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Sourcecode: postgresql-8.4 version File versions

datetime.c

/*-------------------------------------------------------------------------
 *
 * datetime.c
 *      Support functions for date/time types.
 *
 * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *      $PostgreSQL: pgsql/src/backend/utils/adt/datetime.c,v 1.208 2009/06/11 14:49:03 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <ctype.h>
#include <float.h>
#include <limits.h>
#include <math.h>

#include "access/xact.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/datetime.h"
#include "utils/memutils.h"
#include "utils/tzparser.h"


static int DecodeNumber(int flen, char *field, bool haveTextMonth,
                   int fmask, int *tmask,
                   struct pg_tm * tm, fsec_t *fsec, bool *is2digits);
static int DecodeNumberField(int len, char *str,
                          int fmask, int *tmask,
                          struct pg_tm * tm, fsec_t *fsec, bool *is2digits);
static int DecodeTime(char *str, int fmask, int range,
               int *tmask, struct pg_tm * tm, fsec_t *fsec);
static int  DecodeTimezone(char *str, int *tzp);
static const datetkn *datebsearch(const char *key, const datetkn *base, int nel);
static int DecodeDate(char *str, int fmask, int *tmask, bool *is2digits,
               struct pg_tm * tm);
static int ValidateDate(int fmask, bool is2digits, bool bc,
                   struct pg_tm * tm);
static void TrimTrailingZeros(char *str);
static void AppendSeconds(char *cp, int sec, fsec_t fsec,
                    int precision, bool fillzeros);
static void AdjustFractSeconds(double frac, struct pg_tm * tm, fsec_t *fsec,
                           int scale);
static void AdjustFractDays(double frac, struct pg_tm * tm, fsec_t *fsec,
                        int scale);


const int   day_tab[2][13] =
{
      {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 0},
      {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 0}
};

char     *months[] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec", NULL};

char     *days[] = {"Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday", NULL};


/*****************************************************************************
 *     PRIVATE ROUTINES                                                                                *
 *****************************************************************************/

/*
 * Definitions for squeezing values into "value"
 * We set aside a high bit for a sign, and scale the timezone offsets
 * in minutes by a factor of 15 (so can represent quarter-hour increments).
 */
#define ABS_SIGNBIT           ((char) 0200)
#define VALMASK               ((char) 0177)
#define POS(n)                (n)
#define NEG(n)                ((n)|ABS_SIGNBIT)
#define SIGNEDCHAR(c)   ((c)&ABS_SIGNBIT? -((c)&VALMASK): (c))
#define FROMVAL(tp)           (-SIGNEDCHAR((tp)->value) * 15) /* uncompress */
#define TOVAL(tp, v)    ((tp)->value = ((v) < 0? NEG((-(v))/15): POS(v)/15))

/*
 * datetktbl holds date/time keywords.
 *
 * Note that this table must be strictly alphabetically ordered to allow an
 * O(ln(N)) search algorithm to be used.
 *
 * The text field is NOT guaranteed to be NULL-terminated.
 *
 * To keep this table reasonably small, we divide the lexval for TZ and DTZ
 * entries by 15 (so they are on 15 minute boundaries) and truncate the text
 * field at TOKMAXLEN characters.
 * Formerly, we divided by 10 rather than 15 but there are a few time zones
 * which are 30 or 45 minutes away from an even hour, most are on an hour
 * boundary, and none on other boundaries.
 *
 * The static table contains no TZ or DTZ entries, rather those are loaded
 * from configuration files and stored in timezonetktbl, which has the same
 * format as the static datetktbl.
 */
static datetkn *timezonetktbl = NULL;

static int  sztimezonetktbl = 0;

static const datetkn datetktbl[] = {
/*    text, token, lexval */
      {EARLY, RESERV, DTK_EARLY}, /* "-infinity" reserved for "early time" */
      {DA_D, ADBC, AD},             /* "ad" for years > 0 */
      {"allballs", RESERV, DTK_ZULU},           /* 00:00:00 */
      {"am", AMPM, AM},
      {"apr", MONTH, 4},
      {"april", MONTH, 4},
      {"at", IGNORE_DTF, 0},        /* "at" (throwaway) */
      {"aug", MONTH, 8},
      {"august", MONTH, 8},
      {DB_C, ADBC, BC},             /* "bc" for years <= 0 */
      {DCURRENT, RESERV, DTK_CURRENT},    /* "current" is always now */
      {"d", UNITS, DTK_DAY},        /* "day of month" for ISO input */
      {"dec", MONTH, 12},
      {"december", MONTH, 12},
      {"dow", RESERV, DTK_DOW},     /* day of week */
      {"doy", RESERV, DTK_DOY},     /* day of year */
      {"dst", DTZMOD, 6},
      {EPOCH, RESERV, DTK_EPOCH}, /* "epoch" reserved for system epoch time */
      {"feb", MONTH, 2},
      {"february", MONTH, 2},
      {"fri", DOW, 5},
      {"friday", DOW, 5},
      {"h", UNITS, DTK_HOUR},       /* "hour" */
      {LATE, RESERV, DTK_LATE},     /* "infinity" reserved for "late time" */
      {INVALID, RESERV, DTK_INVALID},           /* "invalid" reserved for bad time */
      {"isodow", RESERV, DTK_ISODOW},           /* ISO day of week, Sunday == 7 */
      {"isoyear", UNITS, DTK_ISOYEAR},    /* year in terms of the ISO week date */
      {"j", UNITS, DTK_JULIAN},
      {"jan", MONTH, 1},
      {"january", MONTH, 1},
      {"jd", UNITS, DTK_JULIAN},
      {"jul", MONTH, 7},
      {"julian", UNITS, DTK_JULIAN},
      {"july", MONTH, 7},
      {"jun", MONTH, 6},
      {"june", MONTH, 6},
      {"m", UNITS, DTK_MONTH},      /* "month" for ISO input */
      {"mar", MONTH, 3},
      {"march", MONTH, 3},
      {"may", MONTH, 5},
      {"mm", UNITS, DTK_MINUTE},    /* "minute" for ISO input */
      {"mon", DOW, 1},
      {"monday", DOW, 1},
      {"nov", MONTH, 11},
      {"november", MONTH, 11},
      {NOW, RESERV, DTK_NOW},       /* current transaction time */
      {"oct", MONTH, 10},
      {"october", MONTH, 10},
      {"on", IGNORE_DTF, 0},        /* "on" (throwaway) */
      {"pm", AMPM, PM},
      {"s", UNITS, DTK_SECOND},     /* "seconds" for ISO input */
      {"sat", DOW, 6},
      {"saturday", DOW, 6},
      {"sep", MONTH, 9},
      {"sept", MONTH, 9},
      {"september", MONTH, 9},
      {"sun", DOW, 0},
      {"sunday", DOW, 0},
      {"t", ISOTIME, DTK_TIME},     /* Filler for ISO time fields */
      {"thu", DOW, 4},
      {"thur", DOW, 4},
      {"thurs", DOW, 4},
      {"thursday", DOW, 4},
      {TODAY, RESERV, DTK_TODAY}, /* midnight */
      {TOMORROW, RESERV, DTK_TOMORROW},   /* tomorrow midnight */
      {"tue", DOW, 2},
      {"tues", DOW, 2},
      {"tuesday", DOW, 2},
      {"undefined", RESERV, DTK_INVALID}, /* pre-v6.1 invalid time */
      {"wed", DOW, 3},
      {"wednesday", DOW, 3},
      {"weds", DOW, 3},
      {"y", UNITS, DTK_YEAR},       /* "year" for ISO input */
      {YESTERDAY, RESERV, DTK_YESTERDAY}  /* yesterday midnight */
};

static int  szdatetktbl = sizeof datetktbl / sizeof datetktbl[0];

static datetkn deltatktbl[] = {
      /* text, token, lexval */
      {"@", IGNORE_DTF, 0},         /* postgres relative prefix */
      {DAGO, AGO, 0},                     /* "ago" indicates negative time offset */
      {"c", UNITS, DTK_CENTURY},    /* "century" relative */
      {"cent", UNITS, DTK_CENTURY},       /* "century" relative */
      {"centuries", UNITS, DTK_CENTURY},  /* "centuries" relative */
      {DCENTURY, UNITS, DTK_CENTURY},           /* "century" relative */
      {"d", UNITS, DTK_DAY},        /* "day" relative */
      {DDAY, UNITS, DTK_DAY},       /* "day" relative */
      {"days", UNITS, DTK_DAY},     /* "days" relative */
      {"dec", UNITS, DTK_DECADE}, /* "decade" relative */
      {DDECADE, UNITS, DTK_DECADE},       /* "decade" relative */
      {"decades", UNITS, DTK_DECADE},           /* "decades" relative */
      {"decs", UNITS, DTK_DECADE},  /* "decades" relative */
      {"h", UNITS, DTK_HOUR},       /* "hour" relative */
      {DHOUR, UNITS, DTK_HOUR},     /* "hour" relative */
      {"hours", UNITS, DTK_HOUR}, /* "hours" relative */
      {"hr", UNITS, DTK_HOUR},      /* "hour" relative */
      {"hrs", UNITS, DTK_HOUR},     /* "hours" relative */
      {INVALID, RESERV, DTK_INVALID},           /* reserved for invalid time */
      {"m", UNITS, DTK_MINUTE},     /* "minute" relative */
      {"microsecon", UNITS, DTK_MICROSEC},            /* "microsecond" relative */
      {"mil", UNITS, DTK_MILLENNIUM},           /* "millennium" relative */
      {"millennia", UNITS, DTK_MILLENNIUM},           /* "millennia" relative */
      {DMILLENNIUM, UNITS, DTK_MILLENNIUM},           /* "millennium" relative */
      {"millisecon", UNITS, DTK_MILLISEC},            /* relative */
      {"mils", UNITS, DTK_MILLENNIUM},    /* "millennia" relative */
      {"min", UNITS, DTK_MINUTE}, /* "minute" relative */
      {"mins", UNITS, DTK_MINUTE},  /* "minutes" relative */
      {DMINUTE, UNITS, DTK_MINUTE},       /* "minute" relative */
      {"minutes", UNITS, DTK_MINUTE},           /* "minutes" relative */
      {"mon", UNITS, DTK_MONTH},    /* "months" relative */
      {"mons", UNITS, DTK_MONTH}, /* "months" relative */
      {DMONTH, UNITS, DTK_MONTH}, /* "month" relative */
      {"months", UNITS, DTK_MONTH},
      {"ms", UNITS, DTK_MILLISEC},
      {"msec", UNITS, DTK_MILLISEC},
      {DMILLISEC, UNITS, DTK_MILLISEC},
      {"mseconds", UNITS, DTK_MILLISEC},
      {"msecs", UNITS, DTK_MILLISEC},
      {"qtr", UNITS, DTK_QUARTER},  /* "quarter" relative */
      {DQUARTER, UNITS, DTK_QUARTER},           /* "quarter" relative */
      {"s", UNITS, DTK_SECOND},
      {"sec", UNITS, DTK_SECOND},
      {DSECOND, UNITS, DTK_SECOND},
      {"seconds", UNITS, DTK_SECOND},
      {"secs", UNITS, DTK_SECOND},
      {DTIMEZONE, UNITS, DTK_TZ}, /* "timezone" time offset */
      {"timezone_h", UNITS, DTK_TZ_HOUR}, /* timezone hour units */
      {"timezone_m", UNITS, DTK_TZ_MINUTE},           /* timezone minutes units */
      {"undefined", RESERV, DTK_INVALID}, /* pre-v6.1 invalid time */
      {"us", UNITS, DTK_MICROSEC},  /* "microsecond" relative */
      {"usec", UNITS, DTK_MICROSEC},            /* "microsecond" relative */
      {DMICROSEC, UNITS, DTK_MICROSEC},   /* "microsecond" relative */
      {"useconds", UNITS, DTK_MICROSEC},  /* "microseconds" relative */
      {"usecs", UNITS, DTK_MICROSEC},           /* "microseconds" relative */
      {"w", UNITS, DTK_WEEK},       /* "week" relative */
      {DWEEK, UNITS, DTK_WEEK},     /* "week" relative */
      {"weeks", UNITS, DTK_WEEK}, /* "weeks" relative */
      {"y", UNITS, DTK_YEAR},       /* "year" relative */
      {DYEAR, UNITS, DTK_YEAR},     /* "year" relative */
      {"years", UNITS, DTK_YEAR}, /* "years" relative */
      {"yr", UNITS, DTK_YEAR},      /* "year" relative */
      {"yrs", UNITS, DTK_YEAR}      /* "years" relative */
};

static int  szdeltatktbl = sizeof deltatktbl / sizeof deltatktbl[0];

static const datetkn *datecache[MAXDATEFIELDS] = {NULL};

static const datetkn *deltacache[MAXDATEFIELDS] = {NULL};


/*
 * strtoi --- just like strtol, but returns int not long
 */
static int
strtoi(const char *nptr, char **endptr, int base)
{
      long        val;

      val = strtol(nptr, endptr, base);
#ifdef HAVE_LONG_INT_64
      if (val != (long) ((int32) val))
            errno = ERANGE;
#endif
      return (int) val;
}


/*
 * Calendar time to Julian date conversions.
 * Julian date is commonly used in astronomical applications,
 *    since it is numerically accurate and computationally simple.
 * The algorithms here will accurately convert between Julian day
 *    and calendar date for all non-negative Julian days
 *    (i.e. from Nov 24, -4713 on).
 *
 * These routines will be used by other date/time packages
 * - thomas 97/02/25
 *
 * Rewritten to eliminate overflow problems. This now allows the
 * routines to work correctly for all Julian day counts from
 * 0 to 2147483647      (Nov 24, -4713 to Jun 3, 5874898) assuming
 * a 32-bit integer. Longer types should also work to the limits
 * of their precision.
 */

int
date2j(int y, int m, int d)
{
      int               julian;
      int               century;

      if (m > 2)
      {
            m += 1;
            y += 4800;
      }
      else
      {
            m += 13;
            y += 4799;
      }

      century = y / 100;
      julian = y * 365 - 32167;
      julian += y / 4 - century + century / 4;
      julian += 7834 * m / 256 + d;

      return julian;
}     /* date2j() */

void
j2date(int jd, int *year, int *month, int *day)
{
      unsigned int julian;
      unsigned int quad;
      unsigned int extra;
      int               y;

      julian = jd;
      julian += 32044;
      quad = julian / 146097;
      extra = (julian - quad * 146097) * 4 + 3;
      julian += 60 + quad * 3 + extra / 146097;
      quad = julian / 1461;
      julian -= quad * 1461;
      y = julian * 4 / 1461;
      julian = ((y != 0) ? ((julian + 305) % 365) : ((julian + 306) % 366))
            + 123;
      y += quad * 4;
      *year = y - 4800;
      quad = julian * 2141 / 65536;
      *day = julian - 7834 * quad / 256;
      *month = (quad + 10) % 12 + 1;

      return;
}     /* j2date() */


/*
 * j2day - convert Julian date to day-of-week (0..6 == Sun..Sat)
 *
 * Note: various places use the locution j2day(date - 1) to produce a
 * result according to the convention 0..6 = Mon..Sun.      This is a bit of
 * a crock, but will work as long as the computation here is just a modulo.
 */
int
j2day(int date)
{
      unsigned int day;

      day = date;

      day += 1;
      day %= 7;

      return (int) day;
}     /* j2day() */


/*
 * GetCurrentDateTime()
 *
 * Get the transaction start time ("now()") broken down as a struct pg_tm.
 */
void
GetCurrentDateTime(struct pg_tm * tm)
{
      int               tz;
      fsec_t            fsec;

      timestamp2tm(GetCurrentTransactionStartTimestamp(), &tz, tm, &fsec,
                         NULL, NULL);
      /* Note: don't pass NULL tzp to timestamp2tm; affects behavior */
}

/*
 * GetCurrentTimeUsec()
 *
 * Get the transaction start time ("now()") broken down as a struct pg_tm,
 * including fractional seconds and timezone offset.
 */
void
GetCurrentTimeUsec(struct pg_tm * tm, fsec_t *fsec, int *tzp)
{
      int               tz;

      timestamp2tm(GetCurrentTransactionStartTimestamp(), &tz, tm, fsec,
                         NULL, NULL);
      /* Note: don't pass NULL tzp to timestamp2tm; affects behavior */
      if (tzp != NULL)
            *tzp = tz;
}


/* TrimTrailingZeros()
 * ... resulting from printing numbers with full precision.
 *
 * Before Postgres 8.4, this always left at least 2 fractional digits,
 * but conversations on the lists suggest this isn't desired
 * since showing '0.10' is misleading with values of precision(1).
 */
static void
TrimTrailingZeros(char *str)
{
      int               len = strlen(str);

      while (len > 1 && *(str + len - 1) == '0' && *(str + len - 2) != '.')
      {
            len--;
            *(str + len) = '\0';
      }
}

