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/*

  Copyright (c) 1990-2001 Info-ZIP.  All rights reserved.

  See the accompanying file LICENSE, version 2000-Apr-09 or later

  (the contents of which are also included in zip.h) for terms of use.

  If, for some reason, all these files are missing, the Info-ZIP license

  also may be found at:  ftp://ftp.info-zip.org/pub/infozip/license.html

*/

/* Replacement time library functions, based on platform independent public

 * domain timezone code from ftp://elsie.nci.nih.gov/pub, with mktime and

 * mkgmtime from our own mktime.c in Zip.

 *

 * Contains:  tzset()

 *            __tzset()

 *            gmtime()

 *            localtime()

 *            mktime()

 *            mkgmtime()

 *            GetPlatformLocalTimezone()  [different versions]

 */

/* HISTORY/CHANGES

 * 17 Jun 00, Paul Kienitz, added the PD-based tzset(), localtime(), and so on

 *            to amiga/filedate.c, replacing GNU-based functions which had

 *            replaced time_lib.c, both having been rejected for licensing

 *            reasons.  Support for timezone files and leap seconds was removed.

 *

 * 23 Aug 00, Paul Kienitz, split into separate timezone.c file, made platform

 *            independent, copied in mktime() and mkgmtime() from Zip, renamed

 *            locale_TZ as GetPlatformLocalTimezone(), for use as a generic

 *            hook by other platforms.

 */

#ifndef __timezone_c

#define __timezone_c

#include "zip.h"

#include "timezone.h"

#include 

#include 

#ifdef IZTZ_DEFINESTDGLOBALS

long timezone = 0;

int daylight = 0;

char *tzname[2];

#endif

#ifndef IZTZ_GETLOCALETZINFO

#  define IZTZ_GETLOCALETZINFO(ptzstruct, pgenrulefunct) (FALSE)

#endif

int real_timezone_is_set = FALSE;       /* set by tzset() */

#define TZDEFRULESTRING ",M4.1.0,M10.5.0"

#define TZDEFAULT       "EST5EDT"

#define SECSPERMIN      60

#define MINSPERHOUR     60

#define HOURSPERDAY     24

#define DAYSPERWEEK     7

#define DAYSPERNYEAR    365

#define DAYSPERLYEAR    366

#define SECSPERHOUR     (SECSPERMIN * MINSPERHOUR)

#define SECSPERDAY      ((long) SECSPERHOUR * HOURSPERDAY)

#define MONSPERYEAR 12

#define EPOCH_WDAY      4     /* Jan 1, 1970 was thursday */

#define EPOCH_YEAR      1970

#define TM_YEAR_BASE    1900

#define FIRST_GOOD_YEAR ((time_t) -1 < (time_t) 1 ? EPOCH_YEAR-68 : EPOCH_YEAR)

#define LAST_GOOD_YEAR  (EPOCH_YEAR + ((time_t) -1 < (time_t) 1 ? 67 : 135))

#define YDAYS(month, year) yr_days[leap(year)][month]

/* Nonzero if `y' is a leap year, else zero. */

#define leap(y)  (((y) % 4 == 0 && (y) % 100 != 0) || (y) % 400 == 0)

/* Number of leap years from EPOCH_YEAR  to `y' (not including `y' itself). */

#define _P4      ((EPOCH_YEAR / 4) * 4 + 1)

#define _P100    ((EPOCH_YEAR / 100) * 100 + 1)

#define _P400    ((EPOCH_YEAR / 400) * 400 + 1)

#define nleap(y) (((y) - _P4) / 4 - ((y) - _P100) / 100 + ((y) - _P400) / 400)

/* Length of month `m' (0 .. 11) */

#define monthlen(m, y) (yr_days[0][(m)+1] - yr_days[0][m] + \

                        ((m) == 1 && leap(y)))

/* internal module-level constants */

#ifndef IZ_MKTIME_ONLY

static ZCONST char  gmt[] = "GMT";

static ZCONST int    mon_lengths[2][MONSPERYEAR] = {

    { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },

    { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }

};

#endif /* !IZ_MKTIME_ONLY */

static ZCONST int    yr_days[2][MONSPERYEAR+1] = {

    { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },

    { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }

};

