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localtime.c

/*
** This file is in the public domain, so clarified as of
** 1996-06-05 by Arthur David Olson.
*/

#ifndef lint
#ifndef NOID
static char elsieid[] = "@(#)localtime.c  8.9";
#endif /* !defined NOID */
#endif /* !defined lint */

/*
** Leap second handling from Bradley White.
** POSIX-style TZ environment variable handling from Guy Harris.
*/

/*LINTLIBRARY*/

#include "private.h"
#include "tzfile.h"
#include "fcntl.h"
#include "float.h"      /* for FLT_MAX and DBL_MAX */

#ifndef TZ_ABBR_MAX_LEN
#define TZ_ABBR_MAX_LEN 16
#endif /* !defined TZ_ABBR_MAX_LEN */

#ifndef TZ_ABBR_CHAR_SET
#define TZ_ABBR_CHAR_SET \
      "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 :+-._"
#endif /* !defined TZ_ABBR_CHAR_SET */

#ifndef TZ_ABBR_ERR_CHAR
#define TZ_ABBR_ERR_CHAR      '_'
#endif /* !defined TZ_ABBR_ERR_CHAR */

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

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

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

static char       wildabbr[] = WILDABBR;

static const char gmt[] = "GMT";

/*
** The DST rules to use if TZ has no rules and we can't load TZDEFRULES.
** We default to US rules as of 1999-08-17.
** POSIX 1003.1 section 8.1.1 says that the default DST rules are
** implementation dependent; for historical reasons, US rules are a
** common default.
*/
#ifndef TZDEFRULESTRING
#define TZDEFRULESTRING ",M4.1.0,M10.5.0"
#endif /* !defined TZDEFDST */

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

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

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

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

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

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

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

/*
** Prototypes for static functions.
*/

static long       detzcode(const char * codep);
static time_t           detzcode64(const char * codep);
static int        differ_by_repeat(time_t t1, time_t t0);
static const char *     getzname(const char * strp);
static const char *     getqzname(const char * strp, const int delim);
static const char *     getnum(const char * strp, int * nump, int min,
                        int max);
static const char *     getsecs(const char * strp, long * secsp);
static const char *     getoffset(const char * strp, long * offsetp);
static const char *     getrule(const char * strp, struct rule * rulep);
static void       gmtload(struct state * sp);
static struct tm *      gmtsub(const time_t * timep, long offset,
                        struct tm * tmp);
static struct tm *      localsub(const time_t * timep, long offset,
                        struct tm * tmp);
static int        increment_overflow(int * number, int delta);
static int        leaps_thru_end_of(int y);
static int        long_increment_overflow(long * number, int delta);
static int        long_normalize_overflow(long * tensptr,
                        int * unitsptr, int base);
static int        normalize_overflow(int * tensptr, int * unitsptr,
                        int base);
static void       settzname(void);
static time_t           time1(struct tm * tmp,
                        struct tm * (*funcp)(const time_t *,
                        long, struct tm *),
                        long offset);
static time_t           time2(struct tm *tmp,
                        struct tm * (*funcp)(const time_t *,
                        long, struct tm*),
                        long offset, int * okayp);
static time_t           time2sub(struct tm *tmp,
                        struct tm * (*funcp)(const time_t *,
                        long, struct tm*),
                        long offset, int * okayp, int do_norm_secs);
static struct tm *      timesub(const time_t * timep, long offset,
                        const struct state * sp, struct tm * tmp);
static int        tmcomp(const struct tm * atmp,
                        const struct tm * btmp);
static time_t           transtime(time_t janfirst, int year,
                        const struct rule * rulep, long offset);
static int        typesequiv(const struct state * sp, int a, int b);
static int        tzload(const char * name, struct state * sp,
                        int doextend);
static int        tzparse(const char * name, struct state * sp,
                        int lastditch);

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

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

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

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

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

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

static struct tm  tm;

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

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

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

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

static time_t
detzcode64(codep)
const char * const      codep;
{
      register time_t   result;
      register int      i;

      result = (codep[0] & 0x80) ?  (~(int_fast64_t) 0) : 0;
      for (i = 0; i < 8; ++i)
            result = result * 256 + (codep[i] & 0xff);
      return result;
}

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

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

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

            tzname[ttisp->tt_isdst] =
                  &sp->chars[ttisp->tt_abbrind];
      }
      /*
      ** Finally, scrub the abbreviations.
      ** First, replace bogus characters.
      */
      for (i = 0; i < sp->charcnt; ++i)
            if (strchr(TZ_ABBR_CHAR_SET, sp->chars[i]) == NULL)
                  sp->chars[i] = TZ_ABBR_ERR_CHAR;
      /*
      ** Second, truncate long abbreviations.
      */
      for (i = 0; i < sp->typecnt; ++i) {
            register const struct ttinfo * const      ttisp = &sp->ttis[i];
            register char *                     cp = &sp->chars[ttisp->tt_abbrind];

            if (strlen(cp) > TZ_ABBR_MAX_LEN &&
                  strcmp(cp, GRANDPARENTED) != 0)
                        *(cp + TZ_ABBR_MAX_LEN) = '\0';
      }
}

static int
differ_by_repeat(t1, t0)
const time_t      t1;
const time_t      t0;
{
      if (TYPE_INTEGRAL(time_t) &&
            TYPE_BIT(time_t) - TYPE_SIGNED(time_t) < SECSPERREPEAT_BITS)
                  return 0;
      return t1 - t0 == SECSPERREPEAT;
}

static int
tzload(name, sp, doextend)
register const char *         name;
register struct state * const sp;
register const int            doextend;
{
      register const char *         p;
      register int                  i;
      register int                  fid;
      register int                  stored;
      register int                  nread;
      union {
            struct tzhead     tzhead;
            char        buf[2 * sizeof(struct tzhead) +
                              2 * sizeof *sp +
                              4 * TZ_MAX_TIMES];
      } u;

