EnigmA Amiga Run 1996 March/EnigmA AMIGA RUN 05 (1996)(G.R. Edizioni)(IT)[!][issue 1996-03][Skylink CD IV].iso/earcd/program/ixemlsrc.lha/ixemul/static/localtime.c

C/C++ Source or Header | 1996-01-11 | 39KB | 1,607 lines

/*
** Leap second handling from Bradley White ([e-mail]).
** POSIX-style TZ environment variable handling from Guy Harris
** ([e-mail]).
*/

/*LINTLIBRARY*/

#include "private.h"
#include "tzfile.h"
#include "fcntl.h"

/*
** SunOS 4.1.1 headers lack O_BINARY.
*/

#ifdef O_BINARY
#define OPEN_MODE    (O_RDONLY | O_BINARY)
#endif /* defined O_BINARY */
#ifndef O_BINARY
#define OPEN_MODE    O_RDONLY
#endif /* !defined O_BINARY */

#ifndef WILDABBR
/*
** Someone might make incorrect use of a time zone abbreviation:
**    1.    They might reference tzname[0] before calling tzset (explicitly
**        or implicitly).
**    2.    They might reference tzname[1] before calling tzset (explicitly
**        or implicitly).
**    3.    They might reference tzname[1] after setting to a time zone
**        in which Daylight Saving Time is never observed.
**    4.    They might reference tzname[0] after setting to a time zone
**        in which Standard Time is never observed.
**    5.    They might reference tm.TM_ZONE after calling offtime.
** What's best to do in the above cases is open to debate;
** for now, we just set things up so that in any of the five cases
** WILDABBR is used.  Another possibility:  initialize tzname[0] to the
** string "tzname[0] used before set", and similarly for the other cases.
** And another:  initialize tzname[0] to "ERA", with an explanation in the
** manual page of what this "time zone abbreviation" means (doing this so
** that tzname[0] has the "normal" length of three characters).
*/
#define WILDABBR    "   "
#endif /* !defined WILDABBR */

static char        wildabbr[] = "WILDABBR";

static const char    gmt[] = "GMT";

struct ttinfo {                /* time type information */
    long        tt_gmtoff;    /* GMT offset in seconds */
    int        tt_isdst;    /* used to set tm_isdst */
    int        tt_abbrind;    /* abbreviation list index */
    int        tt_ttisstd;    /* TRUE if transition is std time */
    int        tt_ttisgmt;    /* TRUE if transition is GMT */
};

struct lsinfo {                /* leap second information */
    time_t        ls_trans;    /* transition time */
    long        ls_corr;    /* correction to apply */
};

#define BIGGEST(a, b)    (((a) > (b)) ? (a) : (b))

#ifdef TZNAME_MAX
#define MY_TZNAME_MAX    TZNAME_MAX
#endif /* defined TZNAME_MAX */
#ifndef TZNAME_MAX
#define MY_TZNAME_MAX    255
#endif /* !defined TZNAME_MAX */

struct state {
    int        leapcnt;
    int        timecnt;
    int        typecnt;
    int        charcnt;
    time_t        ats[TZ_MAX_TIMES];
    unsigned char    types[TZ_MAX_TIMES];
    struct ttinfo    ttis[TZ_MAX_TYPES];
    char        chars[BIGGEST(BIGGEST(TZ_MAX_CHARS + 1, sizeof gmt),
                (2 * (MY_TZNAME_MAX + 1)))];
    struct lsinfo    lsis[TZ_MAX_LEAPS];
};

struct rule {
    int        r_type;        /* type of rule--see below */
    int        r_day;        /* day number of rule */
    int        r_week;        /* week number of rule */
    int        r_mon;        /* month number of rule */
    long        r_time;        /* transition time of rule */
};

#define JULIAN_DAY        0    /* Jn - Julian day */
#define DAY_OF_YEAR        1    /* n - day of year */
#define MONTH_NTH_DAY_OF_WEEK    2    /* Mm.n.d - month, week, day of week */

/*
** Prototypes for static functions.
*/

static long        detzcode P((const char * codep));
static const char *    getzname P((const char * strp));
static const char *    getnum P((const char * strp, int * nump, int min,
                int max));
static const char *    getsecs P((const char * strp, long * secsp));
static const char *    getoffset P((const char * strp, long * offsetp));
static const char *    getrule P((const char * strp, struct rule * rulep));
static void        gmtload P((struct state * sp));
static void        gmtsub P((const time_t * timep, long offset,
                struct tm * tmp));
static void        localsub P((const time_t * timep, long offset,
                struct tm * tmp));
static int        increment_overflow P((int * number, int delta));
static int        normalize_overflow P((int * tensptr, int * unitsptr,
                int base));
static void        settzname P((void));
static time_t        time1 P((struct tm * tmp,
                void(*funcp) P((const time_t *,
                long, struct tm *)),
                long offset));
static time_t        time2 P((struct tm *tmp,
                void(*funcp) P((const time_t *,
                long, struct tm*)),
                long offset, int * okayp));
static void        timesub P((const time_t * timep, long offset,
                const struct state * sp, struct tm * tmp));
static int        tmcomp P((const struct tm * atmp,
                const struct tm * btmp));
static time_t        transtime P((time_t janfirst, int year,
                const struct rule * rulep, long offset));
static int        tzload P((const char * name, struct state * sp));
static int        tzparse P((const char * name, struct state * sp,
                int lastditch));