/*
 * Append sections and fractional seconds (if any) at *cp.
 * precision is the max number of fraction digits, fillzeros says to
 * pad to two integral-seconds digits.
 * Note that any sign is stripped from the input seconds values.
 */
static void
AppendSeconds(char *cp, int sec, fsec_t fsec, int precision, bool fillzeros)
{
      if (fsec == 0)
      {
            if (fillzeros)
                  sprintf(cp, "%02d", abs(sec));
            else
                  sprintf(cp, "%d", abs(sec));
      }
      else
      {
#ifdef HAVE_INT64_TIMESTAMP
            if (fillzeros)
                  sprintf(cp, "%02d.%0*d", abs(sec), precision, (int) Abs(fsec));
            else
                  sprintf(cp, "%d.%0*d", abs(sec), precision, (int) Abs(fsec));
#else
            if (fillzeros)
                  sprintf(cp, "%0*.*f", precision + 3, precision, fabs(sec + fsec));
            else
                  sprintf(cp, "%.*f", precision, fabs(sec + fsec));
#endif
            TrimTrailingZeros(cp);
      }
}

/* Variant of above that's specialized to timestamp case */
static void
AppendTimestampSeconds(char *cp, struct pg_tm * tm, fsec_t fsec)
{
      /*
       * In float mode, don't print fractional seconds before 1 AD, since it's
       * unlikely there's any precision left ...
       */
#ifndef HAVE_INT64_TIMESTAMP
      if (tm->tm_year <= 0)
            fsec = 0;
#endif
      AppendSeconds(cp, tm->tm_sec, fsec, MAX_TIMESTAMP_PRECISION, true);
}

/*
 * Multiply frac by scale (to produce seconds) and add to *tm & *fsec.
 * We assume the input frac is less than 1 so overflow is not an issue.
 */
static void
AdjustFractSeconds(double frac, struct pg_tm * tm, fsec_t *fsec, int scale)
{
      int               sec;

      if (frac == 0)
            return;
      frac *= scale;
      sec = (int) frac;
      tm->tm_sec += sec;
      frac -= sec;
#ifdef HAVE_INT64_TIMESTAMP
      *fsec += rint(frac * 1000000);
#else
      *fsec += frac;
#endif
}

/* As above, but initial scale produces days */
static void
AdjustFractDays(double frac, struct pg_tm * tm, fsec_t *fsec, int scale)
{
      int               extra_days;

      if (frac == 0)
            return;
      frac *= scale;
      extra_days = (int) frac;
      tm->tm_mday += extra_days;
      frac -= extra_days;
      AdjustFractSeconds(frac, tm, fsec, SECS_PER_DAY);
}

/* Fetch a fractional-second value with suitable error checking */
static int
ParseFractionalSecond(char *cp, fsec_t *fsec)
{
      double            frac;

      /* Caller should always pass the start of the fraction part */
      Assert(*cp == '.');
      errno = 0;
      frac = strtod(cp, &cp);
      /* check for parse failure */
      if (*cp != '\0' || errno != 0)
            return DTERR_BAD_FORMAT;
#ifdef HAVE_INT64_TIMESTAMP
      *fsec = rint(frac * 1000000);
#else
      *fsec = frac;
#endif
      return 0;
}


/* ParseDateTime()
 *    Break string into tokens based on a date/time context.
 *    Returns 0 if successful, DTERR code if bogus input detected.
 *
 * timestr - the input string
 * workbuf - workspace for field string storage. This must be
 *     larger than the largest legal input for this datetime type --
 *     some additional space will be needed to NUL terminate fields.
 * buflen - the size of workbuf
 * field[] - pointers to field strings are returned in this array
 * ftype[] - field type indicators are returned in this array
 * maxfields - dimensions of the above two arrays
 * *numfields - set to the actual number of fields detected
 *
 * The fields extracted from the input are stored as separate,
 * null-terminated strings in the workspace at workbuf. Any text is
 * converted to lower case.
 *
 * Several field types are assigned:
 *    DTK_NUMBER - digits and (possibly) a decimal point
 *    DTK_DATE - digits and two delimiters, or digits and text
 *    DTK_TIME - digits, colon delimiters, and possibly a decimal point
 *    DTK_STRING - text (no digits or punctuation)
 *    DTK_SPECIAL - leading "+" or "-" followed by text
 *    DTK_TZ - leading "+" or "-" followed by digits (also eats ':', '.', '-')
 *
 * Note that some field types can hold unexpected items:
 *    DTK_NUMBER can hold date fields (yy.ddd)
 *    DTK_STRING can hold months (January) and time zones (PST)
 *    DTK_DATE can hold time zone names (America/New_York, GMT-8)
 */
int
ParseDateTime(const char *timestr, char *workbuf, size_t buflen,
                    char **field, int *ftype, int maxfields, int *numfields)
{
      int               nf = 0;
      const char *cp = timestr;
      char     *bufp = workbuf;
      const char *bufend = workbuf + buflen;

      /*
       * Set the character pointed-to by "bufptr" to "newchar", and increment
       * "bufptr". "end" gives the end of the buffer -- we return an error if
       * there is no space left to append a character to the buffer. Note that
       * "bufptr" is evaluated twice.
       */
#define APPEND_CHAR(bufptr, end, newchar)       \
      do                                                                \
      {                                                                 \
            if (((bufptr) + 1) >= (end))              \
                  return DTERR_BAD_FORMAT;                  \
            *(bufptr)++ = newchar;                          \
      } while (0)

      /* outer loop through fields */
      while (*cp != '\0')
      {
            /* Ignore spaces between fields */
            if (isspace((unsigned char) *cp))
            {
                  cp++;
                  continue;
            }

            /* Record start of current field */
            if (nf >= maxfields)
                  return DTERR_BAD_FORMAT;
            field[nf] = bufp;

            /* leading digit? then date or time */
            if (isdigit((unsigned char) *cp))
            {
                  APPEND_CHAR(bufp, bufend, *cp++);
                  while (isdigit((unsigned char) *cp))
                        APPEND_CHAR(bufp, bufend, *cp++);

                  /* time field? */
                  if (*cp == ':')
                  {
                        ftype[nf] = DTK_TIME;
                        APPEND_CHAR(bufp, bufend, *cp++);
                        while (isdigit((unsigned char) *cp) ||
                                 (*cp == ':') || (*cp == '.'))
                              APPEND_CHAR(bufp, bufend, *cp++);
                  }
                  /* date field? allow embedded text month */
                  else if (*cp == '-' || *cp == '/' || *cp == '.')
                  {
                        /* save delimiting character to use later */
                        char        delim = *cp;

                        APPEND_CHAR(bufp, bufend, *cp++);
                        /* second field is all digits? then no embedded text month */
                        if (isdigit((unsigned char) *cp))
                        {
                              ftype[nf] = ((delim == '.') ? DTK_NUMBER : DTK_DATE);
                              while (isdigit((unsigned char) *cp))
                                    APPEND_CHAR(bufp, bufend, *cp++);

                              /*
                               * insist that the delimiters match to get a three-field
                               * date.
                               */
                              if (*cp == delim)
                              {
                                    ftype[nf] = DTK_DATE;
                                    APPEND_CHAR(bufp, bufend, *cp++);
                                    while (isdigit((unsigned char) *cp) || *cp == delim)
                                          APPEND_CHAR(bufp, bufend, *cp++);
                              }
                        }
                        else
                        {
                              ftype[nf] = DTK_DATE;
                              while (isalnum((unsigned char) *cp) || *cp == delim)
                                    APPEND_CHAR(bufp, bufend, pg_tolower((unsigned char) *cp++));
                        }
                  }

                  /*
                   * otherwise, number only and will determine year, month, day, or
                   * concatenated fields later...
                   */
                  else
                        ftype[nf] = DTK_NUMBER;
            }
            /* Leading decimal point? Then fractional seconds... */
            else if (*cp == '.')
            {
                  APPEND_CHAR(bufp, bufend, *cp++);
                  while (isdigit((unsigned char) *cp))
                        APPEND_CHAR(bufp, bufend, *cp++);

                  ftype[nf] = DTK_NUMBER;
            }

            /*
             * text? then date string, month, day of week, special, or timezone
             */
            else if (isalpha((unsigned char) *cp))
            {
                  bool        is_date;

                  ftype[nf] = DTK_STRING;
                  APPEND_CHAR(bufp, bufend, pg_tolower((unsigned char) *cp++));
                  while (isalpha((unsigned char) *cp))
                        APPEND_CHAR(bufp, bufend, pg_tolower((unsigned char) *cp++));

                  /*
                   * Dates can have embedded '-', '/', or '.' separators.  It could
                   * also be a timezone name containing embedded '/', '+', '-', '_',
                   * or ':' (but '_' or ':' can't be the first punctuation). If the
                   * next character is a digit or '+', we need to check whether what
                   * we have so far is a recognized non-timezone keyword --- if so,
                   * don't believe that this is the start of a timezone.
                   */
                  is_date = false;
                  if (*cp == '-' || *cp == '/' || *cp == '.')
                        is_date = true;
                  else if (*cp == '+' || isdigit((unsigned char) *cp))
                  {
                        *bufp = '\0';     /* null-terminate current field value */
                        /* we need search only the core token table, not TZ names */
                        if (datebsearch(field[nf], datetktbl, szdatetktbl) == NULL)
                              is_date = true;
                  }
                  if (is_date)
                  {
                        ftype[nf] = DTK_DATE;
                        do
                        {
                              APPEND_CHAR(bufp, bufend, pg_tolower((unsigned char) *cp++));
                        } while (*cp == '+' || *cp == '-' ||
                                     *cp == '/' || *cp == '_' ||
                                     *cp == '.' || *cp == ':' ||
                                     isalnum((unsigned char) *cp));
                  }
            }
            /* sign? then special or numeric timezone */
            else if (*cp == '+' || *cp == '-')
            {
                  APPEND_CHAR(bufp, bufend, *cp++);
                  /* soak up leading whitespace */
                  while (isspace((unsigned char) *cp))
                        cp++;
                  /* numeric timezone? */
                  /* note that "DTK_TZ" could also be a signed float or yyyy-mm */
                  if (isdigit((unsigned char) *cp))
                  {
                        ftype[nf] = DTK_TZ;
                        APPEND_CHAR(bufp, bufend, *cp++);
                        while (isdigit((unsigned char) *cp) ||
                                 *cp == ':' || *cp == '.' || *cp == '-')
                              APPEND_CHAR(bufp, bufend, *cp++);
                  }
                  /* special? */
                  else if (isalpha((unsigned char) *cp))
                  {
                        ftype[nf] = DTK_SPECIAL;
                        APPEND_CHAR(bufp, bufend, pg_tolower((unsigned char) *cp++));
                        while (isalpha((unsigned char) *cp))
                              APPEND_CHAR(bufp, bufend, pg_tolower((unsigned char) *cp++));
                  }
                  /* otherwise something wrong... */
                  else
                        return DTERR_BAD_FORMAT;
            }
            /* ignore other punctuation but use as delimiter */
            else if (ispunct((unsigned char) *cp))
            {
                  cp++;
                  continue;
            }
            /* otherwise, something is not right... */
            else
                  return DTERR_BAD_FORMAT;

            /* force in a delimiter after each field */
            *bufp++ = '\0';
            nf++;
      }

      *numfields = nf;

      return 0;
}


/* DecodeDateTime()
 * Interpret previously parsed fields for general date and time.
 * Return 0 if full date, 1 if only time, and negative DTERR code if problems.
 * (Currently, all callers treat 1 as an error return too.)
 *
 *          External format(s):
 *                      "<weekday> <month>-<day>-<year> <hour>:<minute>:<second>"
 *                      "Fri Feb-7-1997 15:23:27"
 *                      "Feb-7-1997 15:23:27"
 *                      "2-7-1997 15:23:27"
 *                      "1997-2-7 15:23:27"
 *                      "1997.038 15:23:27"           (day of year 1-366)
 *          Also supports input in compact time:
 *                      "970207 152327"
 *                      "97038 152327"
 *                      "20011225T040506.789-07"
 *
 * Use the system-provided functions to get the current time zone
 * if not specified in the input string.
 *
 * If the date is outside the range of pg_time_t (in practice that could only
 * happen if pg_time_t is just 32 bits), then assume UTC time zone - thomas
 * 1997-05-27
 */
int
DecodeDateTime(char **field, int *ftype, int nf,
                     int *dtype, struct pg_tm * tm, fsec_t *fsec, int *tzp)
{
      int               fmask = 0,
                        tmask,
                        type;
      int               ptype = 0;        /* "prefix type" for ISO y2001m02d04 format */
      int               i;
      int               val;
      int               dterr;
      int               mer = HR24;
      bool        haveTextMonth = FALSE;
      bool        is2digits = FALSE;
      bool        bc = FALSE;
      pg_tz    *namedTz = NULL;

      /*
       * We'll insist on at least all of the date fields, but initialize the
       * remaining fields in case they are not set later...
       */
      *dtype = DTK_DATE;
      tm->tm_hour = 0;
      tm->tm_min = 0;
      tm->tm_sec = 0;
      *fsec = 0;
      /* don't know daylight savings time status apriori */
      tm->tm_isdst = -1;
      if (tzp != NULL)
            *tzp = 0;

      for (i = 0; i < nf; i++)
      {
            switch (ftype[i])
            {
                  case DTK_DATE:
                        /***
                         * Integral julian day with attached time zone?
                         * All other forms with JD will be separated into
                         * distinct fields, so we handle just this case here.
                         ***/
                        if (ptype == DTK_JULIAN)
                        {
                              char     *cp;
                              int               val;

                              if (tzp == NULL)
                                    return DTERR_BAD_FORMAT;

                              errno = 0;
                              val = strtoi(field[i], &cp, 10);
                              if (errno == ERANGE)
                                    return DTERR_FIELD_OVERFLOW;

                              j2date(val, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
                              /* Get the time zone from the end of the string */
                              dterr = DecodeTimezone(cp, tzp);
                              if (dterr)
                                    return dterr;

                              tmask = DTK_DATE_M | DTK_TIME_M | DTK_M(TZ);
                              ptype = 0;
                              break;
                        }
                        /***
                         * Already have a date? Then this might be a time zone name
                         * with embedded punctuation (e.g. "America/New_York") or a
                         * run-together time with trailing time zone (e.g. hhmmss-zz).
                         * - thomas 2001-12-25
                         *
                         * We consider it a time zone if we already have month & day.
                         * This is to allow the form "mmm dd hhmmss tz year", which
                         * we've historically accepted.
                         ***/
                        else if (ptype != 0 ||
                                     ((fmask & (DTK_M(MONTH) | DTK_M(DAY))) ==
                                      (DTK_M(MONTH) | DTK_M(DAY))))
                        {
                              /* No time zone accepted? Then quit... */
                              if (tzp == NULL)
                                    return DTERR_BAD_FORMAT;

                              if (isdigit((unsigned char) *field[i]) || ptype != 0)
                              {
                                    char     *cp;

                                    if (ptype != 0)
                                    {
                                          /* Sanity check; should not fail this test */
                                          if (ptype != DTK_TIME)
                                                return DTERR_BAD_FORMAT;
                                          ptype = 0;
                                    }

                                    /*
                                     * Starts with a digit but we already have a time
                                     * field? Then we are in trouble with a date and time
                                     * already...
                                     */
                                    if ((fmask & DTK_TIME_M) == DTK_TIME_M)
                                          return DTERR_BAD_FORMAT;

                                    if ((cp = strchr(field[i], '-')) == NULL)
                                          return DTERR_BAD_FORMAT;

                                    /* Get the time zone from the end of the string */
                                    dterr = DecodeTimezone(cp, tzp);
                                    if (dterr)
                                          return dterr;
                                    *cp = '\0';

                                    /*
                                     * Then read the rest of the field as a concatenated
                                     * time
                                     */
                                    dterr = DecodeNumberField(strlen(field[i]), field[i],
                                                                          fmask,
                                                                          &tmask, tm,
                                                                          fsec, &is2digits);
                                    if (dterr < 0)
                                          return dterr;

                                    /*
                                     * modify tmask after returning from
                                     * DecodeNumberField()
                                     */
                                    tmask |= DTK_M(TZ);
                              }
                              else
                              {
                                    namedTz = pg_tzset(field[i]);
                                    if (!namedTz)
                                    {
                                          /*
                                           * We should return an error code instead of
                                           * ereport'ing directly, but then there is no way
                                           * to report the bad time zone name.
                                           */
                                          ereport(ERROR,
                                                      (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                                       errmsg("time zone \"%s\" not recognized",
                                                                  field[i])));
                                    }
                                    /* we'll apply the zone setting below */
                                    tmask = DTK_M(TZ);
                              }
                        }
                        else
                        {
                              dterr = DecodeDate(field[i], fmask,
                                                         &tmask, &is2digits, tm);
                              if (dterr)
                                    return dterr;
                        }
                        break;

                  case DTK_TIME:
                        dterr = DecodeTime(field[i], fmask, INTERVAL_FULL_RANGE,
                                                   &tmask, tm, fsec);
                        if (dterr)
                              return dterr;

                        /*
                         * Check upper limit on hours; other limits checked in
                         * DecodeTime()
                         */
                        /* test for > 24:00:00 */
                        if (tm->tm_hour > 24 ||
                              (tm->tm_hour == 24 &&
                               (tm->tm_min > 0 || tm->tm_sec > 0 || *fsec > 0)))
                              return DTERR_FIELD_OVERFLOW;
                        break;

                  case DTK_TZ:
                        {
                              int               tz;

                              if (tzp == NULL)
                                    return DTERR_BAD_FORMAT;

