gen/common/localtime.c

	localtime.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * 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 1995-2002 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"
      /* from Arthur Olson's 6.1 */

/*LINTLIBRARY*/

#include <tzfile.h>
#include <time.h>
#include <string.h>
#include <ctype.h>
#include <stdio.h>  /* for NULL */
#include <fcntl.h>

#include <sys/param.h>  /* for MAXPATHLEN */

#undef  FILENAME_MAX
#define FILENAME_MAX    MAXPATHLEN

#ifdef __STDC__

#define P(s)        s

#else /* !defined __STDC__ */

/*
** Memory management functions
*/

extern char *   calloc();
extern char *   malloc();

/*
** Communication with the environment
*/

extern char *   getenv();

#define ASTERISK    *
#define P(s)        (/ASTERISK s ASTERISK/)

#define const

#endif /* !defined __STDC__ */

#ifndef TRUE
#define TRUE        1
#define FALSE       0
#endif /* !defined TRUE */

#define ACCESS_MODE O_RDONLY

#define OPEN_MODE   O_RDONLY

/*
** 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).
*/
static const char *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 */
};

struct state {
    int     timecnt;
    int     typecnt;
    int     charcnt;
    time_t      *ats;
    unsigned char   *types;
    struct ttinfo   *ttis;
    char        *chars;
    char        *last_tzload;   /* name of file tzload() last opened */
};

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 int      allocall P((register struct state * sp));
static long     detzcode P((const char * codep));
static void     freeall P((register struct state * sp));
static const char * getzname P((const char * strp, const int i));
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 void     normalize P((int * tensptr, int * unitsptr, int base));
static void     settzname P((void));
static time_t       time1 P((struct tm * tmp, void (* funcp)(),
                long offset));
static time_t       time2 P((struct tm *tmp, void (* funcp)(),
                long offset, int * okayp));
static void     timesub P((const time_t * timep, long offset,
                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));

static struct state *   lclptr;
static struct state *   gmtptr;

static int      lcl_is_set;
static int      gmt_is_set;

#ifdef S5EMUL
char *          tzname[2] = {
    "GMT",
    "   ",
};

time_t          timezone = 0;
time_t          altzone = 0;
int         daylight = 0;
#endif /* defined S5EMUL */

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

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

/*
** Free up existing items pointed to by the specified "state" structure,
** and allocate new ones of sizes specified by that "state" structure.
** Return 0 on success; return -1 and free all previously-allocated items
** on failure.
*/
static int
allocall(sp)
register struct state * const   sp;
{
    freeall(sp);

    if (sp->timecnt != 0) {
        sp->ats = (time_t *)calloc((unsigned)sp->timecnt,
           (unsigned)sizeof (time_t));
        if (sp->ats == NULL)
            return -1;
        sp->types =
           (unsigned char *)calloc((unsigned)sp->timecnt,
           (unsigned)sizeof (unsigned char));
        if (sp->types == NULL) {
            freeall(sp);
            return -1;
        }
    }
    sp->ttis =
      (struct ttinfo *)calloc((unsigned)sp->typecnt,
      (unsigned)sizeof (struct ttinfo));
    if (sp->ttis == NULL) {
        freeall(sp);
        return -1;
    }
    sp->chars = (char *)calloc((unsigned)sp->charcnt + 1,
      (unsigned)sizeof (char));
    if (sp->chars == NULL) {
        freeall(sp);
        return -1;
    }
    return 0;
}

/*
** Free all the items pointed to by the specified "state" structure (except for
** "chars", which might have other references to it), and zero out all the
** pointers to those items.
*/
static void
freeall(sp)
register struct state * const   sp;
{
    if (sp->ttis) {
        free((char *)sp->ttis);
        sp->ttis = 0;
    }
    if (sp->types) {
        free((char *)sp->types);
        sp->types = 0;
    }
    if (sp->ats) {
        free((char *)sp->ats);
        sp->ats = 0;
    }
}