#ifdef ALL_STATE
static struct state *    lclptr;
static struct state *    gmtptr;
#endif /* defined ALL_STATE */

#ifndef ALL_STATE
static struct state    lclmem;
static struct state    gmtmem;
#define lclptr        (&lclmem)
#define gmtptr        (&gmtmem)
#endif /* State Farm */

#ifndef TZ_STRLEN_MAX
#define TZ_STRLEN_MAX 255
#endif /* !defined TZ_STRLEN_MAX */

static char        lcl_TZname[TZ_STRLEN_MAX + 1];
static int        lcl_is_set;
static int        gmt_is_set;

char *            tzname[2] = {
    wildabbr,
    wildabbr
};

/*
** Section 4.12.3 of X3.159-1989 requires that
**    Except for the strftime function, these functions [asctime,
**    ctime, gmtime, localtime] return values in one of two static
**    objects: a broken-down time structure and an array of char.
** Thanks to Paul Eggert ([e-mail]) for noting this.
*/

static struct tm    tm;

#ifdef USG_COMPAT
time_t            timezone = 0;
int            daylight = 0;
#endif /* defined USG_COMPAT */

#ifdef ALTZONE
time_t            altzone = 0;
#endif /* defined ALTZONE */

static long
detzcode(codep)
const char * const    codep;
{
    register long    result;
    register int    i;

    result = (codep[0] & 0x80) ? ~0L : 0L;
    for (i = 0; i < 4; ++i)
        result = (result << 8) | (codep[i] & 0xff);
    return result;
}

static void
settzname P((void))
{
    register struct state * const    sp = lclptr;
    register int            i;

    tzname[0] = wildabbr;
    tzname[1] = wildabbr;
#ifdef USG_COMPAT
    daylight = 0;
    timezone = 0;
#endif /* defined USG_COMPAT */
#ifdef ALTZONE
    altzone = 0;
#endif /* defined ALTZONE */
#ifdef ALL_STATE
    if (sp == NULL) {
        tzname[0] = tzname[1] = gmt;
        return;
    }
#endif /* defined ALL_STATE */
    for (i = 0; i < sp->typecnt; ++i) {
        register const struct ttinfo * const    ttisp = &sp->ttis[i];

        tzname[ttisp->tt_isdst] =
            &sp->chars[ttisp->tt_abbrind];
#ifdef USG_COMPAT
        if (ttisp->tt_isdst)
            daylight = 1;
        if (i == 0 || !ttisp->tt_isdst)
            timezone = -(ttisp->tt_gmtoff);
#endif /* defined USG_COMPAT */
#ifdef ALTZONE
        if (i == 0 || ttisp->tt_isdst)
            altzone = -(ttisp->tt_gmtoff);
#endif /* defined ALTZONE */
    }
    /*
    ** And to get the latest zone names into tzname. . .
    */
    for (i = 0; i < sp->timecnt; ++i) {
        register const struct ttinfo * const    ttisp =
                            &sp->ttis[
                                sp->types[i]];

        tzname[ttisp->tt_isdst] =
            &sp->chars[ttisp->tt_abbrind];
    }
}

static int
tzload(name, sp)
register const char *        name;
register struct state * const    sp;
{
    register const char *    p;
    register int        i;
    register int        fid;

    if (name == NULL && (name = TZDEFAULT) == NULL)
        return -1;
    {
        register int    doaccess;
        /*
        ** Section 4.9.1 of the C standard says that
        ** "FILENAME_MAX expands to an integral constant expression
        ** that is the sie needed for an array of char large enough
        ** to hold the longest file name string that the implementation
        ** guarantees can be opened."
        */
        char        fullname[FILENAME_MAX + 1];

        if (name[0] == ':')
            ++name;
        doaccess = name[0] == '/';
        if (!doaccess) {
            if ((p = TZDIR) == NULL)
                return -1;
            if ((strlen(p) + strlen(name) + 1) >= sizeof fullname)
                return -1;
            (void) strcpy(fullname, p);
            (void) strcat(fullname, "/");
            (void) strcat(fullname, name);
            /*
            ** Set doaccess if '.' (as in "../") shows up in name.
            */
            if (strchr(name, '.') != NULL)
                doaccess = TRUE;
            name = fullname;
        }
        if (doaccess && access(name, R_OK) != 0)
            return -1;
        if ((fid = open(name, OPEN_MODE)) == -1)
            return -1;
    }
    {
        struct tzhead *    tzhp;
        char        buf[sizeof *sp + sizeof *tzhp];
        int        ttisstdcnt;
        int        ttisgmtcnt;

