1/* crond.c - daemon to execute scheduled commands. 2 * 3 * Copyright 2014 Ranjan Kumar <ranjankumar.bth@gmail.com> 4 * 5 * No Standard 6 7USE_CROND(NEWTOY(crond, "fbSl#<0=8d#<0L:c:[-bf][-LS][-ld]", TOYFLAG_USR|TOYFLAG_SBIN|TOYFLAG_NEEDROOT)) 8 9config CROND 10 bool "crond" 11 default n 12 help 13 usage: crond [-fbS] [-l N] [-d N] [-L LOGFILE] [-c DIR] 14 15 A daemon to execute scheduled commands. 16 17 -b Background (default) 18 -c crontab dir 19 -d Set log level, log to stderr 20 -f Foreground 21 -l Set log level. 0 is the most verbose, default 8 22 -S Log to syslog (default) 23 -L Log to file 24*/ 25 26#define FOR_crond 27#include "toys.h" 28 29GLOBALS( 30 char *crontabs_dir; 31 char *logfile; 32 int loglevel_d; 33 int loglevel; 34 35 time_t crontabs_dir_mtime; 36 uint8_t flagd; 37) 38 39typedef struct _var { 40 struct _var *next, *prev; 41 char *name, *val; 42} VAR; 43 44typedef struct _job { 45 struct _job *next, *prev; 46 char min[60], hour[24], dom[31], mon[12], dow[7], *cmd; 47 int isrunning, needstart, mailsize; 48 pid_t pid; 49} JOB; 50 51typedef struct _cronfile { 52 struct _cronfile *next, *prev; 53 struct double_list *job, *var; 54 char *username, *mailto; 55 int invalid; 56} CRONFILE; 57 58static char days[]={"sun""mon""tue""wed""thu""fri""sat"}; 59static char months[]={"jan""feb""mar""apr""may""jun""jul" 60 "aug""sep""oct""nov""dec"}; 61CRONFILE *gclist; 62 63#define LOG_EXIT 0 64#define LOG_LEVEL5 5 65#define LOG_LEVEL7 7 66#define LOG_LEVEL8 8 67#define LOG_LEVEL9 9 // warning 68#define LOG_ERROR 20 69 70static void loginfo(uint8_t loglevel, char *msg, ...) 71{ 72 va_list s, d; 73 74 va_start(s, msg); 75 va_copy(d, s); 76 if (loglevel >= TT.loglevel) { 77 int used; 78 char *smsg; 79 80 if (!TT.flagd && TT.logfile) { 81 int fd = open(TT.logfile, O_WRONLY | O_CREAT | O_APPEND, 0666); 82 if (fd >=0 && fd != 2) { 83 dup2(fd, 2); 84 close(fd); 85 } else if (fd < 0) perror_msg("'%s", TT.logfile); 86 } 87 used = vsnprintf(NULL, 0, msg, d); 88 smsg = xzalloc(++used); 89 vsnprintf(smsg, used, msg, s); 90 if (TT.flagd || TT.logfile) { 91 fflush(NULL); 92 smsg[used-1] = '\n'; 93 writeall((loglevel > 8) ? 2 : 1, smsg, used); 94 } else syslog((loglevel > 8) ? LOG_ERR : LOG_INFO, "%s", smsg); 95 free(smsg); 96 } 97 va_end(d); 98 va_end(s); 99 if (!loglevel) exit(20); 100} 101 102/* 103 * Names can also be used for the 'month' and 'day of week' fields 104 * (First three letters of the particular day or month). 105 */ 106static int getindex(char *src, int size) 107{ 108 int i; 109 char *field = (size == 12) ? months : days; 110 111 // strings are not allowed for min, hour and dom fields. 112 if (!(size == 7 || size == 12)) return -1; 113 114 for (i = 0; field[i]; i += 3) { 115 if (!strncasecmp(src, &field[i], 3)) 116 return (i/3); 117 } 118 return -1; 119} 120 121// set elements of minute, hour, day of month, month and day of week arrays. 122static void fillarray(char *dst, int start, int end, int skip) 123{ 124 int sk = 1; 125 126 if (end < 0) { 127 dst[start] = 1; 128 return; 129 } 130 if (!skip) skip = 1; 131 do { 132 if (!