/* Copyright 1988,1990,1993,1994 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          <paul@vix.com>          uunet!decwrl!vixie!paul
 *
 * $FreeBSD: src/usr.sbin/cron/cron/cron.c,v 1.9.2.2 2001/05/28 23:37:26 babkin Exp $
 */

#define MAIN_PROGRAM


#include "cron.h"
#include <sys/signal.h>
#if SYS_TIME_H
# include <sys/time.h>
#else
# include <time.h>
#endif


static  void    usage(void),
                run_reboot_jobs(cron_db *),
                cron_tick(cron_db *),
                cron_sync(void),
                cron_sleep(cron_db *),
                cron_clean(cron_db *),
#ifdef USE_SIGCHLD
                sigchld_handler(int),
#endif
                sighup_handler(int),
                parse_args(int c, char *v[]);

static time_t   last_time = 0;
static int      dst_enabled = 0;

static void
usage(void)
{
        const char **dflags;

        fprintf(stderr, "usage: cron [-j jitter] [-J rootjitter] "
                        "[-s] [-o] [-x debugflag[,...]]\n");

        for(dflags = DebugFlagNames; *dflags; dflags++) {
                fprintf(stderr, "%s ", *dflags);
        }
        fprintf(stderr, "\n");

        exit(ERROR_EXIT);
}


int
main(int argc, char **argv)
{
        cron_db database;

        ProgramName = argv[0];

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

        parse_args(argc, argv);

#ifdef USE_SIGCHLD
        signal(SIGCHLD, sigchld_handler);
#else
        signal(SIGCLD, SIG_IGN);
#endif
        signal(SIGHUP, sighup_handler);

        acquire_daemonlock(0);
        set_cron_uid();
        set_cron_cwd();

#if defined(POSIX)
        if (setenv("PATH", _PATH_DEFPATH, 1) == -1) {
                log_it("CRON", getpid(), "DEATH",
                       "setenv: cannot set PATH");
                exit(0);
        }
#endif

        /* if there are no debug flags turned on, fork as a daemon should.
         */
# if DEBUGGING
        if (DebugFlags) {
# else
        if (0) {
# endif
                fprintf(stderr, "[%d] cron started\n", getpid());
        } else {
                if (daemon(1, 0) == -1) {
                        log_it("CRON",getpid(),"DEATH","can't become daemon");
                        exit(0);
                }
        }

        acquire_daemonlock(0);
        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(&database);

                load_database(&database);

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

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


static void
run_reboot_jobs(cron_db *db)
{
        user *u;
        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, u);
                        }
                }
        }
        job_runqueue();
}


static void
cron_tick(cron_db *db)
{
        static struct tm lasttm;
        static time_t diff;      /* delta time from the last offset change */
        static time_t difflimit; /* end point for the time zone correction */
        struct tm otztm; /* time in the old time zone */
        int otzminute, otzhour, otzdom, otzmonth, otzdow;
        struct tm *tm;
        int minute, hour, dom, month, dow;
        user *u;
        entry *e;

        tm = localtime(&TargetTime);
        /* 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))

        if (dst_enabled && last_time != 0 
        && TargetTime > last_time /* exclude stepping back */
        && tm->tm_gmtoff != lasttm.tm_gmtoff ) {

                diff = tm->tm_gmtoff - lasttm.tm_gmtoff;

                if ( diff > 0 ) { /* ST->DST */
                        /* mark jobs for an earlier run */
                        difflimit = TargetTime + diff;
                        for (u = db->head;  u != NULL;  u = u->next) {
                                for (e = u->crontab;  e != NULL;  e = e->next) {
                                        e->flags &= ~NOT_UNTIL;
                                        if ( e->lastrun >= TargetTime )
                                                e->lastrun = 0;
                                        /* not include the ends of hourly ranges */
                                        if ( e->lastrun < TargetTime - 3600 )
                                                e->flags |= RUN_AT;
                                        else
                                                e->flags &= ~RUN_AT;
                                }
                        }
                } else { /* diff < 0 : DST->ST */
                        /* mark jobs for skipping */
                        difflimit = TargetTime - diff;
                        for (u = db->head;  u != NULL;  u = u->next) {
                                for (e = u->crontab;  e != NULL;  e = e->next) {
                                        e->flags |= NOT_UNTIL;
                                        e->flags &= ~RUN_AT;
                                }
                        }
                }
        }

        if (diff != 0) {
                /* if the time was reset of the end of special zone is reached */
                if (last_time == 0 || TargetTime >= difflimit) {
                        /* disable the TZ switch checks */
                        diff = 0;
                        difflimit = 0;
                        for (u = db->head;  u != NULL;  u = u->next) {
                                for (e = u->crontab;  e != NULL;  e = e->next) {
                                        e->flags &= ~(RUN_AT|NOT_UNTIL);
                                }
                        }
                } else {
                        /* get the time in the old time zone */
                        time_t difftime = TargetTime + tm->tm_gmtoff - diff;
                        gmtime_r(&difftime, &otztm);

