1 /* $OpenBSD: cron.c,v 1.44 2013/04/17 15:58:45 deraadt Exp $ */ 2 3 /* Copyright 1988,1990,1993,1994 by Paul Vixie 4 * All rights reserved 5 */ 6 7 /* 8 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 9 * Copyright (c) 1997,2000 by Internet Software Consortium, Inc. 10 * 11 * Permission to use, copy, modify, and distribute this software for any 12 * purpose with or without fee is hereby granted, provided that the above 13 * copyright notice and this permission notice appear in all copies. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 16 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 17 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 18 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 19 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 20 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 21 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 22 */ 23 24 #define MAIN_PROGRAM 25 26 #include "cron.h" 27 28 enum timejump { negative, small, medium, large }; 29 30 static void usage(void), 31 run_reboot_jobs(cron_db *), 32 find_jobs(time_t, cron_db *, int, int), 33 set_time(int), 34 cron_sleep(time_t), 35 sigchld_handler(int), 36 sighup_handler(int), 37 sigchld_reaper(void), 38 quit(int), 39 parse_args(int c, char *v[]); 40 41 static volatile sig_atomic_t got_sighup, got_sigchld; 42 static time_t timeRunning, virtualTime, clockTime; 43 static int cronSock; 44 static long GMToff; 45 static cron_db database; 46 static at_db at_database; 47 static double batch_maxload = BATCH_MAXLOAD; 48 49 static void 50 usage(void) { 51 #if DEBUGGING 52 const char **dflags; 53 #endif 54 55 fprintf(stderr, "usage: %s [-n] [-l load_avg] [-x [", ProgramName); 56 #if DEBUGGING 57 for (dflags = DebugFlagNames; *dflags; dflags++) 58 fprintf(stderr, "%s%s", *dflags, dflags[1] ? "," : "]"); 59 #else 60 fprintf(stderr, "debugging flags (none supported in this build)]"); 61 #endif 62 fprintf(stderr, "]\n"); 63 exit(EXIT_FAILURE); 64 } 65 66 int 67 main(int argc, char *argv[]) { 68 struct sigaction sact; 69 int fd; 70 71 ProgramName = argv[0]; 72 73 setlocale(LC_ALL, ""); 74 75 #if defined(BSD) 76 setlinebuf(stdout); 77 setlinebuf(stderr); 78 #endif 79 80 NoFork = 0; 81 parse_args(argc, argv); 82 83 bzero((char *)&sact, sizeof sact); 84 sigemptyset(&sact.sa_mask); 85 sact.sa_flags = 0; 86 #ifdef SA_RESTART 87 sact.sa_flags |= SA_RESTART; 88 #endif 89 sact.sa_handler = sigchld_handler; 90 (void) sigaction(SIGCHLD, &sact, NULL); 91 sact.sa_handler = sighup_handler; 92 (void) sigaction(SIGHUP, &sact, NULL); 93 sact.sa_handler = quit; 94 (void) sigaction(SIGINT, &sact, NULL); 95 (void) sigaction(SIGTERM, &sact, NULL); 96 sact.sa_handler = SIG_IGN; 97 (void) sigaction(SIGPIPE, &sact, NULL); 98 99 acquire_daemonlock(0); 100 set_cron_uid(); 101 set_cron_cwd(); 102 103 if (putenv("PATH="_PATH_DEFPATH) < 0) { 104 log_it("CRON", getpid(), "DEATH", "can't malloc"); 105 exit(EXIT_FAILURE); 106 } 107 108 /* if there are no debug flags turned on, fork as a daemon should. 109 */ 110 if (DebugFlags) { 111 #if DEBUGGING 112 (void) fprintf(stderr, "[%ld] cron started\n", (long)getpid()); 113 #endif 114 } else if (NoFork == 0) { 115 switch (fork()) { 116 case -1: 117 log_it("CRON",getpid(),"DEATH","can't fork"); 118 exit(EXIT_FAILURE); 119 break; 120 case 0: 121 /* child process */ 122 (void) setsid(); 123 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) >= 0) { 124 (void) dup2(fd, STDIN_FILENO); 125 (void) dup2(fd, STDOUT_FILENO); 126 (void) dup2(fd, STDERR_FILENO); 127 if (fd != STDERR_FILENO) 128 (void) close(fd); 129 } 130 