--sk) { 133 dst[start] = 1; 134 sk = skip; 135 } 136 } while (start++ != end); 137} 138 139static long getval(char *num, long low, long high) 140{ 141 long val = strtol(num, &num, 10); 142 143 if (*num || (val < low) || (val > high)) return -1; 144 return val; 145} 146 147//static int parse_and_fillarray(char *dst, int size, char *src) 148static int parse_and_fillarray(char *dst, int min, int max, char *src) 149{ 150 int start, end, skip = 0; 151 char *ptr = strchr(src, '/'); 152 153 if (ptr) { 154 *ptr++ = 0; 155 if ((skip = getval(ptr, min, (min ? max: max-1))) < 0) goto ERROR; 156 } 157 158 if (*src == '-' || *src == ',') goto ERROR; 159 if (*src == '*') { 160 if (*(src+1)) goto ERROR; 161 fillarray(dst, 0, max-1, skip); 162 } else { 163 for (;;) { 164 char *ctoken = strsep(&src, ","), *dtoken; 165 166 if (!ctoken) break; 167 if (!*ctoken) goto ERROR; 168 169 // Get start position. 170 dtoken = strsep(&ctoken, "-"); 171 if (isdigit(*dtoken)) { 172 if ((start = getval(dtoken, min, (min ? max : max-1))) < 0) goto ERROR; 173 start = min ? (start-1) : start; 174 } else if ((start = getindex(dtoken, max)) < 0) goto ERROR; 175 176 // Get end position. 177 if (!ctoken) end = -1; // e.g. N1,N2,N3 178 else if (*ctoken) {// e.g. N-M 179 if (isdigit(*ctoken)) { 180 if ((end = getval(ctoken, min, (min ? max : max-1))) < 0) goto ERROR; 181 end = min ? (end-1) : end; 182 } else if ((end = getindex(ctoken, max)) < 0) goto ERROR; 183 if (end == start) end = -1; 184 } else goto ERROR; // error condition 'N-' 185 fillarray(dst, start, end, skip); 186 } 187 } 188 189 if (TT.flagd && (TT.loglevel <= 5)) { 190 for (start = 0; start < max; start++) 191 fprintf(stderr, "%d", (unsigned char)dst[start]); 192 fputc('\n', stderr); 193 } 194 return 0; 195ERROR: 196 loginfo(LOG_LEVEL9, "parse error at %s", src); 197 return -1; 198} 199 200static char *omitspace(char *line) 201{ 202 while (*line == ' ' || *line == '\t') line++; 203 return line; 204} 205 206static void parse_line(char *line, CRONFILE *cfile) 207{ 208 int count = 0; 209 char *name, *val, *tokens[5] = {0,}; 210 VAR *v; 211 JOB *j; 212 213 line = omitspace(line); 214 if (!*line || *line == '#') return; 215 216 /* 217 * TODO: Enhancement to support 8 special strings 218 * @reboot -> Run once at startup. 219 * @yearly -> Run once a year (0 0 1 1 *). 220 * @annually -> Same as above. 221 * @monthly -> Run once a month (0 0 1 * *). 222 * @weekly -> Run once a week (0 0 * * 0). 223 * @daily -> Run once a day (0 0 * * *). 224 * @midnight -> same as above. 225 * @hourly -> Run once an hour (0 * * * *). 226 */ 227 if (*line == '@') return; 228 if (TT.flagd) loginfo(LOG_LEVEL5, "user:%s entry:%s", cfile->username, line); 229 while (count<5) { 230 int len = strcspn(line, " \t"); 231 232 if (line[len]) line[len++] = '\0'; 233 tokens[count++] = line; 234 line += len; 235 line = omitspace(line); 236 if (!