dt_common.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

static void
abstime2tm(AbsoluteTime _time, int *tzp, struct tm * tm, char **tzn)
{
	time_t		time = (time_t) _time;
	struct tm  *tx;

	if (tzp != NULL)
		tx = localtime((time_t *) &time);
	else
		tx = gmtime((time_t *) &time);

	tm->tm_year = tx->tm_year + 1900;
	tm->tm_mon = tx->tm_mon + 1;
	tm->tm_mday = tx->tm_mday;
	tm->tm_hour = tx->tm_hour;
	tm->tm_min = tx->tm_min;
	tm->tm_sec = tx->tm_sec;
	tm->tm_isdst = tx->tm_isdst;

#if defined(HAVE_TM_ZONE)
	tm->tm_gmtoff = tx->tm_gmtoff;
	tm->tm_zone = tx->tm_zone;

	if (tzp != NULL)
	{
		/*
		 * We have a brute force time zone per SQL99? Then use it without
		 * change since we have already rotated to the time zone.
		 */
		*tzp = -tm->tm_gmtoff;	/* tm_gmtoff is Sun/DEC-ism */

		/*
		 * XXX FreeBSD man pages indicate that this should work - tgl 97/04/23
		 */
		if (tzn != NULL)
		{
			/*
			 * Copy no more than MAXTZLEN bytes of timezone to tzn, in case it
			 * contains an error message, which doesn't fit in the buffer
			 */
			StrNCpy(*tzn, tm->tm_zone, MAXTZLEN + 1);
			if (strlen(tm->tm_zone) > MAXTZLEN)
				tm->tm_isdst = -1;
		}
	}
	else
		tm->tm_isdst = -1;
#elif defined(HAVE_INT_TIMEZONE)
	if (tzp != NULL)
	{
		*tzp = (tm->tm_isdst > 0) ? TIMEZONE_GLOBAL - SECS_PER_HOUR : TIMEZONE_GLOBAL;

		if (tzn != NULL)
		{
			/*
			 * Copy no more than MAXTZLEN bytes of timezone to tzn, in case it
			 * contains an error message, which doesn't fit in the buffer
			 */
			StrNCpy(*tzn, TZNAME_GLOBAL[tm->tm_isdst], MAXTZLEN + 1);
			if (strlen(TZNAME_GLOBAL[tm->tm_isdst]) > MAXTZLEN)
				tm->tm_isdst = -1;
		}
	}
	else
		tm->tm_isdst = -1;
#else							/* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
	if (tzp != NULL)
	{
		/* default to UTC */
		*tzp = 0;
		if (tzn != NULL)
			*tzn = NULL;
	}
	else
		tm->tm_isdst = -1;
#endif
}

void
GetCurrentDateTime(struct tm * tm)
{
	int			tz;

	abstime2tm(time(NULL), &tz, tm, NULL);
}

/* DetermineLocalTimeZone()
 *
 * Given a struct tm in which tm_year, tm_mon, tm_mday, tm_hour, tm_min, and
 * tm_sec fields are set, attempt to determine the applicable local zone
 * (ie, regular or daylight-savings time) at that time.  Set the struct tm's
 * tm_isdst field accordingly, and return the actual timezone offset.
 *
 * This subroutine exists to centralize uses of mktime() and defend against
 * mktime() bugs/restrictions on various platforms.  This should be
 * the *only* call of mktime() in the backend.
 */
static int
DetermineLocalTimeZone(struct tm * tm)
{
	int			tz;

	if (IS_VALID_UTIME(tm->tm_year, tm->tm_mon, tm->tm_mday))
	{
#if defined(HAVE_TM_ZONE) || defined(HAVE_INT_TIMEZONE)

		/*
		 * Some buggy mktime() implementations may change the year/month/day
		 * when given a time right at a DST boundary.  To prevent corruption
		 * of the caller's data, give mktime() a copy...
		 */
		struct tm	tt,
				   *tmp = &tt;

		*tmp = *tm;
		/* change to Unix conventions for year/month */
		tmp->tm_year -= 1900;
		tmp->tm_mon -= 1;

		/* indicate timezone unknown */
		tmp->tm_isdst = -1;

		if (mktime(tmp) != (time_t) -1 && tmp->tm_isdst >= 0)
		{
			/* mktime() succeeded, trust its result */
			tm->tm_isdst = tmp->tm_isdst;