log_it("CRON",getpid(),"STARTUP",CRON_VERSION); 131 break; 132 default: 133 /* parent process should just die */ 134 _exit(EXIT_SUCCESS); 135 } 136 } 137 138 acquire_daemonlock(0); 139 cronSock = open_socket(); 140 database.head = NULL; 141 database.tail = NULL; 142 database.mtime = (time_t) 0; 143 load_database(&database); 144 at_database.head = NULL; 145 at_database.tail = NULL; 146 at_database.mtime = (time_t) 0; 147 scan_atjobs(&at_database, NULL); 148 set_time(TRUE); 149 run_reboot_jobs(&database); 150 timeRunning = virtualTime = clockTime; 151 152 /* 153 * Too many clocks, not enough time (Al. Einstein) 154 * These clocks are in minutes since the epoch, adjusted for timezone. 155 * virtualTime: is the time it *would* be if we woke up 156 * promptly and nobody ever changed the clock. It is 157 * monotonically increasing... unless a timejump happens. 158 * At the top of the loop, all jobs for 'virtualTime' have run. 159 * timeRunning: is the time we last awakened. 160 * clockTime: is the time when set_time was last called. 161 */ 162 while (TRUE) { 163 int timeDiff; 164 enum timejump wakeupKind; 165 166 /* ... wait for the time (in minutes) to change ... */ 167 do { 168 cron_sleep(timeRunning + 1); 169 set_time(FALSE); 170 } while (clockTime == timeRunning); 171 timeRunning = clockTime; 172 173 /* 174 * Calculate how the current time differs from our virtual 175 * clock. Classify the change into one of 4 cases. 176 */ 177 timeDiff = timeRunning - virtualTime; 178 179 /* shortcut for the most common case */ 180 if (timeDiff == 1) { 181 virtualTime = timeRunning; 182 find_jobs(virtualTime, &database, TRUE, TRUE); 183 } else { 184 if (timeDiff > (3*MINUTE_COUNT) || 185 timeDiff < -(3*MINUTE_COUNT)) 186 wakeupKind = large; 187 else if (timeDiff > 5) 188 wakeupKind = medium; 189 else if (timeDiff > 0) 190 wakeupKind = small; 191 else 192 wakeupKind = negative; 193 194 switch (wakeupKind) { 195 case small: 196 /* 197 * case 1: timeDiff is a small positive number 198 * (wokeup late) run jobs for each virtual 199 * minute until caught up. 200 */ 201 Debug(DSCH, ("[%ld], normal case %d minutes to go\n", 202 (long)getpid(), timeDiff)) 203 do { 204 if (job_runqueue()) 205 sleep(10); 206 virtualTime++; 207 find_jobs(virtualTime, &database, 208 TRUE, TRUE); 209 } while (virtualTime < timeRunning); 210 break; 211 212 case medium: 213 /* 214 * case 2: timeDiff is a medium-sized positive 215 * number, for example because we went to DST 216 * run wildcard jobs once, then run any 217 * fixed-time jobs that would otherwise be 218 * skipped if we use up our minute (possible, 219 * if there are a lot of jobs to run) go 220 * around the loop again so that wildcard jobs 221 * have a chance to run, and we do our 222 * housekeeping. 223 */ 224 Debug(DSCH, ("[%ld], DST begins %d minutes to go\n", 225 (long)getpid(), timeDiff)) 226 /* run wildcard jobs for current minute */ 227 find_jobs(timeRunning, &database, TRUE, FALSE); 228 229 /* run fixed-time jobs for each minute missed */ 230 do { 231 if (job_runqueue()) 232 sleep(10); 233 virtualTime++; 234 find_jobs(virtualTime, &database, 235 FALSE, TRUE); 236 set_time(FALSE); 237 } while (virtualTime< timeRunning && 238 clockTime == timeRunning); 239 break; 240 241 case negative: 242 /* 243 * case 3: timeDiff is a small or medium-sized 244 * negative num, eg. because of DST ending. 