#ifndef IZ_MKTIME_ONLY

static ZCONST int   year_lengths[2] = {

    DAYSPERNYEAR, DAYSPERLYEAR

};

/* internal variables */

static struct state statism;

/* prototypes of static functions */

static time_t transtime OF((ZCONST time_t janfirst, ZCONST int year,

                            ZCONST struct rule * ZCONST rulep,

                            ZCONST long offset));

static void generate_transitions OF((register struct state * ZCONST sp,

                                     ZCONST struct rule * ZCONST start,

                                     ZCONST struct rule * ZCONST end));

static ZCONST char *getzname OF((ZCONST char *strp));

static ZCONST char *getnum OF((ZCONST char *strp, int * ZCONST nump,

                               ZCONST int min, ZCONST int max));

static ZCONST char *getsecs OF((ZCONST char *strp, long * ZCONST secsp));

static ZCONST char *getoffset OF((ZCONST char *strp, long * ZCONST offsetp));

static ZCONST char *getrule OF((ZCONST char *strp, struct rule * ZCONST rulep));

static int Parse_TZ OF((ZCONST char *name, register struct state * ZCONST sp));

static time_t transtime(janfirst, year, rulep, offset)

     ZCONST time_t janfirst;

     ZCONST int year;

     ZCONST struct rule * ZCONST rulep;

     ZCONST long offset;

{

    register int    leapyear;

    register time_t value;

    register int    i;

    int             d, m1, yy0, yy1, yy2, dow;

    value = 0;

    leapyear = leap(year);

    switch (rulep->r_type) {

    case JULIAN_DAY:

        /*

        ** Jn - Julian day, 1 == January 1, 60 == March 1 even in leap

        ** years.

        ** In non-leap years, or if the day number is 59 or less, just

        ** add SECSPERDAY times the day number-1 to the time of

        ** January 1, midnight, to get the day.

        */

        value = janfirst + (rulep->r_day - 1) * SECSPERDAY;

        if (leapyear && rulep->r_day >= 60)

            value += SECSPERDAY;

        break;

    case DAY_OF_YEAR:

        /*

        ** n - day of year.

        ** Just add SECSPERDAY times the day number to the time of

        ** January 1, midnight, to get the day.

        */

        value = janfirst + rulep->r_day * SECSPERDAY;

        break;

    case MONTH_NTH_DAY_OF_WEEK:

        /*

        ** Mm.n.d - nth "dth day" of month m.

        */

        value = janfirst;

/*

        for (i = 0; i < rulep->r_mon - 1; ++i)

            value += mon_lengths[leapyear][i] * SECSPERDAY;

*/

        value += yr_days[leapyear][rulep->r_mon - 1] * SECSPERDAY;

        /*

        ** Use Zeller's Congruence to get day-of-week of first day of

        ** month.

        */

        m1 = (rulep->r_mon + 9) % 12 + 1;

        yy0 = (rulep->r_mon <= 2) ? (year - 1) : year;

        yy1 = yy0 / 100;

        yy2 = yy0 % 100;

        dow = ((26 * m1 - 2) / 10 +

            1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;

        if (dow < 0)

            dow += DAYSPERWEEK;

        /*

        ** "dow" is the day-of-week of the first day of the month.  Get

        ** the day-of-month (zero-origin) of the first "dow" day of the

        ** month.

        */

        d = rulep->r_day - dow;

        if (d < 0)

            d += DAYSPERWEEK;

        for (i = 1; i < rulep->r_week; ++i) {

            if (d + DAYSPERWEEK >= mon_lengths[leapyear][rulep->r_mon - 1])

                break;

            d += DAYSPERWEEK;

        }

        /*

        ** "d" is the day-of-month (zero-origin) of the day we want.

        */

        value += d * SECSPERDAY;

        break;

    }

    /*

    ** "value" is the Epoch-relative time of 00:00:00 UTC on the day in

    ** question.  To get the Epoch-relative time of the specified local

    ** time on that day, add the transition time and the current offset

    ** from UTC.

    */

    return value + rulep->r_time + offset;

}

static void generate_transitions(sp, start, end)

     register struct state * ZCONST sp;

     ZCONST struct rule * ZCONST start;

     ZCONST struct rule * ZCONST end;