*line) break; 237 } 238 239 switch (count) { 240 case 1: // form SHELL=/bin/sh 241 name = tokens[0]; 242 if ((val = strchr(name, '='))) *val++ = 0; 243 if (!val || !*val) return; 244 break; 245 case 2: // form SHELL =/bin/sh or SHELL= /bin/sh 246 name = tokens[0]; 247 if ((val = strchr(name, '='))) { 248 *val = 0; 249 val = tokens[1]; 250 } else { 251 if (*(tokens[1]) != '=') return; 252 val = tokens[1] + 1; 253 } 254 if (!*val) return; 255 break; 256 case 3: // NAME = VAL 257 name = tokens[0]; 258 val = tokens[2]; 259 if (*(tokens[1]) != '=') return; 260 break; 261 case 5: 262 // don't have any cmd to execute. 263 if (!*line) return; 264 j = xzalloc(sizeof(JOB)); 265 266 if (parse_and_fillarray(j->min, 0, sizeof(j->min), tokens[0])) 267 goto STOP_PARSING; 268 if (parse_and_fillarray(j->hour, 0, sizeof(j->hour), tokens[1])) 269 goto STOP_PARSING; 270 if (parse_and_fillarray(j->dom, 1, sizeof(j->dom), tokens[2])) 271 goto STOP_PARSING; 272 if (parse_and_fillarray(j->mon, 1, sizeof(j->mon), tokens[3])) 273 goto STOP_PARSING; 274 if (parse_and_fillarray(j->dow, 0, sizeof(j->dow), tokens[4])) 275 goto STOP_PARSING; 276 j->cmd = xstrdup(line); 277 278 if (TT.flagd) loginfo(LOG_LEVEL5, " command:%s", j->cmd); 279 dlist_add_nomalloc((struct double_list **)&cfile->job, (struct double_list *)j); 280 return; 281STOP_PARSING: 282 free(j); 283 return; 284 default: return; 285 } 286 if (!strcmp(name, "MAILTO")) cfile->mailto = xstrdup(val); 287 else { 288 v = xzalloc(sizeof(VAR)); 289 v->name = xstrdup(name); 290 v->val = xstrdup(val); 291 dlist_add_nomalloc((struct double_list **)&cfile->var, (struct double_list *)v); 292 } 293} 294 295static void free_jobs(JOB **jlist) 296{ 297 JOB *j = dlist_pop(jlist); 298 free(j->cmd); 299 free(j); 300} 301 302static void free_cronfile(CRONFILE **list) 303{ 304 CRONFILE *l = dlist_pop(list); 305 VAR *v, *vnode = (VAR *)l->var; 306 307 if (l->username != l->mailto) free(l->mailto); 308 free(l->username); 309 while (vnode && (v = dlist_pop(&vnode))) { 310 free(v->name); 311 free(v->val); 312 free(v); 313 } 314 free(l); 315} 316 317/* 318 * Iterate all cronfiles to identify the completed jobs and freed them. 319 * If all jobs got completed for a cronfile, freed cronfile too. 320 */ 321static void remove_completed_jobs() 322{ 323 CRONFILE *lstart, *list = gclist; 324 325 lstart = list; 326 while (list) { 327 int delete = 1; 328 JOB *jstart, *jlist = (JOB *)list->job; 329 330 list->invalid = 1; 331 jstart = jlist; 332 while (jlist) { 333 jlist->isrunning = 0; 334 if (jlist->pid > 0) { 335 jlist->isrunning = 1; 336 delete = 0; 337 jlist = jlist->next; 338 } else { 339 if (jlist == jstart) { // if 1st node has to delete. 340 jstart = jstart->next; 341 free_jobs(&jlist); 342 continue; 343 } else free_jobs(&jlist); 344 } 345 if (jlist == jstart) break; 346 } 347 list->job = (struct double_list *)jlist; 348 349 if (delete) { 350 if (lstart == list) { 351 lstart = lstart->next; 352 free_cronfile(&list); 353 continue; 354 } else free_cronfile(&list); 355 } 356 list = list->next; 357 if (lstart == list) break; 358 } 359 gclist = list; 360} 361 362// Scan cronfiles and prepare the list of cronfiles with their jobs. 363static void scan_cronfiles() 364{ 365 DIR *dp; 366 struct dirent *entry; 367 368 remove_completed_jobs(); 369 if (chdir(TT.crontabs_dir)) loginfo(LOG_EXIT, "chdir(%s)", TT.crontabs_dir); 370 if (!