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

            if (name[0] == ':')
                  ++name;
            doaccess = name[0] == '/';
            if (!doaccess) {
                  if ((p = TZDIR) == NULL)
                        return -1;
                  if ((strlen(p) + strlen(name) + 1) >= sizeof fullname)
                        return -1;
                  (void) strcpy(fullname, p);
                  (void) strcat(fullname, "/");
                  (void) strcat(fullname, name);
                  /*
                  ** Set doaccess if '.' (as in "../") shows up in name.
                  */
                  if (strchr(name, '.') != NULL)
                        doaccess = TRUE;
                  name = fullname;
            }
            if (doaccess && access(name, R_OK) != 0)
                  return -1;
            if ((fid = open(name, OPEN_MODE)) == -1)
                  return -1;
      }
      nread = read(fid, u.buf, sizeof u.buf);
      if (close(fid) < 0 || nread <= 0)
            return -1;
      for (stored = 4; stored <= 8; stored *= 2) {
            int         ttisstdcnt;
            int         ttisgmtcnt;

            ttisstdcnt = (int) detzcode(u.tzhead.tzh_ttisstdcnt);
            ttisgmtcnt = (int) detzcode(u.tzhead.tzh_ttisgmtcnt);
            sp->leapcnt = (int) detzcode(u.tzhead.tzh_leapcnt);
            sp->timecnt = (int) detzcode(u.tzhead.tzh_timecnt);
            sp->typecnt = (int) detzcode(u.tzhead.tzh_typecnt);
            sp->charcnt = (int) detzcode(u.tzhead.tzh_charcnt);
            p = u.tzhead.tzh_charcnt + sizeof u.tzhead.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) ||
                  (ttisgmtcnt != sp->typecnt && ttisgmtcnt != 0))
                        return -1;
            if (nread - (p - u.buf) <
                  sp->timecnt * stored +        /* ats */
                  sp->timecnt +                 /* types */
                  sp->typecnt * 6 +       /* ttinfos */
                  sp->charcnt +                 /* chars */
                  sp->leapcnt * (stored + 4) +  /* lsinfos */
                  ttisstdcnt +                  /* ttisstds */
                  ttisgmtcnt)             /* ttisgmts */
                        return -1;
            for (i = 0; i < sp->timecnt; ++i) {
                  sp->ats[i] = (stored == 4) ?
                        detzcode(p) : detzcode64(p);
                  p += stored;
            }
            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 = (stored == 4) ?
                        detzcode(p) : detzcode64(p);
                  p += stored;
                  lsisp->ls_corr = detzcode(p);
                  p += 4;
            }
            for (i = 0; i < sp->typecnt; ++i) {
                  register struct ttinfo *      ttisp;

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

                  ttisp = &sp->ttis[i];
                  if (ttisgmtcnt == 0)
                        ttisp->tt_ttisgmt = FALSE;
                  else {
                        ttisp->tt_ttisgmt = *p++;
                        if (ttisp->tt_ttisgmt != TRUE &&
                              ttisp->tt_ttisgmt != FALSE)
                                    return -1;
                  }
            }
            /*
            ** Out-of-sort ats should mean we're running on a
            ** signed time_t system but using a data file with
            ** unsigned values (or vice versa).
            */
            for (i = 0; i < sp->timecnt - 2; ++i)
                  if (sp->ats[i] > sp->ats[i + 1]) {
                        ++i;
                        if (TYPE_SIGNED(time_t)) {
                              /*
                              ** Ignore the end (easy).
                              */
                              sp->timecnt = i;
                        } else {
                              /*
                              ** Ignore the beginning (harder).
                              */
                              register int      j;

                              for (j = 0; j + i < sp->timecnt; ++j) {
                                    sp->ats[j] = sp->ats[j + i];
                                    sp->types[j] = sp->types[j + i];
                              }
                              sp->timecnt = j;
                        }
                        break;
                  }
            /*
            ** If this is an old file, we're done.
            */
            if (u.tzhead.tzh_version[0] == '\0')
                  break;
            nread -= p - u.buf;
            for (i = 0; i < nread; ++i)
                  u.buf[i] = p[i];
            /*
            ** If this is a narrow integer time_t system, we're done.
            */
            if (stored >= (int) sizeof(time_t) && TYPE_INTEGRAL(time_t))
                  break;
      }
      if (doextend && nread > 2 &&
            u.buf[0] == '\n' && u.buf[nread - 1] == '\n' &&
            sp->typecnt + 2 <= TZ_MAX_TYPES) {
                  struct state      ts;
                  register int      result;