{

    register int             year;

    register time_t          janfirst;

    time_t                   starttime;

    time_t                   endtime;

    long                     stdoffset = -sp->ttis[0].tt_gmtoff;

    long                     dstoffset = -sp->ttis[1].tt_gmtoff;

    register time_t *        atp;

    register unsigned char * typep;

    /*

    ** Two transitions per year, from EPOCH_YEAR to LAST_GOOD_YEAR.

    */

    sp->timecnt = 2 * (LAST_GOOD_YEAR - EPOCH_YEAR + 1);

    atp = sp->ats;

    typep = sp->types;

    janfirst = 0;

    for (year = EPOCH_YEAR; year <= LAST_GOOD_YEAR; ++year) {

        starttime = transtime(janfirst, year, start, stdoffset);

        endtime = transtime(janfirst, year, end, dstoffset);

        if (starttime > endtime) {

            *atp++ = endtime;

            *typep++ = 0;   /* DST ends */

            *atp++ = starttime;

            *typep++ = 1;   /* DST begins */

        } else {

            *atp++ = starttime;

            *typep++ = 1;   /* DST begins */

            *atp++ = endtime;

            *typep++ = 0;   /* DST ends */

        }

        janfirst += year_lengths[leap(year)] * SECSPERDAY;

    }

}

static ZCONST char *getzname(strp)

     ZCONST char *strp;

{

    register char   c;

    while ((c = *strp) != '\0' && !isdigit(c) && c != ',' && c != '-' &&

        c != '+')

            ++strp;

    return strp;

}

static ZCONST char *getnum(strp, nump, min, max)

     ZCONST char *strp;

     int * ZCONST nump;

     ZCONST int min;

     ZCONST int max;

{

    register char   c;

    register int    num;

    if (strp == NULL || !isdigit(c = *strp))

        return NULL;

    num = 0;

    do {

        num = num * 10 + (c - '0');

        if (num > max)

            return NULL;    /* illegal value */

        c = *++strp;

    } while (isdigit(c));

    if (num < min)

        return NULL;        /* illegal value */

    *nump = num;

    return strp;

}

static ZCONST char *getsecs(strp, secsp)

     ZCONST char *strp;

     long * ZCONST secsp;

{

    int num;

    /*

    ** `HOURSPERDAY * DAYSPERWEEK - 1' allows quasi-Posix rules like

    ** "M10.4.6/26", which does not conform to Posix,

    ** but which specifies the equivalent of

    ** ``02:00 on the first Sunday on or after 23 Oct''.

    */

    strp = getnum(strp, &num, 0, HOURSPERDAY * DAYSPERWEEK - 1);

    if (strp == NULL)

        return NULL;

    *secsp = num * (long) SECSPERHOUR;

    if (*strp == ':') {

        ++strp;

        strp = getnum(strp, &num, 0, MINSPERHOUR - 1);

        if (strp == NULL)

            return NULL;

        *secsp += num * SECSPERMIN;

        if (*strp == ':') {

            ++strp;

            /* `SECSPERMIN' allows for leap seconds.  */

            strp = getnum(strp, &num, 0, SECSPERMIN);

            if (strp == NULL)

                return NULL;

            *secsp += num;

        }

    }

    return strp;

}

static ZCONST char *getoffset(strp, offsetp)

     ZCONST char *strp;

     long * ZCONST offsetp;

{

    register int    neg = 0;

    if (*strp == '-') {

        neg = 1;

        ++strp;

    } else if (*strp == '+')

        ++strp;

    strp = getsecs(strp, offsetp);

    if (strp == NULL)

        return NULL;        /* illegal time */

    if (neg)

        *offsetp = -*offsetp;

    return strp;

}

static ZCONST char *getrule(strp, rulep)

     ZCONST char *strp;

     struct rule * ZCONST rulep;

{

    if (*strp == 'J') {

        /*

        ** Julian day.

        */

        rulep->r_type = JULIAN_DAY;

        ++strp;

        strp = getnum(strp, &rulep->r_day, 1, DAYSPERNYEAR);

    } else if (*strp == 'M') {

        /*

        ** Month, week, day.

        */

        rulep->r_type = MONTH_NTH_DAY_OF_WEEK;