                        /* make 0-based values out of these so we can use them as indicies
                         */
                        otzminute = otztm.tm_min -FIRST_MINUTE;
                        otzhour = otztm.tm_hour -FIRST_HOUR;
                        otzdom = otztm.tm_mday -FIRST_DOM;
                        otzmonth = otztm.tm_mon +1 /* 0..11 -> 1..12 */ -FIRST_MONTH;
                        otzdow = otztm.tm_wday -FIRST_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) {
                for (e = u->crontab;  e != NULL;  e = e->next) {
                        Debug(DSCH|DEXT, ("user [%s:%d:%d:...] cmd=\"%s\"\n",
                                          env_get("LOGNAME", e->envp),
                                          e->uid, e->gid, e->cmd))

                        if ( diff != 0 && (e->flags & (RUN_AT|NOT_UNTIL)) ) {
                                if (bit_test(e->minute, otzminute)
                                 && bit_test(e->hour, otzhour)
                                 && bit_test(e->month, otzmonth)
                                 && ( ((e->flags & DOM_STAR) || (e->flags & DOW_STAR))
                                          ? (bit_test(e->dow,otzdow) && bit_test(e->dom,otzdom))
                                          : (bit_test(e->dow,otzdow) || bit_test(e->dom,otzdom))
                                        )
                                   ) {
                                        if ( e->flags & RUN_AT ) {
                                                e->flags &= ~RUN_AT;
                                                e->lastrun = TargetTime;
                                                job_add(e, u);
                                                continue;
                                        } else 
                                                e->flags &= ~NOT_UNTIL;
                                } else if ( e->flags & NOT_UNTIL )
                                        continue;
                        }

                        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))
                            )
                           ) {
                                e->flags &= ~RUN_AT;
                                e->lastrun = TargetTime;
                                job_add(e, u);
                        }
                }
        }

        last_time = TargetTime;
        lasttm = *tm;
}


/* 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 cron 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(void)
{
        struct tm *tm;

        TargetTime = time(NULL);
        tm = localtime(&TargetTime);
        TargetTime += (60 - tm->tm_sec);
}


static void
cron_sleep(cron_db *db)
{
        int     seconds_to_wait = 0;

        /*
         * Loop until we reach the top of the next minute, sleep when possible.
         */

        for (;;) {
                seconds_to_wait = (int) (TargetTime - time(NULL));

                /*
                 * If the seconds_to_wait value is insane, jump the cron
                 */

                if (seconds_to_wait < -600 || seconds_to_wait > 600) {
                        cron_clean(db);
                        cron_sync();
                        continue;
                }

                Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
                        getpid(), (long)TargetTime, seconds_to_wait))

                /*
                 * If we've run out of wait time or there are no jobs left
                 * to run, break
                 */

                if (seconds_to_wait <= 0)
                        break;
                if (job_runqueue() == 0) {
                        Debug(DSCH, ("[%d] sleeping for %d seconds\n",
                                getpid(), seconds_to_wait))

                        sleep(seconds_to_wait);
                }
        }
}


/* if the time was changed abruptly, clear the flags related
 * to the daylight time switch handling to avoid strange effects
 */

static void
cron_clean(cron_db *db)
{
        user            *u;
        entry           *e;

        last_time = 0;

        for (u = db->head;  u != NULL;  u = u->next) {
                for (e = u->crontab;  e != NULL;  e = e->next) {
                        e->flags &= ~(RUN_AT|NOT_UNTIL);
                }
        }
}

#ifdef USE_SIGCHLD
static void
sigchld_handler(__unused int x)
{
        WAIT_T          waiter;
        PID_T           pid;

        for (;;) {
#ifdef POSIX
                pid = waitpid(-1, &waiter, WNOHANG);
#else
                pid = wait3(&waiter, WNOHANG, NULL);
#endif
                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, WEXITSTATUS(waiter)))
                }
        }
}
#endif /*USE_SIGCHLD*/


static void
sighup_handler(__unused int x)
{
        log_close();
}


static void
parse_args(int argc, char **argv)
{
        int     argch;
        char    *endp;

        while ((argch = getopt(argc, argv, "j:J:osx:")) != -1) {
                switch (argch) {
                case 'j':
                        Jitter = strtoul(optarg, &endp, 10);
                        if (*optarg == '\0' || *endp != '\0' || Jitter > 60)
                                errx(ERROR_EXIT,
                                     "bad value for jitter: %s", optarg);
                        break;
                case 'J':
                        RootJitter = strtoul(optarg, &endp, 10);
                        if (*optarg == '\0' || *endp != '\0' || RootJitter > 60)
                                errx(ERROR_EXIT,
                                     "bad value for root jitter: %s", optarg);
                        break;
                case 'o':
                        dst_enabled = 0;
                        break;
                case 's':
                        dst_enabled = 1;
                        break;
                case 'x':
                        if (!set_debug_flags(optarg))
                                usage();
                        break;
                default:
                        usage();
                }
        }
}