        i = read(fid, buf, sizeof buf);
        if (close(fid) != 0)
            return -1;
        p = buf;
        p += sizeof tzhp->tzh_reserved;
        ttisstdcnt = (int) detzcode(p);
        p += 4;
        ttisgmtcnt = (int) detzcode(p);
        p += 4;
        sp->leapcnt = (int) detzcode(p);
        p += 4;
        sp->timecnt = (int) detzcode(p);
        p += 4;
        sp->typecnt = (int) detzcode(p);
        p += 4;
        sp->charcnt = (int) detzcode(p);
        p += 4;
        if (sp->leapcnt < 0 || sp->leapcnt > TZ_MAX_LEAPS ||
            sp->typecnt <= 0 || sp->typecnt > TZ_MAX_TYPES ||
            sp->timecnt < 0 || sp->timecnt > TZ_MAX_TIMES ||
            sp->charcnt < 0 || sp->charcnt > TZ_MAX_CHARS ||
            (ttisstdcnt != sp->typecnt && ttisstdcnt != 0) ||
            (ttisgmtcnt != sp->typecnt && ttisgmtcnt != 0))
                return -1;
        if (i - (p - buf) < sp->timecnt * 4 +    /* ats */
            sp->timecnt +            /* types */
            sp->typecnt * (4 + 2) +        /* ttinfos */
            sp->charcnt +            /* chars */
            sp->leapcnt * (4 + 4) +        /* lsinfos */
            ttisstdcnt +            /* ttisstds */
            ttisgmtcnt)            /* ttisgmts */
                return -1;
        for (i = 0; i < sp->timecnt; ++i) {
            sp->ats[i] = detzcode(p);
            p += 4;
        }
        for (i = 0; i < sp->timecnt; ++i) {
            sp->types[i] = (unsigned char) *p++;
            if (sp->types[i] >= sp->typecnt)
                return -1;
        }
        for (i = 0; i < sp->typecnt; ++i) {
            register struct ttinfo *    ttisp;

            ttisp = &sp->ttis[i];
            ttisp->tt_gmtoff = detzcode(p);
            p += 4;
            ttisp->tt_isdst = (unsigned char) *p++;
            if (ttisp->tt_isdst != 0 && ttisp->tt_isdst != 1)
                return -1;
            ttisp->tt_abbrind = (unsigned char) *p++;
            if (ttisp->tt_abbrind < 0 ||
                ttisp->tt_abbrind > sp->charcnt)
                    return -1;
        }
        for (i = 0; i < sp->charcnt; ++i)
            sp->chars[i] = *p++;
        sp->chars[i] = '\0';    /* ensure '\0' at end */
        for (i = 0; i < sp->leapcnt; ++i) {
            register struct lsinfo *    lsisp;

            lsisp = &sp->lsis[i];
            lsisp->ls_trans = detzcode(p);
            p += 4;
            lsisp->ls_corr = detzcode(p);
            p += 4;
        }
        for (i = 0; i < sp->typecnt; ++i) {
            register struct ttinfo *    ttisp;

            ttisp = &sp->ttis[i];
            if (ttisstdcnt == 0)
                ttisp->tt_ttisstd = FALSE;
            else {
                ttisp->tt_ttisstd = *p++;
                if (ttisp->tt_ttisstd != TRUE &&
                    ttisp->tt_ttisstd != FALSE)
                        return -1;
            }
        }
        for (i = 0; i < sp->typecnt; ++i) {
            register struct ttinfo *    ttisp;

            ttisp = &sp->ttis[i];
            if (ttisgmtcnt == 0)
                ttisp->tt_ttisgmt = FALSE;
            else {
                ttisp->tt_ttisgmt = *p++;
                if (ttisp->tt_ttisgmt != TRUE &&
                    ttisp->tt_ttisgmt != FALSE)
                        return -1;
            }
        }
    }
    return 0;
}

static const 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 }
};

static const int    year_lengths[2] = {
    DAYSPERNYEAR, DAYSPERLYEAR
};

/*
** Given a pointer into a time zone string, scan until a character that is not
** a valid character in a zone name is found.  Return a pointer to that
** character.
*/

static const char *
getzname(strp)
register const char *    strp;
{
    register char    c;

    while ((c = *strp) != '\0' && !is_digit(c) && c != ',' && c != '-' &&
        c != '+')
            ++strp;
    return strp;
}

/*
** Given a pointer into a time zone string, extract a number from that string.
** Check that the number is within a specified range; if it is not, return
** NULL.
** Otherwise, return a pointer to the first character not part of the number.
*/

static const char *
getnum(strp, nump, min, max)
register const char *    strp;
int * const        nump;
const int        min;
const int        max;
{
    register char    c;
    register int    num;

    if (strp == NULL || !is_digit(c = *strp))
        return NULL;
    num = 0;
    do {
        num = num * 10 + (c - '0');
        if (num > max)
            return NULL;    /* illegal value */
        c = *++strp;
    } while (is_digit(c));
    if (num < min)
        return NULL;        /* illegal value */
    *nump = num;
    return strp;
}

/*
** Given a pointer into a time zone string, extract a number of seconds,
** in hh[:mm[:ss]] form, from the string.
** If any error occurs, return NULL.
** Otherwise, return a pointer to the first character not part of the number
** of seconds.
*/

static const char *
getsecs(strp, secsp)
register const char *    strp;
long * const        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;
}

/*
** Given a pointer into a time zone string, extract an offset, in
** [+-]hh[:mm[:ss]] form, from the string.
** If any error occurs, return NULL.
** Otherwise, return a pointer to the first character not part of the time.
*/

static const char *
getoffset(strp, offsetp)
register const char *    strp;
long * const        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;
}

/*
** Given a pointer into a time zone string, extract a rule in the form
** date[/time].  See POSIX section 8 for the format of "date" and "time".
** If a valid rule is not found, return NULL.
** Otherwise, return a pointer to the first character not part of the rule.
*/

static const char *
getrule(strp, rulep)
const char *            strp;
register struct rule * const    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 (is_digit(*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;
}