        ++strp;

        strp = getnum(strp, &rulep->r_mon, 1, MONSPERYEAR);

        if (strp == NULL)

            return NULL;

        if (*strp++ != '.')

            return NULL;

        strp = getnum(strp, &rulep->r_week, 1, 5);

        if (strp == NULL)

            return NULL;

        if (*strp++ != '.')

            return NULL;

        strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1);

    } else if (isdigit(*strp)) {

        /*

        ** Day of year.

        */

        rulep->r_type = DAY_OF_YEAR;

        strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1);

    } else  return NULL;        /* invalid format */

    if (strp == NULL)

        return NULL;

    if (*strp == '/') {

        /*

        ** Time specified.

        */

        ++strp;

        strp = getsecs(strp, &rulep->r_time);

    } else

        rulep->r_time = 2 * SECSPERHOUR;    /* default = 2:00:00 */

    return strp;

}

static int Parse_TZ(name, sp)

     ZCONST char *name;

     register struct state * ZCONST sp;

{

    ZCONST char *            stdname;

    ZCONST char *            dstname;

    size_t                   stdlen;

    size_t                   dstlen;

    long                     stdoffset;

    long                     dstoffset;

    register char *          cp;

    dstname = NULL;

    stdname = name;

    name = getzname(name);

    stdlen = name - stdname;

    if (stdlen < 3)

        return -1;

    if (*name == '\0')

        return -1;

    name = getoffset(name, &stdoffset);

    if (name == NULL)

        return -1;

    if (*name != '\0') {

        dstname = name;

        name = getzname(name);

        dstlen = name - dstname;    /* length of DST zone name */

        if (dstlen < 3)

            return -1;

        if (*name != '\0' && *name != ',' && *name != ';') {

            name = getoffset(name, &dstoffset);

            if (name == NULL)

                return -1;

        } else

            dstoffset = stdoffset - SECSPERHOUR;

        if (*name == '\0')

            name = TZDEFRULESTRING;

        if (*name == ',' || *name == ';') {

            struct rule     start;

            struct rule     end;

            ++name;

            if ((name = getrule(name, &start)) == NULL)

                return -1;

            if (*name++ != ',')

                return -1;

            if ((name = getrule(name, &end)) == NULL)

                return -1;

            if (*name != '\0')

                return -1;

            sp->typecnt = 2;    /* standard time and DST */

            sp->ttis[0].tt_gmtoff = -stdoffset;

            sp->ttis[0].tt_isdst = 0;

            sp->ttis[0].tt_abbrind = 0;

            sp->ttis[1].tt_gmtoff = -dstoffset;

            sp->ttis[1].tt_isdst = 1;

            sp->ttis[1].tt_abbrind = stdlen + 1;

            generate_transitions(sp, &start, &end);

        }

    } else {

        dstlen = 0;

        sp->typecnt = 1;        /* only standard time */

        sp->timecnt = 0;

        sp->ttis[0].tt_gmtoff = -stdoffset;

        sp->ttis[0].tt_isdst = 0;

        sp->ttis[0].tt_abbrind = 0;

    }

    sp->charcnt = stdlen + 1;

    if (dstlen != 0)

        sp->charcnt += dstlen + 1;

    if ((size_t) sp->charcnt > sizeof(sp->chars))

        return -1;

    cp = sp->chars;

    (void) strncpy(cp, stdname, stdlen);

    cp += stdlen;

    *cp++ = '\0';

    if (dstlen != 0) {

        (void) strncpy(cp, dstname, dstlen);

        *(cp + dstlen) = '\0';

    }

    return 0;

}

void tzset()

{

    char *TZstring;

    int dstfirst;

    static char *old_TZstring = NULL;

    TZstring = getenv("TZ");    /* read TZ envvar */

    if (old_TZstring && TZstring && !strcmp(old_TZstring, TZstring))