                  u.buf[nread - 1] = '\0';
                  result = tzparse(&u.buf[1], &ts, FALSE);
                  if (result == 0 && ts.typecnt == 2 &&
                        sp->charcnt + ts.charcnt <= TZ_MAX_CHARS) {
                              for (i = 0; i < 2; ++i)
                                    ts.ttis[i].tt_abbrind +=
                                          sp->charcnt;
                              for (i = 0; i < ts.charcnt; ++i)
                                    sp->chars[sp->charcnt++] =
                                          ts.chars[i];
                              i = 0;
                              while (i < ts.timecnt &&
                                    ts.ats[i] <=
                                    sp->ats[sp->timecnt - 1])
                                          ++i;
                              while (i < ts.timecnt &&
                                  sp->timecnt < TZ_MAX_TIMES) {
                                    sp->ats[sp->timecnt] =
                                          ts.ats[i];
                                    sp->types[sp->timecnt] =
                                          sp->typecnt +
                                          ts.types[i];
                                    ++sp->timecnt;
                                    ++i;
                              }
                              sp->ttis[sp->typecnt++] = ts.ttis[0];
                              sp->ttis[sp->typecnt++] = ts.ttis[1];
                  }
      }
      sp->goback = sp->goahead = FALSE;
      if (sp->timecnt > 1) {
            for (i = 1; i < sp->timecnt; ++i)
                  if (typesequiv(sp, sp->types[i], sp->types[0]) &&
                        differ_by_repeat(sp->ats[i], sp->ats[0])) {
                              sp->goback = TRUE;
                              break;
                        }
            for (i = sp->timecnt - 2; i >= 0; --i)
                  if (typesequiv(sp, sp->types[sp->timecnt - 1],
                        sp->types[i]) &&
                        differ_by_repeat(sp->ats[sp->timecnt - 1],
                        sp->ats[i])) {
                              sp->goahead = TRUE;
                              break;
            }
      }
      return 0;
}

static int
typesequiv(sp, a, b)
const struct state * const    sp;
const int               a;
const int               b;
{
      register int      result;

      if (sp == NULL ||
            a < 0 || a >= sp->typecnt ||
            b < 0 || b >= sp->typecnt)
                  result = FALSE;
      else {
            register const struct ttinfo *      ap = &sp->ttis[a];
            register const struct ttinfo *      bp = &sp->ttis[b];
            result = ap->tt_gmtoff == bp->tt_gmtoff &&
                  ap->tt_isdst == bp->tt_isdst &&
                  ap->tt_ttisstd == bp->tt_ttisstd &&
                  ap->tt_ttisgmt == bp->tt_ttisgmt &&
                  strcmp(&sp->chars[ap->tt_abbrind],
                  &sp->chars[bp->tt_abbrind]) == 0;
      }
      return result;
}

static const int  mon_lengths[2][MONSPERYEAR] = {
      { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
      { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
};

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

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

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

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

/*
** Given a pointer into an extended time zone string, scan until the ending
** delimiter of the zone name is located. Return a pointer to the delimiter.
**
** As with getzname above, the legal character set is actually quite
** restricted, with other characters producing undefined results.
** We don't do any checking here; checking is done later in common-case code.
*/

static const char *
getqzname(register const char *strp, const int delim)
{
      register int      c;

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

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

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

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

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

static const char *
getsecs(strp, secsp)
register const char *   strp;
long * const            secsp;
{
      int   num;

      /*
      ** `HOURSPERDAY * DAYSPERWEEK - 1' allows quasi-Posix rules like
      ** "M10.4.6/26", which does not conform to Posix,
      ** but which specifies the equivalent of
      ** ``02:00 on the first Sunday on or after 23 Oct''.
      */
      strp = getnum(strp, &num, 0, HOURSPERDAY * DAYSPERWEEK - 1);
      if (strp == NULL)
            return NULL;
      *secsp = num * (long) SECSPERHOUR;
      if (*strp == ':') {
            ++strp;
            strp = getnum(strp, &num, 0, MINSPERHOUR - 1);
            if (strp == NULL)
                  return NULL;
            *secsp += num * SECSPERMIN;
            if (*strp == ':') {
                  ++strp;
                  /* `SECSPERMIN' allows for leap seconds. */
                  strp = getnum(strp, &num, 0, SECSPERMIN);
                  if (strp == NULL)
                        return NULL;
                  *secsp += num;
            }
      }
      return strp;
}

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

static const char *
getoffset(strp, offsetp)
register const char *   strp;
long * const            offsetp;
{
      register int      neg = 0;

      if (*strp == '-') {
            neg = 1;
            ++strp;
      } else if (*strp == '+')
            ++strp;
      strp = getsecs(strp, offsetp);
      if (strp == NULL)
            return NULL;            /* illegal time */
      if (neg)
            *offsetp = -*offsetp;
      return strp;
}

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

static const char *
getrule(strp, rulep)
const char *                  strp;
register struct rule * const  rulep;
{
      if (*strp == 'J') {
            /*
            ** Julian day.
            */
            rulep->r_type = JULIAN_DAY;
            ++strp;
            strp = getnum(strp, &rulep->r_day, 1, DAYSPERNYEAR);
      } else if (*strp == 'M') {
            /*
            ** Month, week, day.
            */
            rulep->r_type = MONTH_NTH_DAY_OF_WEEK;
            ++strp;
            strp = getnum(strp, &rulep->r_mon, 1, MONSPERYEAR);
            if (strp == NULL)
                  return NULL;
            if (*strp++ != '.')
                  return NULL;
            strp = getnum(strp, &rulep->r_week, 1, 5);
            if (strp == NULL)
                  return NULL;
            if (*strp++ != '.')
                  return NULL;
            strp = getnum(strp, &rulep->r_day, 0, DAYSPERWEEK - 1);
      } else if (is_digit(*strp)) {
            /*
            ** Day of year.
            */
            rulep->r_type = DAY_OF_YEAR;
            strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1);
      } else      return NULL;            /* invalid format */
      if (strp == NULL)
            return NULL;
      if (*strp == '/') {
            /*
            ** Time specified.
            */
            ++strp;
            strp = getsecs(strp, &rulep->r_time);
      } else      rulep->r_time = 2 * SECSPERHOUR;    /* default = 2:00:00 */
      return strp;
}