(dp = opendir("."))) loginfo(LOG_EXIT, "chdir(%s)", "."); 371 372 while ((entry = readdir(dp))) { 373 int fd; 374 char *line; 375 CRONFILE *cfile; 376 377 if (entry->d_name[0] == '.' && (!entry->d_name[1] || 378 (entry->d_name[1] == '.' && !entry->d_name[2]))) 379 continue; 380 381 if (!getpwnam(entry->d_name)) { 382 loginfo(LOG_LEVEL7, "ignoring file '%s' (no such user)", entry->d_name); 383 continue; 384 } 385 if ((fd = open(entry->d_name, O_RDONLY)) < 0) continue; 386 387 // one node for each user 388 cfile = xzalloc(sizeof(CRONFILE)); 389 cfile->username = xstrdup(entry->d_name); 390 391 for (; (line = get_line(fd)); free(line)) 392 parse_line(line, cfile); 393 394 // If there is no job for a cron, remove the VAR list. 395 if (!cfile->job) { 396 VAR *v, *vnode = (VAR *)cfile->var; 397 398 free(cfile->username); 399 if (cfile->mailto) free(cfile->mailto); 400 401 while (vnode && (v = dlist_pop(&vnode))) { 402 free(v->name); 403 free(v->val); 404 free(v); 405 } 406 free(cfile); 407 } else { 408 if (!cfile->mailto) cfile->mailto = cfile->username; 409 dlist_add_nomalloc((struct double_list **)&gclist, 410 (struct double_list *)cfile); 411 } 412 close(fd); 413 } 414 closedir(dp); 415} 416 417/* 418 * Set env variables, if any in the cronfile. Execute given job with the given 419 * SHELL or Default SHELL and send an e-mail with respect to every successfully 420 * completed job (as per the given param 'prog'). 421 */ 422static void do_fork(CRONFILE *cfile, JOB *job, int fd, char *prog) 423{ 424 pid_t pid = vfork(); 425 426 if (pid == 0) { 427 VAR *v, *vstart = (VAR *)cfile->var; 428 struct passwd *pwd = getpwnam(cfile->username); 429 430 if (!pwd) loginfo(LOG_LEVEL9, "can't get uid for %s", cfile->username); 431 else { 432 char *file = "/bin/sh"; 433 434 if (setenv("USER", pwd->pw_name, 1)) _exit(1); 435 for (v = vstart; v;) { 436 if (!strcmp("SHELL", v->name)) file = v->val; 437 if (setenv(v->name, v->val, 1)) _exit(1); 438 if ((v=v->next) == vstart) break; 439 } 440 if (!getenv("HOME")) { 441 if (setenv("HOME", pwd->pw_dir, 1)) 442 _exit(1); 443 } 444 xsetuser(pwd); 445 if (chdir(pwd->pw_dir)) loginfo(LOG_LEVEL9, "chdir(%s)", pwd->pw_dir); 446 if (prog) file = prog; 447 if (TT.flagd) loginfo(LOG_LEVEL5, "child running %s", file); 448 449 if (fd >= 0) { 450 int newfd = prog ? 