usr/src/libexec/crond/crond.c

#if !defined(lint) && !defined(LINT)
static char rcsid[] = "$Header: /home/local/site/cron2.1/orig/RCS/crond.c,v 2.2 1992/05/13 05:56:35 rich Exp $";
#endif

/* Copyright 1988,1990 by Paul Vixie
 * All rights reserved
 *
 * Distribute freely, except: don't remove my name from the source or
 * documentation (don't take credit for my work), mark your changes (don't
 * get me blamed for your possible bugs), don't alter or remove this
 * notice.  May be sold if buildable source is provided to buyer.  No
 * warrantee of any kind, express or implied, is included with this
 * software; use at your own risk, responsibility for damages (if any) to
 * anyone resulting from the use of this software rests entirely with the
 * user.
 *
 * Send bug reports, bug fixes, enhancements, requests, flames, etc., and
 * I'll try to keep a version up to date.  I can be reached as follows:
 * Paul Vixie, 329 Noe Street, San Francisco, CA, 94114, (415) 864-7013,
 * paul@vixie.sf.ca.us || {hoptoad,pacbell,decwrl,crash}!vixie!paul
 *
 * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
 * --------------------         -----   ----------------------
 * CURRENT PATCH LEVEL:         1       00131
 * --------------------         -----   ----------------------
 *
 * 06 Apr 93    Adam Glass      Fixes so it compiles quitely
 *
 */


#define MAIN_PROGRAM


#include "cron.h"
#include <sys/time.h>
#include <sys/signal.h>
#include <sys/types.h>
#if defined(BSD)
# include <sys/wait.h>
# include <sys/resource.h>
#endif /*BSD*/

extern int      fork(), unlink();
extern time_t   time();
extern void     exit();
extern unsigned sleep();

void
usage()
{
        (void) fprintf(stderr, "usage:  %s [-x debugflag[,...]]\n", ProgramName);
        (void) exit(ERROR_EXIT);
}


int
main(argc, argv)
        int     argc;
        char    *argv[];
{
        extern void     set_cron_uid(), be_different(), load_database(),
                        set_cron_cwd(), open_logfile();

        static void     cron_tick(), cron_sleep(), cron_sync(),
                        sigchld_handler(), parse_args(), run_reboot_jobs();

        auto cron_db    database;

        ProgramName = argv[0];

#if defined(BSD)
        setlinebuf(stdout);
        setlinebuf(stderr);
#endif

        parse_args(argc, argv);

# if DEBUGGING
        /* if there are no debug flags turned on, fork as a daemon should.
         */
        if (DebugFlags)
        {
                (void) fprintf(stderr, "[%d] crond started\n", getpid());
        }
        else
# endif /*DEBUGGING*/
        {
                switch (fork())
                {
                case -1:
                        log_it("CROND",getpid(),"DEATH","can't fork");
                        exit(0);
                        break;
                case 0:
                        /* child process */
                        be_different();
                        break;
                default:
                        /* parent process should just die */
                        _exit(0);
                }
        }

#if defined(BSD)
        (void) signal(SIGCHLD, sigchld_handler);
#endif /*BSD*/

#if defined(ATT)
        (void) signal(SIGCLD, SIG_IGN);
#endif /*ATT*/

        acquire_daemonlock();
        set_cron_uid();
        set_cron_cwd();
        database.head = NULL;
        database.tail = NULL;
        database.mtime = (time_t) 0;
        load_database(&database);
        run_reboot_jobs(&database);
        cron_sync();
        while (TRUE)
        {
# if DEBUGGING
                if (!(DebugFlags & DTEST))
# endif /*DEBUGGING*/
                        cron_sleep();

                load_database(&database);

                /* do this iteration
                 */
                cron_tick(&database);

                /* sleep 1 minute
                 */
                TargetTime += 60;
        }
}


static void
run_reboot_jobs(db)
        cron_db *db;
{
        extern void             job_add();
        extern int              job_runqueue();
        register user           *u;
        register entry          *e;

        for (u = db->head;  u != NULL;  u = u->next) {
                for (e = u->crontab;  e != NULL;  e = e->next) {
                        if (e->flags & WHEN_REBOOT) {
                                job_add(e->cmd, u);
                        }
                }
        }
        (void) job_runqueue();
}


static void
cron_tick(db)
        cron_db *db;
{
        extern void             job_add();
        extern char             *env_get();
        extern struct tm        *localtime();
        register struct tm      *tm = localtime(&TargetTime);
        local int               minute, hour, dom, month, dow;
        register user           *u;
        register entry          *e;