#if defined(HAVE_TM_ZONE)
			/* tm_gmtoff is Sun/DEC-ism */
			tz = -tmp->tm_gmtoff;
#elif defined(HAVE_INT_TIMEZONE)
			tz = (tmp->tm_isdst > 0) ? TIMEZONE_GLOBAL - SECS_PER_HOUR : TIMEZONE_GLOBAL;
#endif   /* HAVE_INT_TIMEZONE */
		}
		else
		{
			/*
			 * We have a buggy (not to say deliberately brain damaged)
			 * mktime().  Work around it by using localtime() instead.
			 *
			 * First, generate the time_t value corresponding to the given
			 * y/m/d/h/m/s taken as GMT time.  This will not overflow (at
			 * least not for time_t taken as signed) because of the range
			 * check we did above.
			 */
			long		day,
						mysec,
						locsec,
						delta1,
						delta2;
			time_t		mytime;

			day = (date2j(tm->tm_year, tm->tm_mon, tm->tm_mday) -
				   date2j(1970, 1, 1));
			mysec = tm->tm_sec + (tm->tm_min + (day * HOURS_PER_DAY + tm->tm_hour) * MINS_PER_HOUR) * SECS_PER_MINUTE;
			mytime = (time_t) mysec;

			/*
			 * Use localtime to convert that time_t to broken-down time, and
			 * reassemble to get a representation of local time.
			 */
			tmp = localtime(&mytime);
			day = (date2j(tmp->tm_year + 1900, tmp->tm_mon + 1, tmp->tm_mday) -
				   date2j(1970, 1, 1));
			locsec = tmp->tm_sec + (tmp->tm_min + (day * HOURS_PER_DAY + tmp->tm_hour) * MINS_PER_HOUR) * SECS_PER_MINUTE;

			/*
			 * The local time offset corresponding to that GMT time is now
			 * computable as mysec - locsec.
			 */
			delta1 = mysec - locsec;

			/*
			 * However, if that GMT time and the local time we are actually
			 * interested in are on opposite sides of a daylight-savings-time
			 * transition, then this is not the time offset we want.  So,
			 * adjust the time_t to be what we think the GMT time
			 * corresponding to our target local time is, and repeat the
			 * localtime() call and delta calculation.	We may have to do it
			 * twice before we have a trustworthy delta.
			 *
			 * Note: think not to put a loop here, since if we've been given
			 * an "impossible" local time (in the gap during a spring-forward
			 * transition) we'd never get out of the loop. Twice is enough to
			 * give the behavior we want, which is that "impossible" times are
			 * taken as standard time, while at a fall-back boundary ambiguous
			 * times are also taken as standard.
			 */
			mysec += delta1;
			mytime = (time_t) mysec;
			tmp = localtime(&mytime);
			day = (date2j(tmp->tm_year + 1900, tmp->tm_mon + 1, tmp->tm_mday) -
				   date2j(1970, 1, 1));
			locsec = tmp->tm_sec + (tmp->tm_min + (day * HOURS_PER_DAY + tmp->tm_hour) * MINS_PER_HOUR) * SECS_PER_MINUTE;
			delta2 = mysec - locsec;
			if (delta2 != delta1)
			{
				mysec += (delta2 - delta1);
				mytime = (time_t) mysec;
				tmp = localtime(&mytime);
				day = (date2j(tmp->tm_year + 1900, tmp->tm_mon + 1, tmp->tm_mday) -
					   date2j(1970, 1, 1));
				locsec = tmp->tm_sec + (tmp->tm_min + (day * HOURS_PER_DAY + tmp->tm_hour) * MINS_PER_HOUR) * SECS_PER_MINUTE;
				delta2 = mysec - locsec;
			}
			tm->tm_isdst = tmp->tm_isdst;
			tz = (int) delta2;
		}
#else							/* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
		/* Assume UTC if no system timezone info available */
		tm->tm_isdst = 0;
		tz = 0;
#endif
	}
	else
	{
		/* Given date is out of range, so assume UTC */
		tm->tm_isdst = 0;
		tz = 0;
	}

	return tz;
}

static void
dt2time(double jd, int *hour, int *min, int *sec, fsec_t *fsec)
{
#ifdef HAVE_INT64_TIMESTAMP
	int64		time;
#else
	double		time;
#endif

	time = jd;
#ifdef HAVE_INT64_TIMESTAMP
	*hour = time / USECS_PER_HOUR;
	time -= (*hour) * USECS_PER_HOUR;
	*min = time / USECS_PER_MINUTE;
	time -= (*min) * USECS_PER_MINUTE;
	*sec = time / USECS_PER_SEC;
	*fsec = time - (*sec * USECS_PER_SEC);
#else
	*hour = time / SECS_PER_HOUR;
	time -= (*hour) * SECS_PER_HOUR;
	*min = time / SECS_PER_MINUTE;
	time -= (*min) * SECS_PER_MINUTE;
	*sec = time;
	*fsec = time - *sec;
#endif
}	/* dt2time() */



/* DecodeNumberField()
 * Interpret numeric string as a concatenated date or time field.
 * Use the context of previously decoded fields to help with
 * the interpretation.
 */
static int
DecodeNumberField(int len, char *str, int fmask,
	int *tmask, struct tm * tm, fsec_t *fsec, int *is2digits, bool EuroDates)
{
	char	   *cp;