/*
** Given the Epoch-relative time of January 1, 00:00:00 GMT, in a year, the
** year, a rule, and the offset from GMT at the time that rule takes effect,
** calculate the Epoch-relative time that rule takes effect.
*/

static time_t
transtime(janfirst, year, rulep, offset)
const time_t                janfirst;
const int                year;
register const struct rule * const    rulep;
const long                offset;
{
    register int    leapyear;
    register time_t    value;
    register int    i;
    int        d, m1, yy0, yy1, yy2, dow;

    INITIALIZE(value);
    leapyear = isleap(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;

        /*
        ** 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 GMT 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 GMT.
    */
    return value + rulep->r_time + offset;
}

/*
** Given a POSIX section 8-style TZ string, fill in the rule tables as
** appropriate.
*/

static int
tzparse(name, sp, lastditch)
const char *            name;
register struct state * const    sp;
const int            lastditch;
{
    const char *            stdname;
    const char *            dstname;
    size_t                stdlen;
    size_t                dstlen;
    long                stdoffset;
    long                dstoffset;
    register time_t *        atp;
    register unsigned char *    typep;
    register char *            cp;
    register int            load_result;

    INITIALIZE(dstname);
    stdname = name;
    if (lastditch) {
        stdlen = strlen(name);    /* length of standard zone name */
        name += stdlen;
        if (stdlen >= sizeof sp->chars)
            stdlen = (sizeof sp->chars) - 1;
    } else {
        name = getzname(name);
        stdlen = name - stdname;
        if (stdlen < 3)
            return -1;
    }
    if (*name == '\0')
        return -1;    /* was "stdoffset = 0;" */
    else {
        name = getoffset(name, &stdoffset);
        if (name == NULL)
            return -1;
    }
    load_result = tzload(TZDEFRULES, sp);
    if (load_result != 0)
        sp->leapcnt = 0;        /* so, we're off a little */
    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 == ',' || *name == ';') {
            struct rule    start;
            struct rule    end;
            register int    year;
            register time_t    janfirst;
            time_t        starttime;
            time_t        endtime;

            ++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 */
            /*
            ** Two transitions per year, from EPOCH_YEAR to 2037.
            */
            sp->timecnt = 2 * (2037 - EPOCH_YEAR + 1);
            if (sp->timecnt > TZ_MAX_TIMES)
                return -1;
            sp->ttis[0].tt_gmtoff = -dstoffset;
            sp->ttis[0].tt_isdst = 1;
            sp->ttis[0].tt_abbrind = stdlen + 1;
            sp->ttis[1].tt_gmtoff = -stdoffset;
            sp->ttis[1].tt_isdst = 0;
            sp->ttis[1].tt_abbrind = 0;
            atp = sp->ats;
            typep = sp->types;
            janfirst = 0;
            for (year = EPOCH_YEAR; year <= 2037; ++year) {
                starttime = transtime(janfirst, year, &start,
                    stdoffset);
                endtime = transtime(janfirst, year, &end,
                    dstoffset);
                if (starttime > endtime) {
                    *atp++ = endtime;
                    *typep++ = 1;    /* DST ends */
                    *atp++ = starttime;
                    *typep++ = 0;    /* DST begins */
                } else {
                    *atp++ = starttime;
                    *typep++ = 0;    /* DST begins */
                    *atp++ = endtime;
                    *typep++ = 1;    /* DST ends */
                }
                janfirst += year_lengths[isleap(year)] *
                    SECSPERDAY;
            }
        } else {
            register long    theirstdoffset;
            register long    theirdstoffset;
            register long    theiroffset;
            register int    isdst;
            register int    i;
            register int    j;

            if (*name != '\0')
                return -1;
            if (load_result != 0)
                return -1;
            /*
            ** Initial values of theirstdoffset and theirdstoffset.
            */
            theirstdoffset = 0;
            for (i = 0; i < sp->timecnt; ++i) {
                j = sp->types[i];
                if (!sp->ttis[j].tt_isdst) {
                    theirstdoffset =
                        -sp->ttis[j].tt_gmtoff;
                    break;
                }
            }
            theirdstoffset = 0;
            for (i = 0; i < sp->timecnt; ++i) {
                j = sp->types[i];
                if (sp->ttis[j].tt_isdst) {
                    theirdstoffset =
                        -sp->ttis[j].tt_gmtoff;
                    break;
                }
            }
            /*
            ** Initially we're assumed to be in standard time.
            */
            isdst = FALSE;
            theiroffset = theirstdoffset;
            /*
            ** Now juggle transition times and types
            ** tracking offsets as you do.
            */
            for (i = 0; i < sp->timecnt; ++i) {
                j = sp->types[i];
                sp->types[i] = sp->ttis[j].tt_isdst;
                if (sp->ttis[j].tt_ttisgmt) {
                    /* No adjustment to transition time */
                } else {
                    /*
                    ** If summer time is in effect, and the
                    ** transition time was not specified as
                    ** standard time, add the summer time
                    ** offset to the transition time;
                    ** otherwise, add the standard time
                    ** offset to the transition time.
                    */
                    /*
                    ** Transitions from DST to DDST
                    ** will effectively disappear since
                    ** POSIX provides for only one DST
                    ** offset.
                    */
                    if (isdst && !sp->ttis[j].tt_ttisstd) {
                        sp->ats[i] += dstoffset -
                            theirdstoffset;
                    } else {
                        sp->ats[i] += stdoffset -
                            theirstdoffset;
                    }
                }
                theiroffset = -sp->ttis[j].tt_gmtoff;
                if (sp->ttis[j].tt_isdst)
                    theirdstoffset = theiroffset;
                else    theirstdoffset = theiroffset;
            }
            /*
            ** Finally, fill in ttis.
            ** ttisstd and ttisgmt need not be handled.
            */
            sp->ttis[0].tt_gmtoff = -stdoffset;
            sp->ttis[0].tt_isdst = FALSE;
            sp->ttis[0].tt_abbrind = 0;
            sp->ttis[1].tt_gmtoff = -dstoffset;
            sp->ttis[1].tt_isdst = TRUE;
            sp->ttis[1].tt_abbrind = stdlen + 1;
        }
    } 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 (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;
}

