ifdef USE_SIGCHLD
  43                 sigchld_handler(int),
  44 #endif
  45                 sighup_handler(int),
  46                 parse_args(int c, char *v[]);
  47
  48 static time_t   last_time = 0;
  49 static int      dst_enabled = 0;
  50 struct pidfh *pfh;
  51
  52 static void
  53 usage() {
  54     char **dflags;
  55
  56         fprintf(stderr, "usage: cron [-j jitter] [-J rootjitter] "
  57                         "[-m mailto] [-s] [-o] [-x debugflag[,...]]\n");
  58         fprintf(stderr, "\ndebugflags: ");
  59
  60         for(dflags = DebugFlagNames; *dflags; dflags++) {
  61                 fprintf(stderr, "%s ", *dflags);
  62         }
  63         fprintf(stderr, "\n");
  64
  65         exit(ERROR_EXIT);
  66 }
  67
  68 static void
  69 open_pidfile(void)
  70 {
  71         char    pidfile[MAX_FNAME];
  72         char    buf[MAX_TEMPSTR];
  73         int     otherpid;
  74
  75         (void) snprintf(pidfile, sizeof(pidfile), PIDFILE, PIDDIR);
  76         pfh = pidfile_open(pidfile, 0600, &otherpid);
  77         if (pfh == NULL) {
  78                 if (errno == EEXIST) {
  79                         snprintf(buf, sizeof(buf),
  80                             "cron already running, pid: %d", otherpid);
  81                 } else {
  82                         snprintf(buf, sizeof(buf),
  83                             "can't open or create %s: %s", pidfile,
  84                             strerror(errno));
  85                 }
  86                 log_it("CRON", getpid(), "DEATH", buf);
  87                 errx(ERROR_EXIT, "%s", buf);
  88         }
  89 }
  90
  91 int
  92 main(argc, argv)
  93         int     argc;
  94         char    *argv[];
  95 {
  96         cron_db database;
  97
  98         ProgramName = argv[0];
  99
 100 #if defined(BSD)
 101         setlinebuf(stdout);
 102         setlinebuf(stderr);
 103 #endif
 104
 105         parse_args(argc, argv);
 106
 107 #ifdef USE_SIGCHLD
 108         (void) signal(SIGCHLD, sigchld_handler);
 109 #else
 110         (void) signal(SIGCLD, SIG_IGN);
 111 #endif
 112         (void) signal(SIGHUP, sighup_handler);
 113
 114         open_pidfile();
 115         set_cron_uid();
 116         set_cron_cwd();
 117
 118 #if defined(POSIX)
 119         setenv("PATH", _PATH_DEFPATH, 1);
 120 #endif
 121
 122         /* if there are no debug flags turned on, fork as a daemon should.