245 * Just run the wildcard jobs. The fixed-time 246 * jobs probably have already run, and should 247 * not be repeated. Virtual time does not 248 * change until we are caught up. 249 */ 250 Debug(DSCH, ("[%ld], DST ends %d minutes to go\n", 251 (long)getpid(), timeDiff)) 252 find_jobs(timeRunning, &database, TRUE, FALSE); 253 break; 254 default: 255 /* 256 * other: time has changed a *lot*, 257 * jump virtual time, and run everything 258 */ 259 Debug(DSCH, ("[%ld], clock jumped\n", 260 (long)getpid())) 261 virtualTime = timeRunning; 262 find_jobs(timeRunning, &database, TRUE, TRUE); 263 } 264 } 265 266 /* Jobs to be run (if any) are loaded; clear the queue. */ 267 job_runqueue(); 268 269 /* Run any jobs in the at queue. */ 270 atrun(&at_database, batch_maxload, 271 timeRunning * SECONDS_PER_MINUTE - GMToff); 272 273 /* Check to see if we received a signal while running jobs. */ 274 if (got_sighup) { 275 got_sighup = 0; 276 log_close(); 277 } 278 if (got_sigchld) { 279 got_sigchld = 0; 280 sigchld_reaper(); 281 } 282 load_database(&database); 283 scan_atjobs(&at_database, NULL); 284 } 285 } 286 287 static void 288 run_reboot_jobs(cron_db *db) { 289 user *u; 290 entry *e; 291 292 for (u = db->head; u != NULL; u = u->next) { 293 for (e = u->crontab; e != NULL; e = e->next) { 294 if (e->flags & WHEN_REBOOT) 295 job_add(e, u); 296 } 297 } 298 (void) job_runqueue(); 299 } 300 301 static void 302 find_jobs(time_t vtime, cron_db *db, int doWild, int doNonWild) { 303 time_t virtualSecond = vtime * SECONDS_PER_MINUTE; 304 struct tm *tm = gmtime(&virtualSecond); 305 int minute, hour, dom, month, dow; 306 user *u; 307 entry *e; 308 309 /* make 0-based values out of these so we can use them as indices 310 */ 311 minute = tm->tm_min -FIRST_MINUTE; 312 hour = tm->tm_hour -FIRST_HOUR; 313 dom = tm->tm_mday -FIRST_DOM; 314 month = tm->tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH; 315 dow = tm->tm_wday -FIRST_DOW; 316 317 Debug(DSCH, ("[%ld] tick(%d,%d,%d,%d,%d) %s %s\n", 318 (long)getpid(), minute, hour, dom, month, dow, 319 doWild?" ":"No wildcard",doNonWild?" ":"Wildcard only")) 320 321 /* the dom/dow situation is odd. '* * 1,15 * Sun' will run on the 322 * first and fifteenth AND every Sunday; '* * * * Sun' will run *only* 323 * on Sundays; '* * 1,15 * *' will run *only* the 1st and 15th. this 324 * is why we keep 'e->dow_star' and 'e->dom_star'. yes, it's bizarre. 325 * like many bizarre things, it's the standard. 326 */ 327 for (u = db->head; u != NULL; u = u->next) { 328 for (e = u->crontab; e != NULL; e = e->next) { 329 Debug(DSCH|DEXT, ("user [%s:%lu:%lu:...] cmd=\"%s\"\n", 330 e->pwd->pw_name, (unsigned long)e->pwd->pw_uid, 331 (unsigned long)e->pwd->pw_gid, e->cmd)) 332 if (bit_test(e->minute, minute) && 333 bit_test(e->hour, hour) && 334 bit_test(e->month, month) && 335 ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR)) 336 ? (bit_test(e->dow,dow) && bit_test(e->dom,dom)) 337 : (bit_test(e->dow,dow) || bit_test(e->dom,dom)) 338 ) 339 ) { 340 if ((doNonWild && 341 !(e->flags & (MIN_STAR|HR_STAR))) || 342 (doWild && (e->flags & (MIN_STAR|HR_STAR)))) 343 job_add(e, u); 344 } 345 } 346 } 347 } 348 349 /* 350 * Set StartTime and clockTime to the current time. 351 * These are used for computing what time it really is right now. 352 * Note that clockTime is a unix wallclock time converted to minutes. 353 */ 354 static void 355 set_time(int initialize) { 356 struct tm tm; 357 static int isdst; 358 359 StartTime = time(NULL); 360 361 /* We adjust the time to GMT so we can catch DST changes. */ 362 tm = *localtime(&StartTime); 363 if (initialize || tm.tm_isdst != isdst) { 364 isdst = tm.tm_isdst; 365 GMToff = get_gmtoff(&StartTime, &tm); 366 Debug(DSCH, ("[%ld] GMToff=%ld\n", 367 (long)getpid(), (long)GMToff)) 368 } 369 clockTime = (StartTime + GMToff) / (time_t)SECONDS_PER_MINUTE; 370 } 371 372 /* 373 * Try to just hit the next minute. 