/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2002-2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * Time routines, snagged from libc.
 */

#pragma ident   "%Z%%M% %I%     %E% SMI"

#include <errno.h>
#include <sys/types.h>
#include <sys/bootvfs.h>
#include <sys/salib.h>
#include <sys/promif.h>
#include <stdio.h>
#include <time.h>

#define CBUFSIZ 26

static time_t   start_time, secs_since_boot;

const int       __year_lengths[2] = {
        DAYS_PER_NYEAR, DAYS_PER_LYEAR
};
const int       __mon_lengths[2][MONS_PER_YEAR] = {
        31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31,
        31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};

/*
 * Initializes our "clock" to the creation date of /timestamp, which is
 * made on the fly for us by the web server. Thereafter, time() will keep
 * time sort of up to date.
 */
void
init_boot_time(void)
{
        struct stat sb;

        if (start_time == 0) {
                if (stat("/timestamp", &sb) < 0)
                        prom_panic("init_boot_time: cannot stat /timestamp");

                start_time = sb.st_ctim.tv_sec;
                secs_since_boot = prom_gettime() / 1000;
        }
}

/*
 * Time is crudely incremented.
 */
time_t
time(time_t *tloc)
{
        time_t  time_now;

        time_now = start_time + ((prom_gettime() / 1000) - secs_since_boot);

        if (tloc != NULL)
                *tloc = time_now;

        if (start_time == 0)
                return (0);
        else
                return (time_now);
}

struct tm *
gmtime(const time_t *clock)
{
        static struct tm        result;
        struct tm       *tmp;
        long            days;
        int             rem;
        long            y;
        long            newy;
        const int       *ip;

        tmp = &result;
        days = *clock / SECS_PER_DAY;
        rem = *clock % SECS_PER_DAY;
        while (rem < 0) {
                rem += SECS_PER_DAY;
                --days;
        }
        while (rem >= SECS_PER_DAY) {
                rem -= SECS_PER_DAY;
                ++days;
        }
        tmp->tm_hour = (int)(rem / SECS_PER_HOUR);
        rem = rem % SECS_PER_HOUR;
        tmp->tm_min = (int)(rem / SECS_PER_MIN);
        tmp->tm_sec = (int)(rem % SECS_PER_MIN);
        tmp->tm_wday = (int)((EPOCH_WDAY + days) % DAYS_PER_WEEK);
        if (tmp->tm_wday < 0)
                tmp->tm_wday += DAYS_PER_WEEK;
        y = EPOCH_YEAR;

#define LEAPS_THRU_END_OF(y)    ((y) / 4 - (y) / 100 + (y) / 400)

        while (days < 0 || days >= (long)__year_lengths[isleap(y)]) {
                newy = y + days / DAYS_PER_NYEAR;
                if (days < 0)
                        --newy;
                days -= ((long)newy - (long)y) * DAYS_PER_NYEAR +
                        LEAPS_THRU_END_OF(newy > 0 ? newy - 1L : newy) -
                        LEAPS_THRU_END_OF(y > 0 ? y - 1L : y);
                y = newy;
        }

        tmp->tm_year = y - TM_YEAR_BASE;
        tmp->tm_yday = days;
        ip = __mon_lengths[isleap(y)];
        for (tmp->tm_mon = 0; days >= ip[tmp->tm_mon]; ++(tmp->tm_mon))
                days = days - ip[tmp->tm_mon];
        tmp->tm_mday = (days + 1);
        tmp->tm_isdst = 0;
        return (tmp);
}

/*
 * The standalone booter runs in GMT.
 */
struct tm *
localtime(const time_t *clock)
{
        return (gmtime(clock));
}

static char *
ct_numb(char *cp, int n)
{
        cp++;
        if (n >= 10)
                *cp++ = (n / 10) % 10 + '0';
        else
                *cp++ = ' ';            /* Pad with blanks */
        *cp++ = n % 10 + '0';
        return (cp);
}

char *
asctime(const struct tm *t)
{
        char *cp;
        const char *ncp;
        const int *tp;
        const char *Date = "Day Mon 00 00:00:00 1900\n";
        const char *Day  = "SunMonTueWedThuFriSat";
        const char *Month = "JanFebMarAprMayJunJulAugSepOctNovDec";
        static char cbuf[CBUFSIZ];

        cp = cbuf;
        for (ncp = Date; *cp++ = *ncp++; /* */);
        ncp = Day + (3 * t->tm_wday);
        cp = cbuf;
        *cp++ = *ncp++;
        *cp++ = *ncp++;
        *cp++ = *ncp++;
        cp++;
        tp = &t->tm_mon;
        ncp = Month + ((*tp) * 3);
        *cp++ = *ncp++;
        *cp++ = *ncp++;
        *cp++ = *ncp++;
        cp = ct_numb(cp, *--tp);
        cp = ct_numb(cp, *--tp + 100);
        cp = ct_numb(cp, *--tp + 100);
        --tp;
        cp = ct_numb(cp, *tp + 100);
        if (t->tm_year < 100) {
                /* Common case: "19" already in buffer */
                cp += 2;
        } else if (t->tm_year < 8100) {
                cp = ct_numb(cp, (1900 + t->tm_year) / 100);
                cp--;
        } else {
                /* Only 4-digit years are supported */
                errno = EOVERFLOW;
                return (NULL);
        }
        (void) ct_numb(cp, t->tm_year + 100);
        return (cbuf);
}

char *
ctime(const time_t *t)
{
        return (asctime(localtime(t)));
}