 123          */
 124 # if DEBUGGING
 125         if (DebugFlags) {
 126 # else
 127         if (0) {
 128 # endif
 129                 (void) fprintf(stderr, "[%d] cron started\n", getpid());
 130         } else {
 131                 if (daemon(1, 0) == -1) {
 132                         pidfile_remove(pfh);
 133                         log_it("CRON",getpid(),"DEATH","can't become daemon");
 134                         exit(0);
 135                 }
 136         }
 137
 138         if (madvise(NULL, 0, MADV_PROTECT) != 0)
 139                 log_it("CRON", getpid(), "WARNING", "madvise() failed");
 140
 141         pidfile_write(pfh);
 142         database.head = NULL;
 143         database.tail = NULL;
 144         database.mtime = (time_t) 0;
 145         load_database(&database);
 146         run_reboot_jobs(&database);
 147         cron_sync();
 148         while (TRUE) {
 149 # if DEBUGGING
 150             /* if (!(DebugFlags & DTEST)) */
 151 # endif /*DEBUGGING*/
 152                         cron_sleep(&database);
 153
 154                 load_database(&database);
 155
 156                 /* do this iteration
 157                  */
 158                 cron_tick(&database);
 159
 160                 /* sleep 1 minute
 161                  */
 162                 TargetTime += 60;
 163         }
 164 }
 165
 166
 167 static void
 168 run_reboot_jobs(db)
 169         cron_db *db;
 170 {
 171         register user           *u;
 172         register entry          *e;
 173
 174         for (u = db->head;  u != NULL;  u = u->next) {
 175                 for (e = u->crontab;  e != NULL;  e = e->next) {
 176                         if (e->flags & WHEN_REBOOT) {
 177                                 job_add(e, u);
 178                         }
 179                 }
 180         }
 181         (void) job_runqueue();
 182 }
 183
 184
 185 static void
 186 cron_tick(db)
 187         cron_db *db;
 188 {
 189         static struct tm        lasttm;
 190         static time_t   diff = 0, /* time difference in seconds from the last offset change */
 191                 difflimit = 0; /* end point for the time zone correction */
 192         struct tm       otztm; /* time in the old time zone */
 193         int             otzminute, otzhour, otzdom, otzmonth, otzdow;
 194         register struct tm      *tm = localtime(&TargetTime);
 195         register int            minute, hour, dom, month, dow;
 196         register user           *u;
 197         register entry          *e;
 198
 199         /* make 0-based values out of these so we can use them as indicies
 200          */
 201         minute = tm->tm_min -FIRST_MINUTE;
 202         hour = tm->tm_hour -FIRST_HOUR;
 203         dom = tm->tm_mday -FIRST_DOM;
 204         month = tm->tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 205         dow = tm->tm_wday -FIRST_DOW;
 206
 207         Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d)\n",
 208                 getpid(), minute, hour, dom, month, dow))
 209
 210         if (dst_enabled && last_time != 0
 211         && TargetTime > last_time /* exclude stepping back */
 212         && tm->tm_gmtoff != lasttm.tm_gmtoff ) {
 213
 214                 diff = tm->tm_gmtoff - lasttm.tm_gmtoff;
 215
 216                 if ( diff > 0 ) { /* ST->DST */
 217                         /* mark jobs for an earlier run */
 218                         difflimit = TargetTime + diff;
 219                         for (u = db->head;  u != NULL;  u = u->next) {
 220                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 221                                         e->flags &= ~NOT_UNTIL;
 222                                         if ( e->lastrun >= TargetTime )
 223                                                 e->lastrun = 0;
 224                                         /* not include the ends of hourly ranges */
 225                                         if ( e->lastrun < TargetTime - 3600 )
 226                                                 e->flags |= RUN_AT;
 227                                         else
 228                                                 e->flags &= ~RUN_AT;
 229                                 }
 230                         }
 231                 } else { /* diff < 0 : DST->ST */
 232                         /* mark jobs for skipping */
 233                         difflimit = TargetTime - diff;
 234                         for (u = db->head;  u != NULL;  u = u->next) {
 235                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 236                                         e->flags |= NOT_UNTIL;
 237                                         e->flags &= ~RUN_AT;
 238                                 }
 239                         }
 240                 }
 241         }
 242
 243         if (diff != 0) {
 244                 /* if the time was reset of the end of special zone is reached */
 245                 if (last_time == 0 || TargetTime >= difflimit) {
 246                         /* disable the TZ switch checks */
 247                         diff = 0;
 248                         difflimit = 0;
 249                         for (u = db->head;  u != NULL;  u = u->next) {
 250                                 for (e = u->crontab;  e != NULL;  e = e->next) {
 251                                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 252                                 }
 253                         }
 254                 } else {
 255                         /* get the time in the old time zone */
 256                         time_t difftime = TargetTime + tm->tm_gmtoff - diff;
 257                         gmtime_r(&difftime, &otztm);
 258
 259                         /* make 0-based values out of these so we can use them as indicies
 260                          */
 261                         otzminute = otztm.tm_min -FIRST_MINUTE;
 262                         otzhour = otztm.tm_hour -FIRST_HOUR;
 263                         otzdom = otztm.tm_mday -FIRST_DOM;
 264                         otzmonth = otztm.tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
 265                         otzdow = otztm.tm_wday -FIRST_DOW;
 266                 }
 267         }
 268
 269         /* the dom/dow situation is odd.  '* * 1,15 * Sun' will run on the
 270          * first and fifteenth AND every Sunday;  '* * * * Sun' will run *only*
 271          * on Sundays;  '* * 1,15 * *' will run *only* the 1st and 15th.  this
 272          * is why we keep 'e->dow_star' and 'e->dom_star'.  yes, it's bizarre.