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

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

      INITIALIZE(value);
      leapyear = isleap(year);
      switch (rulep->r_type) {

      case JULIAN_DAY:
            /*
            ** Jn - Julian day, 1 == January 1, 60 == March 1 even in leap
            ** years.
            ** In non-leap years, or if the day number is 59 or less, just
            ** add SECSPERDAY times the day number-1 to the time of
            ** January 1, midnight, to get the day.
            */
            value = janfirst + (rulep->r_day - 1) * SECSPERDAY;
            if (leapyear && rulep->r_day >= 60)
                  value += SECSPERDAY;
            break;

      case DAY_OF_YEAR:
            /*
            ** n - day of year.
            ** Just add SECSPERDAY times the day number to the time of
            ** January 1, midnight, to get the day.
            */
            value = janfirst + rulep->r_day * SECSPERDAY;
            break;

      case MONTH_NTH_DAY_OF_WEEK:
            /*
            ** Mm.n.d - nth "dth day" of month m.
            */
            value = janfirst;
            for (i = 0; i < rulep->r_mon - 1; ++i)
                  value += mon_lengths[leapyear][i] * SECSPERDAY;

            /*
            ** Use Zeller's Congruence to get day-of-week of first day of
            ** month.
            */
            m1 = (rulep->r_mon + 9) % 12 + 1;
            yy0 = (rulep->r_mon <= 2) ? (year - 1) : year;
            yy1 = yy0 / 100;
            yy2 = yy0 % 100;
            dow = ((26 * m1 - 2) / 10 +
                  1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
            if (dow < 0)
                  dow += DAYSPERWEEK;

            /*
            ** "dow" is the day-of-week of the first day of the month. Get
            ** the day-of-month (zero-origin) of the first "dow" day of the
            ** month.
            */
            d = rulep->r_day - dow;
            if (d < 0)
                  d += DAYSPERWEEK;
            for (i = 1; i < rulep->r_week; ++i) {
                  if (d + DAYSPERWEEK >=
                        mon_lengths[leapyear][rulep->r_mon - 1])
                              break;
                  d += DAYSPERWEEK;
            }

            /*
            ** "d" is the day-of-month (zero-origin) of the day we want.
            */
            value += d * SECSPERDAY;
            break;
      }

      /*
      ** "value" is the Epoch-relative time of 00:00:00 UTC on the day in
      ** question. To get the Epoch-relative time of the specified local
      ** time on that day, add the transition time and the current offset
      ** from UTC.
      */
      return value + rulep->r_time + offset;
}

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

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

      INITIALIZE(dstname);
      stdname = name;
      if (lastditch) {
            stdlen = strlen(name);  /* length of standard zone name */
            name += stdlen;
            if (stdlen >= sizeof sp->chars)
                  stdlen = (sizeof sp->chars) - 1;
            stdoffset = 0;
      } else {
            if (*name == '<') {
                  name++;
                  stdname = name;
                  name = getqzname(name, '>');
                  if (*name != '>')
                        return (-1);
                  stdlen = name - stdname;
                  name++;
            } else {
                  name = getzname(name);
                  stdlen = name - stdname;
            }
            if (*name == '\0')
                  return -1;
            name = getoffset(name, &stdoffset);
            if (name == NULL)
                  return -1;
      }
      load_result = tzload(TZDEFRULES, sp, FALSE);
      if (load_result != 0)
            sp->leapcnt = 0;        /* so, we're off a little */
      if (*name != '\0') {
            if (*name == '<') {
                  dstname = ++name;
                  name = getqzname(name, '>');
                  if (*name != '>')
                        return -1;
                  dstlen = name - dstname;
                  name++;
            } else {
                  dstname = name;
                  name = getzname(name);
                  dstlen = name - dstname; /* length of DST zone name */
            }
            if (*name != '\0' && *name != ',' && *name != ';') {
                  name = getoffset(name, &dstoffset);
                  if (name == NULL)
                        return -1;
            } else      dstoffset = stdoffset - SECSPERHOUR;
            if (*name == '\0' && load_result != 0)
                  name = TZDEFRULESTRING;
            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 forward.
                  */
                  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;
                  sp->timecnt = 0;
                  for (year = EPOCH_YEAR;
                      sp->timecnt + 2 <= TZ_MAX_TIMES;
                      ++year) {
                        time_t      newfirst;