                              dterr = DecodeTimezone(field[i], &tz);
                              if (dterr)
                                    return dterr;
                              *tzp = tz;
                              tmask = DTK_M(TZ);
                        }
                        break;

                  case DTK_NUMBER:

                        /*
                         * Was this an "ISO date" with embedded field labels? An
                         * example is "y2001m02d04" - thomas 2001-02-04
                         */
                        if (ptype != 0)
                        {
                              char     *cp;
                              int               val;

                              errno = 0;
                              val = strtoi(field[i], &cp, 10);
                              if (errno == ERANGE)
                                    return DTERR_FIELD_OVERFLOW;

                              /*
                               * only a few kinds are allowed to have an embedded
                               * decimal
                               */
                              if (*cp == '.')
                                    switch (ptype)
                                    {
                                          case DTK_JULIAN:
                                          case DTK_TIME:
                                          case DTK_SECOND:
                                                break;
                                          default:
                                                return DTERR_BAD_FORMAT;
                                                break;
                                    }
                              else if (*cp != '\0')
                                    return DTERR_BAD_FORMAT;

                              switch (ptype)
                              {
                                    case DTK_YEAR:
                                          tm->tm_year = val;
                                          tmask = DTK_M(YEAR);
                                          break;

                                    case DTK_MONTH:

                                          /*
                                           * already have a month and hour? then assume
                                           * minutes
                                           */
                                          if ((fmask & DTK_M(MONTH)) != 0 &&
                                                (fmask & DTK_M(HOUR)) != 0)
                                          {
                                                tm->tm_min = val;
                                                tmask = DTK_M(MINUTE);
                                          }
                                          else
                                          {
                                                tm->tm_mon = val;
                                                tmask = DTK_M(MONTH);
                                          }
                                          break;

                                    case DTK_DAY:
                                          tm->tm_mday = val;
                                          tmask = DTK_M(DAY);
                                          break;

                                    case DTK_HOUR:
                                          tm->tm_hour = val;
                                          tmask = DTK_M(HOUR);
                                          break;

                                    case DTK_MINUTE:
                                          tm->tm_min = val;
                                          tmask = DTK_M(MINUTE);
                                          break;

                                    case DTK_SECOND:
                                          tm->tm_sec = val;
                                          tmask = DTK_M(SECOND);
                                          if (*cp == '.')
                                          {
                                                dterr = ParseFractionalSecond(cp, fsec);
                                                if (dterr)
                                                      return dterr;
                                                tmask = DTK_ALL_SECS_M;
                                          }
                                          break;

                                    case DTK_TZ:
                                          tmask = DTK_M(TZ);
                                          dterr = DecodeTimezone(field[i], tzp);
                                          if (dterr)
                                                return dterr;
                                          break;

                                    case DTK_JULIAN:
                                          /***
                                           * previous field was a label for "julian date"?
                                           ***/
                                          tmask = DTK_DATE_M;
                                          j2date(val, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
                                          /* fractional Julian Day? */
                                          if (*cp == '.')
                                          {
                                                double            time;

                                                errno = 0;
                                                time = strtod(cp, &cp);
                                                if (*cp != '\0' || errno != 0)
                                                      return DTERR_BAD_FORMAT;

#ifdef HAVE_INT64_TIMESTAMP
                                                time *= USECS_PER_DAY;
#else
                                                time *= SECS_PER_DAY;
#endif
                                                dt2time(time,
                                                            &tm->tm_hour, &tm->tm_min,
                                                            &tm->tm_sec, fsec);
                                                tmask |= DTK_TIME_M;
                                          }
                                          break;

                                    case DTK_TIME:
                                          /* previous field was "t" for ISO time */
                                          dterr = DecodeNumberField(strlen(field[i]), field[i],
                                                                                (fmask | DTK_DATE_M),
                                                                                &tmask, tm,
                                                                                fsec, &is2digits);
                                          if (dterr < 0)
                                                return dterr;
                                          if (tmask != DTK_TIME_M)
                                                return DTERR_BAD_FORMAT;
                                          break;

                                    default:
                                          return DTERR_BAD_FORMAT;
                                          break;
                              }

                              ptype = 0;
                              *dtype = DTK_DATE;
                        }
                        else
                        {
                              char     *cp;
                              int               flen;

                              flen = strlen(field[i]);
                              cp = strchr(field[i], '.');

                              /* Embedded decimal and no date yet? */
                              if (cp != NULL && !(fmask & DTK_DATE_M))
                              {
                                    dterr = DecodeDate(field[i], fmask,
                                                               &tmask, &is2digits, tm);
                                    if (dterr)
                                          return dterr;
                              }
                              /* embedded decimal and several digits before? */
                              else if (cp != NULL && flen - strlen(cp) > 2)
                              {
                                    /*
                                     * Interpret as a concatenated date or time Set the
                                     * type field to allow decoding other fields later.
                                     * Example: 20011223 or 040506
                                     */
                                    dterr = DecodeNumberField(flen, field[i], fmask,
                                                                          &tmask, tm,
                                                                          fsec, &is2digits);
                                    if (dterr < 0)
                                          return dterr;
                              }
                              else if (flen > 4)
                              {
                                    dterr = DecodeNumberField(flen, field[i], fmask,
                                                                          &tmask, tm,
                                                                          fsec, &is2digits);
                                    if (dterr < 0)
                                          return dterr;
                              }
                              /* otherwise it is a single date/time field... */
                              else
                              {
                                    dterr = DecodeNumber(flen, field[i],
                                                                   haveTextMonth, fmask,
                                                                   &tmask, tm,
                                                                   fsec, &is2digits);
                                    if (dterr)
                                          return dterr;
                              }
                        }
                        break;

                  case DTK_STRING:
                  case DTK_SPECIAL:
                        type = DecodeSpecial(i, field[i], &val);
                        if (type == IGNORE_DTF)
                              continue;

                        tmask = DTK_M(type);
                        switch (type)
                        {
                              case RESERV:
                                    switch (val)
                                    {
                                          case DTK_CURRENT:
                                                ereport(ERROR,
                                                       (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                                        errmsg("date/time value \"current\" is no longer supported")));

                                                return DTERR_BAD_FORMAT;
                                                break;

                                          case DTK_NOW:
                                                tmask = (DTK_DATE_M | DTK_TIME_M | DTK_M(TZ));
                                                *dtype = DTK_DATE;
                                                GetCurrentTimeUsec(tm, fsec, tzp);
                                                break;

                                          case DTK_YESTERDAY:
                                                tmask = DTK_DATE_M;
                                                *dtype = DTK_DATE;
                                                GetCurrentDateTime(tm);
                                                j2date(date2j(tm->tm_year, tm->tm_mon, tm->tm_mday) - 1,
                                                      &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
                                                tm->tm_hour = 0;
                                                tm->tm_min = 0;
                                                tm->tm_sec = 0;
                                                break;

                                          case DTK_TODAY:
                                                tmask = DTK_DATE_M;
                                                *dtype = DTK_DATE;
                                                GetCurrentDateTime(tm);
                                                tm->tm_hour = 0;
                                                tm->tm_min = 0;
                                                tm->tm_sec = 0;
                                                break;

                                          case DTK_TOMORROW:
                                                tmask = DTK_DATE_M;
                                                *dtype = DTK_DATE;
                                                GetCurrentDateTime(tm);
                                                j2date(date2j(tm->tm_year, tm->tm_mon, tm->tm_mday) + 1,
                                                      &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
                                                tm->tm_hour = 0;
                                                tm->tm_min = 0;
                                                tm->tm_sec = 0;
                                                break;

                                          case DTK_ZULU:
                                                tmask = (DTK_TIME_M | DTK_M(TZ));
                                                *dtype = DTK_DATE;
                                                tm->tm_hour = 0;
                                                tm->tm_min = 0;
                                                tm->tm_sec = 0;
                                                if (tzp != NULL)
                                                      *tzp = 0;
                                                break;

                                          default:
                                                *dtype = val;
                                    }

                                    break;

                              case MONTH:

                                    /*
                                     * already have a (numeric) month? then see if we can
                                     * substitute...
                                     */
                                    if ((fmask & DTK_M(MONTH)) && !haveTextMonth &&
                                          !(fmask & DTK_M(DAY)) && tm->tm_mon >= 1 &&
                                          tm->tm_mon <= 31)
                                    {
                                          tm->tm_mday = tm->tm_mon;
                                          tmask = DTK_M(DAY);
                                    }
                                    haveTextMonth = TRUE;
                                    tm->tm_mon = val;
                                    break;

                              case DTZMOD:

                                    /*
                                     * daylight savings time modifier (solves "MET DST"
                                     * syntax)
                                     */
                                    tmask |= DTK_M(DTZ);
                                    tm->tm_isdst = 1;
                                    if (tzp == NULL)
                                          return DTERR_BAD_FORMAT;
                                    *tzp += val * MINS_PER_HOUR;
                                    break;

                              case DTZ:

                                    /*
                                     * set mask for TZ here _or_ check for DTZ later when
                                     * getting default timezone
                                     */
                                    tmask |= DTK_M(TZ);
                                    tm->tm_isdst = 1;
                                    if (tzp == NULL)
                                          return DTERR_BAD_FORMAT;
                                    *tzp = val * MINS_PER_HOUR;
                                    break;

                              case TZ:
                                    tm->tm_isdst = 0;
                                    if (tzp == NULL)
                                          return DTERR_BAD_FORMAT;
                                    *tzp = val * MINS_PER_HOUR;
                                    break;

                              case IGNORE_DTF:
                                    break;

                              case AMPM:
                                    mer = val;
                                    break;

                              case ADBC:
                                    bc = (val == BC);
                                    break;

                              case DOW:
                                    tm->tm_wday = val;
                                    break;

                              case UNITS:
                                    tmask = 0;
                                    ptype = val;
                                    break;

                              case ISOTIME:

                                    /*
                                     * This is a filler field "t" indicating that the next
                                     * field is time. Try to verify that this is sensible.
                                     */
                                    tmask = 0;

                                    /* No preceding date? Then quit... */
                                    if ((fmask & DTK_DATE_M) != DTK_DATE_M)
                                          return DTERR_BAD_FORMAT;

                                    /***
                                     * We will need one of the following fields:
                                     *    DTK_NUMBER should be hhmmss.fff
                                     *    DTK_TIME should be hh:mm:ss.fff
                                     *    DTK_DATE should be hhmmss-zz
                                     ***/
                                    if (i >= nf - 1 ||
                                          (ftype[i + 1] != DTK_NUMBER &&
                                           ftype[i + 1] != DTK_TIME &&
                                           ftype[i + 1] != DTK_DATE))
                                          return DTERR_BAD_FORMAT;

                                    ptype = val;
                                    break;

                              case UNKNOWN_FIELD:

                                    /*
                                     * Before giving up and declaring error, check to see
                                     * if it is an all-alpha timezone name.
                                     */
                                    namedTz = pg_tzset(field[i]);
                                    if (!namedTz)
                                          return DTERR_BAD_FORMAT;
                                    /* we'll apply the zone setting below */
                                    tmask = DTK_M(TZ);
                                    break;

                              default:
                                    return DTERR_BAD_FORMAT;
                        }
                        break;

                  default:
                        return DTERR_BAD_FORMAT;
            }

            if (tmask & fmask)
                  return DTERR_BAD_FORMAT;
            fmask |= tmask;
      }                                         /* end loop over fields */

      /* do final checking/adjustment of Y/M/D fields */
      dterr = ValidateDate(fmask, is2digits, bc, tm);
      if (dterr)
            return dterr;

      /* handle AM/PM */
      if (mer != HR24 && tm->tm_hour > 12)
            return DTERR_FIELD_OVERFLOW;
      if (mer == AM && tm->tm_hour == 12)
            tm->tm_hour = 0;
      else if (mer == PM && tm->tm_hour != 12)
            tm->tm_hour += 12;

      /* do additional checking for full date specs... */
      if (*dtype == DTK_DATE)
      {
            if ((fmask & DTK_DATE_M) != DTK_DATE_M)
            {
                  if ((fmask & DTK_TIME_M) == DTK_TIME_M)
                        return 1;
                  return DTERR_BAD_FORMAT;
            }

            /*
             * If we had a full timezone spec, compute the offset (we could not do
             * it before, because we need the date to resolve DST status).
             */
            if (namedTz != NULL)
            {
                  /* daylight savings time modifier disallowed with full TZ */
                  if (fmask & DTK_M(DTZMOD))
                        return DTERR_BAD_FORMAT;

                  *tzp = DetermineTimeZoneOffset(tm, namedTz);
            }

            /* timezone not specified? then find local timezone if possible */
            if (tzp != NULL && !(fmask & DTK_M(TZ)))
            {
                  /*
                   * daylight savings time modifier but no standard timezone? then
                   * error
                   */
                  if (fmask & DTK_M(DTZMOD))
                        return DTERR_BAD_FORMAT;

                  *tzp = DetermineTimeZoneOffset(tm, session_timezone);
            }
      }

      return 0;
}


/* DetermineTimeZoneOffset()
 *
 * Given a struct pg_tm in which tm_year, tm_mon, tm_mday, tm_hour, tm_min, and
 * tm_sec fields are set, attempt to determine the applicable time zone
 * (ie, regular or daylight-savings time) at that time.  Set the struct pg_tm's
 * tm_isdst field accordingly, and return the actual timezone offset.
 *
 * Note: it might seem that we should use mktime() for this, but bitter
 * experience teaches otherwise.  This code is much faster than most versions
 * of mktime(), anyway.
 */
int
DetermineTimeZoneOffset(struct pg_tm * tm, pg_tz *tzp)
{
      int               date,
                        sec;
      pg_time_t   day,
                        mytime,
                        prevtime,
                        boundary,
                        beforetime,
                        aftertime;
      long int    before_gmtoff,
                        after_gmtoff;
      int               before_isdst,
                        after_isdst;
      int               res;

      if (tzp == session_timezone && HasCTZSet)
      {
            tm->tm_isdst = 0;       /* for lack of a better idea */
            return CTimeZone;
      }

      /*
       * First, generate the pg_time_t value corresponding to the given
       * y/m/d/h/m/s taken as GMT time.  If this overflows, punt and decide the
       * timezone is GMT.  (We only need to worry about overflow on machines
       * where pg_time_t is 32 bits.)
       */
      if (!IS_VALID_JULIAN(tm->tm_year, tm->tm_mon, tm->tm_mday))
            goto overflow;
      date = date2j(tm->tm_year, tm->tm_mon, tm->tm_mday) - UNIX_EPOCH_JDATE;

      day = ((pg_time_t) date) * SECS_PER_DAY;
      if (day / SECS_PER_DAY != date)
            goto overflow;
      sec = tm->tm_sec + (tm->tm_min + tm->tm_hour * MINS_PER_HOUR) * SECS_PER_MINUTE;
      mytime = day + sec;
      /* since sec >= 0, overflow could only be from +day to -mytime */
      if (mytime < 0 && day > 0)
            goto overflow;

      /*
       * Find the DST time boundary just before or following the target time. We
       * assume that all zones have GMT offsets less than 24 hours, and that DST
       * boundaries can't be closer together than 48 hours, so backing up 24
       * hours and finding the "next" boundary will work.
       */
      prevtime = mytime - SECS_PER_DAY;
      if (mytime < 0 && prevtime > 0)
            goto overflow;

      res = pg_next_dst_boundary(&prevtime,
                                             &before_gmtoff, &before_isdst,
                                             &boundary,
                                             &after_gmtoff, &after_isdst,
                                             tzp);
      if (res < 0)
            goto overflow;                /* failure? */

      if (res == 0)
      {
            /* Non-DST zone, life is simple */
            tm->tm_isdst = before_isdst;
            return -(int) before_gmtoff;
      }

      /*
       * Form the candidate pg_time_t values with local-time adjustment
       */
      beforetime = mytime - before_gmtoff;
      if ((before_gmtoff > 0 &&
             mytime < 0 && beforetime > 0) ||
            (before_gmtoff <= 0 &&
             mytime > 0 && beforetime < 0))
            goto overflow;
      aftertime = mytime - after_gmtoff;
      if ((after_gmtoff > 0 &&
             mytime < 0 && aftertime > 0) ||
            (after_gmtoff <= 0 &&
             mytime > 0 && aftertime < 0))
            goto overflow;

      /*
       * If both before or both after the boundary time, we know what to do
       */
      if (beforetime <= boundary && aftertime < boundary)
      {
            tm->tm_isdst = before_isdst;
            return -(int) before_gmtoff;
      }
      if (beforetime > boundary && aftertime >= boundary)
      {
            tm->tm_isdst = after_isdst;
            return -(int) after_gmtoff;
      }

      /*
       * It's an invalid or ambiguous time due to timezone transition. Prefer
       * the standard-time interpretation.
       */
      if (after_isdst == 0)
      {
            tm->tm_isdst = after_isdst;
            return -(int) after_gmtoff;
      }
      tm->tm_isdst = before_isdst;
      return -(int) before_gmtoff;

overflow:
      /* Given date is out of range, so assume UTC */
      tm->tm_isdst = 0;
      return 0;
}