 273          * like many bizarre things, it's the standard.
 274          */
 275         for (u = db->head;  u != NULL;  u = u->next) {
 276                 for (e = u->crontab;  e != NULL;  e = e->next) {
 277                         Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
 278                                           env_get("LOGNAME", e->envp),
 279                                           e->uid, e->gid, e->cmd))
 280
 281                         if ( diff != 0 && (e->flags & (RUN_AT|NOT_UNTIL)) ) {
 282                                 if (bit_test(e->minute, otzminute)
 283                                  && bit_test(e->hour, otzhour)
 284                                  && bit_test(e->month, otzmonth)
 285                                  && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 286                                           ? (bit_test(e->dow,otzdow) && bit_test(e->dom,otzdom))
 287                                           : (bit_test(e->dow,otzdow) || bit_test(e->dom,otzdom))
 288                                         )
 289                                    ) {
 290                                         if ( e->flags & RUN_AT ) {
 291                                                 e->flags &= ~RUN_AT;
 292                                                 e->lastrun = TargetTime;
 293                                                 job_add(e, u);
 294                                                 continue;
 295                                         } else
 296                                                 e->flags &= ~NOT_UNTIL;
 297                                 } else if ( e->flags & NOT_UNTIL )
 298                                         continue;
 299                         }
 300
 301                         if (bit_test(e->minute, minute)
 302                          && bit_test(e->hour, hour)
 303                          && bit_test(e->month, month)
 304                          && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 305                               ? (bit_test(e->dow,dow) && bit_test(e->dom,dom))
 306                               : (bit_test(e->dow,dow) || bit_test(e->dom,dom))
 307                             )
 308                            ) {
 309                                 e->flags &= ~RUN_AT;
 310                                 e->lastrun = TargetTime;
 311                                 job_add(e, u);
 312                         }
 313                 }
 314         }
 315
 316         last_time = TargetTime;
 317         lasttm = *tm;
 318 }
 319
 320
 321 /* the task here is to figure out how long it's going to be until :00 of the
 322  * following minute and initialize TargetTime to this value.  TargetTime
 323  * will subsequently slide 60 seconds at a time, with correction applied
 324  * implicitly in cron_sleep().  it would be nice to let cron execute in
 325  * the "current minute" before going to sleep, but by restarting cron you
 326  * could then get it to execute a given minute's jobs more than once.
 327  * instead we have the chance of missing a minute's jobs completely, but
 328  * that's something sysadmin's know to expect what with crashing computers..
 329  */
 330 static void
 331 cron_sync() {
 332         register struct tm      *tm;
 333
 334         TargetTime = time((time_t*)0);
 335         tm = localtime(&TargetTime);
 336         TargetTime += (60 - tm->tm_sec);
 337 }
 338
 339
 340 static void
 341 cron_sleep(db)
 342         cron_db *db;
 343 {
 344         int     seconds_to_wait = 0;
 345
 346         /*
 347          * Loop until we reach the top of the next minute, sleep when possible.