0 : 1; 451 if (fd != newfd) { 452 dup2(fd, newfd); 453 close(fd); 454 } 455 dup2(1, 2); 456 } 457 setpgrp(); 458 execlp(file, file, (prog ? "-ti" : "-c"), (prog ? NULL : job->cmd), (char *) NULL); 459 loginfo(LOG_ERROR, "can't execute '%s' for user %s", file, cfile->username); 460 461 if (!prog) dprintf(1, "Exec failed: %s -c %s\n", file, job->cmd); 462 _exit(EXIT_SUCCESS); 463 } 464 } 465 if (pid < 0) { 466 loginfo(LOG_ERROR, "can't vfork"); 467 pid = 0; 468 } 469 if (fd >=0) close(fd); 470 job->pid = pid; 471} 472 473// Send an e-mail for each successfully completed jobs. 474static void sendmail(CRONFILE *cfile, JOB *job) 475{ 476 pid_t pid = job->pid; 477 int mailfd; 478 struct stat sb; 479 480 job->pid = 0; 481 if (pid <=0 || job->mailsize <=0) { 482 job->isrunning = 0; 483 job->needstart = 1; 484 return; 485 } 486 snprintf(toybuf, sizeof(toybuf), "/var/spool/cron/cron.%s.%d", 487 cfile->username, (int)pid); 488 489 mailfd = open(toybuf, O_RDONLY); 490 unlink(toybuf); 491 if (mailfd < 0) return; 492 493 if (fstat(mailfd, &sb) == -1 || sb.st_uid != 0 || sb.st_nlink != 0 494 || sb.st_size == job->mailsize || !S_ISREG(sb.st_mode)) { 495 xclose(mailfd); 496 return; 497 } 498 job->mailsize = 0; 499 do_fork(cfile, job, mailfd, "sendmail"); 500} 501 502// Count the number of jobs, which are not completed. 503static int count_running_jobs() 504{ 505 CRONFILE *cfile = gclist; 506 JOB *job, *jstart; 507 int count = 0; 508 509 while (cfile) { 510 job = jstart = (JOB *)cfile->job; 511 while (job) { 512 int ret; 513 514 if (!job->isrunning || job->pid<=0) goto NEXT_JOB; 515 job->isrunning = 0; 516 ret = waitpid(job->pid, NULL, WNOHANG); 517 if (ret < 0 || ret == job->pid) { 518 sendmail(cfile, job); 519 if (job->pid) count += (job->isrunning=1); 520 else { 521 job->isrunning = 0; 522 job->needstart = 1; 523 } 524 } 525 else count += (job->isrunning=1); 526 527NEXT_JOB: 528 if ((job = job->next) == jstart) break; 529 } 530 if ((cfile = cfile->next) == gclist) break; 531 } 532 return count; 533} 534 535// Execute jobs one by one and prepare for the e-mail sending. 536static void execute_jobs(void) 537{ 538 CRONFILE *cfile = gclist; 539 JOB *job, *jstart; 540 541 while (cfile) { 542 job = jstart = (JOB *)cfile->job; 543 while (job) { 544 if (job->needstart) { 545 job->needstart = 0; 546 if (job->pid < 0) { 547 int mailfd = -1; 548 549 job->mailsize = job->pid = 0; 550 snprintf(toybuf, sizeof(toybuf), "/var/spool/cron/cron.%s.%d", 551 cfile->username, getpid()); 552 if ((mailfd = open(toybuf, O_CREAT|O_TRUNC|O_WRONLY|O_EXCL|O_APPEND, 553 0600)) < 0) { 554 loginfo(LOG_ERROR, "can't create mail file %s for user %s, " 555 "discarding output", toybuf, cfile->username); 556 } else { 557 dprintf(mailfd, "To: %s\nSubject: cron: %s\n\n", cfile->mailto, job->cmd); 558 job->mailsize = lseek(mailfd, 0, SEEK_CUR); 559 } 560 do_fork(cfile, job, mailfd, NULL); 561 if (mailfd >= 0) { 562 if (job->pid <= 0) unlink(toybuf); 563 else { 564 char *mailfile = xmprintf("/var/spool/cron/cron.%s.%d", 565 cfile->username, (int)job->pid); 566 rename(toybuf, mailfile); 567 free(mailfile); 568 } 569 } 570 loginfo(LOG_LEVEL8, "USER %s pid %3d cmd %s", 571 cfile->username, job->pid, job->cmd); 572 if (job->pid < 0) job->needstart = 1; 573 else job->isrunning = 1; 574 } 575 } 576 if ((job = job->next) == jstart) break; 577 } 578 if ((cfile = cfile->next) == gclist) break; 579 } 580} 581 582// Identify jobs, which needs to be started at the given time interval. 