usr.sbin/cron/cron.c

   1 /*      $NetBSD: cron.c,v 1.12 2006/05/21 19:26:43 christos Exp $       */
   2
   3 /* Copyright 1988,1990,1993,1994 by Paul Vixie
   4  * All rights reserved
   5  *
   6  * Distribute freely, except: don't remove my name from the source or
   7  * documentation (don't take credit for my work), mark your changes (don't
   8  * get me blamed for your possible bugs), don't alter or remove this
   9  * notice.  May be sold if buildable source is provided to buyer.  No
  10  * warrantee of any kind, express or implied, is included with this
  11  * software; use at your own risk, responsibility for damages (if any) to
  12  * anyone resulting from the use of this software rests entirely with the
  13  * user.
  14  *
  15  * Send bug reports, bug fixes, enhancements, requests, flames, etc., and
  16  * I'll try to keep a version up to date.  I can be reached as follows:
  17  * Paul Vixie          <paul@vix.com>          uunet!decwrl!vixie!paul
  18  */
  19
  20 #include <sys/cdefs.h>
  21 #if !defined(lint) && !defined(LINT)
  22 #if 0
  23 static char rcsid[] = "Id: cron.c,v 2.11 1994/01/15 20:43:43 vixie Exp";
  24 #else
  25 __RCSID("$NetBSD: cron.c,v 1.12 2006/05/21 19:26:43 christos Exp $");
  26 #endif
  27 #endif
  28
  29
  30 #define MAIN_PROGRAM
  31
  32
  33 #include "cron.h"
  34 #include <sys/signal.h>
  35 #if SYS_TIME_H
  36 # include <sys/time.h>
  37 #else
  38 # include <time.h>
  39 #endif
  40
  41
  42 static  void    usage(void),
  43                 run_reboot_jobs(cron_db *),
  44                 cron_tick(cron_db *),
  45                 cron_sync(void),
  46                 cron_sleep(void),
  47 #ifdef USE_SIGCHLD
  48                 sigchld_handler(int),
  49 #endif
  50                 sighup_handler(int),
  51                 parse_args(int c, char *v[]);
  52
  53
  54 static void
  55 usage(void) {
  56         fprintf(stderr, "usage:  %s [-x debugflag[,...]]\n", getprogname());
  57         exit(ERROR_EXIT);
  58 }
  59
  60
  61 int
  62 main(int argc, char **argv)
  63 {
  64         cron_db database;
  65
  66         setprogname(argv[0]);
  67
  68 #if defined(BSD)
  69         setlinebuf(stdout);
  70         setlinebuf(stderr);
  71 #endif
  72
  73         parse_args(argc, argv);
  74
  75 #ifdef USE_SIGCHLD
  76         (void) signal(SIGCHLD, sigchld_handler);
  77 #else
  78         (void) signal(SIGCLD, SIG_IGN);
  79 #endif
  80         (void) signal(SIGHUP, sighup_handler);
  81
  82         acquire_daemonlock(0);
  83         set_cron_uid();
  84         set_cron_cwd();
  85
  86 #if defined(POSIX)
  87         setenv("PATH", _PATH_DEFPATH, 1);
  88 #endif
  89
  90         /* if there are no debug flags turned on, fork as a daemon should.
  91          */
  92 # if DEBUGGING
  93         if (DebugFlags) {
  94 # else
  95         if (0) {
  96 # endif
  97                 (void) fprintf(stderr, "[%d] cron started\n", getpid());
  98         } else {
  99                 if (daemon(1, 0)) {
 100                         log_it("CRON",getpid(),"DEATH","can't fork");
 101                         exit(1);
 102                 }
 103         }
 104
 105         acquire_daemonlock(0);
 106         database.head = NULL;
 107         database.tail = NULL;
 108         database.mtime = (time_t) 0;
 109         load_database(&database);
 110         run_reboot_jobs(&database);
 111         cron_sync();
 112         while (TRUE) {
 113 # if DEBUGGING
 114                 if (!(DebugFlags & DTEST))
 115 # endif /*DEBUGGING*/
 116                         cron_sleep();
 117
 118                 load_database(&database);
 119
 120                 /* do this iteration
 121                  */
 122                 cron_tick(&database);
 123
 124                 /* sleep 1 minute
 125                  */
 126                 TargetTime += 60;
 127         }
 128 }
 129
 130
 131 static void
 132 run_reboot_jobs(cron_db *db)
 133 {
 134         user            *u;
 135         entry           *e;
 136
 137         for (u = db->head;  u != NULL;  u = u->next) {
 138                 for (e = u->crontab;  e != NULL;  e = e->next) {
 139                         if (e->flags & WHEN_REBOOT) {
 140                                 job_add(e, u);
 141                         }
 142                 }
 143         }
 144         (void) job_runqueue();
 145 }
 146
 147
 148 static void
 149 cron_tick(cron_db *db)
 150 {
 151         char            *orig_tz, *job_tz;
 152         struct tm       *tm;
 153         int             minute, hour, dom, month, dow;
 154         user            *u;
 155         entry           *e;
 156
 157         /* make 0-based values out of these so we can use them as indicies
 158          */
 159 #define maketime(tz1, tz2) do { \
 160         char *t = tz1; \
 161         if (t != NULL && *t != '\0') \
 162                 setenv("TZ", t, 1); \
 163         else if ((tz2) != NULL) \
 164                 setenv("TZ", (tz2), 1); \
 165         else \
 166                 unsetenv("TZ"); \
 167         tm = localtime(&TargetTime); \
 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         } while (0)
 174
 175         orig_tz = getenv("TZ");
 176         maketime(NULL, orig_tz);
 177
 178         Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d)\n",
 179                 getpid(), minute, hour, dom, month, dow))
 180
 181         /* the dom/dow situation is odd.  '* * 1,15 * Sun' will run on the
 182          * first and fifteenth AND every Sunday;  '* * * * Sun' will run *only*
 183          * on Sundays;  '* * 1,15 * *' will run *only* the 1st and 15th.  this
 184          * is why we keep 'e->dow_star' and 'e->dom_star'.  yes, it's bizarre.