 348          */
 349
 350         for (;;) {
 351                 seconds_to_wait = (int) (TargetTime - time((time_t*)0));
 352
 353                 /*
 354                  * If the seconds_to_wait value is insane, jump the cron
 355                  */
 356
 357                 if (seconds_to_wait < -600 || seconds_to_wait > 600) {
 358                         cron_clean(db);
 359                         cron_sync();
 360                         continue;
 361                 }
 362
 363                 Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
 364                         getpid(), (long)TargetTime, seconds_to_wait))
 365
 366                 /*
 367                  * If we've run out of wait time or there are no jobs left
 368                  * to run, break
 369                  */
 370
 371                 if (seconds_to_wait <= 0)
 372                         break;
 373                 if (job_runqueue() == 0) {
 374                         Debug(DSCH, ("[%d] sleeping for %d seconds\n",
 375                                 getpid(), seconds_to_wait))
 376
 377                         sleep(seconds_to_wait);
 378                 }
 379         }
 380 }
 381
 382
 383 /* if the time was changed abruptly, clear the flags related
 384  * to the daylight time switch handling to avoid strange effects
 385  */
 386
 387 static void
 388 cron_clean(db)
 389         cron_db *db;
 390 {
 391         user            *u;
 392         entry           *e;
 393
 394         last_time = 0;
 395
 396         for (u = db->head;  u != NULL;  u = u->next) {
 397                 for (e = u->crontab;  e != NULL;  e = e->next) {
 398                         e->flags &= ~(RUN_AT|NOT_UNTIL);
 399                 }
 400         }
 401 }
 402
 403 #ifdef USE_SIGCHLD
 404 static void
 405 sigchld_handler(int x)
 406 {
 407         WAIT_T          waiter;
 408         PID_T           pid;
 409
 410         for (;;) {
 411 #ifdef POSIX
 412                 pid = waitpid(-1, &waiter, WNOHANG);
 413 #else
 414                 pid = wait3(&waiter, WNOHANG, (struct rusage *)0);
 415 #endif
 416                 switch (pid) {
 417                 case -1:
 418                         Debug(DPROC,
 419                                 ("[%d] sigchld...no children\n", getpid()))
 420                         return;
 421                 case 0:
 422                         Debug(DPROC,
 423                                 ("[%d] sigchld...no dead kids\n", getpid()))
 424                         return;
 425                 default:
 426                         Debug(DPROC,
 427                                 ("[%d] sigchld...pid #%d died, stat=%d\n",
 428                                 getpid(), pid, WEXITSTATUS(waiter)))
 429                 }
 430         }
 431 }
 432 #endif /*USE_SIGCHLD*/
 433
 434
 435 static void
 436 sighup_handler(int x)
 437 {
 438         log_close();
 439 }
 440
 441
 442 static void
 443 parse_args(argc, argv)
 444         int     argc;
 445         char    *argv[];
 446 {
 447         int     argch;
 448         char    *endp;
 449
 450         while ((argch = getopt(argc, argv, "j:J:m:osx:")) != -1) {
 451                 switch (argch) {
 452                 case 'j':
 453                         Jitter = strtoul(optarg, &endp, 10);
 454                         if (*optarg == '\0' || *endp != '\0' || Jitter > 60)
 455                                 errx(ERROR_EXIT,
 456                                      "bad value for jitter: %s", optarg);
 457                         break;
 458                 case 'J':
 459                         RootJitter = strtoul(optarg, &endp, 10);
 460                         if (*optarg == '\0' || *endp != '\0' || RootJitter > 60)
 461                                 errx(ERROR_EXIT,
 462                                      "bad value for root jitter: %s", optarg);
 463                         break;
 464                 case 'm':
 465                         defmailto = optarg;
 466                         break;
 467                 case 'o':
 468                         dst_enabled = 0;
 469                         break;
 470                 case 's':
 471                         dst_enabled = 1;
 472                         break;
 473                 case 'x':
 474                         if (!set_debug_flags(optarg))
 475                                 usage();
 476                         break;
 477                 default:
 478                         usage();
 479                 }
 480         }
 481 }
 482