static void
gmtload(sp)
struct state * const    sp;
{
    if (tzload(gmt, sp) != 0)
        (void) tzparse(gmt, sp, TRUE);
}

#if !defined(STD_INSPIRED) && !defined(amigados)
/*
** A non-static declaration of tzsetwall in a system header file
** may cause a warning about this upcoming static declaration...
*/
static
#endif /* !defined STD_INSPIRED */
void
tzsetwall P((void))
{
    if (lcl_is_set < 0)
        return;
    lcl_is_set = -1;

#ifdef ALL_STATE
    if (lclptr == NULL) {
        lclptr = (struct state *) malloc(sizeof *lclptr);
        if (lclptr == NULL) {
            settzname();    /* all we can do */
            return;
        }
    }
#endif /* defined ALL_STATE */
    if (tzload((char *) NULL, lclptr) != 0)
        gmtload(lclptr);
    settzname();
}

void
tzset P((void))
{
    register const char *    name;

    name = getenv("TZ");
    if (name == NULL) {
        tzsetwall();
        return;
    }

    if (lcl_is_set > 0  &&  strcmp(lcl_TZname, name) == 0)
        return;
    lcl_is_set = (strlen(name) < sizeof(lcl_TZname));
    if (lcl_is_set)
        (void) strcpy(lcl_TZname, name);

#ifdef ALL_STATE
    if (lclptr == NULL) {
        lclptr = (struct state *) malloc(sizeof *lclptr);
        if (lclptr == NULL) {
            settzname();    /* all we can do */
            return;
        }
    }
#endif /* defined ALL_STATE */
    if (*name == '\0') {
        /*
        ** User wants it fast rather than right.
        */
        lclptr->leapcnt = 0;        /* so, we're off a little */
        lclptr->timecnt = 0;
        lclptr->ttis[0].tt_gmtoff = 0;
        lclptr->ttis[0].tt_abbrind = 0;
        (void) strcpy(lclptr->chars, gmt);
    } else if (tzload(name, lclptr) != 0)
        if (name[0] == ':' || tzparse(name, lclptr, FALSE) != 0)
            (void) gmtload(lclptr);
    settzname();
}

/*
** The easy way to behave "as if no library function calls" localtime
** is to not call it--so we drop its guts into "localsub", which can be
** freely called.  (And no, the PANS doesn't require the above behavior--
** but it *is* desirable.)
**
** The unused offset argument is for the benefit of mktime variants.
*/

/*ARGSUSED*/
static void
localsub(timep, offset, tmp)
const time_t * const    timep;
const long        offset;
struct tm * const    tmp;
{
    register struct state *        sp;
    register const struct ttinfo *    ttisp;
    register int            i;
    const time_t            t = *timep;

    sp = lclptr;
#ifdef ALL_STATE
    if (sp == NULL) {
        gmtsub(timep, offset, tmp);
        return;
    }
#endif /* defined ALL_STATE */
    if (sp->timecnt == 0 || t < sp->ats[0]) {
        i = 0;
        while (sp->ttis[i].tt_isdst)
            if (++i >= sp->typecnt) {
                i = 0;
                break;
            }
    } else {
        for (i = 1; i < sp->timecnt; ++i)
            if (t < sp->ats[i])
                break;
        i = sp->types[i - 1];
    }
    ttisp = &sp->ttis[i];
    /*
    ** To get (wrong) behavior that's compatible with System V Release 2.0
    ** you'd replace the statement below with
    **    t += ttisp->tt_gmtoff;
    **    timesub(&t, 0L, sp, tmp);
    */
    timesub(&t, ttisp->tt_gmtoff, sp, tmp);
    tmp->tm_isdst = ttisp->tt_isdst;
    tzname[tmp->tm_isdst] = &sp->chars[ttisp->tt_abbrind];
#ifdef TM_ZONE
    tmp->TM_ZONE = &sp->chars[ttisp->tt_abbrind];
#endif /* defined TM_ZONE */
}

struct tm *
localtime(timep)
const time_t * const    timep;
{
    tzset();
    localsub(timep, 0L, &tm);
    return &tm;
}