	/*
	 * Have a decimal point? Then this is a date or something with a seconds
	 * field...
	 */
	if ((cp = strchr(str, '.')) != NULL)
	{
#ifdef HAVE_INT64_TIMESTAMP
		char		fstr[MAXDATELEN + 1];

		/*
		 * OK, we have at most six digits to care about. Let's construct a
		 * string and then do the conversion to an integer.
		 */
		strcpy(fstr, (cp + 1));
		strcpy(fstr + strlen(fstr), "000000");
		*(fstr + 6) = '\0';
		*fsec = strtol(fstr, NULL, 10);
#else
		*fsec = strtod(cp, NULL);
#endif
		*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;
		}
		/* yyddd? */
		else if (len == 5)
		{
			*tmask = DTK_DATE_M;
			tm->tm_mday = atoi(str + 2);
			*(str + 2) = '\0';
			tm->tm_mon = 1;
			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 -1;
}	/* DecodeNumberField() */


/* DecodeNumber()
 * Interpret plain numeric field as a date value in context.
 */
static int
DecodeNumber(int flen, char *str, int fmask,
	int *tmask, struct tm * tm, fsec_t *fsec, int *is2digits, bool EuroDates)
{
	int			val;
	char	   *cp;

	*tmask = 0;

	val = strtol(str, &cp, 10);
	if (cp == str)
		return -1;

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

		*fsec = strtod(cp, &cp);
		if (*cp != '\0')
			return -1;
	}
	else if (*cp != '\0')
		return -1;

	/* Special case day of year? */
	if (flen == 3 && (fmask & DTK_M(YEAR)) && val >= 1 && val <= 366)
	{
		*tmask = (DTK_M(DOY) | DTK_M(MONTH) | DTK_M(DAY));
		tm->tm_yday = val;
		j2date(date2j(tm->tm_year, 1, 1) + tm->tm_yday - 1,
			   &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
	}

	/***
	 * Enough digits to be unequivocal year? Used to test for 4 digits or
	 * more, but we now test first for a three-digit doy so anything
	 * bigger than two digits had better be an explicit year.
	 * - thomas 1999-01-09
	 * Back to requiring a 4 digit year. We accept a two digit
	 * year farther down. - thomas 2000-03-28
	 ***/
	else if (flen >= 4)
	{
		*tmask = DTK_M(YEAR);

		/* already have a year? then see if we can substitute... */
		if ((fmask & DTK_M(YEAR)) && !(fmask & DTK_M(DAY)) &&
			tm->tm_year >= 1 && tm->tm_year <= 31)
		{
			tm->tm_mday = tm->tm_year;
			*tmask = DTK_M(DAY);
		}

		tm->tm_year = val;
	}

	/* already have year? then could be month */
	else if ((fmask & DTK_M(YEAR)) && !(fmask & DTK_M(MONTH)) && val >= 1 && val <= MONTHS_PER_YEAR)
	{
		*tmask = DTK_M(MONTH);
		tm->tm_mon = val;
	}
	/* no year and EuroDates enabled? then could be day */
	else if ((EuroDates || (fmask & DTK_M(MONTH))) &&
			 !(fmask & DTK_M(YEAR)) && !(fmask & DTK_M(DAY)) &&
			 val >= 1 && val <= 31)
	{
		*tmask = DTK_M(DAY);
		tm->tm_mday = val;
	}
	else if (!(fmask & DTK_M(MONTH)) && val >= 1 && val <= MONTHS_PER_YEAR)
	{
		*tmask = DTK_M(MONTH);
		tm->tm_mon = val;
	}
	else if (!(fmask & DTK_M(DAY)) && val >= 1 && val <= 31)
	{
		*tmask = DTK_M(DAY);
		tm->tm_mday = val;
	}

	/*
	 * Check for 2 or 4 or more digits, but currently we reach here only if
	 * two digits. - thomas 2000-03-28
	 */
	else if (!(fmask & DTK_M(YEAR)) && (flen >= 4 || flen == 2))
	{
		*tmask = DTK_M(YEAR);
		tm->tm_year = val;

		/* adjust ONLY if exactly two digits... */
		*is2digits = (flen == 2);
	}
	else
		return -1;

	return 0;
}	/* DecodeNumber() */

/* DecodeDate()
 * Decode date string which includes delimiters.
 * Insist on a complete set of fields.
 */
static int
DecodeDate(char *str, int fmask, int *tmask, struct tm * tm, bool EuroDates)
{
	fsec_t		fsec;

	int			nf = 0;
	int			i,
				len;
	int			bc = FALSE;
	int			is2digits = FALSE;
	int			type,
				val,
				dmask = 0;
	char	   *field[MAXDATEFIELDS];

	/* 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))