                        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 */
                        }
                        sp->timecnt += 2;
                        newfirst = janfirst;
                        newfirst += year_lengths[isleap(year)] *
                              SECSPERDAY;
                        if (newfirst <= janfirst)
                              break;
                        janfirst = newfirst;
                  }
            } else {
                  register long     theirstdoffset;
                  register long     theirdstoffset;
                  register long     theiroffset;
                  register int      isdst;
                  register int      i;
                  register int      j;

                  if (*name != '\0')
                        return -1;
                  /*
                  ** Initial values of theirstdoffset and theirdstoffset.
                  */
                  theirstdoffset = 0;
                  for (i = 0; i < sp->timecnt; ++i) {
                        j = sp->types[i];
                        if (!sp->ttis[j].tt_isdst) {
                              theirstdoffset =
                                    -sp->ttis[j].tt_gmtoff;
                              break;
                        }
                  }
                  theirdstoffset = 0;
                  for (i = 0; i < sp->timecnt; ++i) {
                        j = sp->types[i];
                        if (sp->ttis[j].tt_isdst) {
                              theirdstoffset =
                                    -sp->ttis[j].tt_gmtoff;
                              break;
                        }
                  }
                  /*
                  ** Initially we're assumed to be in standard time.
                  */
                  isdst = FALSE;
                  theiroffset = theirstdoffset;
                  /*
                  ** Now juggle transition times and types
                  ** tracking offsets as you do.
                  */
                  for (i = 0; i < sp->timecnt; ++i) {
                        j = sp->types[i];
                        sp->types[i] = sp->ttis[j].tt_isdst;
                        if (sp->ttis[j].tt_ttisgmt) {
                              /* No adjustment to transition time */
                        } else {
                              /*
                              ** If summer time is in effect, and the
                              ** transition time was not specified as
                              ** standard time, add the summer time
                              ** offset to the transition time;
                              ** otherwise, add the standard time
                              ** offset to the transition time.
                              */
                              /*
                              ** Transitions from DST to DDST
                              ** will effectively disappear since
                              ** POSIX provides for only one DST
                              ** offset.
                              */
                              if (isdst && !sp->ttis[j].tt_ttisstd) {
                                    sp->ats[i] += dstoffset -
                                          theirdstoffset;
                              } else {
                                    sp->ats[i] += stdoffset -
                                          theirstdoffset;
                              }
                        }
                        theiroffset = -sp->ttis[j].tt_gmtoff;
                        if (sp->ttis[j].tt_isdst)
                              theirdstoffset = theiroffset;
                        else  theirstdoffset = theiroffset;
                  }
                  /*
                  ** Finally, fill in ttis.
                  ** ttisstd and ttisgmt need not be handled.
                  */
                  sp->ttis[0].tt_gmtoff = -stdoffset;
                  sp->ttis[0].tt_isdst = FALSE;
                  sp->ttis[0].tt_abbrind = 0;
                  sp->ttis[1].tt_gmtoff = -dstoffset;
                  sp->ttis[1].tt_isdst = TRUE;
                  sp->ttis[1].tt_abbrind = stdlen + 1;
                  sp->typecnt = 2;
            }
      } else {
            dstlen = 0;
            sp->typecnt = 1;        /* only standard time */
            sp->timecnt = 0;
            sp->ttis[0].tt_gmtoff = -stdoffset;
            sp->ttis[0].tt_isdst = 0;
            sp->ttis[0].tt_abbrind = 0;
      }
      sp->charcnt = stdlen + 1;
      if (dstlen != 0)
            sp->charcnt += dstlen + 1;
      if ((size_t) sp->charcnt > sizeof sp->chars)
            return -1;
      cp = sp->chars;
      (void) strncpy(cp, stdname, stdlen);
      cp += stdlen;
      *cp++ = '\0';
      if (dstlen != 0) {
            (void) strncpy(cp, dstname, dstlen);
            *(cp + dstlen) = '\0';
      }
      return 0;
}

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

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

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

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

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

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

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

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

/*ARGSUSED*/
static struct tm *
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;
      register struct tm *          result;
      const time_t                  t = *timep;

      sp = lclptr;
#ifdef ALL_STATE
      if (sp == NULL)
            return gmtsub(timep, offset, tmp);
#endif /* defined ALL_STATE */
      if ((sp->goback && t < sp->ats[0]) ||
            (sp->goahead && t > sp->ats[sp->timecnt - 1])) {
                  time_t                  newt = t;
                  register time_t         seconds;
                  register time_t         tcycles;
                  register int_fast64_t   icycles;

                  if (t < sp->ats[0])
                        seconds = sp->ats[0] - t;
                  else  seconds = t - sp->ats[sp->timecnt - 1];
                  --seconds;
                  tcycles = seconds / YEARSPERREPEAT / AVGSECSPERYEAR;
                  ++tcycles;
                  icycles = tcycles;
                  if (tcycles - icycles >= 1 || icycles - tcycles >= 1)
                        return NULL;
                  seconds = icycles;
                  seconds *= YEARSPERREPEAT;
                  seconds *= AVGSECSPERYEAR;
                  if (t < sp->ats[0])
                        newt += seconds;
                  else  newt -= seconds;
                  if (newt < sp->ats[0] ||
                        newt > sp->ats[sp->timecnt - 1])
                              return NULL;      /* "cannot happen" */
                  result = localsub(&newt, offset, tmp);
                  if (result == tmp) {
                        register time_t   newy;