/*
** gmtsub is to gmtime as localsub is to localtime.
*/

static void
gmtsub(timep, offset, tmp)
const time_t * const    timep;
const long        offset;
struct tm * const    tmp;
{
    if (!gmt_is_set) {
        gmt_is_set = TRUE;
#ifdef ALL_STATE
        gmtptr = (struct state *) malloc(sizeof *gmtptr);
        if (gmtptr != NULL)
#endif /* defined ALL_STATE */
            gmtload(gmtptr);
    }
    timesub(timep, offset, gmtptr, tmp);
#ifdef TM_ZONE
    /*
    ** Could get fancy here and deliver something such as
    ** "GMT+xxxx" or "GMT-xxxx" if offset is non-zero,
    ** but this is no time for a treasure hunt.
    */
    if (offset != 0)
        tmp->TM_ZONE = wildabbr;
    else {
#ifdef ALL_STATE
        if (gmtptr == NULL)
            tmp->TM_ZONE = gmt;
        else    tmp->TM_ZONE = gmtptr->chars;
#endif /* defined ALL_STATE */
#ifndef ALL_STATE
        tmp->TM_ZONE = gmtptr->chars;
#endif /* State Farm */
    }
#endif /* defined TM_ZONE */
}

struct tm *
gmtime(timep)
const time_t * const    timep;
{
    gmtsub(timep, 0L, &tm);
    return &tm;
}

#ifdef STD_INSPIRED

struct tm *
offtime(timep, offset)
const time_t * const    timep;
const long        offset;
{
    gmtsub(timep, offset, &tm);
    return &tm;
}

#endif /* defined STD_INSPIRED */

static void
timesub(timep, offset, sp, tmp)
const time_t * const            timep;
const long                offset;
register const struct state * const    sp;
register struct tm * const        tmp;
{
    register const struct lsinfo *    lp;
    register long            days;
    register long            rem;
    register int            y;
    register int            yleap;
    register const int *        ip;
    register long            corr;
    register int            hit;
    register int            i;

    corr = 0;
    hit = 0;
#ifdef ALL_STATE
    i = (sp == NULL) ? 0 : sp->leapcnt;
#endif /* defined ALL_STATE */
#ifndef ALL_STATE
    i = sp->leapcnt;
#endif /* State Farm */
    while (--i >= 0) {
        lp = &sp->lsis[i];
        if (*timep >= lp->ls_trans) {
            if (*timep == lp->ls_trans) {
                hit = ((i == 0 && lp->ls_corr > 0) ||
                    lp->ls_corr > sp->lsis[i - 1].ls_corr);
                if (hit)
                    while (i > 0 &&
                        sp->lsis[i].ls_trans ==
                        sp->lsis[i - 1].ls_trans + 1 &&
                        sp->lsis[i].ls_corr ==
                        sp->lsis[i - 1].ls_corr + 1) {
                            ++hit;
                            --i;
                    }
            }
            corr = lp->ls_corr;
            break;
        }
    }
    days = *timep / SECSPERDAY;
    rem = *timep % SECSPERDAY;
#ifdef mc68k
    if (*timep == 0x80000000) {
        /*
        ** A 3B1 muffs the division on the most negative number.
        */
        days = -24855;
        rem = -11648;
    }
#endif /* defined mc68k */
    rem += (offset - corr);
    while (rem < 0) {
        rem += SECSPERDAY;
        --days;
    }
    while (rem >= SECSPERDAY) {
        rem -= SECSPERDAY;
        ++days;
    }
    tmp->tm_hour = (int) (rem / SECSPERHOUR);
    rem = rem % SECSPERHOUR;
    tmp->tm_min = (int) (rem / SECSPERMIN);
    tmp->tm_sec = (int) (rem % SECSPERMIN);
    if (hit)
        /*
        ** A positive leap second requires a special
        ** representation.  This uses "... ??:59:60" et seq.
        */
        tmp->tm_sec += hit;
    tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYSPERWEEK);
    if (tmp->tm_wday < 0)
        tmp->tm_wday += DAYSPERWEEK;
    y = EPOCH_YEAR;
#define LEAPS_THRU_END_OF(y)    ((y) / 4 - (y) / 100 + (y) / 400)
    while (days < 0 || days >= (long) year_lengths[yleap = isleap(y)]) {
        register int    newy;

        newy = y + days / DAYSPERNYEAR;
        if (days < 0)
            --newy;
        days -= (newy - y) * DAYSPERNYEAR +
            LEAPS_THRU_END_OF(newy - 1) -
            LEAPS_THRU_END_OF(y - 1);
        y = newy;
    }
    tmp->tm_year = y - TM_YEAR_BASE;
    tmp->tm_yday = (int) days;
    ip = mon_lengths[yleap];
    for (tmp->tm_mon = 0; days >= (long) ip[tmp->tm_mon]; ++(tmp->tm_mon))
        days = days - (long) ip[tmp->tm_mon];
    tmp->tm_mday = (int) (days + 1);
    tmp->tm_isdst = 0;
#ifdef TM_GMTOFF
    tmp->TM_GMTOFF = offset;
#endif /* defined TM_GMTOFF */
}

char *
ctime(timep)
const time_t * const    timep;
{
/*
** Section 4.12.3.2 of X3.159-1989 requires that
**    The ctime funciton converts the calendar time pointed to by timer
**    to local time in the form of a string.  It is equivalent to
**        asctime(localtime(timer))
*/
    return asctime(localtime(timep));
}

/*
** Adapted from code provided by Robert Elz, who writes:
**    The "best" way to do mktime I think is based on an idea of Bob
**    Kridle's (so its said...) from a long time ago. (mtxinu!kridle now).
**    It does a binary search of the time_t space.  Since time_t's are
**    just 32 bits, its a max of 32 iterations (even at 64 bits it
**    would still be very reasonable).
*/