 185          * like many bizarre things, it's the standard.
 186          */
 187         for (u = db->head;  u != NULL;  u = u->next) {
 188                 for (e = u->crontab;  e != NULL;  e = e->next) {
 189                         Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
 190                                           env_get("LOGNAME", e->envp),
 191                                           e->uid, e->gid, e->cmd))
 192                         job_tz = env_get("CRON_TZ", e->envp);
 193                         maketime(job_tz, orig_tz);
 194                         if (bit_test(e->minute, minute)
 195                          && bit_test(e->hour, hour)
 196                          && bit_test(e->month, month)
 197                          && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
 198                               ? (bit_test(e->dow,dow) && bit_test(e->dom,dom))
 199                               : (bit_test(e->dow,dow) || bit_test(e->dom,dom))
 200                             )
 201                            ) {
 202                                 job_add(e, u);
 203                         }
 204                 }
 205         }
 206         if (orig_tz != NULL)
 207                 setenv("TZ", orig_tz, 1);
 208         else
 209                 unsetenv("TZ");
 210 }
 211
 212
 213 /* the task here is to figure out how long it's going to be until :00 of the
 214  * following minute and initialize TargetTime to this value.  TargetTime
 215  * will subsequently slide 60 seconds at a time, with correction applied
 216  * implicitly in cron_sleep().  it would be nice to let cron execute in
 217  * the "current minute" before going to sleep, but by restarting cron you
 218  * could then get it to execute a given minute's jobs more than once.
 219  * instead we have the chance of missing a minute's jobs completely, but
 220  * that's something sysadmin's know to expect what with crashing computers..
 221  */
 222 static void
 223 cron_sync(void) {
 224         struct tm       *tm;
 225
 226         TargetTime = time((time_t*)0);
 227         tm = localtime(&TargetTime);
 228         TargetTime += (60 - tm->tm_sec);
 229 }
 230
 231
 232 static void
 233 cron_sleep(void) {
 234         int     seconds_to_wait;
 235
 236         do {
 237                 seconds_to_wait = (int) (TargetTime - time((time_t*)0));
 238                 Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
 239                         getpid(), (long)TargetTime, seconds_to_wait))
 240
 241                 /* if we intend to sleep, this means that it's finally
 242                  * time to empty the job queue (execute it).
 243                  *
 244                  * if we run any jobs, we'll probably screw up our timing,
 245                  * so go recompute.
 246                  *
 247                  * note that we depend here on the left-to-right nature
 248                  * of &&, and the short-circuiting.
 249                  */
 250         } while (seconds_to_wait > 0 && job_runqueue());
 251
 252         while ((seconds_to_wait = (int) (TargetTime - time((time_t *)0))) > 0) {
 253                 Debug(DSCH, ("[%d] sleeping for %d seconds\n",
 254                         getpid(), seconds_to_wait))
 255                 sleep((unsigned int) seconds_to_wait);
 256         }
 257 }
 258
 259
 260 #ifdef USE_SIGCHLD
 261 static void
 262 sigchld_handler(int x __unused)
 263 {
 264         WAIT_T          waiter;
 265         PID_T           pid;
 266
 267         for (;;) {
 268 #ifdef POSIX
 269                 pid = waitpid(-1, &waiter, WNOHANG);
 270 #else
 271                 pid = wait3(&waiter, WNOHANG, (struct rusage *)0);
 272 #endif
 273                 switch (pid) {
 274                 case -1:
 275                         Debug(DPROC,
 276                                 ("[%d] sigchld...no children\n", getpid()))
 277                         return;
 278                 case 0:
 279                         Debug(DPROC,
 280                                 ("[%d] sigchld...no dead kids\n", getpid()))
 281                         return;
 282                 default:
 283                         Debug(DPROC,
 284                                 ("[%d] sigchld...pid #%d died, stat=%d\n",
 285                                 getpid(), pid, WEXITSTATUS(waiter)))
 286                 }
 287         }
 288 }
 289 #endif /*USE_SIGCHLD*/
 290
 291
 292 static void
 293 sighup_handler(int x __unused)
 294 {
 295         log_close();
 296 }
 297
 298
 299 static void
 300 parse_args(int argc, char **argv)
 301 {
 302         int     argch;
 303
 304         while (-1 != (argch = getopt(argc, argv, "x:"))) {
 305                 switch (argch) {
 306                 default:
 307                         usage();
 308                 case 'x':
 309                         if (!set_debug_flags(optarg))
 310                                 usage();
 311                         break;
 312                 }
 313         }
 314 }