setting all of the fields to INT_MIN took forever to run
[unix-history] / usr / src / lib / libc / gen / ctime.c
index 200605f..4c3b8cd 100644 (file)
 /*
 /*
- * Copyright (c) 1987 Regents of the University of California.
- * All rights reserved.  The Berkeley software License Agreement
- * specifies the terms and conditions for redistribution.
+ * 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.
+ *
+ * %sccs.include.redist.c%
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)ctime.c    5.8 (Berkeley) %G%";
-#endif LIBC_SCCS and not lint
+static char sccsid[] = "@(#)ctime.c    8.2 (Berkeley) %G%";
+#endif /* LIBC_SCCS and not lint */
 
 
-#include "sys/param.h"
-#include "sys/time.h"
-#include "tzfile.h"
+/*
+** Leap second handling from Bradley White (bww@k.gp.cs.cmu.edu).
+** POSIX-style TZ environment variable handling from Guy Harris
+** (guy@auspex.com).
+*/
 
 
-char *
-ctime(t)
-time_t *t;
-{
-       struct tm       *localtime();
-       char    *asctime();
+/*LINTLIBRARY*/
 
 
-       return(asctime(localtime(t)));
-}
+#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>
 
 
-/*
-** A la X3J11
-*/
+#ifdef __STDC__
+#include <stdlib.h>
 
 
-char *
-asctime(timeptr)
-register struct tm *   timeptr;
-{
-       static char     wday_name[DAYS_PER_WEEK][3] = {
-               "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
-       };
-       static char     mon_name[MONS_PER_YEAR][3] = {
-               "Jan", "Feb", "Mar", "Apr", "May", "Jun",
-               "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
-       };
-       static char     result[26];
+#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
 
 
-       (void) sprintf(result, "%.3s %.3s%3d %.2d:%.2d:%.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;
-}
+#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
 
 #ifndef TRUE
 #define TRUE           1
 #define FALSE          0
-#endif /* !TRUE */
+#endif /* !defined TRUE */
 
 
-extern char *          getenv();
-extern char *          strcpy();
-extern char *          strcat();
-struct tm *            offtime();
+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 */
 
 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 {
 };
 
 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];
        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];
+       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 */
 };
 
 };
 
-static struct state    s;
+#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 */
 
 
-static int             tz_is_set;
+/*
+** 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] = {
 
 char *                 tzname[2] = {
-       "GMT",
-       "GMT"
+       WILDABBR,
+       WILDABBR
 };
 
 #ifdef USG_COMPAT
 time_t                 timezone = 0;
 int                    daylight = 0;
 };
 
 #ifdef USG_COMPAT
 time_t                 timezone = 0;
 int                    daylight = 0;
-#endif /* USG_COMPAT */
+#endif /* defined USG_COMPAT */
+
+#ifdef ALTZONE
+time_t                 altzone = 0;
+#endif /* defined ALTZONE */
 
 static long
 detzcode(codep)
 
 static long
 detzcode(codep)
-char * codep;
+const char * const     codep;
 {
        register long   result;
        register int    i;
 {
        register long   result;
        register int    i;
@@ -101,267 +201,890 @@ char *  codep;
        return result;
 }
 
        return result;
 }
 
-static
-tzload(name)
-register char *        name;
+static void
+settzname()
 {
 {
-       register int    i;
-       register int    fid;
+       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]];
 
 
-       if (name == 0 && (name = TZDEFAULT) == 0)
+               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;
        {
                return -1;
        {
-               register char * p;
-               register int    doaccess;
-               char            fullname[MAXPATHLEN];
+               char            fullname[FILENAME_MAX + 1];
 