        /* do not repeatedly parse an unchanged TZ specification */

        return;

    if ((TZstring && TZstring[0] && Parse_TZ(TZstring, &statism) == 0)

                || IZTZ_GETLOCALETZINFO(&statism, generate_transitions)

                || Parse_TZ(gmt, &statism) == 0) {

        daylight  = statism.typecnt > 1;

        dstfirst  = daylight && statism.ttis[0].tt_isdst && !statism.ttis[1].tt_isdst;

        timezone  = -statism.ttis[dstfirst].tt_gmtoff;

        tzname[0] = statism.chars + statism.ttis[dstfirst].tt_abbrind;

        tzname[1] = statism.chars + statism.ttis[!dstfirst].tt_abbrind;

        real_timezone_is_set = TRUE;

        if (TZstring) {

            if (old_TZstring)

                old_TZstring = realloc(old_TZstring, strlen(TZstring) + 1);

            else

                old_TZstring = malloc(strlen(TZstring) + 1);

            if (old_TZstring)

                strcpy(old_TZstring, TZstring);

        }

    } else {

        timezone = 0;   /* default is GMT0 which means no offsets */

        daylight = 0;   /* from local system time                 */

        real_timezone_is_set = FALSE;

        if (old_TZstring) {

            free(old_TZstring);

            old_TZstring = NULL;

        }

    }

#ifdef IZTZ_SETLOCALTZINFO

    /* Some SAS/C library functions, e.g. stat(), call library       */

    /* __tzset() themselves. So envvar TZ *must* exist in order to   */

    /* to get the right offset from GMT.  XXX  TRY HARD to fix this! */

    set_TZ(timezone, daylight);

#endif /* IZTZ_SETLOCALTZINFO */

}

/* XXX  Does this also help SAS/C library work? */

void __tzset()

{

    if (!real_timezone_is_set) tzset();

}

static struct tm _tmbuf;

struct tm *gmtime(when)

     ZCONST time_t *when;

{

    long days = *when / SECSPERDAY;

    long secs = *when % SECSPERDAY;

    int isleap;

    memset(&_tmbuf, 0, sizeof(_tmbuf));   /* get any nonstandard fields */

    _tmbuf.tm_wday = (days + EPOCH_WDAY) % 7;

    _tmbuf.tm_year = EPOCH_YEAR - TM_YEAR_BASE;

    isleap = leap(_tmbuf.tm_year + TM_YEAR_BASE);

    while (days >= year_lengths[isleap]) {

        days -= year_lengths[isleap];

        _tmbuf.tm_year++;

        isleap = leap(_tmbuf.tm_year + TM_YEAR_BASE);

    }

    _tmbuf.tm_mon = 0;

    _tmbuf.tm_yday = days;

    while (days >= mon_lengths[isleap][_tmbuf.tm_mon])

        days -= mon_lengths[isleap][_tmbuf.tm_mon++];

    _tmbuf.tm_mday = days + 1;

    _tmbuf.tm_isdst = 0;

    _tmbuf.tm_sec = secs % SECSPERMIN;

    _tmbuf.tm_min = (secs / SECSPERMIN) % SECSPERMIN;

    _tmbuf.tm_hour = secs / SECSPERHOUR;

    return &_tmbuf;

}

struct tm *localtime(when)

     ZCONST time_t *when;

{

    time_t     localwhen = *when;

    int        timetype;

    struct tm *ret;

    __tzset();

    if (statism.timecnt == 0 || localwhen < statism.ats[0])

        timetype = statism.ttis[0].tt_isdst && statism.typecnt > 1 &&

                   !statism.ttis[1].tt_isdst;

    else {

        for (timetype = 1; timetype < statism.timecnt; ++timetype)

            if (localwhen < statism.ats[timetype])

                break;

        timetype = statism.types[timetype - 1];

    }

    localwhen += statism.ttis[timetype].tt_gmtoff;

    ret = gmtime(&localwhen);

    ret->tm_isdst = statism.ttis[timetype].tt_isdst;

    return ret;

}

#ifdef NEED__ISINDST

int _isindst(tb)

    struct tm *tb;

{

    time_t     localt;          /* time_t equivalent of given tm struct */

    time_t     univt;           /* assumed UTC value of given time */

    long       tzoffset_adj;    /* timezone-adjustment `remainder' */

    int        bailout_cnt;     /* counter of tries for tz correction */

    int        timetype;

    __tzset();

    /* when DST is unsupported in current timezone, DST is always off */

    if (statism.typecnt <= 1) return FALSE;

    localt = mkgmtime(tb);

    if (localt == (time_t)-1)

