[apple/network_cmds.git] / rtadvd.tproj / timer.c

/*      $KAME: timer.c,v 1.9 2002/06/10 19:59:47 itojun Exp $   */

/*
 * Copyright (C) 1998 WIDE Project.
 * 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. Neither the name of the project 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 PROJECT 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 PROJECT 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.
 */

#include <sys/time.h>

#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <search.h>
#include "timer.h"
#include "rtadvd_logging.h"

static struct rtadvd_timer timer_head;

#define MILLION 1000000
#define TIMEVAL_EQUAL(t1,t2) ((t1)->tv_sec == (t2)->tv_sec &&\
 (t1)->tv_usec == (t2)->tv_usec)

static struct timeval tm_max = {0x7fffffff, 0x7fffffff};

void
rtadvd_timer_init()
{
        memset(&timer_head, 0, sizeof(timer_head));

        timer_head.next = timer_head.prev = &timer_head;
        timer_head.tm = tm_max;
}

struct rtadvd_timer *
rtadvd_add_timer(struct rtadvd_timer *(*timeout)(void *),
    void (*update)(void *, struct timeval *),
    void *timeodata, void *updatedata)
{
        struct rtadvd_timer *newtimer;

        if ((newtimer = malloc(sizeof(*newtimer))) == NULL) {
                errorlog("<%s> can't allocate memory", __func__);
                exit(1);
        }

        memset(newtimer, 0, sizeof(*newtimer));

        if (timeout == NULL) {
                errorlog("<%s> timeout function unspecified", __func__);
                exit(1);
        }
        newtimer->expire = timeout;
        newtimer->update = update;
        newtimer->expire_data = timeodata;
        newtimer->update_data = updatedata;
        newtimer->tm = tm_max;

        /* link into chain */
        insque(newtimer, &timer_head);

        return(newtimer);
}

void
rtadvd_remove_timer(struct rtadvd_timer **timer)
{
        remque(*timer);
        free(*timer);
        *timer = NULL;
}

void
rtadvd_set_timer(struct timeval *tm, struct rtadvd_timer *timer)
{
        struct timeval now;

        /* reset the timer */
        gettimeofday(&now, NULL);

        TIMEVAL_ADD(&now, tm, &timer->tm);

        /* update the next expiration time */
        if (TIMEVAL_LT(timer->tm, timer_head.tm))
                timer_head.tm = timer->tm;

        return;
}

/*
 * Check expiration for each timer. If a timer expires,
 * call the expire function for the timer and update the timer.
 * Return the next interval for select() call.
 */
struct timeval *
rtadvd_check_timer()
{
        static struct timeval returnval;
        struct timeval now;
        struct rtadvd_timer *tm = timer_head.next, *tm_next;

        gettimeofday(&now, NULL);

        timer_head.tm = tm_max;

        for (tm = timer_head.next; tm != &timer_head; tm = tm_next) {
                tm_next = tm->next;

                if (TIMEVAL_LEQ(tm->tm, now)) {
                        if (((*tm->expire)(tm->expire_data) == NULL))
                                continue; /* the timer was removed */
                        if (tm->update)
                                (*tm->update)(tm->update_data, &tm->tm);
                        TIMEVAL_ADD(&tm->tm, &now, &tm->tm);
                }

                if (TIMEVAL_LT(tm->tm, timer_head.tm))
                        timer_head.tm = tm->tm;
        }

        if (TIMEVAL_EQUAL(&tm_max, &timer_head.tm)) {
                /* no need to timeout */
                return(NULL);
        } else if (TIMEVAL_LT(timer_head.tm, now)) {
                /* this may occur when the interval is too small */
                returnval.tv_sec = returnval.tv_usec = 0;
        } else
                TIMEVAL_SUB(&timer_head.tm, &now, &returnval);
        return(&returnval);
}

struct timeval *
rtadvd_timer_rest(struct rtadvd_timer *timer)
{
        static struct timeval returnval, now;

        gettimeofday(&now, NULL);
        if (TIMEVAL_LEQ(timer->tm, now)) {
                debuglog("<%s> a timer must be expired, but not yet",
                       __func__);
                returnval.tv_sec = returnval.tv_usec = 0;
        }
        else
                TIMEVAL_SUB(&timer->tm, &now, &returnval);

        return(&returnval);
}

/* result = a + b */
void
TIMEVAL_ADD(struct timeval *a, struct timeval *b, struct timeval *result)
{
        long l;

        if ((l = a->tv_usec + b->tv_usec) < MILLION) {
                result->tv_usec = l;
                result->tv_sec = a->tv_sec + b->tv_sec;
        }
        else {
                result->tv_usec = l - MILLION;
                result->tv_sec = a->tv_sec + b->tv_sec + 1;
        }
}

/*
 * result = a - b
 * XXX: this function assumes that a >= b.
 */
void
TIMEVAL_SUB(struct timeval *a, struct timeval *b, struct timeval *result)
{
        long l;

        if ((l = a->tv_usec - b->tv_usec) >= 0) {
                result->tv_usec = l;
                result->tv_sec = a->tv_sec - b->tv_sec;
        }
        else {
                result->tv_usec = MILLION + l;
                result->tv_sec = a->tv_sec - b->tv_sec - 1;
        }
}