 
-               doaccess = name[0] == '/';
-               if (!doaccess) {
-                       if ((p = TZDIR) == 0)
+               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);
                                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.
-                       */
-                       while (*name != '\0')
-                               if (*name++ == '.')
-                                       doaccess = TRUE;
                        name = fullname;
                }
                        name = fullname;
                }
-               if (doaccess && access(name, 4) != 0)
-                       return -1;
-               if ((fid = open(name, 0)) == -1)
+               if ((fid = open(name, OPEN_MODE)) == -1)
                        return -1;
        }
        {
                        return -1;
        }
        {
-               register char *                 p;
-               register struct tzhead *        tzhp;
-               char                            buf[sizeof s];
+               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;
 
                i = read(fid, buf, sizeof buf);
                if (close(fid) != 0 || i < sizeof *tzhp)
                        return -1;
                tzhp = (struct tzhead *) buf;
-               s.timecnt = (int) detzcode(tzhp->tzh_timecnt);
-               s.typecnt = (int) detzcode(tzhp->tzh_typecnt);
-               s.charcnt = (int) detzcode(tzhp->tzh_charcnt);
-               if (s.timecnt > TZ_MAX_TIMES ||
-                       s.typecnt == 0 ||
-                       s.typecnt > TZ_MAX_TYPES ||
-                       s.charcnt > TZ_MAX_CHARS)
+               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 +
                                return -1;
                if (i < sizeof *tzhp +
-                       s.timecnt * (4 + sizeof (char)) +
-                       s.typecnt * (4 + 2 * sizeof (char)) +
-                       s.charcnt * sizeof (char))
+                       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;
                                return -1;
                p = buf + sizeof *tzhp;
-               for (i = 0; i < s.timecnt; ++i) {
-                       s.ats[i] = detzcode(p);
+               for (i = 0; i < sp->timecnt; ++i) {
+                       sp->ats[i] = detzcode(p);
                        p += 4;
                }
                        p += 4;
                }
-               for (i = 0; i < s.timecnt; ++i)
-                       s.types[i] = (unsigned char) *p++;
-               for (i = 0; i < s.typecnt; ++i) {
+               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;
 
                        register struct ttinfo *        ttisp;
 
-                       ttisp = &s.ttis[i];
+                       ttisp = &sp->ttis[i];
                        ttisp->tt_gmtoff = detzcode(p);
                        p += 4;
                        ttisp->tt_isdst = (unsigned char) *p++;
                        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++;
                        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;
                }
                }
-               for (i = 0; i < s.charcnt; ++i)
-                       s.chars[i] = *p++;
-               s.chars[i] = '\0';      /* ensure '\0' at end */
+
+               /*
+               ** "d" is the day-of-month (zero-origin) of the day we want.
+               */
+               value += d * SECSPERDAY;
+               break;
        }
        }
+
        /*
        /*
-       ** Check that all the local time type indices are valid.
+       ** "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.
        */
        */
-       for (i = 0; i < s.timecnt; ++i)
-               if (s.types[i] >= s.typecnt)
+       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;
                        return -1;
-       /*
-       ** Check that all abbreviation indices are valid.
-       */
-       for (i = 0; i < s.typecnt; ++i)
-               if (s.ttis[i].tt_abbrind >= s.charcnt)
+       }
+       if (*name == '\0')
+               return -1;
+       else {
+               name = getoffset(name, &stdoffset);
+               if (name == NULL)
                        return -1;
                        return -1;
-       /*
-       ** Set tzname elements to initial values.
-       */
-       tzname[0] = tzname[1] = &s.chars[0];
-#ifdef USG_COMPAT
-       timezone = s.ttis[0].tt_gmtoff;
-       daylight = 0;
-#endif /* USG_COMPAT */
-       for (i = 1; i < s.typecnt; ++i) {
-               register struct ttinfo *        ttisp;
+       }
+       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;
 
 
-               ttisp = &s.ttis[i];
-               if (ttisp->tt_isdst) {
-                       tzname[1] = &s.chars[ttisp->tt_abbrind];
-#ifdef USG_COMPAT
-                       daylight = 1;
-#endif /* USG_COMPAT */ 
+                       ++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 {
                } else {
-                       tzname[0] = &s.chars[ttisp->tt_abbrind];
-#ifdef USG_COMPAT
-                       timezone = ttisp->tt_gmtoff;
-#endif /* USG_COMPAT */ 
-               }
-       }
-       return 0;
-}
+                       int             sawstd;
+                       int             sawdst;
+                       long            stdfix;
+                       long            dstfix;
+                       long            oldfix;
+                       int             isdst;
+                       register int    i;
 
