usr/src/usr.sbin/sendmail/src/clock.c

/*
 * Copyright (c) 1983 Eric P. Allman
 * Copyright (c) 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char sccsid[] = "@(#)clock.c     8.1 (Berkeley) 6/7/93";
#endif /* not lint */

# include "sendmail.h"
# include <signal.h>

# ifndef sigmask
#  define sigmask(s)    (1 << ((s) - 1))
# endif

/*
**  SETEVENT -- set an event to happen at a specific time.
**
**      Events are stored in a sorted list for fast processing.
**      An event only applies to the process that set it.
**
**      Parameters:
**              intvl -- intvl until next event occurs.
**              func -- function to call on event.
**              arg -- argument to func on event.
**
**      Returns:
**              none.
**
**      Side Effects:
**              none.
*/

static void tick();

EVENT *
setevent(intvl, func, arg)
        time_t intvl;
        int (*func)();
        int arg;
{
        register EVENT **evp;
        register EVENT *ev;
        auto time_t now;

        if (intvl <= 0)
        {
                syserr("554 setevent: intvl=%ld\n", intvl);
                return (NULL);
        }

        (void) time(&now);

        /* search event queue for correct position */
        for (evp = &EventQueue; (ev = *evp) != NULL; evp = &ev->ev_link)
        {
                if (ev->ev_time >= now + intvl)
                        break;
        }

        /* insert new event */
        ev = (EVENT *) xalloc(sizeof *ev);
        ev->ev_time = now + intvl;
        ev->ev_func = func;
        ev->ev_arg = arg;
        ev->ev_pid = getpid();
        ev->ev_link = *evp;
        *evp = ev;

        if (tTd(5, 5))
                printf("setevent: intvl=%ld, for=%ld, func=%x, arg=%d, ev=%x\n",
                        intvl, now + intvl, func, arg, ev);

        tick();
        return (ev);
}
\f/*
**  CLREVENT -- remove an event from the event queue.
**
**      Parameters:
**              ev -- pointer to event to remove.
**
**      Returns:
**              none.
**
**      Side Effects:
**              arranges for event ev to not happen.
*/

clrevent(ev)
        register EVENT *ev;
{
        register EVENT **evp;

        if (tTd(5, 5))
                printf("clrevent: ev=%x\n", ev);
        if (ev == NULL)
                return;

        /* find the parent event */
        (void) signal(SIGALRM, SIG_IGN);
        for (evp = &EventQueue; *evp != NULL; evp = &(*evp)->ev_link)
        {
                if (*evp == ev)
                        break;
        }

        /* now remove it */
        if (*evp != NULL)
        {
                *evp = ev->ev_link;
                free((char *) ev);
        }

        /* restore clocks and pick up anything spare */
        tick();
}
\f/*
**  TICK -- take a clock tick
**
**      Called by the alarm clock.  This routine runs events as needed.
**
**      Parameters:
**              none.
**
**      Returns:
**              none.
**
**      Side Effects:
**              calls the next function in EventQueue.
*/

static void
tick()
{
        register time_t now;
        register EVENT *ev;
        int mypid = getpid();

        (void) signal(SIGALRM, SIG_IGN);
        (void) alarm(0);
        now = curtime();

        if (tTd(5, 4))
                printf("tick: now=%ld\n", now);

        while ((ev = EventQueue) != NULL &&
               (ev->ev_time <= now || ev->ev_pid != mypid))
        {
                int (*f)();
                int arg;
                int pid;

                /* process the event on the top of the queue */
                ev = EventQueue;
                EventQueue = EventQueue->ev_link;
                if (tTd(5, 6))
                        printf("tick: ev=%x, func=%x, arg=%d, pid=%d\n", ev,
                                ev->ev_func, ev->ev_arg, ev->ev_pid);

                /* we must be careful in here because ev_func may not return */
                (void) signal(SIGALRM, tick);
#ifdef SIGVTALRM
                /* reset 4.2bsd signal mask to allow future alarms */
                (void) sigsetmask(sigblock(0) & ~sigmask(SIGALRM));
#endif /* SIGVTALRM */

                f = ev->ev_func;
                arg = ev->ev_arg;
                pid = ev->ev_pid;
                free((char *) ev);
                if (pid != getpid())
                        continue;
                if (EventQueue != NULL)
                {
                        if (EventQueue->ev_time > now)
                                (void) alarm((unsigned) (EventQueue->ev_time - now));
                        else
                                (void) alarm(3);
                }
                (*f)(arg);
                (void) alarm(0);
                now = curtime();
        }
        (void) signal(SIGALRM, tick);
        if (EventQueue != NULL)
                (void) alarm((unsigned) (EventQueue->ev_time - now));
}
\f/*
**  SLEEP -- a version of sleep that works with this stuff
**
**      Because sleep uses the alarm facility, I must reimplement
**      it here.
**
**      Parameters:
**              intvl -- time to sleep.
**
**      Returns:
**              none.
**
**      Side Effects:
**              waits for intvl time.  However, other events can
**              be run during that interval.
*/

static bool     SleepDone;

unsigned int
sleep(intvl)
        unsigned int intvl;
{
        static int endsleep();

        if (intvl == 0)
                return;
        SleepDone = FALSE;
        (void) setevent((time_t) intvl, endsleep, 0);
        while (!SleepDone)
                pause();
}

static
endsleep()
{
        SleepDone = TRUE;
}