#ifndef WRONG
#define WRONG    (-1)
#endif /* !defined WRONG */

/*
** Simplified normalize logic courtesy Paul Eggert ([e-mail]).
*/

static int
increment_overflow(number, delta)
int *    number;
int    delta;
{
    int    number0;

    number0 = *number;
    *number += delta;
    return (*number < number0) != (delta < 0);
}

static int
normalize_overflow(tensptr, unitsptr, base)
int * const    tensptr;
int * const    unitsptr;
const int    base;
{
    register int    tensdelta;

    tensdelta = (*unitsptr >= 0) ?
        (*unitsptr / base) :
        (-1 - (-1 - *unitsptr) / base);
    *unitsptr -= tensdelta * base;
    return increment_overflow(tensptr, tensdelta);
}

static int
tmcomp(atmp, btmp)
register const struct tm * const atmp;
register const struct tm * const btmp;
{
    register int    result;

    if ((result = (atmp->tm_year - btmp->tm_year)) == 0 &&
        (result = (atmp->tm_mon - btmp->tm_mon)) == 0 &&
        (result = (atmp->tm_mday - btmp->tm_mday)) == 0 &&
        (result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
        (result = (atmp->tm_min - btmp->tm_min)) == 0)
            result = atmp->tm_sec - btmp->tm_sec;
    return result;
}

static time_t
time2(tmp, funcp, offset, okayp)
struct tm * const    tmp;
void (* const        funcp) P((const time_t*, long, struct tm*));
const long        offset;
int * const        okayp;
{
    register const struct state *    sp;
    register int            dir;
    register int            bits;
    register int            i, j ;
    register int            saved_seconds;
    time_t                newt;
    time_t                t;
    struct tm            yourtm, mytm;

    *okayp = FALSE;
    yourtm = *tmp;
    if (normalize_overflow(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR))
        return WRONG;
    if (normalize_overflow(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY))
        return WRONG;
    if (normalize_overflow(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR))
        return WRONG;
    /*
    ** Turn yourtm.tm_year into an actual year number for now.
    ** It is converted back to an offset from TM_YEAR_BASE later.
    */
    if (increment_overflow(&yourtm.tm_year, TM_YEAR_BASE))
        return WRONG;
    while (yourtm.tm_mday <= 0) {
        if (increment_overflow(&yourtm.tm_year, -1))
            return WRONG;
        yourtm.tm_mday += year_lengths[isleap(yourtm.tm_year)];
    }
    while (yourtm.tm_mday > DAYSPERLYEAR) {
        yourtm.tm_mday -= year_lengths[isleap(yourtm.tm_year)];
        if (increment_overflow(&yourtm.tm_year, 1))
            return WRONG;
    }
    for ( ; ; ) {
        i = mon_lengths[isleap(yourtm.tm_year)][yourtm.tm_mon];
        if (yourtm.tm_mday <= i)
            break;
        yourtm.tm_mday -= i;
        if (++yourtm.tm_mon >= MONSPERYEAR) {
            yourtm.tm_mon = 0;
            if (increment_overflow(&yourtm.tm_year, 1))
                return WRONG;
        }
    }
    if (increment_overflow(&yourtm.tm_year, -TM_YEAR_BASE))
        return WRONG;
    if (yourtm.tm_year + TM_YEAR_BASE < EPOCH_YEAR) {
        /*
        ** We can't set tm_sec to 0, because that might push the
        ** time below the minimum representable time.
        ** Set tm_sec to 59 instead.
        ** This assumes that the minimum representable time is
        ** not in the same minute that a leap second was deleted from,
        ** which is a safer assumption than using 58 would be.
        */
        if (increment_overflow(&yourtm.tm_sec, 1 - SECSPERMIN))
            return WRONG;
        saved_seconds = yourtm.tm_sec;
        yourtm.tm_sec = SECSPERMIN - 1;
    } else {
        saved_seconds = yourtm.tm_sec;
        yourtm.tm_sec = 0;
    }
    /*
    ** Calculate the number of magnitude bits in a time_t
    ** (this works regardless of whether time_t is
    ** signed or unsigned, though lint complains if unsigned).
    */
    for (bits = 0, t = 1; t > 0; ++bits, t <<= 1)
        continue;
    /*
    ** If time_t is signed, then 0 is the median value,
    ** if time_t is unsigned, then 1 << bits is median.
    */
    t = (t < 0) ? 0 : ((time_t) 1 << bits);
    for ( ; ; ) {
        (*funcp)(&t, offset, &mytm);
        dir = tmcomp(&mytm, &yourtm);
        if (dir != 0) {
            if (bits-- < 0)
                return WRONG;
            if (bits < 0)
                --t;
            else if (dir > 0)
                t -= (time_t) 1 << bits;
            else    t += (time_t) 1 << bits;
            continue;
        }
        if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
            break;
        /*
        ** Right time, wrong type.
        ** Hunt for right time, right type.
        ** It's okay to guess wrong since the guess
        ** gets checked.
        */
        /*
        ** The (void *) casts are the benefit of SunOS 3.3 on Sun 2's.
        */
        sp = (const struct state *)
            (((void *) funcp == (void *) localsub) ?
            lclptr : gmtptr);
#ifdef ALL_STATE
        if (sp == NULL)
            return WRONG;
#endif /* defined ALL_STATE */
        for (i = sp->typecnt - 1; i >= 0; --i) {
            if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
                continue;
            for (j = sp->typecnt - 1; j >= 0; --j) {
                if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
                    continue;
                newt = t + sp->ttis[j].tt_gmtoff -
                    sp->ttis[i].tt_gmtoff;
                (*funcp)(&newt, offset, &mytm);
                if (tmcomp(&mytm, &yourtm) != 0)
                    continue;
                if (mytm.tm_isdst != yourtm.tm_isdst)
                    continue;
                /*
                ** We have a match.
                */
                t = newt;
                goto label;
            }
        }
        return WRONG;
    }
label:
    newt = t + saved_seconds;
    if ((newt < t) != (saved_seconds < 0))
        return WRONG;
    t = newt;
    (*funcp)(&t, offset, tmp);
    *okayp = TRUE;
    return t;
}