        /* make 0-based values out of these so we can use them as indicies
         */
        minute = tm->tm_min -FIRST_MINUTE;
        hour = tm->tm_hour -FIRST_HOUR;
        dom = tm->tm_mday -FIRST_DOM;
        month = tm->tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
        dow = tm->tm_wday -FIRST_DOW;

        Debug(DSCH, ("[%d] tick(%d,%d,%d,%d,%d)\n",
                getpid(), minute, hour, dom, month, dow))

        /* the dom/dow situation is odd.  '* * 1,15 * Sun' will run on the
         * first and fifteenth AND every Sunday;  '* * * * Sun' will run *only*
         * on Sundays;  '* * 1,15 * *' will run *only* the 1st and 15th.  this
         * is why we keep 'e->dow_star' and 'e->dom_star'.  yes, it's bizarre.
         * like many bizarre things, it's the standard.
         */
        for (u = db->head;  u != NULL;  u = u->next) {
                Debug(DSCH|DEXT, ("user [%s:%d:%d:...]\n",
                        env_get(USERENV,u->envp), u->uid, u->gid))
                for (e = u->crontab;  e != NULL;  e = e->next) {
                        Debug(DSCH|DEXT, ("entry [%s]\n", e->cmd))
                        if (bit_test(e->minute, minute)
                         && bit_test(e->hour, hour)
                         && bit_test(e->month, month)
                         && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
                              ? (bit_test(e->dow,dow) && bit_test(e->dom,dom))
                              : (bit_test(e->dow,dow) || bit_test(e->dom,dom))
                            )
                           ) {
                                job_add(e->cmd, u);
                        }
                }
        }
}


/* the task here is to figure out how long it's going to be until :00 of the
 * following minute and initialize TargetTime to this value.  TargetTime
 * will subsequently slide 60 seconds at a time, with correction applied
 * implicitly in cron_sleep().  it would be nice to let crond execute in
 * the "current minute" before going to sleep, but by restarting cron you
 * could then get it to execute a given minute's jobs more than once.
 * instead we have the chance of missing a minute's jobs completely, but
 * that's something sysadmin's know to expect what with crashing computers..
 */
static void
cron_sync()
{
        extern struct tm        *localtime();
        register struct tm      *tm;

        TargetTime = time((time_t*)0);
        tm = localtime(&TargetTime);
        TargetTime += (60 - tm->tm_sec);
}


static void
cron_sleep()
{
        extern void     do_command();
        extern int      job_runqueue();
        register int    seconds_to_wait;

        do {
                seconds_to_wait = (int) (TargetTime - time((time_t*)0));
                Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
                        getpid(), TargetTime, seconds_to_wait))

                /* if we intend to sleep, this means that it's finally
                 * time to empty the job queue (execute it).
                 *
                 * if we run any jobs, we'll probably screw up our timing,
                 * so go recompute.
                 *
                 * note that we depend here on the left-to-right nature
                 * of &&, and the short-circuiting.
                 */
        } while (seconds_to_wait > 0 && job_runqueue());

        if (seconds_to_wait > 0)
        {
                Debug(DSCH, ("[%d] sleeping for %d seconds\n",
                        getpid(), seconds_to_wait))
                (void) sleep((unsigned int) seconds_to_wait);
        }
}


#if defined(BSD)
static void
sigchld_handler()
{
        union wait      waiter;
        int             pid;

        for (;;)
        {
                pid = wait3((int *) &waiter, WNOHANG, (struct rusage *)0);
                switch (pid)
                {
                case -1:
                        Debug(DPROC,
                                ("[%d] sigchld...no children\n", getpid()))
                        return;
                case 0:
                        Debug(DPROC,
                                ("[%d] sigchld...no dead kids\n", getpid()))
                        return;
                default:
                        Debug(DPROC,
                                ("[%d] sigchld...pid #%d died, stat=%d\n",
                                getpid(), pid, waiter.w_status))
                }
        }
}
#endif /*BSD*/


static void
parse_args(argc, argv)
        int     argc;
        char    *argv[];
{
        extern  int     optind, getopt();
        extern  void    usage();
        extern  char    *optarg;

        int     argch;

        while (EOF != (argch = getopt(argc, argv, "x:")))
        {
                switch (argch)
                {
                default:
                        usage();
                case 'x':
                        if (!set_debug_flags(optarg))
                                usage();
                        break;
                }
        }
}