 
-static
-tzsetkernel()
-{
-       struct timeval  tv;
-       struct timezone tz;
-       char    *tztab();
+                       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 (gettimeofday(&tv, &tz))
+                               /*
+                               ** 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;
                return -1;
-       s.timecnt = 0;          /* UNIX counts *west* of Greenwich */
-       s.ttis[0].tt_gmtoff = tz.tz_minuteswest * -SECS_PER_MIN;
-       s.ttis[0].tt_abbrind = 0;
-       (void)strcpy(s.chars, tztab(tz.tz_minuteswest, 0));
-       tzname[0] = tzname[1] = s.chars;
-#ifdef USG_COMPAT
-       timezone = tz.tz_minuteswest * 60;
-       daylight = tz.tz_dsttime;
-#endif /* USG_COMPAT */
+       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;
 }
 
        return 0;
 }
 
-static
-tzsetgmt()
+static void
+gmtload(sp)
+struct state * const   sp;
 {
 {
-       s.timecnt = 0;
-       s.ttis[0].tt_gmtoff = 0;
-       s.ttis[0].tt_abbrind = 0;
-       (void) strcpy(s.chars, "GMT");
-       tzname[0] = tzname[1] = s.chars;
-#ifdef USG_COMPAT
-       timezone = 0;
-       daylight = 0;
-#endif /* USG_COMPAT */
+       if (tzload(GMT, sp) != 0)
+               (void) tzparse(GMT, sp, TRUE);
 }
 
 void
 tzset()
 {
 }
 
 void
 tzset()
 {
-       register char * name;
+       register const char *   name;
+       void tzsetwall();
 
 
-       tz_is_set = TRUE;
        name = getenv("TZ");
        name = getenv("TZ");
-       if (!name || *name) {                   /* did not request GMT */
-               if (name && !tzload(name))      /* requested name worked */
-                       return;
-               if (!tzload((char *)0))         /* default name worked */
+       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;
                        return;
-               if (!tzsetkernel())             /* kernel guess worked */
+               }
+       }
+#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;
                        return;
+               }
        }
        }
-       tzsetgmt();                             /* GMT is default */
+#endif /* defined ALL_STATE */
+       if (tzload((char *) NULL, lclptr) != 0)
+               gmtload(lclptr);
+       settzname();
 }
 
 }
 
-struct tm *
-localtime(timep)
-time_t *       timep;
+/*
+** 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 ttinfo *        ttisp;
-       register struct tm *            tmp;
+       register struct state * sp;
+       register const struct ttinfo *  ttisp;
        register int                    i;
        register int                    i;
-       time_t                          t;
+       const time_t                    t = *timep;
 
 
-       if (!tz_is_set)
-               (void) tzset();
-       t = *timep;
-       if (s.timecnt == 0 || t < s.ats[0]) {
+       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;
                i = 0;
-               while (s.ttis[i].tt_isdst)
-                       if (++i >= s.timecnt) {
+               while (sp->ttis[i].tt_isdst)
+                       if (++i >= sp->typecnt) {
                                i = 0;
                                break;
                        }
        } else {
                                i = 0;
                                break;
                        }
        } else {
-               for (i = 1; i < s.timecnt; ++i)
-                       if (t < s.ats[i])
+               for (i = 1; i < sp->timecnt; ++i)
+                       if (t < sp->ats[i])
                                break;
                                break;
-               i = s.types[i - 1];
+               i = sp->types[i - 1];
        }
        }
-       ttisp = &s.ttis[i];
+       ttisp = &sp->ttis[i];
        /*
        ** To get (wrong) behavior that's compatible with System V Release 2.0
        ** you'd replace the statement below with
        /*
        ** To get (wrong) behavior that's compatible with System V Release 2.0
        ** you'd replace the statement below with
-       **      tmp = offtime((time_t) (t + ttisp->tt_gmtoff), 0L);
+       **      t += ttisp->tt_gmtoff;
+       **      timesub(&t, 0L, sp, tmp);
        */
        */
-       tmp = offtime(&t, ttisp->tt_gmtoff);
+       timesub(&t, ttisp->tt_gmtoff, sp, tmp);
        tmp->tm_isdst = ttisp->tt_isdst;
        tmp->tm_isdst = ttisp->tt_isdst;
-       tzname[tmp->tm_isdst] = &s.chars[ttisp->tt_abbrind];
-       tmp->tm_zone = &s.chars[ttisp->tt_abbrind];
-       return tmp;
+       tzname[tmp->tm_isdst] = (char *) &sp->chars[ttisp->tt_abbrind];
+       tmp->tm_zone = &sp->chars[ttisp->tt_abbrind];
 }
 