/* DecodeTimeOnly()
 * Interpret parsed string as time fields only.
 * Returns 0 if successful, DTERR code if bogus input detected.
 *
 * Note that support for time zone is here for
 * SQL92 TIME WITH TIME ZONE, but it reveals
 * bogosity with SQL92 date/time standards, since
 * we must infer a time zone from current time.
 * - thomas 2000-03-10
 * Allow specifying date to get a better time zone,
 * if time zones are allowed. - thomas 2001-12-26
 */
int
DecodeTimeOnly(char **field, int *ftype, int nf,
                     int *dtype, struct pg_tm * tm, fsec_t *fsec, int *tzp)
{
      int               fmask = 0,
                        tmask,
                        type;
      int               ptype = 0;        /* "prefix type" for ISO h04mm05s06 format */
      int               i;
      int               val;
      int               dterr;
      bool        is2digits = FALSE;
      bool        bc = FALSE;
      int               mer = HR24;
      pg_tz    *namedTz = NULL;

      *dtype = DTK_TIME;
      tm->tm_hour = 0;
      tm->tm_min = 0;
      tm->tm_sec = 0;
      *fsec = 0;
      /* don't know daylight savings time status apriori */
      tm->tm_isdst = -1;

      if (tzp != NULL)
            *tzp = 0;

      for (i = 0; i < nf; i++)
      {
            switch (ftype[i])
            {
                  case DTK_DATE:

                        /*
                         * Time zone not allowed? Then should not accept dates or time
                         * zones no matter what else!
                         */
                        if (tzp == NULL)
                              return DTERR_BAD_FORMAT;

                        /* Under limited circumstances, we will accept a date... */
                        if (i == 0 && nf >= 2 &&
                              (ftype[nf - 1] == DTK_DATE || ftype[1] == DTK_TIME))
                        {
                              dterr = DecodeDate(field[i], fmask,
                                                         &tmask, &is2digits, tm);
                              if (dterr)
                                    return dterr;
                        }
                        /* otherwise, this is a time and/or time zone */
                        else
                        {
                              if (isdigit((unsigned char) *field[i]))
                              {
                                    char     *cp;

                                    /*
                                     * Starts with a digit but we already have a time
                                     * field? Then we are in trouble with time already...
                                     */
                                    if ((fmask & DTK_TIME_M) == DTK_TIME_M)
                                          return DTERR_BAD_FORMAT;

                                    /*
                                     * Should not get here and fail. Sanity check only...
                                     */
                                    if ((cp = strchr(field[i], '-')) == NULL)
                                          return DTERR_BAD_FORMAT;

                                    /* Get the time zone from the end of the string */
                                    dterr = DecodeTimezone(cp, tzp);
                                    if (dterr)
                                          return dterr;
                                    *cp = '\0';

                                    /*
                                     * Then read the rest of the field as a concatenated
                                     * time
                                     */
                                    dterr = DecodeNumberField(strlen(field[i]), field[i],
                                                                          (fmask | DTK_DATE_M),
                                                                          &tmask, tm,
                                                                          fsec, &is2digits);
                                    if (dterr < 0)
                                          return dterr;
                                    ftype[i] = dterr;

                                    tmask |= DTK_M(TZ);
                              }
                              else
                              {
                                    namedTz = pg_tzset(field[i]);
                                    if (!namedTz)
                                    {
                                          /*
                                           * We should return an error code instead of
                                           * ereport'ing directly, but then there is no way
                                           * to report the bad time zone name.
                                           */
                                          ereport(ERROR,
                                                      (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                                                       errmsg("time zone \"%s\" not recognized",
                                                                  field[i])));
                                    }
                                    /* we'll apply the zone setting below */
                                    ftype[i] = DTK_TZ;
                                    tmask = DTK_M(TZ);
                              }
                        }
                        break;

                  case DTK_TIME:
                        dterr = DecodeTime(field[i], (fmask | DTK_DATE_M),
                                                   INTERVAL_FULL_RANGE,
                                                   &tmask, tm, fsec);
                        if (dterr)
                              return dterr;
                        break;

                  case DTK_TZ:
                        {
                              int               tz;

                              if (tzp == NULL)
                                    return DTERR_BAD_FORMAT;

                              dterr = DecodeTimezone(field[i], &tz);
                              if (dterr)
                                    return dterr;
                              *tzp = tz;
                              tmask = DTK_M(TZ);
                        }
                        break;

                  case DTK_NUMBER:

                        /*
                         * Was this an "ISO time" with embedded field labels? An
                         * example is "h04m05s06" - thomas 2001-02-04
                         */
                        if (ptype != 0)
                        {
                              char     *cp;
                              int               val;

                              /* Only accept a date under limited circumstances */
                              switch (ptype)
                              {
                                    case DTK_JULIAN:
                                    case DTK_YEAR:
                                    case DTK_MONTH:
                                    case DTK_DAY:
                                          if (tzp == NULL)
                                                return DTERR_BAD_FORMAT;
                                    default:
                                          break;
                              }

                              errno = 0;
                              val = strtoi(field[i], &cp, 10);
                              if (errno == ERANGE)
                                    return DTERR_FIELD_OVERFLOW;

                              /*
                               * only a few kinds are allowed to have an embedded
                               * decimal
                               */
                              if (*cp == '.')
                                    switch (ptype)
                                    {
                                          case DTK_JULIAN:
                                          case DTK_TIME:
                                          case DTK_SECOND:
                                                break;
                                          default:
                                                return DTERR_BAD_FORMAT;
                                                break;
                                    }
                              else if (*cp != '\0')
                                    return DTERR_BAD_FORMAT;

                              switch (ptype)
                              {
                                    case DTK_YEAR:
                                          tm->tm_year = val;
                                          tmask = DTK_M(YEAR);
                                          break;

                                    case DTK_MONTH:

                                          /*
                                           * already have a month and hour? then assume
                                           * minutes
                                           */
                                          if ((fmask & DTK_M(MONTH)) != 0 &&
                                                (fmask & DTK_M(HOUR)) != 0)
                                          {
                                                tm->tm_min = val;
                                                tmask = DTK_M(MINUTE);
                                          }
                                          else
                                          {
                                                tm->tm_mon = val;
                                                tmask = DTK_M(MONTH);
                                          }
                                          break;

                                    case DTK_DAY:
                                          tm->tm_mday = val;
                                          tmask = DTK_M(DAY);
                                          break;

                                    case DTK_HOUR:
                                          tm->tm_hour = val;
                                          tmask = DTK_M(HOUR);
                                          break;

                                    case DTK_MINUTE:
                                          tm->tm_min = val;
                                          tmask = DTK_M(MINUTE);
                                          break;

                                    case DTK_SECOND:
                                          tm->tm_sec = val;
                                          tmask = DTK_M(SECOND);
                                          if (*cp == '.')
                                          {
                                                dterr = ParseFractionalSecond(cp, fsec);
                                                if (dterr)
                                                      return dterr;
                                                tmask = DTK_ALL_SECS_M;
                                          }
                                          break;

                                    case DTK_TZ:
                                          tmask = DTK_M(TZ);
                                          dterr = DecodeTimezone(field[i], tzp);
                                          if (dterr)
                                                return dterr;
                                          break;

                                    case DTK_JULIAN:
                                          /***
                                           * previous field was a label for "julian date"?
                                           ***/
                                          tmask = DTK_DATE_M;
                                          j2date(val, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
                                          if (*cp == '.')
                                          {
                                                double            time;

                                                errno = 0;
                                                time = strtod(cp, &cp);
                                                if (*cp != '\0' || errno != 0)
                                                      return DTERR_BAD_FORMAT;

#ifdef HAVE_INT64_TIMESTAMP
                                                time *= USECS_PER_DAY;
#else
                                                time *= SECS_PER_DAY;
#endif
                                                dt2time(time,
                                                            &tm->tm_hour, &tm->tm_min,
                                                            &tm->tm_sec, fsec);
                                                tmask |= DTK_TIME_M;
                                          }
                                          break;

                                    case DTK_TIME:
                                          /* previous field was "t" for ISO time */
                                          dterr = DecodeNumberField(strlen(field[i]), field[i],
                                                                                (fmask | DTK_DATE_M),
                                                                                &tmask, tm,
                                                                                fsec, &is2digits);
                                          if (dterr < 0)
                                                return dterr;
                                          ftype[i] = dterr;

                                          if (tmask != DTK_TIME_M)
                                                return DTERR_BAD_FORMAT;
                                          break;

                                    default:
                                          return DTERR_BAD_FORMAT;
                                          break;
                              }

                              ptype = 0;
                              *dtype = DTK_DATE;
                        }
                        else
                        {
                              char     *cp;
                              int               flen;

                              flen = strlen(field[i]);
                              cp = strchr(field[i], '.');

                              /* Embedded decimal? */
                              if (cp != NULL)
                              {
                                    /*
                                     * Under limited circumstances, we will accept a
                                     * date...
                                     */
                                    if (i == 0 && nf >= 2 && ftype[nf - 1] == DTK_DATE)
                                    {
                                          dterr = DecodeDate(field[i], fmask,
                                                                     &tmask, &is2digits, tm);
                                          if (dterr)
                                                return dterr;
                                    }
                                    /* embedded decimal and several digits before? */
                                    else if (flen - strlen(cp) > 2)
                                    {
                                          /*
                                           * Interpret as a concatenated date or time Set
                                           * the type field to allow decoding other fields
                                           * later. Example: 20011223 or 040506
                                           */
                                          dterr = DecodeNumberField(flen, field[i],
                                                                                (fmask | DTK_DATE_M),
                                                                                &tmask, tm,
                                                                                fsec, &is2digits);
                                          if (dterr < 0)
                                                return dterr;
                                          ftype[i] = dterr;
                                    }
                                    else
                                          return DTERR_BAD_FORMAT;
                              }
                              else if (flen > 4)
                              {
                                    dterr = DecodeNumberField(flen, field[i],
                                                                          (fmask | DTK_DATE_M),
                                                                          &tmask, tm,
                                                                          fsec, &is2digits);
                                    if (dterr < 0)
                                          return dterr;
                                    ftype[i] = dterr;
                              }
                              /* otherwise it is a single date/time field... */
                              else
                              {
                                    dterr = DecodeNumber(flen, field[i],
                                                                   FALSE,
                                                                   (fmask | DTK_DATE_M),
                                                                   &tmask, tm,
                                                                   fsec, &is2digits);
                                    if (dterr)
                                          return dterr;
                              }
                        }
                        break;

                  case DTK_STRING:
                  case DTK_SPECIAL:
                        type = DecodeSpecial(i, field[i], &val);
                        if (type == IGNORE_DTF)
                              continue;

                        tmask = DTK_M(type);
                        switch (type)
                        {
                              case RESERV:
                                    switch (val)
                                    {
                                          case DTK_CURRENT:
                                                ereport(ERROR,
                                                       (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                                        errmsg("date/time value \"current\" is no longer supported")));
                                                return DTERR_BAD_FORMAT;
                                                break;

                                          case DTK_NOW:
                                                tmask = DTK_TIME_M;
                                                *dtype = DTK_TIME;
                                                GetCurrentTimeUsec(tm, fsec, NULL);
                                                break;

                                          case DTK_ZULU:
                                                tmask = (DTK_TIME_M | DTK_M(TZ));
                                                *dtype = DTK_TIME;
                                                tm->tm_hour = 0;
                                                tm->tm_min = 0;
                                                tm->tm_sec = 0;
                                                tm->tm_isdst = 0;
                                                break;

                                          default:
                                                return DTERR_BAD_FORMAT;
                                    }

                                    break;

                              case DTZMOD:

                                    /*
                                     * daylight savings time modifier (solves "MET DST"
                                     * syntax)
                                     */
                                    tmask |= DTK_M(DTZ);
                                    tm->tm_isdst = 1;
                                    if (tzp == NULL)
                                          return DTERR_BAD_FORMAT;
                                    *tzp += val * MINS_PER_HOUR;
                                    break;

                              case DTZ:

                                    /*
                                     * set mask for TZ here _or_ check for DTZ later when
                                     * getting default timezone
                                     */
                                    tmask |= DTK_M(TZ);
                                    tm->tm_isdst = 1;
                                    if (tzp == NULL)
                                          return DTERR_BAD_FORMAT;
                                    *tzp = val * MINS_PER_HOUR;
                                    ftype[i] = DTK_TZ;
                                    break;

                              case TZ:
                                    tm->tm_isdst = 0;
                                    if (tzp == NULL)
                                          return DTERR_BAD_FORMAT;
                                    *tzp = val * MINS_PER_HOUR;
                                    ftype[i] = DTK_TZ;
                                    break;

                              case IGNORE_DTF:
                                    break;

                              case AMPM:
                                    mer = val;
                                    break;

                              case ADBC:
                                    bc = (val == BC);
                                    break;

                              case UNITS:
                                    tmask = 0;
                                    ptype = val;
                                    break;

                              case ISOTIME:
                                    tmask = 0;

                                    /***
                                     * We will need one of the following fields:
                                     *    DTK_NUMBER should be hhmmss.fff
                                     *    DTK_TIME should be hh:mm:ss.fff
                                     *    DTK_DATE should be hhmmss-zz
                                     ***/
                                    if (i >= nf - 1 ||
                                          (ftype[i + 1] != DTK_NUMBER &&
                                           ftype[i + 1] != DTK_TIME &&
                                           ftype[i + 1] != DTK_DATE))
                                          return DTERR_BAD_FORMAT;

                                    ptype = val;
                                    break;

                              case UNKNOWN_FIELD:

                                    /*
                                     * Before giving up and declaring error, check to see
                                     * if it is an all-alpha timezone name.
                                     */
                                    namedTz = pg_tzset(field[i]);
                                    if (!namedTz)
                                          return DTERR_BAD_FORMAT;
                                    /* we'll apply the zone setting below */
                                    tmask = DTK_M(TZ);
                                    break;

                              default:
                                    return DTERR_BAD_FORMAT;
                        }
                        break;

                  default:
                        return DTERR_BAD_FORMAT;
            }

            if (tmask & fmask)
                  return DTERR_BAD_FORMAT;
            fmask |= tmask;
      }                                         /* end loop over fields */

      /* do final checking/adjustment of Y/M/D fields */
      dterr = ValidateDate(fmask, is2digits, bc, tm);
      if (dterr)
            return dterr;

      /* handle AM/PM */
      if (mer != HR24 && tm->tm_hour > 12)
            return DTERR_FIELD_OVERFLOW;
      if (mer == AM && tm->tm_hour == 12)
            tm->tm_hour = 0;
      else if (mer == PM && tm->tm_hour != 12)
            tm->tm_hour += 12;

      if (tm->tm_hour < 0 || tm->tm_min < 0 || tm->tm_min > 59 ||
            tm->tm_sec < 0 || tm->tm_sec > 60 || tm->tm_hour > 24 ||
      /* test for > 24:00:00 */
            (tm->tm_hour == 24 &&
             (tm->tm_min > 0 || tm->tm_sec > 0 || *fsec > 0)) ||
#ifdef HAVE_INT64_TIMESTAMP
            *fsec < INT64CONST(0) || *fsec > USECS_PER_SEC
#else
            *fsec < 0 || *fsec > 1
#endif
            )
            return DTERR_FIELD_OVERFLOW;

      if ((fmask & DTK_TIME_M) != DTK_TIME_M)
            return DTERR_BAD_FORMAT;

      /*
       * If we had a full timezone spec, compute the offset (we could not do it
       * before, because we may need the date to resolve DST status).
       */
      if (namedTz != NULL)
      {
            long int    gmtoff;

            /* daylight savings time modifier disallowed with full TZ */
            if (fmask & DTK_M(DTZMOD))
                  return DTERR_BAD_FORMAT;

            /* if non-DST zone, we do not need to know the date */
            if (pg_get_timezone_offset(namedTz, &gmtoff))
            {
                  *tzp = -(int) gmtoff;
            }
            else
            {
                  /* a date has to be specified */
                  if ((fmask & DTK_DATE_M) != DTK_DATE_M)
                        return DTERR_BAD_FORMAT;
                  *tzp = DetermineTimeZoneOffset(tm, namedTz);
            }
      }

      /* timezone not specified? then find local timezone if possible */
      if (tzp != NULL && !(fmask & DTK_M(TZ)))
      {
            struct pg_tm tt,
                           *tmp = &tt;

            /*
             * daylight savings time modifier but no standard timezone? then error
             */
            if (fmask & DTK_M(DTZMOD))
                  return DTERR_BAD_FORMAT;

            if ((fmask & DTK_DATE_M) == 0)
                  GetCurrentDateTime(tmp);
            else
            {
                  tmp->tm_year = tm->tm_year;
                  tmp->tm_mon = tm->tm_mon;
                  tmp->tm_mday = tm->tm_mday;
            }
            tmp->tm_hour = tm->tm_hour;
            tmp->tm_min = tm->tm_min;
            tmp->tm_sec = tm->tm_sec;
            *tzp = DetermineTimeZoneOffset(tmp, session_timezone);
            tm->tm_isdst = tmp->tm_isdst;
      }

      return 0;
}

/* DecodeDate()
 * Decode date string which includes delimiters.
 * Return 0 if okay, a DTERR code if not.
 *
 *    str: field to be parsed
 *    fmask: bitmask for field types already seen
 *    *tmask: receives bitmask for fields found here
 *    *is2digits: set to TRUE if we find 2-digit year
 *    *tm: field values are stored into appropriate members of this struct
 */
static int
DecodeDate(char *str, int fmask, int *tmask, bool *is2digits,
               struct pg_tm * tm)
{
      fsec_t            fsec;
      int               nf = 0;
      int               i,
                        len;
      int               dterr;
      bool        haveTextMonth = FALSE;
      int               type,
                        val,
                        dmask = 0;
      char     *field[MAXDATEFIELDS];