#ifdef S5EMUL
static void
settzname()
{
    register const struct state * const sp = lclptr;
    register int                i;

    tzname[0] = (char *)GMT;
    tzname[1] = (char *)WILDABBR;
    daylight = 0;
    timezone = 0;
    altzone = 0;
    if (sp == NULL)
        return;
    for (i = 0; i < sp->typecnt; ++i) {
        register const struct ttinfo * const    ttisp = &sp->ttis[i];

        tzname[ttisp->tt_isdst] =
            (char *) &sp->chars[ttisp->tt_abbrind];
        if (ttisp->tt_isdst)
            daylight = 1;
        if (i == 0 || !ttisp->tt_isdst)
            timezone = -(ttisp->tt_gmtoff);
        if (i == 0 || ttisp->tt_isdst)
            altzone = -(ttisp->tt_gmtoff);
    }
    /*
    ** 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] =
            (char *) &sp->chars[ttisp->tt_abbrind];
    }
}
#endif

/*
** Maximum size of a time zone file.
*/
#define MAX_TZFILESZ    (sizeof (struct tzhead) + \
            TZ_MAX_TIMES * (4 + sizeof (char)) + \
            TZ_MAX_TYPES * (4 + 2 * sizeof (char)) + \
            TZ_MAX_CHARS * sizeof (char) + \
            TZ_MAX_LEAPS * 2 * 4 + \
            TZ_MAX_TYPES * sizeof (char))

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 = (const char *)TZDEFAULT) == NULL)
        return -1;
    {
        register int    doaccess;
        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 (sp->last_tzload && strcmp(sp->last_tzload, name) == 0)
            return (0);
        if (doaccess && access(name, ACCESS_MODE) != 0)
            return -1;
        if ((fid = open(name, OPEN_MODE)) == -1)
            return -1;
    }
    {
        register const struct tzhead *  tzhp;
        char                buf[MAX_TZFILESZ];
        int             leapcnt;
        int             ttisstdcnt;

        i = read(fid, buf, sizeof buf);
        if (close(fid) != 0 || i < sizeof *tzhp)
            return -1;
        tzhp = (struct tzhead *) buf;
        ttisstdcnt = (int) detzcode(tzhp->tzh_ttisstdcnt);
        leapcnt = (int) detzcode(tzhp->tzh_leapcnt);
        sp->timecnt = (int) detzcode(tzhp->tzh_timecnt);
        sp->typecnt = (int) detzcode(tzhp->tzh_typecnt);
        sp->charcnt = (int) detzcode(tzhp->tzh_charcnt);
        if (leapcnt < 0 || 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))
                return -1;
        if (i < sizeof *tzhp +
            sp->timecnt * (4 + sizeof (char)) +
            sp->typecnt * (4 + 2 * sizeof (char)) +
            sp->charcnt * sizeof (char) +
            leapcnt * 2 * 4 +
            ttisstdcnt * sizeof (char))
                return -1;
        if (allocall(sp) < 0)
            return -1;
        p = buf + sizeof *tzhp;
        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-1; ++i)
            sp->chars[i] = *p++;
        sp->chars[i] = '\0';    /* ensure '\0' at end */
        p += (4 + 4) * leapcnt; /* skip leap seconds list */
        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;
            }
        }
    }
    if (sp->last_tzload)
        free(sp->last_tzload);
    sp->last_tzload = strdup(name);
    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.
** Support both quoted and unquoted timezones.
*/

static const char *
getzname(strp, quoted)
const char *    strp;
int quoted;
{
    unsigned char   c;

    if (quoted) {
        while ((c = (unsigned char)*strp) != '\0' &&
            (isalnum(c) || (c == '+') || (c == '-')))
                ++strp;
    } else {
        while ((c = (unsigned char)*strp) != '\0' && !isdigit(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 || !isdigit(*strp))
        return NULL;
    num = 0;
    while ((c = *strp) != '\0' && isdigit(c)) {
        num = num * 10 + (c - '0');
        if (num > max)
            return NULL;    /* illegal value */
        ++strp;
    }
    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;