                        newy = tmp->tm_year;
                        if (t < sp->ats[0])
                              newy -= icycles * YEARSPERREPEAT;
                        else  newy += icycles * YEARSPERREPEAT;
                        tmp->tm_year = newy;
                        if (tmp->tm_year != newy)
                              return NULL;
                  }
                  return result;
      }
      if (sp->timecnt == 0 || t < sp->ats[0]) {
            i = 0;
            while (sp->ttis[i].tt_isdst)
                  if (++i >= sp->typecnt) {
                        i = 0;
                        break;
                  }
      } else {
            register int      lo = 1;
            register int      hi = sp->timecnt;

            while (lo < hi) {
                  register int      mid = (lo + hi) >> 1;

                  if (t < sp->ats[mid])
                        hi = mid;
                  else  lo = mid + 1;
            }
            i = (int) sp->types[lo - 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);
      */
      result = timesub(&t, ttisp->tt_gmtoff, sp, tmp);
      tmp->tm_isdst = ttisp->tt_isdst;
      tzname[tmp->tm_isdst] = &sp->chars[ttisp->tt_abbrind];
#ifdef TM_ZONE
      tmp->TM_ZONE = &sp->chars[ttisp->tt_abbrind];
#endif /* defined TM_ZONE */
      return result;
}

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

/*
** Re-entrant version of localtime.
*/

struct tm *
localtime_r(timep, tmp)
const time_t * const    timep;
struct tm *       tmp;
{
      return localsub(timep, 0L, tmp);
}

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

static struct tm *
gmtsub(timep, offset, tmp)
const time_t * const    timep;
const long        offset;
struct tm * const tmp;
{
      register struct tm *    result;

      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);
      }
      result = timesub(timep, offset, gmtptr, tmp);
#ifdef TM_ZONE
      /*
      ** Could get fancy here and deliver something such as
      ** "UTC+xxxx" or "UTC-xxxx" if offset is non-zero,
      ** but this is no time for a treasure hunt.
      */
      if (offset != 0)
            tmp->TM_ZONE = wildabbr;
      else {
#ifdef ALL_STATE
            if (gmtptr == NULL)
                  tmp->TM_ZONE = gmt;
            else  tmp->TM_ZONE = gmtptr->chars;
#endif /* defined ALL_STATE */
#ifndef ALL_STATE
            tmp->TM_ZONE = gmtptr->chars;
#endif /* State Farm */
      }
#endif /* defined TM_ZONE */
      return result;
}

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

/*
* Re-entrant version of gmtime.
*/

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

#ifdef STD_INSPIRED

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

#endif /* defined STD_INSPIRED */

/*
** Return the number of leap years through the end of the given year
** where, to make the math easy, the answer for year zero is defined as zero.
*/

static int
leaps_thru_end_of(y)
register const int      y;
{
      return (y >= 0) ? (y / 4 - y / 100 + y / 400) :
            -(leaps_thru_end_of(-(y + 1)) + 1);
}

static struct tm *
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 time_t               tdays;
      register int                  idays;      /* unsigned would be so 2003 */
      register long                 rem;
      int                     y;
      register const int *          ip;
      register long                 corr;
      register int                  hit;
      register int                  i;

      corr = 0;
      hit = 0;
#ifdef ALL_STATE
      i = (sp == NULL) ? 0 : sp->leapcnt;
#endif /* defined ALL_STATE */
#ifndef ALL_STATE
      i = sp->leapcnt;
#endif /* State Farm */
      while (--i >= 0) {
            lp = &sp->lsis[i];
            if (*timep >= lp->ls_trans) {
                  if (*timep == lp->ls_trans) {
                        hit = ((i == 0 && lp->ls_corr > 0) ||
                              lp->ls_corr > sp->lsis[i - 1].ls_corr);
                        if (hit)
                              while (i > 0 &&
                                    sp->lsis[i].ls_trans ==
                                    sp->lsis[i - 1].ls_trans + 1 &&
                                    sp->lsis[i].ls_corr ==
                                    sp->lsis[i - 1].ls_corr + 1) {
                                          ++hit;
                                          --i;
                              }
                  }
                  corr = lp->ls_corr;
                  break;
            }
      }
      y = EPOCH_YEAR;
      tdays = *timep / SECSPERDAY;
      rem = *timep - tdays * SECSPERDAY;
      while (tdays < 0 || tdays >= year_lengths[isleap(y)]) {
            int         newy;
            register time_t   tdelta;
            register int      idelta;
            register int      leapdays;

            tdelta = tdays / DAYSPERLYEAR;
            idelta = tdelta;
            if (tdelta - idelta >= 1 || idelta - tdelta >= 1)
                  return NULL;
            if (idelta == 0)
                  idelta = (tdays < 0) ? -1 : 1;
            newy = y;
            if (increment_overflow(&newy, idelta))
                  return NULL;
            leapdays = leaps_thru_end_of(newy - 1) -
                  leaps_thru_end_of(y - 1);
            tdays -= ((time_t) newy - y) * DAYSPERNYEAR;
            tdays -= leapdays;
            y = newy;
      }
      {
            register long     seconds;