      *tmask = 0;

      /* parse this string... */
      while (*str != '\0' && nf < MAXDATEFIELDS)
      {
            /* skip field separators */
            while (!isalnum((unsigned char) *str))
                  str++;

            field[nf] = str;
            if (isdigit((unsigned char) *str))
            {
                  while (isdigit((unsigned char) *str))
                        str++;
            }
            else if (isalpha((unsigned char) *str))
            {
                  while (isalpha((unsigned char) *str))
                        str++;
            }

            /* Just get rid of any non-digit, non-alpha characters... */
            if (*str != '\0')
                  *str++ = '\0';
            nf++;
      }

      /* look first for text fields, since that will be unambiguous month */
      for (i = 0; i < nf; i++)
      {
            if (isalpha((unsigned char) *field[i]))
            {
                  type = DecodeSpecial(i, field[i], &val);
                  if (type == IGNORE_DTF)
                        continue;

                  dmask = DTK_M(type);
                  switch (type)
                  {
                        case MONTH:
                              tm->tm_mon = val;
                              haveTextMonth = TRUE;
                              break;

                        default:
                              return DTERR_BAD_FORMAT;
                  }
                  if (fmask & dmask)
                        return DTERR_BAD_FORMAT;

                  fmask |= dmask;
                  *tmask |= dmask;

                  /* mark this field as being completed */
                  field[i] = NULL;
            }
      }

      /* now pick up remaining numeric fields */
      for (i = 0; i < nf; i++)
      {
            if (field[i] == NULL)
                  continue;

            if ((len = strlen(field[i])) <= 0)
                  return DTERR_BAD_FORMAT;

            dterr = DecodeNumber(len, field[i], haveTextMonth, fmask,
                                           &dmask, tm,
                                           &fsec, is2digits);
            if (dterr)
                  return dterr;

            if (fmask & dmask)
                  return DTERR_BAD_FORMAT;

            fmask |= dmask;
            *tmask |= dmask;
      }

      if ((fmask & ~(DTK_M(DOY) | DTK_M(TZ))) != DTK_DATE_M)
            return DTERR_BAD_FORMAT;

      /* validation of the field values must wait until ValidateDate() */

      return 0;
}

/* ValidateDate()
 * Check valid year/month/day values, handle BC and DOY cases
 * Return 0 if okay, a DTERR code if not.
 */
static int
ValidateDate(int fmask, bool is2digits, bool bc, struct pg_tm * tm)
{
      if (fmask & DTK_M(YEAR))
      {
            if (bc)
            {
                  /* there is no year zero in AD/BC notation */
                  if (tm->tm_year <= 0)
                        return DTERR_FIELD_OVERFLOW;
                  /* internally, we represent 1 BC as year zero, 2 BC as -1, etc */
                  tm->tm_year = -(tm->tm_year - 1);
            }
            else if (is2digits)
            {
                  /* process 1 or 2-digit input as 1970-2069 AD, allow '0' and '00' */
                  if (tm->tm_year < 0)    /* just paranoia */
                        return DTERR_FIELD_OVERFLOW;
                  if (tm->tm_year < 70)
                        tm->tm_year += 2000;
                  else if (tm->tm_year < 100)
                        tm->tm_year += 1900;
            }
            else
            {
                  /* there is no year zero in AD/BC notation */
                  if (tm->tm_year <= 0)
                        return DTERR_FIELD_OVERFLOW;
            }
      }

      /* now that we have correct year, decode DOY */
      if (fmask & DTK_M(DOY))
      {
            j2date(date2j(tm->tm_year, 1, 1) + tm->tm_yday - 1,
                     &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
      }

      /* check for valid month */
      if (fmask & DTK_M(MONTH))
      {
            if (tm->tm_mon < 1 || tm->tm_mon > MONTHS_PER_YEAR)
                  return DTERR_MD_FIELD_OVERFLOW;
      }

      /* minimal check for valid day */
      if (fmask & DTK_M(DAY))
      {
            if (tm->tm_mday < 1 || tm->tm_mday > 31)
                  return DTERR_MD_FIELD_OVERFLOW;
      }

      if ((fmask & DTK_DATE_M) == DTK_DATE_M)
      {
            /*
             * Check for valid day of month, now that we know for sure the month
             * and year.  Note we don't use MD_FIELD_OVERFLOW here, since it seems
             * unlikely that "Feb 29" is a YMD-order error.
             */
            if (tm->tm_mday > day_tab[isleap(tm->tm_year)][tm->tm_mon - 1])
                  return DTERR_FIELD_OVERFLOW;
      }

      return 0;
}


/* DecodeTime()
 * Decode time string which includes delimiters.
 * Return 0 if okay, a DTERR code if not.
 *
 * Only check the lower limit on hours, since this same code can be
 * used to represent time spans.
 */
static int
DecodeTime(char *str, int fmask, int range,
               int *tmask, struct pg_tm * tm, fsec_t *fsec)
{
      char     *cp;
      int               dterr;

      *tmask = DTK_TIME_M;

      errno = 0;
      tm->tm_hour = strtoi(str, &cp, 10);
      if (errno == ERANGE)
            return DTERR_FIELD_OVERFLOW;
      if (*cp != ':')
            return DTERR_BAD_FORMAT;
      errno = 0;
      tm->tm_min = strtoi(cp + 1, &cp, 10);
      if (errno == ERANGE)
            return DTERR_FIELD_OVERFLOW;
      if (*cp == '\0')
      {
            tm->tm_sec = 0;
            *fsec = 0;
            /* If it's a MINUTE TO SECOND interval, take 2 fields as being mm:ss */
            if (range == (INTERVAL_MASK(MINUTE) | INTERVAL_MASK(SECOND)))
            {
                  tm->tm_sec = tm->tm_min;
                  tm->tm_min = tm->tm_hour;
                  tm->tm_hour = 0;
            }
      }
      else if (*cp == '.')
      {
            /* always assume mm:ss.sss is MINUTE TO SECOND */
            dterr = ParseFractionalSecond(cp, fsec);
            if (dterr)
                  return dterr;
            tm->tm_sec = tm->tm_min;
            tm->tm_min = tm->tm_hour;
            tm->tm_hour = 0;
      }
      else if (*cp == ':')
      {
            errno = 0;
            tm->tm_sec = strtoi(cp + 1, &cp, 10);
            if (errno == ERANGE)
                  return DTERR_FIELD_OVERFLOW;
            if (*cp == '\0')
                  *fsec = 0;
            else if (*cp == '.')
            {
                  dterr = ParseFractionalSecond(cp, fsec);
                  if (dterr)
                        return dterr;
            }
            else
                  return DTERR_BAD_FORMAT;
      }
      else
            return DTERR_BAD_FORMAT;

      /* do a sanity check */
#ifdef HAVE_INT64_TIMESTAMP
      if (tm->tm_hour < 0 || tm->tm_min < 0 || tm->tm_min > 59 ||
            tm->tm_sec < 0 || tm->tm_sec > 60 || *fsec < INT64CONST(0) ||
            *fsec > USECS_PER_SEC)
            return DTERR_FIELD_OVERFLOW;
#else
      if (tm->tm_hour < 0 || tm->tm_min < 0 || tm->tm_min > 59 ||
            tm->tm_sec < 0 || tm->tm_sec > 60 || *fsec < 0 || *fsec > 1)
            return DTERR_FIELD_OVERFLOW;
#endif

      return 0;
}


/* DecodeNumber()
 * Interpret plain numeric field as a date value in context.
 * Return 0 if okay, a DTERR code if not.
 */
static int
DecodeNumber(int flen, char *str, bool haveTextMonth, int fmask,
                   int *tmask, struct pg_tm * tm, fsec_t *fsec, bool *is2digits)
{
      int               val;
      char     *cp;
      int               dterr;

      *tmask = 0;

      errno = 0;
      val = strtoi(str, &cp, 10);
      if (errno == ERANGE)
            return DTERR_FIELD_OVERFLOW;
      if (cp == str)
            return DTERR_BAD_FORMAT;

      if (*cp == '.')
      {
            /*
             * More than two digits before decimal point? Then could be a date or
             * a run-together time: 2001.360 20011225 040506.789
             */
            if (cp - str > 2)
            {
                  dterr = DecodeNumberField(flen, str,
                                                        (fmask | DTK_DATE_M),
                                                        tmask, tm,
                                                        fsec, is2digits);
                  if (dterr < 0)
                        return dterr;
                  return 0;
            }

            dterr = ParseFractionalSecond(cp, fsec);
            if (dterr)
                  return dterr;
      }
      else if (*cp != '\0')
            return DTERR_BAD_FORMAT;

      /* Special case for day of year */
      if (flen == 3 && (fmask & DTK_DATE_M) == DTK_M(YEAR) && val >= 1 &&
            val <= 366)
      {
            *tmask = (DTK_M(DOY) | DTK_M(MONTH) | DTK_M(DAY));
            tm->tm_yday = val;
            /* tm_mon and tm_mday can't actually be set yet ... */
            return 0;
      }

      /* Switch based on what we have so far */
      switch (fmask & DTK_DATE_M)
      {
            case 0:

                  /*
                   * Nothing so far; make a decision about what we think the input
                   * is.      There used to be lots of heuristics here, but the
                   * consensus now is to be paranoid.  It *must* be either
                   * YYYY-MM-DD (with a more-than-two-digit year field), or the
                   * field order defined by DateOrder.
                   */
                  if (flen >= 3 || DateOrder == DATEORDER_YMD)
                  {
                        *tmask = DTK_M(YEAR);
                        tm->tm_year = val;
                  }
                  else if (DateOrder == DATEORDER_DMY)
                  {
                        *tmask = DTK_M(DAY);
                        tm->tm_mday = val;
                  }
                  else
                  {
                        *tmask = DTK_M(MONTH);
                        tm->tm_mon = val;
                  }
                  break;

            case (DTK_M(YEAR)):
                  /* Must be at second field of YY-MM-DD */
                  *tmask = DTK_M(MONTH);
                  tm->tm_mon = val;
                  break;

            case (DTK_M(MONTH)):
                  if (haveTextMonth)
                  {
                        /*
                         * We are at the first numeric field of a date that included a
                         * textual month name.  We want to support the variants
                         * MON-DD-YYYY, DD-MON-YYYY, and YYYY-MON-DD as unambiguous
                         * inputs.  We will also accept MON-DD-YY or DD-MON-YY in
                         * either DMY or MDY modes, as well as YY-MON-DD in YMD mode.
                         */
                        if (flen >= 3 || DateOrder == DATEORDER_YMD)
                        {
                              *tmask = DTK_M(YEAR);
                              tm->tm_year = val;
                        }
                        else
                        {
                              *tmask = DTK_M(DAY);
                              tm->tm_mday = val;
                        }
                  }
                  else
                  {
                        /* Must be at second field of MM-DD-YY */
                        *tmask = DTK_M(DAY);
                        tm->tm_mday = val;
                  }
                  break;

            case (DTK_M(YEAR) | DTK_M(MONTH)):
                  if (haveTextMonth)
                  {
                        /* Need to accept DD-MON-YYYY even in YMD mode */
                        if (flen >= 3 && *is2digits)
                        {
                              /* Guess that first numeric field is day was wrong */
                              *tmask = DTK_M(DAY);          /* YEAR is already set */
                              tm->tm_mday = tm->tm_year;
                              tm->tm_year = val;
                              *is2digits = FALSE;
                        }
                        else
                        {
                              *tmask = DTK_M(DAY);
                              tm->tm_mday = val;
                        }
                  }
                  else
                  {
                        /* Must be at third field of YY-MM-DD */
                        *tmask = DTK_M(DAY);
                        tm->tm_mday = val;
                  }
                  break;

            case (DTK_M(DAY)):
                  /* Must be at second field of DD-MM-YY */
                  *tmask = DTK_M(MONTH);
                  tm->tm_mon = val;
                  break;

            case (DTK_M(MONTH) | DTK_M(DAY)):
                  /* Must be at third field of DD-MM-YY or MM-DD-YY */
                  *tmask = DTK_M(YEAR);
                  tm->tm_year = val;
                  break;

            case (DTK_M(YEAR) | DTK_M(MONTH) | DTK_M(DAY)):
                  /* we have all the date, so it must be a time field */
                  dterr = DecodeNumberField(flen, str, fmask,
                                                        tmask, tm,
                                                        fsec, is2digits);
                  if (dterr < 0)
                        return dterr;
                  return 0;

            default:
                  /* Anything else is bogus input */
                  return DTERR_BAD_FORMAT;
      }

      /*
       * When processing a year field, mark it for adjustment if it's only one
       * or two digits.
       */
      if (*tmask == DTK_M(YEAR))
            *is2digits = (flen <= 2);

      return 0;
}


/* DecodeNumberField()
 * Interpret numeric string as a concatenated date or time field.
 * Return a DTK token (>= 0) if successful, a DTERR code (< 0) if not.
 *
 * Use the context of previously decoded fields to help with
 * the interpretation.
 */
static int
DecodeNumberField(int len, char *str, int fmask,
                        int *tmask, struct pg_tm * tm, fsec_t *fsec, bool *is2digits)
{
      char     *cp;

      /*
       * Have a decimal point? Then this is a date or something with a seconds
       * field...
       */
      if ((cp = strchr(str, '.')) != NULL)
      {
            /*
             * Can we use ParseFractionalSecond here?  Not clear whether trailing
             * junk should be rejected ...
             */
            double            frac;

            errno = 0;
            frac = strtod(cp, NULL);
            if (errno != 0)
                  return DTERR_BAD_FORMAT;
#ifdef HAVE_INT64_TIMESTAMP
            *fsec = rint(frac * 1000000);
#else
            *fsec = frac;
#endif
            /* Now truncate off the fraction for further processing */
            *cp = '\0';
            len = strlen(str);
      }
      /* No decimal point and no complete date yet? */
      else if ((fmask & DTK_DATE_M) != DTK_DATE_M)
      {
            /* yyyymmdd? */
            if (len == 8)
            {
                  *tmask = DTK_DATE_M;

                  tm->tm_mday = atoi(str + 6);
                  *(str + 6) = '\0';
                  tm->tm_mon = atoi(str + 4);
                  *(str + 4) = '\0';
                  tm->tm_year = atoi(str + 0);

                  return DTK_DATE;
            }
            /* yymmdd? */
            else if (len == 6)
            {
                  *tmask = DTK_DATE_M;
                  tm->tm_mday = atoi(str + 4);
                  *(str + 4) = '\0';
                  tm->tm_mon = atoi(str + 2);
                  *(str + 2) = '\0';
                  tm->tm_year = atoi(str + 0);
                  *is2digits = TRUE;

                  return DTK_DATE;
            }
      }

      /* not all time fields are specified? */
      if ((fmask & DTK_TIME_M) != DTK_TIME_M)
      {
            /* hhmmss */
            if (len == 6)
            {
                  *tmask = DTK_TIME_M;
                  tm->tm_sec = atoi(str + 4);
                  *(str + 4) = '\0';
                  tm->tm_min = atoi(str + 2);
                  *(str + 2) = '\0';
                  tm->tm_hour = atoi(str + 0);

                  return DTK_TIME;
            }
            /* hhmm? */
            else if (len == 4)
            {
                  *tmask = DTK_TIME_M;
                  tm->tm_sec = 0;
                  tm->tm_min = atoi(str + 2);
                  *(str + 2) = '\0';
                  tm->tm_hour = atoi(str + 0);

                  return DTK_TIME;
            }
      }

      return DTERR_BAD_FORMAT;
}


/* DecodeTimezone()
 * Interpret string as a numeric timezone.
 *
 * Return 0 if okay (and set *tzp), a DTERR code if not okay.
 *
 * NB: this must *not* ereport on failure; see commands/variable.c.
 *
 * Note: we allow timezone offsets up to 13:59.  There are places that
 * use +1300 summer time.
 */
static int
DecodeTimezone(char *str, int *tzp)
{
      int               tz;
      int               hr,
                        min,
                        sec = 0;
      char     *cp;

      /* leading character must be "+" or "-" */
      if (*str != '+' && *str != '-')
            return DTERR_BAD_FORMAT;

      errno = 0;
      hr = strtoi(str + 1, &cp, 10);
      if (errno == ERANGE)
            return DTERR_TZDISP_OVERFLOW;

      /* explicit delimiter? */
      if (*cp == ':')
      {
            errno = 0;
            min = strtoi(cp + 1, &cp, 10);
            if (errno == ERANGE)
                  return DTERR_TZDISP_OVERFLOW;
            if (*cp == ':')
            {
                  errno = 0;
                  sec = strtoi(cp + 1, &cp, 10);
                  if (errno == ERANGE)
                        return DTERR_TZDISP_OVERFLOW;
            }
      }
      /* otherwise, might have run things together... */
      else if (*cp == '\0' && strlen(str) > 3)
      {
            min = hr % 100;
            hr = hr / 100;
            /* we could, but don't, support a run-together hhmmss format */
      }
      else
            min = 0;

      if (hr < 0 || hr > 14)
            return DTERR_TZDISP_OVERFLOW;
      if (min < 0 || min >= 60)
            return DTERR_TZDISP_OVERFLOW;
      if (sec < 0 || sec >= 60)
            return DTERR_TZDISP_OVERFLOW;

      tz = (hr * MINS_PER_HOUR + min) * SECS_PER_MINUTE + sec;
      if (*str == '-')
            tz = -tz;