    strp = getnum(strp, &num, 0, HOURSPERDAY);
    if (strp == NULL)
        return NULL;
    *secsp = num * SECSPERHOUR;
    if (*strp == ':') {
        ++strp;
        strp = getnum(strp, &num, 0, MINSPERHOUR - 1);
        if (strp == NULL)
            return NULL;
        *secsp += num * SECSPERMIN;
        if (*strp == ':') {
            ++strp;
            strp = getnum(strp, &num, 0, SECSPERMIN - 1);
            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;

    if (*strp == '-') {
        neg = 1;
        ++strp;
    } else if (isdigit(*strp) || *strp++ == '+')
        neg = 0;
    else    return NULL;        /* illegal offset */
    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 (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;
}

/*
** 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;

    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;
struct state * const    sp;
const int           lastditch;
{
    const char *            stdname;
    const char *            dstname;
    int             stdlen;
    int             dstlen;
    long                stdoffset;
    long                dstoffset;
    time_t *            atp;
    unsigned char *         typep;
    char *              cp;

    freeall(sp);            /* */
    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 {
        if (*name == '<') {
            name++;
            stdname++;
            name = getzname(name, 1);
            if (*name != '>') {
                return (-1);
            }
            stdlen = name - stdname;
            name++;
        } else {
            name = getzname(name, 0);
            stdlen = name - stdname;
        }
        if (stdlen < 3)
            return -1;
    }
    if (*name == '\0')
        stdoffset = 0;
    else {
        name = getoffset(name, &stdoffset);
        if (name == NULL)
            return -1;
    }
    if (*name != '\0') {
        dstname = name;
        if (*name == '<') {
            name++;
            dstname++;
            name = getzname(name, 1);
            if (*name != '>') {
                return (-1);
            }
            dstlen = name - dstname;
            name++;
        } else {
            name = getzname(name, 0);
            dstlen = name - dstname;
        }
        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->charcnt = stdlen + 1 + dstlen + 1;
            if (allocall(sp) < 0)
                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 {
            int     sawstd;
            int     sawdst;
            long        stdfix;
            long        dstfix;
            long        oldfix;
            int     isdst;
            register int    i;

            if (*name != '\0')
                return -1;
            if (tzload(TZDEFRULES, sp) != 0) {
                freeall(sp);
                return -1;
            }
            /*
            ** Discard zone abbreviations from file, and allocate
            ** space for the ones from TZ.
            */
            free(sp->chars);
            sp->charcnt = stdlen + 1 + dstlen + 1;
            sp->chars = (char *)calloc((unsigned)sp->charcnt,
              (unsigned)sizeof (char));
            /*
            ** Compute the difference between the real and
            ** prototype standard and summer time offsets
            ** from GMT, and put the real standard and summer
            ** time offsets into the rules in place of the
            ** prototype offsets.
            */
            sawstd = FALSE;
            sawdst = FALSE;
            stdfix = 0;
            dstfix = 0;
            for (i = 0; i < sp->typecnt; ++i) {
                if (sp->ttis[i].tt_isdst) {
                    oldfix = dstfix;
                    dstfix =
                        sp->ttis[i].tt_gmtoff + dstoffset;
                    if (sawdst && (oldfix != dstfix))
                        return -1;
                    sp->ttis[i].tt_gmtoff = -dstoffset;
                    sp->ttis[i].tt_abbrind = stdlen + 1;
                    sawdst = TRUE;
                } else {
                    oldfix = stdfix;
                    stdfix =
                        sp->ttis[i].tt_gmtoff + stdoffset;
                    if (sawstd && (oldfix != stdfix))
                        return -1;
                    sp->ttis[i].tt_gmtoff = -stdoffset;
                    sp->ttis[i].tt_abbrind = 0;
                    sawstd = TRUE;
                }
            }
            /*
            ** Make sure we have both standard and summer time.
            */
            if (!sawdst || !sawstd)
                return -1;
            /*
            ** Now correct the transition times by shifting
            ** them by the difference between the real and
            ** prototype offsets.  Note that this difference
            ** can be different in standard and summer time;
            ** the prototype probably has a 1-hour difference
            ** between standard and summer time, but a different
            ** difference can be specified in TZ.
            */
            isdst = FALSE;  /* we start in standard time */
            for (i = 0; i < sp->timecnt; ++i) {
                register const struct ttinfo *  ttisp;

