datetime.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

					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;

					default:
						return DTERR_BAD_FORMAT;
				}
				break;

			default:
				return DTERR_BAD_FORMAT;
		}

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

	if (fmask & DTK_M(YEAR))
	{
		/* there is no year zero in AD/BC notation; i.e. "1 BC" == year 0 */
		if (bc)
		{
			if (tm->tm_year > 0)
				tm->tm_year = -(tm->tm_year - 1);
			else
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_DATETIME_FORMAT),
						 errmsg("inconsistent use of year %04d and \"BC\"",
								tm->tm_year)));
		}
		else if (is2digits)
		{
			if (tm->tm_year < 70)
				tm->tm_year += 2000;
			else if (tm->tm_year < 100)
				tm->tm_year += 1900;
		}
	}

	/* 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 (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;
		}

		/*
		 * 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;

		/* 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, global_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 == global_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;
	int			is2digits = FALSE;
	int			mer = HR24;

	*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, 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
					{
						dterr = DecodePosixTimezone(field[i], tzp);
						if (dterr)
							return dterr;

						ftype[i] = DTK_TZ;
						tmask = DTK_M(TZ);
					}
				}
				break;

			case DTK_TIME:
				dterr = DecodeTime(field[i], (fmask | DTK_DATE_M),
								   &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;

					/*
					 * Already have a time zone? Then maybe this is the second
					 * field of a POSIX time: EST+3 (equivalent to PST)
					 */
					if (i > 0 && (fmask & DTK_M(TZ)) != 0 &&
						ftype[i - 1] == DTK_TZ &&
						isalpha((unsigned char) *field[i - 1]))
					{
						*tzp -= tz;
						tmask = 0;
					}
					else
					{
						*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 = strtol(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;