583static void schedule_jobs(time_t ctime, time_t ptime) 584{ 585 time_t tm = ptime-ptime%60; 586 587 for (; tm <= ctime; tm += 60) { 588 struct tm *lt; 589 CRONFILE *cfile = gclist; 590 JOB *job, *jstart; 591 592 if (tm <= ptime) continue; 593 lt = localtime(&tm); 594 595 while (cfile) { 596 if (TT.flagd) loginfo(LOG_LEVEL5, "file %s:", cfile->username); 597 if (cfile->invalid) goto NEXT_CRONFILE; 598 job = jstart = (JOB *)cfile->job; 599 600 while (job) { 601 if (TT.flagd) loginfo(LOG_LEVEL5, " line %s", job->cmd); 602 603 if (job->min[lt->tm_min] && job->hour[lt->tm_hour] 604 && (job->dom[lt->tm_mday] || job->dow[lt->tm_wday]) 605 && job->mon[lt->tm_mon-1]) { 606 if (TT.flagd) 607 loginfo(LOG_LEVEL5, " job: %d %s\n", (int)job->pid, job->cmd); 608 if (job->pid > 0) { 609 loginfo(LOG_LEVEL8, "user %s: process already running: %s", 610 cfile->username, job->cmd); 611 } else if (!job->pid) { 612 job->pid = -1; 613 job->needstart = 1; 614 job->isrunning = 0; 615 } 616 } 617 if ((job = job->next) == jstart) break; 618 } 619NEXT_CRONFILE: 620 if ((cfile = cfile->next) == gclist) break; 621 } 622 } 623} 624 625void crond_main(void) 626{ 627 time_t ctime, ptime; 628 int sleepfor = 60; 629 struct stat sb; 630 631 TT.flagd = (toys.optflags & FLAG_d); 632 633 // Setting default params. 634 if (TT.flagd) TT.loglevel = TT.loglevel_d; 635 if (!(toys.optflags & (FLAG_f | FLAG_b))) toys.optflags |= FLAG_b; 636 if (!(toys.optflags & (FLAG_S | FLAG_L))) toys.optflags |= FLAG_S; 637 638 if ((toys.optflags & FLAG_c) 639 && (TT.crontabs_dir[strlen(TT.crontabs_dir)-1] != '/')) 640 TT.crontabs_dir = xmprintf("%s/", TT.crontabs_dir); 641 642 if (!TT.crontabs_dir) TT.crontabs_dir = xstrdup("/var/spool/cron/crontabs/"); 643 if (toys.optflags & FLAG_b) daemon(0,0); 644 645 if (!TT.flagd && !TT.logfile) 646 openlog(toys.which->name, LOG_CONS | LOG_PID, LOG_CRON); 647 648 // Set default shell once. 649 if (setenv("SHELL", "/bin/sh", 1)) error_exit("Can't set default shell"); 650 xchdir(TT.crontabs_dir); 651 loginfo(LOG_LEVEL8, "crond started, log level %d", TT.loglevel); 652 653 if (stat(TT.crontabs_dir, &sb)) sb.st_mtime = 0; 654 TT.crontabs_dir_mtime = sb.st_mtime; 655 scan_cronfiles(); 656 ctime = time(NULL); 657 658 while (1) { 659 long tdiff; 660 661 ptime = ctime; 662 sleep(sleepfor - (ptime%sleepfor) +1); 663 tdiff =(long) ((ctime = time(NULL)) - ptime); 664 665 if (stat(TT.crontabs_dir, &sb)) sb.st_mtime = 0; 666 if (TT.crontabs_dir_mtime != sb.st_mtime) { 667 TT.crontabs_dir_mtime = sb.st_mtime; 668 scan_cronfiles(); 669 } 670 671 if (TT.flagd) loginfo(LOG_LEVEL5, "wakeup diff=%ld\n", tdiff); 672 if (tdiff < -60 * 60 || tdiff > 60 * 60) 673 loginfo(LOG_LEVEL9, "time disparity of %ld minutes detected", tdiff / 60); 674 else if (tdiff > 0) { 675 schedule_jobs(ctime, ptime); 676 execute_jobs(); 677 if (count_running_jobs()) sleepfor = 10; 678 else sleepfor = 60; 679 } 680 } 681} 682