            seconds = tdays * SECSPERDAY + 0.5;
            tdays = seconds / SECSPERDAY;
            rem += seconds - tdays * SECSPERDAY;
      }
      /*
      ** Given the range, we can now fearlessly cast...
      */
      idays = tdays;
      rem += offset - corr;
      while (rem < 0) {
            rem += SECSPERDAY;
            --idays;
      }
      while (rem >= SECSPERDAY) {
            rem -= SECSPERDAY;
            ++idays;
      }
      while (idays < 0) {
            if (increment_overflow(&y, -1))
                  return NULL;
            idays += year_lengths[isleap(y)];
      }
      while (idays >= year_lengths[isleap(y)]) {
            idays -= year_lengths[isleap(y)];
            if (increment_overflow(&y, 1))
                  return NULL;
      }
      tmp->tm_year = y;
      if (increment_overflow(&tmp->tm_year, -TM_YEAR_BASE))
            return NULL;
      tmp->tm_yday = idays;
      /*
      ** The "extra" mods below avoid overflow problems.
      */
      tmp->tm_wday = EPOCH_WDAY +
            ((y - EPOCH_YEAR) % DAYSPERWEEK) *
            (DAYSPERNYEAR % DAYSPERWEEK) +
            leaps_thru_end_of(y - 1) -
            leaps_thru_end_of(EPOCH_YEAR - 1) +
            idays;
      tmp->tm_wday %= DAYSPERWEEK;
      if (tmp->tm_wday < 0)
            tmp->tm_wday += DAYSPERWEEK;
      tmp->tm_hour = (int) (rem / SECSPERHOUR);
      rem %= SECSPERHOUR;
      tmp->tm_min = (int) (rem / SECSPERMIN);
      /*
      ** A positive leap second requires a special
      ** representation. This uses "... ??:59:60" et seq.
      */
      tmp->tm_sec = (int) (rem % SECSPERMIN) + hit;
      ip = mon_lengths[isleap(y)];
      for (tmp->tm_mon = 0; idays >= ip[tmp->tm_mon]; ++(tmp->tm_mon))
            idays -= ip[tmp->tm_mon];
      tmp->tm_mday = (int) (idays + 1);
      tmp->tm_isdst = 0;
#ifdef TM_GMTOFF
      tmp->TM_GMTOFF = offset;
#endif /* defined TM_GMTOFF */
      return tmp;
}

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

char *
ctime_r(timep, buf)
const time_t * const    timep;
char *                  buf;
{
      struct tm   mytm;

      return asctime_r(localtime_r(timep, &mytm), buf);
}

/*
** 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.
**    It does a binary search of the time_t space. Since time_t's are
**    just 32 bits, its a max of 32 iterations (even at 64 bits it
**    would still be very reasonable).
*/

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

/*
** Simplified normalize logic courtesy Paul Eggert.
*/

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

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

static int
long_increment_overflow(number, delta)
long *      number;
int   delta;
{
      long  number0;

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

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

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

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

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

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

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

static time_t
time2sub(tmp, funcp, offset, okayp, do_norm_secs)
struct tm * const tmp;
struct tm * (* const    funcp)(const time_t*, long, struct tm*);
const long        offset;
int * const       okayp;
const int         do_norm_secs;
{
      register const struct state * sp;
      register int                  dir;
      register int                  i, j;
      register int                  saved_seconds;
      register long                 li;
      register time_t               lo;
      register time_t               hi;
      long                    y;
      time_t                        newt;
      time_t                        t;
      struct tm               yourtm, mytm;

      *okayp = FALSE;
      yourtm = *tmp;
      if (do_norm_secs) {
            if (normalize_overflow(&yourtm.tm_min, &yourtm.tm_sec,
                  SECSPERMIN))
                        return WRONG;
      }
      if (normalize_overflow(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR))
            return WRONG;
      if (normalize_overflow(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY))
            return WRONG;
      y = yourtm.tm_year;
      if (long_normalize_overflow(&y, &yourtm.tm_mon, MONSPERYEAR))
            return WRONG;
      /*
      ** Turn y into an actual year number for now.
      ** It is converted back to an offset from TM_YEAR_BASE later.
      */
      if (long_increment_overflow(&y, TM_YEAR_BASE))
            return WRONG;
      while (yourtm.tm_mday <= 0) {
            if (long_increment_overflow(&y, -1))
                  return WRONG;
            li = y + (1 < yourtm.tm_mon);
            yourtm.tm_mday += year_lengths[isleap(li)];
      }
      while (yourtm.tm_mday > DAYSPERLYEAR) {
            li = y + (1 < yourtm.tm_mon);
            yourtm.tm_mday -= year_lengths[isleap(li)];
            if (long_increment_overflow(&y, 1))
                  return WRONG;
      }
      for ( ; ; ) {
            i = mon_lengths[isleap(y)][yourtm.tm_mon];
            if (yourtm.tm_mday <= i)
                  break;
            yourtm.tm_mday -= i;
            if (++yourtm.tm_mon >= MONSPERYEAR) {
                  yourtm.tm_mon = 0;
                  if (long_increment_overflow(&y, 1))
                        return WRONG;
            }
      }
      if (long_increment_overflow(&y, -TM_YEAR_BASE))
            return WRONG;
      yourtm.tm_year = y;
      if (yourtm.tm_year != y)
            return WRONG;
      if (yourtm.tm_sec >= 0 && yourtm.tm_sec < SECSPERMIN)
            saved_seconds = 0;
      else if (y + TM_YEAR_BASE < EPOCH_YEAR) {
            /*
            ** We can't set tm_sec to 0, because that might push the
            ** time below the minimum representable time.
            ** Set tm_sec to 59 instead.
            ** This assumes that the minimum representable time is
            ** not in the same minute that a leap second was deleted from,
            ** which is a safer assumption than using 58 would be.
            */
            if (increment_overflow(&yourtm.tm_sec, 1 - SECSPERMIN))
                  return WRONG;
            saved_seconds = yourtm.tm_sec;
            yourtm.tm_sec = SECSPERMIN - 1;
      } else {
            saved_seconds = yourtm.tm_sec;
            yourtm.tm_sec = 0;
      }
      /*
      ** Do a binary search (this works whatever time_t's type is).
      */
      if (!TYPE_SIGNED(time_t)) {
            lo = 0;
            hi = lo - 1;
      } else if (!TYPE_INTEGRAL(time_t)) {
            if (sizeof(time_t) > sizeof(float))
                  hi = (time_t) DBL_MAX;
            else  hi = (time_t) FLT_MAX;
            lo = -hi;
      } else {
            lo = 1;
            for (i = 0; i < (int) TYPE_BIT(time_t) - 1; ++i)
                  lo *= 2;
            hi = -(lo + 1);
      }
      for ( ; ; ) {
            t = lo / 2 + hi / 2;
            if (t < lo)
                  t = lo;
            else if (t > hi)
                  t = hi;
            if ((*funcp)(&t, offset, &mytm) == NULL) {
                  /*
                  ** Assume that t is too extreme to be represented in
                  ** a struct tm; arrange things so that it is less
                  ** extreme on the next pass.
                  */
                  dir = (t > 0) ? 1 : -1;
            } else      dir = tmcomp(&mytm, &yourtm);
            if (dir != 0) {
                  if (t == lo) {
                        ++t;
                        if (t <= lo)
                              return WRONG;
                        ++lo;
                  } else if (t == hi) {
                        --t;
                        if (t >= hi)
                              return WRONG;
                        --hi;
                  }
                  if (lo > hi)
                        return WRONG;
                  if (dir > 0)
                        hi = t;
                  else  lo = t;
                  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 = sp->typecnt - 1; i >= 0; --i) {
                  if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
                        continue;
                  for (j = sp->typecnt - 1; j >= 0; --j) {
                        if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
                              continue;
                        newt = t + sp->ttis[j].tt_gmtoff -
                              sp->ttis[i].tt_gmtoff;
                        if ((*funcp)(&newt, offset, &mytm) == NULL)
                              continue;
                        if (tmcomp(&mytm, &yourtm) != 0)
                              continue;
                        if (mytm.tm_isdst != yourtm.tm_isdst)
                              continue;
                        /*
                        ** We have a match.
                        */
                        t = newt;
                        goto label;
                  }
            }
            return WRONG;
      }
label:
      newt = t + saved_seconds;
      if ((newt < t) != (saved_seconds < 0))
            return WRONG;
      t = newt;
      if ((*funcp)(&t, offset, tmp))
            *okayp = TRUE;
      return t;
}