 struct tm *
 }
 
 struct tm *
-gmtime(clock)
-time_t *       clock;
+localtime(timep)
+const time_t * const   timep;
 {
 {
-       register struct tm *    tmp;
+       static struct tm        tm;
 
 
-       tmp = offtime(clock, 0L);
-       tzname[0] = "GMT";
-       tmp->tm_zone = "GMT";           /* UCT ? */
-       return tmp;
+       localsub(timep, 0L, &tm);
+       return &tm;
 }
 
 }
 
-static int     mon_lengths[2][MONS_PER_YEAR] = {
-       31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31,
-       31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
-};
+/*
+** gmtsub is to gmtime as localsub is to localtime.
+*/
 
 
-static int     year_lengths[2] = {
-       DAYS_PER_NYEAR, DAYS_PER_LYEAR
-};
+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 *
 
 struct tm *
-offtime(clock, offset)
-time_t *       clock;
-long           offset;
+gmtime(timep)
+const time_t * const   timep;
 {
 {
-       register struct tm *    tmp;
-       register long           days;
-       register long           rem;
-       register int            y;
-       register int            yleap;
-       register int *          ip;
        static struct tm        tm;
 
        static struct tm        tm;
 
-       tmp = &tm;
-       days = *clock / SECS_PER_DAY;
-       rem = *clock % SECS_PER_DAY;
-       rem += offset;
+       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) {
        while (rem < 0) {
-               rem += SECS_PER_DAY;
+               rem += SECSPERDAY;
                --days;
        }
                --days;
        }
-       while (rem >= SECS_PER_DAY) {
-               rem -= SECS_PER_DAY;
+       while (rem >= SECSPERDAY) {
+               rem -= SECSPERDAY;
                ++days;
        }
                ++days;
        }
-       tmp->tm_hour = (int) (rem / SECS_PER_HOUR);
-       rem = rem % SECS_PER_HOUR;
-       tmp->tm_min = (int) (rem / SECS_PER_MIN);
-       tmp->tm_sec = (int) (rem % SECS_PER_MIN);
-       tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYS_PER_WEEK);
+       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)
        if (tmp->tm_wday < 0)
-               tmp->tm_wday += DAYS_PER_WEEK;
+               tmp->tm_wday += DAYSPERWEEK;
        y = EPOCH_YEAR;
        if (days >= 0)
                for ( ; ; ) {
        y = EPOCH_YEAR;
        if (days >= 0)
                for ( ; ; ) {
@@ -383,7 +1106,250 @@ long             offset;
                days = days - (long) ip[tmp->tm_mon];
        tmp->tm_mday = (int) (days + 1);
        tmp->tm_isdst = 0;
                days = days - (long) ip[tmp->tm_mon];
        tmp->tm_mday = (int) (days + 1);
        tmp->tm_isdst = 0;
-       tmp->tm_zone = "";
        tmp->tm_gmtoff = offset;
        tmp->tm_gmtoff = offset;
-       return tmp;
+}
+
+/*
+** 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);
 }
 }