                /*
                ** 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.
                */
                ttisp = &sp->ttis[sp->types[i]];
                sp->ats[i] +=
                    (isdst && !ttisp->tt_ttisstd) ?
                        dstfix : stdfix;
                isdst = ttisp->tt_isdst;
            }
        }
    } else {
        dstlen = 0;
        sp->typecnt = 1;        /* only standard time */
        sp->timecnt = 0;
        sp->charcnt = stdlen + 1;
        if (allocall(sp) < 0)
            return -1;
        sp->ttis[0].tt_gmtoff = -stdoffset;
        sp->ttis[0].tt_isdst = 0;
        sp->ttis[0].tt_abbrind = 0;
    }
    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);
}

void
tzsetwall()
{
    lcl_is_set = TRUE;
    if (lclptr == NULL) {
        lclptr = (struct state *) calloc(1, (unsigned)sizeof *lclptr);
        if (lclptr == NULL) {
#ifdef S5EMUL
            settzname();    /* all we can do */
#endif
            return;
        }
    }
    if (tzload((char *) NULL, lclptr) != 0)
        gmtload(lclptr);
#ifdef S5EMUL
    settzname();
#endif
}

void
tzset()
{
    register const char *   name;

    name = (const char *)getenv("TZ");
    if (name == NULL) {
        tzsetwall();
        return;
    }
    lcl_is_set = TRUE;
    if (lclptr == NULL) {
        lclptr = (struct state *) calloc(1, (unsigned)sizeof *lclptr);
        if (lclptr == NULL) {
#ifdef S5EMUL
            settzname();    /* all we can do */
#endif
            return;
        }
    }
    if (*name == '\0') {
        /*
        ** User wants it fast rather than right.
        */
        lclptr->timecnt = 0;
        lclptr->typecnt = 1;
        lclptr->charcnt = sizeof GMT;
        if (allocall(lclptr) < 0)
            return;
        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) tzparse(name, lclptr, TRUE);
#ifdef S5EMUL
    settzname();
#endif
}

/*
** 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.
*/

static struct tm    tm;

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

    if (!lcl_is_set)
        tzset();
    sp = lclptr;
    if (sp == NULL) {
        gmtsub(timep, offset, tmp);
        return;
    }
    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];
    timesub(&t, ttisp->tt_gmtoff, tmp);
    tmp->tm_isdst = ttisp->tt_isdst;
#ifdef S5EMUL
    tzname[tmp->tm_isdst] = (char *) &sp->chars[ttisp->tt_abbrind];
#endif /* S5EMUL */
    tmp->tm_zone = &sp->chars[ttisp->tt_abbrind];
}

struct tm *
localtime(timep)
const time_t * const    timep;
{
    time_t      temp_time = *(const time_t*)timep;

    _ltzset(&temp_time);    /*
                 * base localtime calls this to initialize
                 * some things, so we'll do it here, too.
                 */
    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;
        gmtptr = (struct state *) calloc(1, (unsigned)sizeof *gmtptr);
        if (gmtptr != NULL)
            gmtload(gmtptr);
    }
    timesub(timep, offset, tmp);
    /*
    ** 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 = (char *)WILDABBR;
    else {
        if (gmtptr == NULL)
            tmp->tm_zone = (char *)GMT;
        else    tmp->tm_zone = gmtptr->chars;
    }
}