static time_t
time2(tmp, funcp, offset, okayp)
struct tm * const tmp;
struct tm * (* const    funcp)(const time_t*, long, struct tm*);
const long        offset;
int * const       okayp;
{
      time_t      t;

      /*
      ** First try without normalization of seconds
      ** (in case tm_sec contains a value associated with a leap second).
      ** If that fails, try with normalization of seconds.
      */
      t = time2sub(tmp, funcp, offset, okayp, FALSE);
      return *okayp ? t : time2sub(tmp, funcp, offset, okayp, TRUE);
}

static time_t
time1(tmp, funcp, offset)
struct tm * const tmp;
struct tm * (* const    funcp)(const time_t *, long, struct tm *);
const long        offset;
{
      register time_t               t;
      register const struct state * sp;
      register int                  samei, otheri;
      register int                  sameind, otherind;
      register int                  i;
      register int                  nseen;
      int                     seen[TZ_MAX_TYPES];
      int                     types[TZ_MAX_TYPES];
      int                     okay;

      if (tmp->tm_isdst > 1)
            tmp->tm_isdst = 1;
      t = time2(tmp, funcp, offset, &okay);
#ifdef PCTS
      /*
      ** PCTS code courtesy Grant Sullivan.
      */
      if (okay)
            return t;
      if (tmp->tm_isdst < 0)
            tmp->tm_isdst = 0;      /* reset to std and try again */
#endif /* defined PCTS */
#ifndef PCTS
      if (okay || tmp->tm_isdst < 0)
            return t;
#endif /* !defined PCTS */
      /*
      ** We're supposed to assume that somebody took a time of one type
      ** and did some math on it that yielded a "struct tm" that's bad.
      ** We try to divine the type they started from and adjust to the
      ** type they need.
      */
      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)
            seen[i] = FALSE;
      nseen = 0;
      for (i = sp->timecnt - 1; i >= 0; --i)
            if (!seen[sp->types[i]]) {
                  seen[sp->types[i]] = TRUE;
                  types[nseen++] = sp->types[i];
            }
      for (sameind = 0; sameind < nseen; ++sameind) {
            samei = types[sameind];
            if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
                  continue;
            for (otherind = 0; otherind < nseen; ++otherind) {
                  otheri = types[otherind];
                  if (sp->ttis[otheri].tt_isdst == tmp->tm_isdst)
                        continue;
                  tmp->tm_sec += sp->ttis[otheri].tt_gmtoff -
                              sp->ttis[samei].tt_gmtoff;
                  tmp->tm_isdst = !tmp->tm_isdst;
                  t = time2(tmp, funcp, offset, &okay);
                  if (okay)
                        return t;
                  tmp->tm_sec -= sp->ttis[otheri].tt_gmtoff -
                              sp->ttis[samei].tt_gmtoff;
                  tmp->tm_isdst = !tmp->tm_isdst;
            }
      }
      return WRONG;
}

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

#ifdef STD_INSPIRED

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

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

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

#endif /* defined STD_INSPIRED */

#ifdef CMUCS

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

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

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

#endif /* defined CMUCS */

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

#ifdef STD_INSPIRED

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

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

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

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

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

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

#endif /* defined STD_INSPIRED */

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