      *tzp = -tz;

      if (*cp != '\0')
            return DTERR_BAD_FORMAT;

      return 0;
}

/* DecodeSpecial()
 * Decode text string using lookup table.
 *
 * Implement a cache lookup since it is likely that dates
 *    will be related in format.
 *
 * NB: this must *not* ereport on failure;
 * see commands/variable.c.
 */
int
DecodeSpecial(int field, char *lowtoken, int *val)
{
      int               type;
      const datetkn *tp;

      tp = datecache[field];
      if (tp == NULL || strncmp(lowtoken, tp->token, TOKMAXLEN) != 0)
      {
            tp = datebsearch(lowtoken, timezonetktbl, sztimezonetktbl);
            if (tp == NULL)
                  tp = datebsearch(lowtoken, datetktbl, szdatetktbl);
      }
      if (tp == NULL)
      {
            type = UNKNOWN_FIELD;
            *val = 0;
      }
      else
      {
            datecache[field] = tp;
            type = tp->type;
            switch (type)
            {
                  case TZ:
                  case DTZ:
                  case DTZMOD:
                        *val = FROMVAL(tp);
                        break;

                  default:
                        *val = tp->value;
                        break;
            }
      }

      return type;
}


/* ClearPgTM
 *
 * Zero out a pg_tm and associated fsec_t
 */
static inline void
ClearPgTm(struct pg_tm * tm, fsec_t *fsec)
{
      tm->tm_year = 0;
      tm->tm_mon = 0;
      tm->tm_mday = 0;
      tm->tm_hour = 0;
      tm->tm_min = 0;
      tm->tm_sec = 0;
      *fsec = 0;
}


/* DecodeInterval()
 * Interpret previously parsed fields for general time interval.
 * Returns 0 if successful, DTERR code if bogus input detected.
 * dtype, tm, fsec are output parameters.
 *
 * Allow "date" field DTK_DATE since this could be just
 *    an unsigned floating point number. - thomas 1997-11-16
 *
 * Allow ISO-style time span, with implicit units on number of days
 *    preceding an hh:mm:ss field. - thomas 1998-04-30
 */
int
DecodeInterval(char **field, int *ftype, int nf, int range,
                     int *dtype, struct pg_tm * tm, fsec_t *fsec)
{
      bool        is_before = FALSE;
      char     *cp;
      int               fmask = 0,
                        tmask,
                        type;
      int               i;
      int               dterr;
      int               val;
      double            fval;

      *dtype = DTK_DELTA;
      type = IGNORE_DTF;
      ClearPgTm(tm, fsec);

      /* read through list backwards to pick up units before values */
      for (i = nf - 1; i >= 0; i--)
      {
            switch (ftype[i])
            {
                  case DTK_TIME:
                        dterr = DecodeTime(field[i], fmask, range,
                                                   &tmask, tm, fsec);
                        if (dterr)
                              return dterr;
                        type = DTK_DAY;
                        break;

                  case DTK_TZ:

                        /*
                         * Timezone is a token with a leading sign character and at
                         * least one digit; there could be ':', '.', '-' embedded in
                         * it as well.
                         */
                        Assert(*field[i] == '-' || *field[i] == '+');

                        /*
                         * Try for hh:mm or hh:mm:ss.  If not, fall through to
                         * DTK_NUMBER case, which can handle signed float numbers and
                         * signed year-month values.
                         */
                        if (strchr(field[i] + 1, ':') != NULL &&
                              DecodeTime(field[i] + 1, fmask, INTERVAL_FULL_RANGE,
                                             &tmask, tm, fsec) == 0)
                        {
                              if (*field[i] == '-')
                              {
                                    /* flip the sign on all fields */
                                    tm->tm_hour = -tm->tm_hour;
                                    tm->tm_min = -tm->tm_min;
                                    tm->tm_sec = -tm->tm_sec;
                                    *fsec = -(*fsec);
                              }

                              /*
                               * Set the next type to be a day, if units are not
                               * specified. This handles the case of '1 +02:03' since we
                               * are reading right to left.
                               */
                              type = DTK_DAY;
                              tmask = DTK_M(TZ);
                              break;
                        }
                        /* FALL THROUGH */

                  case DTK_DATE:
                  case DTK_NUMBER:
                        if (type == IGNORE_DTF)
                        {
                              /* use typmod to decide what rightmost field is */
                              switch (range)
                              {
                                    case INTERVAL_MASK(YEAR):
                                          type = DTK_YEAR;
                                          break;
                                    case INTERVAL_MASK(MONTH):
                                    case INTERVAL_MASK(YEAR) | INTERVAL_MASK(MONTH):
                                          type = DTK_MONTH;
                                          break;
                                    case INTERVAL_MASK(DAY):
                                          type = DTK_DAY;
                                          break;
                                    case INTERVAL_MASK(HOUR):
                                    case INTERVAL_MASK(DAY) | INTERVAL_MASK(HOUR):
                                          type = DTK_HOUR;
                                          break;
                                    case INTERVAL_MASK(MINUTE):
                                    case INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE):
                                    case INTERVAL_MASK(DAY) | INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE):
                                          type = DTK_MINUTE;
                                          break;
                                    case INTERVAL_MASK(SECOND):
                                    case INTERVAL_MASK(MINUTE) | INTERVAL_MASK(SECOND):
                                    case INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE) | INTERVAL_MASK(SECOND):
                                    case INTERVAL_MASK(DAY) | INTERVAL_MASK(HOUR) | INTERVAL_MASK(MINUTE) | INTERVAL_MASK(SECOND):
                                          type = DTK_SECOND;
                                          break;
                                    default:
                                          type = DTK_SECOND;
                                          break;
                              }
                        }

                        errno = 0;
                        val = strtoi(field[i], &cp, 10);
                        if (errno == ERANGE)
                              return DTERR_FIELD_OVERFLOW;

                        if (*cp == '-')
                        {
                              /* SQL "years-months" syntax */
                              int               val2;

                              val2 = strtoi(cp + 1, &cp, 10);
                              if (errno == ERANGE || val2 < 0 || val2 >= MONTHS_PER_YEAR)
                                    return DTERR_FIELD_OVERFLOW;
                              if (*cp != '\0')
                                    return DTERR_BAD_FORMAT;
                              type = DTK_MONTH;
                              if (*field[i] == '-')
                                    val2 = -val2;
                              val = val * MONTHS_PER_YEAR + val2;
                              fval = 0;
                        }
                        else if (*cp == '.')
                        {
                              errno = 0;
                              fval = strtod(cp, &cp);
                              if (*cp != '\0' || errno != 0)
                                    return DTERR_BAD_FORMAT;

                              if (*field[i] == '-')
                                    fval = -fval;
                        }
                        else if (*cp == '\0')
                              fval = 0;
                        else
                              return DTERR_BAD_FORMAT;

                        tmask = 0;        /* DTK_M(type); */

                        switch (type)
                        {
                              case DTK_MICROSEC:
#ifdef HAVE_INT64_TIMESTAMP
                                    *fsec += rint(val + fval);
#else
                                    *fsec += (val + fval) * 1e-6;
#endif
                                    tmask = DTK_M(MICROSECOND);
                                    break;

                              case DTK_MILLISEC:
#ifdef HAVE_INT64_TIMESTAMP
                                    *fsec += rint((val + fval) * 1000);
#else
                                    *fsec += (val + fval) * 1e-3;
#endif
                                    tmask = DTK_M(MILLISECOND);
                                    break;

                              case DTK_SECOND:
                                    tm->tm_sec += val;
#ifdef HAVE_INT64_TIMESTAMP
                                    *fsec += rint(fval * 1000000);
#else
                                    *fsec += fval;
#endif

                                    /*
                                     * If any subseconds were specified, consider this
                                     * microsecond and millisecond input as well.
                                     */
                                    if (fval == 0)
                                          tmask = DTK_M(SECOND);
                                    else
                                          tmask = DTK_ALL_SECS_M;
                                    break;

                              case DTK_MINUTE:
                                    tm->tm_min += val;
                                    AdjustFractSeconds(fval, tm, fsec, SECS_PER_MINUTE);
                                    tmask = DTK_M(MINUTE);
                                    break;

                              case DTK_HOUR:
                                    tm->tm_hour += val;
                                    AdjustFractSeconds(fval, tm, fsec, SECS_PER_HOUR);
                                    tmask = DTK_M(HOUR);
                                    type = DTK_DAY; /* set for next field */
                                    break;

                              case DTK_DAY:
                                    tm->tm_mday += val;
                                    AdjustFractSeconds(fval, tm, fsec, SECS_PER_DAY);
                                    tmask = DTK_M(DAY);
                                    break;

                              case DTK_WEEK:
                                    tm->tm_mday += val * 7;
                                    AdjustFractDays(fval, tm, fsec, 7);
                                    tmask = DTK_M(WEEK);
                                    break;

                              case DTK_MONTH:
                                    tm->tm_mon += val;
                                    AdjustFractDays(fval, tm, fsec, DAYS_PER_MONTH);
                                    tmask = DTK_M(MONTH);
                                    break;

                              case DTK_YEAR:
                                    tm->tm_year += val;
                                    if (fval != 0)
                                          tm->tm_mon += fval * MONTHS_PER_YEAR;
                                    tmask = DTK_M(YEAR);
                                    break;

                              case DTK_DECADE:
                                    tm->tm_year += val * 10;
                                    if (fval != 0)
                                          tm->tm_mon += fval * MONTHS_PER_YEAR * 10;
                                    tmask = DTK_M(DECADE);
                                    break;

                              case DTK_CENTURY:
                                    tm->tm_year += val * 100;
                                    if (fval != 0)
                                          tm->tm_mon += fval * MONTHS_PER_YEAR * 100;
                                    tmask = DTK_M(CENTURY);
                                    break;

                              case DTK_MILLENNIUM:
                                    tm->tm_year += val * 1000;
                                    if (fval != 0)
                                          tm->tm_mon += fval * MONTHS_PER_YEAR * 1000;
                                    tmask = DTK_M(MILLENNIUM);
                                    break;

                              default:
                                    return DTERR_BAD_FORMAT;
                        }
                        break;

                  case DTK_STRING:
                  case DTK_SPECIAL:
                        type = DecodeUnits(i, field[i], &val);
                        if (type == IGNORE_DTF)
                              continue;

                        tmask = 0;        /* DTK_M(type); */
                        switch (type)
                        {
                              case UNITS:
                                    type = val;
                                    break;

                              case AGO:
                                    is_before = TRUE;
                                    type = val;
                                    break;

                              case RESERV:
                                    tmask = (DTK_DATE_M || DTK_TIME_M);
                                    *dtype = val;
                                    break;

                              default:
                                    return DTERR_BAD_FORMAT;
                        }
                        break;

                  default:
                        return DTERR_BAD_FORMAT;
            }

            if (tmask & fmask)
                  return DTERR_BAD_FORMAT;
            fmask |= tmask;
      }

      /* ensure that at least one time field has been found */
      if (fmask == 0)
            return DTERR_BAD_FORMAT;

      /* ensure fractional seconds are fractional */
      if (*fsec != 0)
      {
            int               sec;

#ifdef HAVE_INT64_TIMESTAMP
            sec = *fsec / USECS_PER_SEC;
            *fsec -= sec * USECS_PER_SEC;
#else
            TMODULO(*fsec, sec, 1.0);
#endif
            tm->tm_sec += sec;
      }

      /*----------
       * The SQL standard defines the interval literal
       *     '-1 1:00:00'
       * to mean "negative 1 days and negative 1 hours", while Postgres
       * traditionally treats this as meaning "negative 1 days and positive
       * 1 hours".  In SQL_STANDARD intervalstyle, we apply the leading sign
       * to all fields if there are no other explicit signs.
       *
       * We leave the signs alone if there are additional explicit signs.
       * This protects us against misinterpreting postgres-style dump output,
       * since the postgres-style output code has always put an explicit sign on
       * all fields following a negative field.  But note that SQL-spec output
       * is ambiguous and can be misinterpreted on load!    (So it's best practice
       * to dump in postgres style, not SQL style.)
       *----------
       */
      if (IntervalStyle == INTSTYLE_SQL_STANDARD && *field[0] == '-')
      {
            /* Check for additional explicit signs */
            bool        more_signs = false;

            for (i = 1; i < nf; i++)
            {
                  if (*field[i] == '-' || *field[i] == '+')
                  {
                        more_signs = true;
                        break;
                  }
            }

            if (!more_signs)
            {
                  /*
                   * Rather than re-determining which field was field[0], just force
                   * 'em all negative.
                   */
                  if (*fsec > 0)
                        *fsec = -(*fsec);
                  if (tm->tm_sec > 0)
                        tm->tm_sec = -tm->tm_sec;
                  if (tm->tm_min > 0)
                        tm->tm_min = -tm->tm_min;
                  if (tm->tm_hour > 0)
                        tm->tm_hour = -tm->tm_hour;
                  if (tm->tm_mday > 0)
                        tm->tm_mday = -tm->tm_mday;
                  if (tm->tm_mon > 0)
                        tm->tm_mon = -tm->tm_mon;
                  if (tm->tm_year > 0)
                        tm->tm_year = -tm->tm_year;
            }
      }

      /* finally, AGO negates everything */
      if (is_before)
      {
            *fsec = -(*fsec);
            tm->tm_sec = -tm->tm_sec;
            tm->tm_min = -tm->tm_min;
            tm->tm_hour = -tm->tm_hour;
            tm->tm_mday = -tm->tm_mday;
            tm->tm_mon = -tm->tm_mon;
            tm->tm_year = -tm->tm_year;
      }

      return 0;
}


/*
 * Helper functions to avoid duplicated code in DecodeISO8601Interval.
 *
 * Parse a decimal value and break it into integer and fractional parts.
 * Returns 0 or DTERR code.
 */
static int
ParseISO8601Number(char *str, char **endptr, int *ipart, double *fpart)
{
      double            val;

      if (!(isdigit((unsigned char) *str) || *str == '-' || *str == '.'))
            return DTERR_BAD_FORMAT;
      errno = 0;
      val = strtod(str, endptr);
      /* did we not see anything that looks like a double? */
      if (*endptr == str || errno != 0)
            return DTERR_BAD_FORMAT;
      /* watch out for overflow */
      if (val < INT_MIN || val > INT_MAX)
            return DTERR_FIELD_OVERFLOW;
      /* be very sure we truncate towards zero (cf dtrunc()) */
      if (val >= 0)
            *ipart = (int) floor(val);
      else
            *ipart = (int) -floor(-val);
      *fpart = val - *ipart;
      return 0;
}

/*
 * Determine number of integral digits in a valid ISO 8601 number field
 * (we should ignore sign and any fraction part)
 */
static int
ISO8601IntegerWidth(char *fieldstart)
{
      /* We might have had a leading '-' */
      if (*fieldstart == '-')
            fieldstart++;
      return strspn(fieldstart, "0123456789");
}


/* DecodeISO8601Interval()
 *    Decode an ISO 8601 time interval of the "format with designators"
 *    (section 4.4.3.2) or "alternative format" (section 4.4.3.3)
 *    Examples:  P1D    for 1 day
 *                   PT1H for 1 hour
 *                   P2Y6M7DT1H30M for 2 years, 6 months, 7 days 1 hour 30 min
 *                   P0002-06-07T01:30:00 the same value in alternative format
 *
 * Returns 0 if successful, DTERR code if bogus input detected.
 * Note: error code should be DTERR_BAD_FORMAT if input doesn't look like
 * ISO8601, otherwise this could cause unexpected error messages.
 * dtype, tm, fsec are output parameters.
 *
 *    A couple exceptions from the spec:
 *     - a week field ('W') may coexist with other units
 *     - allows decimals in fields other than the least significant unit.
 */
int
DecodeISO8601Interval(char *str,
                                int *dtype, struct pg_tm * tm, fsec_t *fsec)
{
      bool        datepart = true;
      bool        havefield = false;

      *dtype = DTK_DELTA;
      ClearPgTm(tm, fsec);

      if (strlen(str) < 2 || str[0] != 'P')
            return DTERR_BAD_FORMAT;

      str++;
      while (*str)
      {
            char     *fieldstart;
            int               val;
            double            fval;
            char        unit;
            int               dterr;

            if (*str == 'T')        /* T indicates the beginning of the time part */
            {
                  datepart = false;
                  havefield = false;
                  str++;
                  continue;
            }

            fieldstart = str;
            dterr = ParseISO8601Number(str, &str, &val, &fval);
            if (dterr)
                  return dterr;

