[apple/libc.git] / gen / ctime.c

/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1987, 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Arthur David Olson of the National Cancer Institute.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */


/*
** Leap second handling from Bradley White (bww@k.gp.cs.cmu.edu).
** POSIX-style TZ environment variable handling from Guy Harris
** (guy@auspex.com).
*/

/*LINTLIBRARY*/

#include <sys/param.h>
#include <fcntl.h>
#include <time.h>
#include <tzfile.h>
#include <string.h>
#include <ctype.h>
#include <stdio.h>
#include <unistd.h>

#ifdef __STDC__
#include <stdlib.h>

#define P(s)            s
#define alloc_size_t    size_t
#define qsort_size_t    size_t
#define fread_size_t    size_t
#define fwrite_size_t   size_t

#else /* !defined __STDC__ */

#define P(s)            ()

typedef char *          genericptr_t;
typedef unsigned        alloc_size_t;
typedef int             qsort_size_t;
typedef int             fread_size_t;
typedef int             fwrite_size_t;

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

#endif /* !defined __STDC__ */

extern time_t   time();

#define ACCESS_MODE     O_RDONLY
#define OPEN_MODE       O_RDONLY

#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 */

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

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

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[(TZ_MAX_CHARS + 1 > sizeof GMT) ?
                                TZ_MAX_CHARS + 1 : sizeof GMT];
        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 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,
                                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 */

static int              lcl_is_set;
static int              gmt_is_set;

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

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

static void
settzname()
{
        register const 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] =
                        (char *) &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] =
                        (char *) &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;
        {
                char            fullname[FILENAME_MAX + 1];

                if (name[0] == ':')
                        ++name;
                if (name[0] != '/') {
                        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);
                        name = fullname;
                }
                if ((fid = open(name, OPEN_MODE)) == -1)
                        return -1;
        }
        {
                register const struct tzhead *  tzhp;
                char                            buf[sizeof *sp + sizeof *tzhp];
                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);
                sp->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 (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))
                                return -1;
                if (i < sizeof *tzhp +
                        sp->timecnt * (4 + sizeof (char)) +
                        sp->typecnt * (4 + 2 * sizeof (char)) +
                        sp->charcnt * sizeof (char) +
                        sp->leapcnt * 2 * 4 +
                        ttisstdcnt * sizeof (char))
                                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; ++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;
                        }
                }
        }
        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' && !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;
register struct state * const   sp;
const int                       lastditch;
{
        const char *                    stdname;
        const char *                    dstname;
        int                             stdlen;
        int                             dstlen;
        long                            stdoffset;
        long                            dstoffset;
        register time_t *               atp;
        register unsigned char *        typep;
        register char *                 cp;
        register int                    load_result;

        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;
        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 {
                        int             sawstd;
                        int             sawdst;
                        long            stdfix;
                        long            dstfix;
                        long            oldfix;
                        int             isdst;
                        register int    i;

                        if (*name != '\0')
                                return -1;
                        if (load_result != 0)
                                return -1;
                        /*
                        ** 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->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);
}

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

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

void
tzsetwall()
{
        lcl_is_set = TRUE;
#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();
}

/*
** 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;

        if (!lcl_is_set)
                tzset();
        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] = (char *) &sp->chars[ttisp->tt_abbrind];
        tmp->tm_zone = &sp->chars[ttisp->tt_abbrind];
}

struct tm *
localtime(timep)
const time_t * const    timep;
{
        static struct tm        tm;

        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);
        /*
        ** 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 */
        }
}

struct tm *
gmtime(timep)
const time_t * const    timep;
{
        static struct tm        tm;

        gmtsub(timep, 0L, &tm);
        return &tm;
}

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 = FALSE;
#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);
                        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 /* 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".
                */
                ++(tmp->tm_sec);
        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;
}

/*
** A la X3J11
*/

char *
asctime(timeptr)
register const struct tm *      timeptr;
{
        static const char       wday_name[DAYSPERWEEK][3] = {
                "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
        };
        static const char       mon_name[MONSPERYEAR][3] = {
                "Jan", "Feb", "Mar", "Apr", "May", "Jun",
                "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
        };
        static char     result[26];

        (void) sprintf(result, "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %d\n",
                wday_name[timeptr->tm_wday],
                mon_name[timeptr->tm_mon],
                timeptr->tm_mday, timeptr->tm_hour,
                timeptr->tm_min, timeptr->tm_sec,
                TM_YEAR_BASE + timeptr->tm_year);
        return result;
}

char *
ctime(timep)
const time_t * const    timep;
{
        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 */

static void
normalize(tensptr, unitsptr, base)
int * const     tensptr;
int * const     unitsptr;
const int       base;
{
        if (*unitsptr >= base) {
                *tensptr += *unitsptr / base;
                *unitsptr %= base;
        } else if (*unitsptr < 0) {
                *tensptr -= 1 + (-(*unitsptr + 1)) / base;
                *unitsptr = base - 1 - (-(*unitsptr + 1)) % 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) {
                --yourtm.tm_year;
                yourtm.tm_mday +=
                        year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)];
        }
        while (yourtm.tm_mday > DAYSPERLYEAR) {
                yourtm.tm_mday -=
                    year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)];
                ++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);
#ifdef ALL_STATE
                if (sp == NULL)
                        return WRONG;
#endif /* defined ALL_STATE */
                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);
#ifdef ALL_STATE
        if (sp == NULL)
                return WRONG;
#endif /* defined ALL_STATE */
        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);
}