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

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

static void
timesub(timep, offset, tmp)
const time_t * const            timep;
const long              offset;
register struct tm * const      tmp;
{
    register long           days;
    register long           rem;
    register int            y;
    register int            yleap;
    register const int *        ip;

    days = *timep / SECSPERDAY;
    rem = *timep % SECSPERDAY;
    rem += offset;
    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);
    tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYSPERWEEK);
    if (tmp->tm_wday < 0)
        tmp->tm_wday += DAYSPERWEEK;
    y = EPOCH_YEAR;
    if (days >= 0)
        for ( ; ; ) {
            yleap = isleap(y);
            if (days < (long) year_lengths[yleap])
                break;
            ++y;
            days = days - (long) year_lengths[yleap];
        }
    else do {
        --y;
        yleap = isleap(y);
        days = days + (long) year_lengths[yleap];
    } while (days < 0);
    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;
    tmp->tm_gmtoff = offset;
}

/*
** 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 */

static void
normalize(tensptr, unitsptr, base)
int * const tensptr;
int * const unitsptr;
const int   base;
{
    int tmp;

    if (*unitsptr >= base) {
        *tensptr += *unitsptr / base;
        *unitsptr %= base;
    } else if (*unitsptr < 0) {
        /* tmp has the range 0 to abs(*unitptr) -1 */
        tmp = -1 - (*unitsptr);
        *tensptr -= (tmp/base + 1);
        *unitsptr = (base - 1) - (tmp % base);
    }
}

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)();
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 (yourtm.tm_sec >= SECSPERMIN + 2 || yourtm.tm_sec < 0)
        normalize(&yourtm.tm_min, &yourtm.tm_sec, SECSPERMIN);
    normalize(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR);
    normalize(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY);
    normalize(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR);
    while (yourtm.tm_mday <= 0) {
        if (yourtm.tm_mon == 0) {
            yourtm.tm_mon = 12;
            --yourtm.tm_year;
        }
        yourtm.tm_mday +=
            mon_lengths[isleap(yourtm.tm_year +
               TM_YEAR_BASE)][--yourtm.tm_mon];
        if (yourtm.tm_mon >= MONSPERYEAR) {
            yourtm.tm_mon = 0;
            --yourtm.tm_year;
        }
    }
    for ( ; ; ) {
        i = mon_lengths[isleap(yourtm.tm_year +
            TM_YEAR_BASE)][yourtm.tm_mon];
        if (yourtm.tm_mday <= i)
            break;
        yourtm.tm_mday -= i;
        if (++yourtm.tm_mon >= MONSPERYEAR) {
            yourtm.tm_mon = 0;
            ++yourtm.tm_year;
        }
    }
    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)
        ;
    /*
    ** 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.
        */
        sp = (const struct state *)
            ((funcp == localsub) ? lclptr : gmtptr);
        if (sp == NULL)
            return WRONG;
        for (i = 0; i < sp->typecnt; ++i) {
            if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
                continue;
            for (j = 0; j < sp->typecnt; ++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:
    t += saved_seconds;
    (*funcp)(&t, offset, tmp);
    *okayp = TRUE;
    return t;
}

static time_t
time1(tmp, funcp, offset)
struct tm * const   tmp;
void (* const       funcp)();
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);
    if (okay || tmp->tm_isdst < 0)
        return t;
    /*
    ** 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.
    */
    sp = (const struct state *) ((funcp == localsub) ? lclptr : gmtptr);
    if (sp == NULL)
        return WRONG;
    for (samei = 0; samei < sp->typecnt; ++samei) {
        if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
            continue;
        for (otheri = 0; otheri < sp->typecnt; ++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;
{
    return time1(tmp, localsub, 0L);
}

time_t
timelocal(tmp)
struct tm * const   tmp;
{
    tmp->tm_isdst = -1;
    return mktime(tmp);
}

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

time_t
timeoff(tmp, offset)
struct tm * const   tmp;
const long      offset;
{

    return time1(tmp, gmtsub, offset);
}