        /* specified time is out-of-range, default to FALSE */

        return FALSE;

    univt = localt - statism.ttis[0].tt_gmtoff;

    bailout_cnt = 3;

    do {

        if (statism.timecnt == 0 || univt < statism.ats[0])

            timetype = statism.ttis[0].tt_isdst && statism.typecnt > 1 &&

                       !statism.ttis[1].tt_isdst;

        else {

            for (timetype = 1; timetype < statism.timecnt; ++timetype)

                if (univt < statism.ats[timetype])

                    break;

            timetype = statism.types[timetype - 1];

        }

        if ((tzoffset_adj = localt - univt - statism.ttis[timetype].tt_gmtoff)

            == 0L)

            break;

        univt += tzoffset_adj;

    } while (--bailout_cnt > 0);

    /* return TRUE when DST is active at given time */

    return (statism.ttis[timetype].tt_isdst);

}

#endif /* NEED__ISINDST */

#endif /* !IZ_MKTIME_ONLY */

/* Return the equivalent in seconds past 12:00:00 a.m. Jan 1, 1970 GMT

   of the local time and date in the exploded time structure `tm',

   adjust out of range fields in `tm' and set `tm->tm_yday', `tm->tm_wday'.

   If `tm->tm_isdst < 0' was passed to mktime(), the correct setting of

   tm_isdst is determined and returned. Otherwise, mktime() assumes this

   field as valid; its information is used when converting local time

   to UTC.

   Return -1 if time in `tm' cannot be represented as time_t value. */

time_t mktime(tm)

     struct tm *tm;

{

  struct tm *ltm;               /* Local time. */

  time_t loctime;               /* The time_t value of local time. */

  time_t then;                  /* The time to return. */

  long tzoffset_adj;            /* timezone-adjustment `remainder' */

  int bailout_cnt;              /* counter of tries for tz correction */

  int save_isdst;               /* Copy of the tm->isdst input value */

  save_isdst = tm->tm_isdst;

  loctime = mkgmtime(tm);

  if (loctime == -1) {

    tm->tm_isdst = save_isdst;

    return (time_t)-1;

  }

  /* Correct for the timezone and any daylight savings time.

     The correction is verified and repeated when not correct, to

     take into account the rare case that a change to or from daylight

     savings time occurs between when it is the time in `tm' locally

     and when it is that time in Greenwich. After the second correction,

     the "timezone & daylight" offset should be correct in all cases. To

     be sure, we allow a third try, but then the loop is stopped. */

  bailout_cnt = 3;

  then = loctime;

  do {

    ltm = localtime(&then);

    if (ltm == (struct tm *)NULL ||

        (tzoffset_adj = loctime - mkgmtime(ltm)) == 0L)

      break;

    then += tzoffset_adj;

  } while (--bailout_cnt > 0);

  if (ltm == (struct tm *)NULL || tzoffset_adj != 0L) {

    /* Signal failure if timezone adjustment did not converge. */

    tm->tm_isdst = save_isdst;

    return (time_t)-1;

  }

  if (save_isdst >= 0) {

    if (ltm->tm_isdst  && !save_isdst)

    {

      if (then + 3600 < then)

        then = (time_t)-1;

      else

        then += 3600;

    }

    else if (!ltm->tm_isdst && save_isdst)

    {

      if (then - 3600 > then)

        then = (time_t)-1;

      else

        then -= 3600;

    }

    ltm->tm_isdst = save_isdst;

  }

  if (tm != ltm)  /* `tm' may already point to localtime's internal storage */

    *tm = *ltm;

  return then;

}

#ifndef NO_TIME_T_MAX

   /* Provide default values for the upper limit of the time_t range.

      These are the result of the decomposition into a `struct tm' for

      the time value 0xFFFFFFFEL ( = (time_t)-2 ).