            /*
             * Note: we could step off the end of the string here.      Code below
             * *must* exit the loop if unit == '\0'.
             */
            unit = *str++;

            if (datepart)
            {
                  switch (unit)           /* before T: Y M W D */
                  {
                        case 'Y':
                              tm->tm_year += val;
                              tm->tm_mon += (fval * 12);
                              break;
                        case 'M':
                              tm->tm_mon += val;
                              AdjustFractDays(fval, tm, fsec, DAYS_PER_MONTH);
                              break;
                        case 'W':
                              tm->tm_mday += val * 7;
                              AdjustFractDays(fval, tm, fsec, 7);
                              break;
                        case 'D':
                              tm->tm_mday += val;
                              AdjustFractSeconds(fval, tm, fsec, SECS_PER_DAY);
                              break;
                        case 'T':         /* ISO 8601 4.4.3.3 Alternative Format / Basic */
                        case '\0':
                              if (ISO8601IntegerWidth(fieldstart) == 8 && !havefield)
                              {
                                    tm->tm_year += val / 10000;
                                    tm->tm_mon += (val / 100) % 100;
                                    tm->tm_mday += val % 100;
                                    AdjustFractSeconds(fval, tm, fsec, SECS_PER_DAY);
                                    if (unit == '\0')
                                          return 0;
                                    datepart = false;
                                    havefield = false;
                                    continue;
                              }
                              /* Else fall through to extended alternative format */
                        case '-':         /* ISO 8601 4.4.3.3 Alternative Format,
                                                 * Extended */
                              if (havefield)
                                    return DTERR_BAD_FORMAT;

                              tm->tm_year += val;
                              tm->tm_mon += (fval * 12);
                              if (unit == '\0')
                                    return 0;
                              if (unit == 'T')
                              {
                                    datepart = false;
                                    havefield = false;
                                    continue;
                              }

                              dterr = ParseISO8601Number(str, &str, &val, &fval);
                              if (dterr)
                                    return dterr;
                              tm->tm_mon += val;
                              AdjustFractDays(fval, tm, fsec, DAYS_PER_MONTH);
                              if (*str == '\0')
                                    return 0;
                              if (*str == 'T')
                              {
                                    datepart = false;
                                    havefield = false;
                                    continue;
                              }
                              if (*str != '-')
                                    return DTERR_BAD_FORMAT;
                              str++;

                              dterr = ParseISO8601Number(str, &str, &val, &fval);
                              if (dterr)
                                    return dterr;
                              tm->tm_mday += val;
                              AdjustFractSeconds(fval, tm, fsec, SECS_PER_DAY);
                              if (*str == '\0')
                                    return 0;
                              if (*str == 'T')
                              {
                                    datepart = false;
                                    havefield = false;
                                    continue;
                              }
                              return DTERR_BAD_FORMAT;
                        default:
                              /* not a valid date unit suffix */
                              return DTERR_BAD_FORMAT;
                  }
            }
            else
            {
                  switch (unit)           /* after T: H M S */
                  {
                        case 'H':
                              tm->tm_hour += val;
                              AdjustFractSeconds(fval, tm, fsec, SECS_PER_HOUR);
                              break;
                        case 'M':
                              tm->tm_min += val;
                              AdjustFractSeconds(fval, tm, fsec, SECS_PER_MINUTE);
                              break;
                        case 'S':
                              tm->tm_sec += val;
                              AdjustFractSeconds(fval, tm, fsec, 1);
                              break;
                        case '\0':        /* ISO 8601 4.4.3.3 Alternative Format */
                              if (ISO8601IntegerWidth(fieldstart) == 6 && !havefield)
                              {
                                    tm->tm_hour += val / 10000;
                                    tm->tm_min += (val / 100) % 100;
                                    tm->tm_sec += val % 100;
                                    AdjustFractSeconds(fval, tm, fsec, 1);
                                    return 0;
                              }
                              /* Else fall through to extended alternative format */
                        case ':':         /* ISO 8601 4.4.3.3 Alternative Format,
                                                 * Extended */
                              if (havefield)
                                    return DTERR_BAD_FORMAT;

                              tm->tm_hour += val;
                              AdjustFractSeconds(fval, tm, fsec, SECS_PER_HOUR);
                              if (unit == '\0')
                                    return 0;

                              dterr = ParseISO8601Number(str, &str, &val, &fval);
                              if (dterr)
                                    return dterr;
                              tm->tm_min += val;
                              AdjustFractSeconds(fval, tm, fsec, SECS_PER_MINUTE);
                              if (*str == '\0')
                                    return 0;
                              if (*str != ':')
                                    return DTERR_BAD_FORMAT;
                              str++;

                              dterr = ParseISO8601Number(str, &str, &val, &fval);
                              if (dterr)
                                    return dterr;
                              tm->tm_sec += val;
                              AdjustFractSeconds(fval, tm, fsec, 1);
                              if (*str == '\0')
                                    return 0;
                              return DTERR_BAD_FORMAT;

                        default:
                              /* not a valid time unit suffix */
                              return DTERR_BAD_FORMAT;
                  }
            }

            havefield = true;
      }

      return 0;
}


/* DecodeUnits()
 * Decode text string using lookup table.
 * This routine supports time interval decoding
 * (hence, it need not recognize timezone names).
 */
int
DecodeUnits(int field, char *lowtoken, int *val)
{
      int               type;
      const datetkn *tp;

      tp = deltacache[field];
      if (tp == NULL || strncmp(lowtoken, tp->token, TOKMAXLEN) != 0)
      {
            tp = datebsearch(lowtoken, deltatktbl, szdeltatktbl);
      }
      if (tp == NULL)
      {
            type = UNKNOWN_FIELD;
            *val = 0;
      }
      else
      {
            deltacache[field] = tp;
            type = tp->type;
            if (type == TZ || type == DTZ)
                  *val = FROMVAL(tp);
            else
                  *val = tp->value;
      }

      return type;
}     /* DecodeUnits() */

/*
 * Report an error detected by one of the datetime input processing routines.
 *
 * dterr is the error code, str is the original input string, datatype is
 * the name of the datatype we were trying to accept.
 *
 * Note: it might seem useless to distinguish DTERR_INTERVAL_OVERFLOW and
 * DTERR_TZDISP_OVERFLOW from DTERR_FIELD_OVERFLOW, but SQL99 mandates three
 * separate SQLSTATE codes, so ...
 */
void
DateTimeParseError(int dterr, const char *str, const char *datatype)
{
      switch (dterr)
      {
            case DTERR_FIELD_OVERFLOW:
                  ereport(ERROR,
                              (errcode(ERRCODE_DATETIME_FIELD_OVERFLOW),
                               errmsg("date/time field value out of range: \"%s\"",
                                          str)));
                  break;
            case DTERR_MD_FIELD_OVERFLOW:
                  /* <nanny>same as above, but add hint about DateStyle</nanny> */
                  ereport(ERROR,
                              (errcode(ERRCODE_DATETIME_FIELD_OVERFLOW),
                               errmsg("date/time field value out of range: \"%s\"",
                                          str),
                  errhint("Perhaps you need a different \"datestyle\" setting.")));
                  break;
            case DTERR_INTERVAL_OVERFLOW:
                  ereport(ERROR,
                              (errcode(ERRCODE_INTERVAL_FIELD_OVERFLOW),
                               errmsg("interval field value out of range: \"%s\"",
                                          str)));
                  break;
            case DTERR_TZDISP_OVERFLOW:
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_TIME_ZONE_DISPLACEMENT_VALUE),
                               errmsg("time zone displacement out of range: \"%s\"",
                                          str)));
                  break;
            case DTERR_BAD_FORMAT:
            default:
                  ereport(ERROR,
                              (errcode(ERRCODE_INVALID_DATETIME_FORMAT),
                               errmsg("invalid input syntax for type %s: \"%s\"",
                                          datatype, str)));
                  break;
      }
}

/* datebsearch()
 * Binary search -- from Knuth (6.2.1) Algorithm B.  Special case like this
 * is WAY faster than the generic bsearch().
 */
static const datetkn *
datebsearch(const char *key, const datetkn *base, int nel)
{
      const datetkn *last = base + nel - 1,
                     *position;
      int               result;

      while (last >= base)
      {
            position = base + ((last - base) >> 1);
            result = key[0] - position->token[0];
            if (result == 0)
            {
                  result = strncmp(key, position->token, TOKMAXLEN);
                  if (result == 0)
                        return position;
            }
            if (result < 0)
                  last = position - 1;
            else
                  base = position + 1;
      }
      return NULL;
}

/* EncodeTimezone()
 *          Append representation of a numeric timezone offset to str.
 */
static void
EncodeTimezone(char *str, int tz, int style)
{
      int               hour,
                        min,
                        sec;

      sec = abs(tz);
      min = sec / SECS_PER_MINUTE;
      sec -= min * SECS_PER_MINUTE;
      hour = min / MINS_PER_HOUR;
      min -= hour * MINS_PER_HOUR;

      str += strlen(str);
      /* TZ is negated compared to sign we wish to display ... */
      *str++ = (tz <= 0 ? '+' : '-');

      if (sec != 0)
            sprintf(str, "%02d:%02d:%02d", hour, min, sec);
      else if (min != 0 || style == USE_XSD_DATES)
            sprintf(str, "%02d:%02d", hour, min);
      else
            sprintf(str, "%02d", hour);
}

/* EncodeDateOnly()
 * Encode date as local time.
 */
void
EncodeDateOnly(struct pg_tm * tm, int style, char *str)
{
      Assert(tm->tm_mon >= 1 && tm->tm_mon <= MONTHS_PER_YEAR);

      switch (style)
      {
            case USE_ISO_DATES:
            case USE_XSD_DATES:
                  /* compatible with ISO date formats */
                  if (tm->tm_year > 0)
                        sprintf(str, "%04d-%02d-%02d",
                                    tm->tm_year, tm->tm_mon, tm->tm_mday);
                  else
                        sprintf(str, "%04d-%02d-%02d %s",
                                    -(tm->tm_year - 1), tm->tm_mon, tm->tm_mday, "BC");
                  break;

            case USE_SQL_DATES:
                  /* compatible with Oracle/Ingres date formats */
                  if (DateOrder == DATEORDER_DMY)
                        sprintf(str, "%02d/%02d", tm->tm_mday, tm->tm_mon);
                  else
                        sprintf(str, "%02d/%02d", tm->tm_mon, tm->tm_mday);
                  if (tm->tm_year > 0)
                        sprintf(str + 5, "/%04d", tm->tm_year);
                  else
                        sprintf(str + 5, "/%04d %s", -(tm->tm_year - 1), "BC");
                  break;

            case USE_GERMAN_DATES:
                  /* German-style date format */
                  sprintf(str, "%02d.%02d", tm->tm_mday, tm->tm_mon);
                  if (tm->tm_year > 0)
                        sprintf(str + 5, ".%04d", tm->tm_year);
                  else
                        sprintf(str + 5, ".%04d %s", -(tm->tm_year - 1), "BC");
                  break;

            case USE_POSTGRES_DATES:
            default:
                  /* traditional date-only style for Postgres */
                  if (DateOrder == DATEORDER_DMY)
                        sprintf(str, "%02d-%02d", tm->tm_mday, tm->tm_mon);
                  else
                        sprintf(str, "%02d-%02d", tm->tm_mon, tm->tm_mday);
                  if (tm->tm_year > 0)
                        sprintf(str + 5, "-%04d", tm->tm_year);
                  else
                        sprintf(str + 5, "-%04d %s", -(tm->tm_year - 1), "BC");
                  break;
      }
}


/* EncodeTimeOnly()
 * Encode time fields only.
 */
void
EncodeTimeOnly(struct pg_tm * tm, fsec_t fsec, int *tzp, int style, char *str)
{
      sprintf(str, "%02d:%02d:", tm->tm_hour, tm->tm_min);
      str += strlen(str);

      AppendSeconds(str, tm->tm_sec, fsec, MAX_TIME_PRECISION, true);

      if (tzp != NULL)
            EncodeTimezone(str, *tzp, style);
}


/* EncodeDateTime()
 * Encode date and time interpreted as local time.
 * Support several date styles:
 *    Postgres - day mon hh:mm:ss yyyy tz
 *    SQL - mm/dd/yyyy hh:mm:ss.ss tz
 *    ISO - yyyy-mm-dd hh:mm:ss+/-tz
 *    German - dd.mm.yyyy hh:mm:ss tz
 *    XSD - yyyy-mm-ddThh:mm:ss.ss+/-tz
 * Variants (affects order of month and day for Postgres and SQL styles):
 *    US - mm/dd/yyyy
 *    European - dd/mm/yyyy
 */
void
EncodeDateTime(struct pg_tm * tm, fsec_t fsec, int *tzp, char **tzn, int style, char *str)
{
      int               day;

      Assert(tm->tm_mon >= 1 && tm->tm_mon <= MONTHS_PER_YEAR);

      switch (style)
      {
            case USE_ISO_DATES:
            case USE_XSD_DATES:
                  /* Compatible with ISO-8601 date formats */

                  if (style == USE_ISO_DATES)
                        sprintf(str, "%04d-%02d-%02d %02d:%02d:",
                                    (tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1),
                                    tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min);
                  else
                        sprintf(str, "%04d-%02d-%02dT%02d:%02d:",
                                    (tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1),
                                    tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min);

                  AppendTimestampSeconds(str + strlen(str), tm, fsec);

                  /*
                   * tzp == NULL indicates that we don't want *any* time zone info
                   * in the output string. *tzn != NULL indicates that we have alpha
                   * time zone info available. tm_isdst != -1 indicates that we have
                   * a valid time zone translation.
                   */
                  if (tzp != NULL && tm->tm_isdst >= 0)
                        EncodeTimezone(str, *tzp, style);

                  if (tm->tm_year <= 0)
                        sprintf(str + strlen(str), " BC");
                  break;

            case USE_SQL_DATES:
                  /* Compatible with Oracle/Ingres date formats */

                  if (DateOrder == DATEORDER_DMY)
                        sprintf(str, "%02d/%02d", tm->tm_mday, tm->tm_mon);
                  else
                        sprintf(str, "%02d/%02d", tm->tm_mon, tm->tm_mday);

                  sprintf(str + 5, "/%04d %02d:%02d:",
                              (tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1),
                              tm->tm_hour, tm->tm_min);

                  AppendTimestampSeconds(str + strlen(str), tm, fsec);

                  if (tzp != NULL && tm->tm_isdst >= 0)
                  {
                        if (*tzn != NULL)
                              sprintf(str + strlen(str), " %.*s", MAXTZLEN, *tzn);
                        else
                              EncodeTimezone(str, *tzp, style);
                  }

                  if (tm->tm_year <= 0)
                        sprintf(str + strlen(str), " BC");
                  break;

            case USE_GERMAN_DATES:
                  /* German variant on European style */

                  sprintf(str, "%02d.%02d", tm->tm_mday, tm->tm_mon);

                  sprintf(str + 5, ".%04d %02d:%02d:",
                              (tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1),
                              tm->tm_hour, tm->tm_min);

                  AppendTimestampSeconds(str + strlen(str), tm, fsec);

                  if (tzp != NULL && tm->tm_isdst >= 0)
                  {
                        if (*tzn != NULL)
                              sprintf(str + strlen(str), " %.*s", MAXTZLEN, *tzn);
                        else
                              EncodeTimezone(str, *tzp, style);
                  }

                  if (tm->tm_year <= 0)
                        sprintf(str + strlen(str), " BC");
                  break;

            case USE_POSTGRES_DATES:
            default:
                  /* Backward-compatible with traditional Postgres abstime dates */

                  day = date2j(tm->tm_year, tm->tm_mon, tm->tm_mday);
                  tm->tm_wday = j2day(day);

                  strncpy(str, days[tm->tm_wday], 3);
                  strcpy(str + 3, " ");

                  if (DateOrder == DATEORDER_DMY)
                        sprintf(str + 4, "%02d %3s", tm->tm_mday, months[tm->tm_mon - 1]);
                  else
                        sprintf(str + 4, "%3s %02d", months[tm->tm_mon - 1], tm->tm_mday);

                  sprintf(str + 10, " %02d:%02d:", tm->tm_hour, tm->tm_min);

                  AppendTimestampSeconds(str + strlen(str), tm, fsec);

                  sprintf(str + strlen(str), " %04d",
                              (tm->tm_year > 0) ? tm->tm_year : -(tm->tm_year - 1));

                  if (tzp != NULL && tm->tm_isdst >= 0)
                  {
                        if (*tzn != NULL)
                              sprintf(str + strlen(str), " %.*s", MAXTZLEN, *tzn);
                        else
                        {
                              /*
                               * We have a time zone, but no string version. Use the
                               * numeric form, but be sure to include a leading space to
                               * avoid formatting something which would be rejected by
                               * the date/time parser later. - thomas 2001-10-19
                               */
                              sprintf(str + strlen(str), " ");
                              EncodeTimezone(str, *tzp, style);
                        }
                  }

                  if (tm->tm_year <= 0)
                        sprintf(str + strlen(str), " BC");
                  break;
      }
}


/*
 * Helper functions to avoid duplicated code in EncodeInterval.
 */

/* Append an ISO-8601-style interval field, but only if value isn't zero */
static char *
AddISO8601IntPart(char *cp, int value, char units)
{
      if (value == 0)
            return cp;
      sprintf(cp, "%d%c", value, units);
      return cp + strlen(cp);
}

/* Append a postgres-style interval field, but only if value isn't zero */
static char *
AddPostgresIntPart(char *cp, int value, const char *units,
                           bool *is_zero, bool *is_before)
{
      if (value == 0)
            return cp;
      sprintf(cp, "%s%s%d %s%s",
                  (!*is_zero) ? " " : "",
                  (*is_before && value > 0) ? "+" : "",
                  value,
                  units,
                  (value != 1) ? "s" : "");