static time_t
time1(tmp, funcp, offset)
struct tm * const    tmp;
void (* const        funcp) P((const time_t *, long, struct tm *));
const long        offset;
{
    register time_t            t;
    register const struct state *    sp;
    register int            samei, otheri;
    int                okay;

    if (tmp->tm_isdst > 1)
        tmp->tm_isdst = 1;
    t = time2(tmp, funcp, offset, &okay);
#ifdef PCTS
    /*
    ** PCTS code courtesy Grant Sullivan ([e-mail]).
    */
    if (okay)
        return t;
    if (tmp->tm_isdst < 0)
        tmp->tm_isdst = 0;    /* reset to std and try again */
#endif /* defined PCTS */
#ifndef PCTS
    if (okay || tmp->tm_isdst < 0)
        return t;
#endif /* !defined PCTS */
    /*
    ** We're supposed to assume that somebody took a time of one type
    ** and did some math on it that yielded a "struct tm" that's bad.
    ** We try to divine the type they started from and adjust to the
    ** type they need.
    */
    /*
    ** The (void *) casts are the benefit of SunOS 3.3 on Sun 2's.
    */
    sp = (const struct state *) (((void *) funcp == (void *) localsub) ?
        lclptr : gmtptr);
#ifdef ALL_STATE
    if (sp == NULL)
        return WRONG;
#endif /* defined ALL_STATE */
    for (samei = sp->typecnt - 1; samei >= 0; --samei) {
        if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
            continue;
        for (otheri = sp->typecnt - 1; otheri >= 0; --otheri) {
            if (sp->ttis[otheri].tt_isdst == tmp->tm_isdst)
                continue;
            tmp->tm_sec += sp->ttis[otheri].tt_gmtoff -
                    sp->ttis[samei].tt_gmtoff;
            tmp->tm_isdst = !tmp->tm_isdst;
            t = time2(tmp, funcp, offset, &okay);
            if (okay)
                return t;
            tmp->tm_sec -= sp->ttis[otheri].tt_gmtoff -
                    sp->ttis[samei].tt_gmtoff;
            tmp->tm_isdst = !tmp->tm_isdst;
        }
    }
    return WRONG;
}

time_t
mktime(tmp)
struct tm * const    tmp;
{
    tzset();
    return time1(tmp, localsub, 0L);
}

#ifdef STD_INSPIRED

time_t
timelocal(tmp)
struct tm * const    tmp;
{
    tmp->tm_isdst = -1;    /* in case it wasn't initialized */
    return mktime(tmp);
}

time_t
timegm(tmp)
struct tm * const    tmp;
{
    tmp->tm_isdst = 0;
    return time1(tmp, gmtsub, 0L);
}

time_t
timeoff(tmp, offset)
struct tm * const    tmp;
const long        offset;
{
    tmp->tm_isdst = 0;
    return time1(tmp, gmtsub, offset);
}

#endif /* defined STD_INSPIRED */

#ifdef CMUCS

/*
** The following is supplied for compatibility with
** previous versions of the CMUCS runtime library.
*/

long
gtime(tmp)
struct tm * const    tmp;
{
    const time_t    t = mktime(tmp);

    if (t == WRONG)
        return -1;
    return t;
}

#endif /* defined CMUCS */

/*
** XXX--is the below the right way to conditionalize??
*/

#ifdef STD_INSPIRED

/*
** IEEE Std 1003.1-1988 (POSIX) legislates that 536457599
** shall correspond to "Wed Dec 31 23:59:59 GMT 1986", which
** is not the case if we are accounting for leap seconds.
** So, we provide the following conversion routines for use
** when exchanging timestamps with POSIX conforming systems.
*/

static long
leapcorr(timep)
time_t *    timep;
{
    register struct state *        sp;
    register struct lsinfo *    lp;
    register int            i;

    sp = lclptr;
    i = sp->leapcnt;
    while (--i >= 0) {
        lp = &sp->lsis[i];
        if (*timep >= lp->ls_trans)
            return lp->ls_corr;
    }
    return 0;
}

time_t
time2posix(t)
time_t    t;
{
    tzset();
    return t - leapcorr(&t);
}

time_t
posix2time(t)
time_t    t;
{
    time_t    x;
    time_t    y;

    tzset();
    /*
    ** For a positive leap second hit, the result
    ** is not unique.  For a negative leap second
    ** hit, the corresponding time doesn't exist,
    ** so we return an adjacent second.
    */
    x = t + leapcorr(&t);
    y = x - leapcorr(&x);
    if (y < t) {
        do {
            x++;
            y = x - leapcorr(&x);
        } while (y < t);
        if (t != y)
            return x - 1;
    } else if (y > t) {
        do {
            --x;
            y = x - leapcorr(&x);
        } while (y > t);
        if (t != y)
            return x + 1;
    }
    return x;
}

#endif /* defined STD_INSPIRED */