      Note: `(time_t)-1' is reserved for "invalid time"!  */

#  ifndef TM_YEAR_MAX

#    define TM_YEAR_MAX         2106

#  endif

#  ifndef TM_MON_MAX

#    define TM_MON_MAX          1       /* February */

#  endif

#  ifndef TM_MDAY_MAX

#    define TM_MDAY_MAX         7

#  endif

#  ifndef TM_HOUR_MAX

#    define TM_HOUR_MAX         6

#  endif

#  ifndef TM_MIN_MAX

#    define TM_MIN_MAX          28

#  endif

#  ifndef TM_SEC_MAX

#    define TM_SEC_MAX          14

#  endif

#endif /* NO_TIME_T_MAX */

/* Adjusts out-of-range values for `tm' field `tm_member'. */

#define ADJUST_TM(tm_member, tm_carry, modulus) \

  if ((tm_member) < 0) { \

    tm_carry -= (1 - ((tm_member)+1) / (modulus)); \

    tm_member = (modulus-1) + (((tm_member)+1) % (modulus)); \

  } else if ((tm_member) >= (modulus)) { \

    tm_carry += (tm_member) / (modulus); \

    tm_member = (tm_member) % (modulus); \

  }

/* Return the equivalent in seconds past 12:00:00 a.m. Jan 1, 1970 GMT

   of the Greenwich Mean time and date in the exploded time structure `tm'.

   This function does always put back normalized values into the `tm' struct,

   parameter, including the calculated numbers for `tm->tm_yday',

   `tm->tm_wday', and `tm->tm_isdst'.

   Returns -1 if the time in the `tm' parameter cannot be represented

   as valid `time_t' number. */

time_t mkgmtime(tm)

     struct tm *tm;

{

  int years, months, days, hours, minutes, seconds;

  years = tm->tm_year + TM_YEAR_BASE;   /* year - 1900 -> year */

  months = tm->tm_mon;                  /* 0..11 */

  days = tm->tm_mday - 1;               /* 1..31 -> 0..30 */

  hours = tm->tm_hour;                  /* 0..23 */

  minutes = tm->tm_min;                 /* 0..59 */

  seconds = tm->tm_sec;                 /* 0..61 in ANSI C. */

  ADJUST_TM(seconds, minutes, 60)

  ADJUST_TM(minutes, hours, 60)

  ADJUST_TM(hours, days, 24)

  ADJUST_TM(months, years, 12)

  if (days < 0)

    do {

      if (--months < 0) {

        --years;

        months = 11;

      }

      days += monthlen(months, years);

    } while (days < 0);

  else

    while (days >= monthlen(months, years)) {

      days -= monthlen(months, years);

      if (++months >= 12) {

        ++years;

        months = 0;

      }

    }

  /* Restore adjusted values in tm structure */

  tm->tm_year = years - TM_YEAR_BASE;

  tm->tm_mon = months;

  tm->tm_mday = days + 1;

  tm->tm_hour = hours;

  tm->tm_min = minutes;

  tm->tm_sec = seconds;

  /* Set `days' to the number of days into the year. */

  days += YDAYS(months, years);

  tm->tm_yday = days;

  /* Now calculate `days' to the number of days since Jan 1, 1970. */

  days = (unsigned)days + 365 * (unsigned)(years - EPOCH_YEAR) +

         (unsigned)(nleap (years));

  tm->tm_wday = ((unsigned)days + EPOCH_WDAY) % 7;

  tm->tm_isdst = 0;

  if (years < EPOCH_YEAR)

    return (time_t)-1;

#if (defined(TM_YEAR_MAX) && defined(TM_MON_MAX) && defined(TM_MDAY_MAX))

#if (defined(TM_HOUR_MAX) && defined(TM_MIN_MAX) && defined(TM_SEC_MAX))

  if (years > TM_YEAR_MAX ||

      (years == TM_YEAR_MAX &&

       (tm->tm_yday > (YDAYS(TM_MON_MAX, TM_YEAR_MAX) + (TM_MDAY_MAX - 1)) ||

        (tm->tm_yday == (YDAYS(TM_MON_MAX, TM_YEAR_MAX) + (TM_MDAY_MAX - 1)) &&

         (hours > TM_HOUR_MAX ||

          (hours == TM_HOUR_MAX &&

           (minutes > TM_MIN_MAX ||

            (minutes == TM_MIN_MAX && seconds > TM_SEC_MAX) )))))))

    return (time_t)-1;

#endif

#endif

  return (time_t)(SECSPERDAY * (unsigned long)(unsigned)days +

                  SECSPERHOUR * (unsigned long)hours +

                  (unsigned long)(SECSPERMIN * minutes + seconds));

}

#endif /* __timezone_c */