      /*
       * Each nonzero field sets is_before for (only) the next one.  This is a
       * tad bizarre but it's how it worked before...
       */
      *is_before = (value < 0);
      *is_zero = FALSE;
      return cp + strlen(cp);
}

/* Append a verbose-style interval field, but only if value isn't zero */
static char *
AddVerboseIntPart(char *cp, int value, const char *units,
                          bool *is_zero, bool *is_before)
{
      if (value == 0)
            return cp;
      /* first nonzero value sets is_before */
      if (*is_zero)
      {
            *is_before = (value < 0);
            value = abs(value);
      }
      else if (*is_before)
            value = -value;
      sprintf(cp, " %d %s%s", value, units, (value == 1) ? "" : "s");
      *is_zero = FALSE;
      return cp + strlen(cp);
}


/* EncodeInterval()
 * Interpret time structure as a delta time and convert to string.
 *
 * Support "traditional Postgres" and ISO-8601 styles.
 * Actually, afaik ISO does not address time interval formatting,
 *    but this looks similar to the spec for absolute date/time.
 * - thomas 1998-04-30
 *
 * Actually, afaik, ISO 8601 does specify formats for "time
 * intervals...[of the]...format with time-unit designators", which
 * are pretty ugly.  The format looks something like
 *       P1Y1M1DT1H1M1.12345S
 * but useful for exchanging data with computers instead of humans.
 * - ron 2003-07-14
 *
 * And ISO's SQL 2008 standard specifies standards for
 * "year-month literal"s (that look like '2-3') and
 * "day-time literal"s (that look like ('4 5:6:7')
 */
void
EncodeInterval(struct pg_tm * tm, fsec_t fsec, int style, char *str)
{
      char     *cp = str;
      int               year = tm->tm_year;
      int               mon = tm->tm_mon;
      int               mday = tm->tm_mday;
      int               hour = tm->tm_hour;
      int               min = tm->tm_min;
      int               sec = tm->tm_sec;
      bool        is_before = FALSE;
      bool        is_zero = TRUE;

      /*
       * The sign of year and month are guaranteed to match, since they are
       * stored internally as "month". But we'll need to check for is_before and
       * is_zero when determining the signs of day and hour/minute/seconds
       * fields.
       */
      switch (style)
      {
                  /* SQL Standard interval format */
            case INTSTYLE_SQL_STANDARD:
                  {
                        bool        has_negative = year < 0 || mon < 0 ||
                        mday < 0 || hour < 0 ||
                        min < 0 || sec < 0 || fsec < 0;
                        bool        has_positive = year > 0 || mon > 0 ||
                        mday > 0 || hour > 0 ||
                        min > 0 || sec > 0 || fsec > 0;
                        bool        has_year_month = year != 0 || mon != 0;
                        bool        has_day_time = mday != 0 || hour != 0 ||
                        min != 0 || sec != 0 || fsec != 0;
                        bool        has_day = mday != 0;
                        bool        sql_standard_value = !(has_negative && has_positive) &&
                        !(has_year_month && has_day_time);

                        /*
                         * SQL Standard wants only 1 "<sign>" preceding the whole
                         * interval ... but can't do that if mixed signs.
                         */
                        if (has_negative && sql_standard_value)
                        {
                              *cp++ = '-';
                              year = -year;
                              mon = -mon;
                              mday = -mday;
                              hour = -hour;
                              min = -min;
                              sec = -sec;
                              fsec = -fsec;
                        }

                        if (!has_negative && !has_positive)
                        {
                              sprintf(cp, "0");
                        }
                        else if (!sql_standard_value)
                        {
                              /*
                               * For non sql-standard interval values, force outputting
                               * the signs to avoid ambiguities with intervals with
                               * mixed sign components.
                               */
                              char        year_sign = (year < 0 || mon < 0) ? '-' : '+';
                              char        day_sign = (mday < 0) ? '-' : '+';
                              char        sec_sign = (hour < 0 || min < 0 ||
                                                                  sec < 0 || fsec < 0) ? '-' : '+';

                              sprintf(cp, "%c%d-%d %c%d %c%d:%02d:",
                                          year_sign, abs(year), abs(mon),
                                          day_sign, abs(mday),
                                          sec_sign, abs(hour), abs(min));
                              cp += strlen(cp);
                              AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
                        }
                        else if (has_year_month)
                        {
                              sprintf(cp, "%d-%d", year, mon);
                        }
                        else if (has_day)
                        {
                              sprintf(cp, "%d %d:%02d:", mday, hour, min);
                              cp += strlen(cp);
                              AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
                        }
                        else
                        {
                              sprintf(cp, "%d:%02d:", hour, min);
                              cp += strlen(cp);
                              AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
                        }
                  }
                  break;

                  /* ISO 8601 "time-intervals by duration only" */
            case INTSTYLE_ISO_8601:
                  /* special-case zero to avoid printing nothing */
                  if (year == 0 && mon == 0 && mday == 0 &&
                        hour == 0 && min == 0 && sec == 0 && fsec == 0)
                  {
                        sprintf(cp, "PT0S");
                        break;
                  }
                  *cp++ = 'P';
                  cp = AddISO8601IntPart(cp, year, 'Y');
                  cp = AddISO8601IntPart(cp, mon, 'M');
                  cp = AddISO8601IntPart(cp, mday, 'D');
                  if (hour != 0 || min != 0 || sec != 0 || fsec != 0)
                        *cp++ = 'T';
                  cp = AddISO8601IntPart(cp, hour, 'H');
                  cp = AddISO8601IntPart(cp, min, 'M');
                  if (sec != 0 || fsec != 0)
                  {
                        if (sec < 0 || fsec < 0)
                              *cp++ = '-';
                        AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, false);
                        cp += strlen(cp);
                        *cp++ = 'S';
                        *cp++ = '\0';
                  }
                  break;

                  /* Compatible with postgresql < 8.4 when DateStyle = 'iso' */
            case INTSTYLE_POSTGRES:
                  cp = AddPostgresIntPart(cp, year, "year", &is_zero, &is_before);
                  cp = AddPostgresIntPart(cp, mon, "mon", &is_zero, &is_before);
                  cp = AddPostgresIntPart(cp, mday, "day", &is_zero, &is_before);
                  if (is_zero || hour != 0 || min != 0 || sec != 0 || fsec != 0)
                  {
                        bool        minus = (hour < 0 || min < 0 || sec < 0 || fsec < 0);

                        sprintf(cp, "%s%s%02d:%02d:",
                                    is_zero ? "" : " ",
                                    (minus ? "-" : (is_before ? "+" : "")),
                                    abs(hour), abs(min));
                        cp += strlen(cp);
                        AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, true);
                  }
                  break;

                  /* Compatible with postgresql < 8.4 when DateStyle != 'iso' */
            case INTSTYLE_POSTGRES_VERBOSE:
            default:
                  strcpy(cp, "@");
                  cp++;
                  cp = AddVerboseIntPart(cp, year, "year", &is_zero, &is_before);
                  cp = AddVerboseIntPart(cp, mon, "mon", &is_zero, &is_before);
                  cp = AddVerboseIntPart(cp, mday, "day", &is_zero, &is_before);
                  cp = AddVerboseIntPart(cp, hour, "hour", &is_zero, &is_before);
                  cp = AddVerboseIntPart(cp, min, "min", &is_zero, &is_before);
                  if (sec != 0 || fsec != 0)
                  {
                        *cp++ = ' ';
                        if (sec < 0 || (sec == 0 && fsec < 0))
                        {
                              if (is_zero)
                                    is_before = TRUE;
                              else if (!is_before)
                                    *cp++ = '-';
                        }
                        else if (is_before)
                              *cp++ = '-';
                        AppendSeconds(cp, sec, fsec, MAX_INTERVAL_PRECISION, false);
                        cp += strlen(cp);
                        sprintf(cp, " sec%s",
                                    (abs(sec) != 1 || fsec != 0) ? "s" : "");
                        is_zero = FALSE;
                  }
                  /* identically zero? then put in a unitless zero... */
                  if (is_zero)
                        strcat(cp, " 0");
                  if (is_before)
                        strcat(cp, " ago");
                  break;
      }
}


/*
 * We've been burnt by stupid errors in the ordering of the datetkn tables
 * once too often.      Arrange to check them during postmaster start.
 */
static bool
CheckDateTokenTable(const char *tablename, const datetkn *base, int nel)
{
      bool        ok = true;
      int               i;

      for (i = 1; i < nel; i++)
      {
            if (strncmp(base[i - 1].token, base[i].token, TOKMAXLEN) >= 0)
            {
                  elog(LOG, "ordering error in %s table: \"%.*s\" >= \"%.*s\"",
                         tablename,
                         TOKMAXLEN, base[i - 1].token,
                         TOKMAXLEN, base[i].token);
                  ok = false;
            }
      }
      return ok;
}

bool
CheckDateTokenTables(void)
{
      bool        ok = true;

      Assert(UNIX_EPOCH_JDATE == date2j(1970, 1, 1));
      Assert(POSTGRES_EPOCH_JDATE == date2j(2000, 1, 1));

      ok &= CheckDateTokenTable("datetktbl", datetktbl, szdatetktbl);
      ok &= CheckDateTokenTable("deltatktbl", deltatktbl, szdeltatktbl);
      return ok;
}

/*
 * This function gets called during timezone config file load or reload
 * to create the final array of timezone tokens.  The argument array
 * is already sorted in name order.  This data is in a temporary memory
 * context and must be copied to somewhere permanent.
 */
void
InstallTimeZoneAbbrevs(tzEntry *abbrevs, int n)
{
      datetkn    *newtbl;
      int               i;

      /*
       * Copy the data into TopMemoryContext and convert to datetkn format.
       */
      newtbl = (datetkn *) MemoryContextAlloc(TopMemoryContext,
                                                                  n * sizeof(datetkn));
      for (i = 0; i < n; i++)
      {
            strncpy(newtbl[i].token, abbrevs[i].abbrev, TOKMAXLEN);
            newtbl[i].type = abbrevs[i].is_dst ? DTZ : TZ;
            TOVAL(&newtbl[i], abbrevs[i].offset / 60);
      }

      /* Check the ordering, if testing */
      Assert(CheckDateTokenTable("timezone offset", newtbl, n));

      /* Now safe to replace existing table (if any) */
      if (timezonetktbl)
            pfree(timezonetktbl);
      timezonetktbl = newtbl;
      sztimezonetktbl = n;

      /* clear date cache in case it contains any stale timezone names */
      for (i = 0; i < MAXDATEFIELDS; i++)
            datecache[i] = NULL;
}

/*
 * This set-returning function reads all the available time zone abbreviations
 * and returns a set of (abbrev, utc_offset, is_dst).
 */
Datum
pg_timezone_abbrevs(PG_FUNCTION_ARGS)
{
      FuncCallContext *funcctx;
      int            *pindex;
      Datum       result;
      HeapTuple   tuple;
      Datum       values[3];
      bool        nulls[3];
      char        buffer[TOKMAXLEN + 1];
      unsigned char *p;
      struct pg_tm tm;
      Interval   *resInterval;

      /* stuff done only on the first call of the function */
      if (SRF_IS_FIRSTCALL())
      {
            TupleDesc   tupdesc;
            MemoryContext oldcontext;

            /* create a function context for cross-call persistence */
            funcctx = SRF_FIRSTCALL_INIT();

            /*
             * switch to memory context appropriate for multiple function calls
             */
            oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

            /* allocate memory for user context */
            pindex = (int *) palloc(sizeof(int));
            *pindex = 0;
            funcctx->user_fctx = (void *) pindex;

            /*
             * build tupdesc for result tuples. This must match this function's
             * pg_proc entry!
             */
            tupdesc = CreateTemplateTupleDesc(3, false);
            TupleDescInitEntry(tupdesc, (AttrNumber) 1, "abbrev",
                                       TEXTOID, -1, 0);
            TupleDescInitEntry(tupdesc, (AttrNumber) 2, "utc_offset",
                                       INTERVALOID, -1, 0);
            TupleDescInitEntry(tupdesc, (AttrNumber) 3, "is_dst",
                                       BOOLOID, -1, 0);

            funcctx->tuple_desc = BlessTupleDesc(tupdesc);
            MemoryContextSwitchTo(oldcontext);
      }

      /* stuff done on every call of the function */
      funcctx = SRF_PERCALL_SETUP();
      pindex = (int *) funcctx->user_fctx;

      if (*pindex >= sztimezonetktbl)
            SRF_RETURN_DONE(funcctx);

      MemSet(nulls, 0, sizeof(nulls));

      /*
       * Convert name to text, using upcasing conversion that is the inverse of
       * what ParseDateTime() uses.
       */
      strncpy(buffer, timezonetktbl[*pindex].token, TOKMAXLEN);
      buffer[TOKMAXLEN] = '\0';     /* may not be null-terminated */
      for (p = (unsigned char *) buffer; *p; p++)
            *p = pg_toupper(*p);

      values[0] = CStringGetTextDatum(buffer);

      MemSet(&tm, 0, sizeof(struct pg_tm));
      tm.tm_min = (-1) * FROMVAL(&timezonetktbl[*pindex]);
      resInterval = (Interval *) palloc(sizeof(Interval));
      tm2interval(&tm, 0, resInterval);
      values[1] = IntervalPGetDatum(resInterval);

      Assert(timezonetktbl[*pindex].type == DTZ ||
               timezonetktbl[*pindex].type == TZ);
      values[2] = BoolGetDatum(timezonetktbl[*pindex].type == DTZ);

      (*pindex)++;

      tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
      result = HeapTupleGetDatum(tuple);

      SRF_RETURN_NEXT(funcctx, result);
}

/*
 * This set-returning function reads all the available full time zones
 * and returns a set of (name, abbrev, utc_offset, is_dst).
 */
Datum
pg_timezone_names(PG_FUNCTION_ARGS)
{
      MemoryContext oldcontext;
      FuncCallContext *funcctx;
      pg_tzenum  *tzenum;
      pg_tz    *tz;
      Datum       result;
      HeapTuple   tuple;
      Datum       values[4];
      bool        nulls[4];
      int               tzoff;
      struct pg_tm tm;
      fsec_t            fsec;
      char     *tzn;
      Interval   *resInterval;
      struct pg_tm itm;

      /* stuff done only on the first call of the function */
      if (SRF_IS_FIRSTCALL())
      {
            TupleDesc   tupdesc;

            /* create a function context for cross-call persistence */
            funcctx = SRF_FIRSTCALL_INIT();

            /*
             * switch to memory context appropriate for multiple function calls
             */
            oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

            /* initialize timezone scanning code */
            tzenum = pg_tzenumerate_start();
            funcctx->user_fctx = (void *) tzenum;

            /*
             * build tupdesc for result tuples. This must match this function's
             * pg_proc entry!
             */
            tupdesc = CreateTemplateTupleDesc(4, false);
            TupleDescInitEntry(tupdesc, (AttrNumber) 1, "name",
                                       TEXTOID, -1, 0);
            TupleDescInitEntry(tupdesc, (AttrNumber) 2, "abbrev",
                                       TEXTOID, -1, 0);
            TupleDescInitEntry(tupdesc, (AttrNumber) 3, "utc_offset",
                                       INTERVALOID, -1, 0);
            TupleDescInitEntry(tupdesc, (AttrNumber) 4, "is_dst",
                                       BOOLOID, -1, 0);

            funcctx->tuple_desc = BlessTupleDesc(tupdesc);
            MemoryContextSwitchTo(oldcontext);
      }

      /* stuff done on every call of the function */
      funcctx = SRF_PERCALL_SETUP();
      tzenum = (pg_tzenum *) funcctx->user_fctx;

      /* search for another zone to display */
      for (;;)
      {
            oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
            tz = pg_tzenumerate_next(tzenum);
            MemoryContextSwitchTo(oldcontext);

            if (!tz)
            {
                  pg_tzenumerate_end(tzenum);
                  funcctx->user_fctx = NULL;
                  SRF_RETURN_DONE(funcctx);
            }

            /* Convert now() to local time in this zone */
            if (timestamp2tm(GetCurrentTransactionStartTimestamp(),
                                     &tzoff, &tm, &fsec, &tzn, tz) != 0)
                  continue;               /* ignore if conversion fails */

            /* Ignore zic's rather silly "Factory" time zone */
            if (tzn && strcmp(tzn, "Local time zone must be set--see zic manual page") == 0)
                  continue;

            /* Found a displayable zone */
            break;
      }

      MemSet(nulls, 0, sizeof(nulls));

      values[0] = CStringGetTextDatum(pg_get_timezone_name(tz));
      values[1] = CStringGetTextDatum(tzn ? tzn : "");

      MemSet(&itm, 0, sizeof(struct pg_tm));
      itm.tm_sec = -tzoff;
      resInterval = (Interval *) palloc(sizeof(Interval));
      tm2interval(&itm, 0, resInterval);
      values[2] = IntervalPGetDatum(resInterval);

      values[3] = BoolGetDatum(tm.tm_isdst > 0);

      tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
      result = HeapTupleGetDatum(tuple);

      SRF_RETURN_NEXT(funcctx, result);
}

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