374 */ 375 static void 376 cron_sleep(time_t target) { 377 int fd, nfds; 378 unsigned char poke; 379 struct timeval t1, t2, tv; 380 struct sockaddr_un s_un; 381 socklen_t sunlen; 382 static fd_set *fdsr; 383 384 gettimeofday(&t1, NULL); 385 t1.tv_sec += GMToff; 386 tv.tv_sec = (target * SECONDS_PER_MINUTE - t1.tv_sec) + 1; 387 tv.tv_usec = 0; 388 389 if (fdsr == NULL) { 390 fdsr = (fd_set *)calloc(howmany(cronSock + 1, NFDBITS), 391 sizeof(fd_mask)); 392 } 393 394 while (timerisset(&tv) && tv.tv_sec < 65) { 395 Debug(DSCH, ("[%ld] Target time=%lld, sec-to-wait=%lld\n", 396 (long)getpid(), (long long)target*SECONDS_PER_MINUTE, 397 (long long)tv.tv_sec)) 398 399 poke = RELOAD_CRON | RELOAD_AT; 400 if (fdsr) 401 FD_SET(cronSock, fdsr); 402 /* Sleep until we time out, get a poke, or get a signal. */ 403 nfds = select(cronSock + 1, fdsr, NULL, NULL, &tv); 404 if (nfds == 0) 405 break; /* timer expired */ 406 if (nfds == -1 && errno != EINTR) 407 break; /* an error occurred */ 408 if (nfds > 0) { 409 Debug(DSCH, ("[%ld] Got a poke on the socket\n", 410 (long)getpid())) 411 sunlen = sizeof(s_un); 412 fd = accept(cronSock, (struct sockaddr *)&s_un, &sunlen); 413 if (fd >= 0 && fcntl(fd, F_SETFL, O_NONBLOCK) == 0) { 414 (void) read(fd, &poke, 1); 415 close(fd); 416 if (poke & RELOAD_CRON) { 417 database.mtime = (time_t)0; 418 load_database(&database); 419 } 420 if (poke & RELOAD_AT) { 421 /* 422 * We run any pending at jobs right 423 * away so that "at now" really runs 424 * jobs immediately. 425 */ 426 gettimeofday(&t2, NULL); 427 at_database.mtime = (time_t)0; 428 if (scan_atjobs(&at_database, &t2)) 429 atrun(&at_database, 430 batch_maxload, t2.tv_sec); 431 } 432 } 433 } else { 434 /* Interrupted by a signal. */ 435 if (got_sighup) { 436 got_sighup = 0; 437 log_close(); 438 } 439 if (got_sigchld) { 440 got_sigchld = 0; 441 sigchld_reaper(); 442 } 443 } 444 445 /* Adjust tv and continue where we left off. */ 446 gettimeofday(&t2, NULL); 447 t2.tv_sec += GMToff; 448 timersub(&t2, &t1, &t1); 449 timersub(&tv, &t1, &tv); 450 memcpy(&t1, &t2, sizeof(t1)); 451 if (tv.tv_sec < 0) 452 tv.tv_sec = 0; 453 if (tv.tv_usec < 0) 454 tv.tv_usec = 0; 455 } 456 } 457 458 static void 459 sighup_handler(int x) { 460 got_sighup = 1; 461 } 462 463 static void 464 sigchld_handler(int x) { 465 got_sigchld = 1; 466 } 467 468 static void 469 quit(int x) { 470 (void) unlink(_PATH_CRON_PID); 471 _exit(0); 472 } 473 474 static void 475 sigchld_reaper(void) { 476 WAIT_T waiter; 477 PID_T pid; 478 479 do { 480 pid = waitpid(-1, &waiter, WNOHANG); 481 switch (pid) { 482 case -1: 483 if (errno == EINTR) 484 continue; 485 Debug(DPROC, 486 ("[%ld] sigchld...no children\n", 487 (long)getpid())) 488 break; 489 case 0: 490 Debug(DPROC, 491 ("[%ld] sigchld...no dead kids\n", 492 (long)getpid())) 493 break; 494 default: 495 Debug(DPROC, 496 ("[%ld] sigchld...pid #%ld died, stat=%d\n", 497 (long)getpid(), (long)pid, WEXITSTATUS(waiter))) 498 break; 499 } 500 } while (pid > 0); 501 } 502 503 static void 504 parse_args(int argc, char *argv[]) { 505 int argch; 506 char *ep; 507 508 while (-1 != (argch = getopt(argc, argv, "l:nx:"))) { 509 switch (argch) { 510 case 'l': 511 errno = 0; 512 batch_maxload = strtod(optarg, &ep); 513 if (*ep != '\0' || ep == optarg || errno == ERANGE || 514 batch_maxload < 0) { 515 fprintf(stderr, "Illegal load average: %s\n", 516 optarg); 517 usage(); 518 } 519 break; 520 case 'n': 521 NoFork = 1; 522 break; 523 case 'x': 524 if (!set_debug_flags(optarg)) 525 usage(); 526 break; 527 default: 528 usage(); 529 } 530 } 531 } 532