nabstime.c

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/*-------------------------------------------------------------------------
 *
 * nabstime.c
 *	  Utilities for the built-in type "AbsoluteTime".
 *	  Functions for the built-in type "RelativeTime".
 *	  Functions for the built-in type "TimeInterval".
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/nabstime.c,v 1.117.2.1 2004/05/05 17:28:57 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <ctype.h>
#include <time.h>
#include <sys/time.h>
#include <float.h>
#include <limits.h>

#include "access/xact.h"
#include "libpq/pqformat.h"
#include "miscadmin.h"
#include "utils/builtins.h"


#define MIN_DAYNUM -24856		/* December 13, 1901 */
#define MAX_DAYNUM 24854		/* January 18, 2038 */

#define INVALID_RELTIME_STR		"Undefined RelTime"
#define INVALID_RELTIME_STR_LEN (sizeof(INVALID_RELTIME_STR)-1)
#define RELTIME_LABEL			'@'
#define RELTIME_PAST			"ago"
#define DIRMAXLEN				(sizeof(RELTIME_PAST)-1)

/*
 * Unix epoch is Jan  1 00:00:00 1970.
 * Postgres knows about times sixty-eight years on either side of that
 * for these 4-byte types.
 *
 * "tinterval" is two 4-byte fields.
 * Definitions for parsing tinterval.
 */

#define IsSpace(C)				((C) == ' ')

#define T_INTERVAL_INVAL   0	/* data represents no valid interval */
#define T_INTERVAL_VALID   1	/* data represents a valid interval */
/*
 * ['Mon May 10 23:59:12 1943 PST' 'Sun Jan 14 03:14:21 1973 PST']
 * 0		1		  2			3		  4			5		  6
 * 1234567890123456789012345678901234567890123456789012345678901234
 *
 * we allocate some extra -- timezones are usually 3 characters but
 * this is not in the POSIX standard...
 */
#define T_INTERVAL_LEN					80
#define INVALID_INTERVAL_STR			"Undefined Range"
#define INVALID_INTERVAL_STR_LEN		(sizeof(INVALID_INTERVAL_STR)-1)

#define ABSTIMEMIN(t1, t2) \
	(DatumGetBool(DirectFunctionCall2(abstimele, \
				  AbsoluteTimeGetDatum(t1), \
				  AbsoluteTimeGetDatum(t2))) ? (t1) : (t2))
#define ABSTIMEMAX(t1, t2) \
	(DatumGetBool(DirectFunctionCall2(abstimelt, \
				  AbsoluteTimeGetDatum(t1), \
				  AbsoluteTimeGetDatum(t2))) ? (t2) : (t1))


/*
 * Function prototypes -- internal to this file only
 */

static AbsoluteTime tm2abstime(struct tm * tm, int tz);
static void reltime2tm(RelativeTime time, struct tm * tm);
static int istinterval(char *i_string,
			AbsoluteTime *i_start,
			AbsoluteTime *i_end);


/*
 * GetCurrentAbsoluteTime()
 *
 * Get the current system time (relative to Unix epoch).
 */
AbsoluteTime
GetCurrentAbsoluteTime(void)
{
	time_t		now;

	now = time(NULL);
	return (AbsoluteTime) now;
}


/*
 * GetCurrentAbsoluteTimeUsec()
 *
 * Get the current system time (relative to Unix epoch), including fractional
 * seconds expressed as microseconds.
 */
AbsoluteTime
GetCurrentAbsoluteTimeUsec(int *usec)
{
	time_t		now;
	struct timeval tp;

	gettimeofday(&tp, NULL);
	now = tp.tv_sec;
	*usec = tp.tv_usec;
	return (AbsoluteTime) now;
}


/*
 * AbsoluteTimeUsecToTimestampTz()
 *
 * Convert system time including microseconds to TimestampTz representation.
 */
TimestampTz
AbsoluteTimeUsecToTimestampTz(AbsoluteTime sec, int usec)
{
	TimestampTz result;

#ifdef HAVE_INT64_TIMESTAMP
	result = ((sec - ((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * 86400))
			  * INT64CONST(1000000)) + usec;
#else
	result = sec - ((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * 86400)
		+ (usec / 1000000.0);
#endif

	return result;
}


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

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

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

	abstime2tm(GetCurrentTransactionStartTimeUsec(&usec), &tz, tm, NULL);
	/* Note: don't pass NULL tzp to abstime2tm; affects behavior */
	if (tzp != NULL)
		*tzp = tz;
#ifdef HAVE_INT64_TIMESTAMP
	*fsec = usec;
#else
	*fsec = usec / 1000000.0;
#endif
}


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

	/*
	 * If HasCTZSet is true then we have a brute force time zone
	 * specified. Go ahead and rotate to the local time zone since we will
	 * later bypass any calls which adjust the tm fields.
	 */
	if (HasCTZSet && (tzp != NULL))
		time -= CTimeZone;

	if ((!HasCTZSet) && (tzp != NULL))
		tx = localtime(&time);
	else
		tx = gmtime(&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.
		 */
		if (HasCTZSet)
		{
			*tzp = CTimeZone;
			tm->tm_gmtoff = CTimeZone;
			tm->tm_isdst = 0;
			tm->tm_zone = NULL;
			if (tzn != NULL)
				*tzn = NULL;
		}
		else
		{
			*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)
					ereport(WARNING,
							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
							 errmsg("invalid time zone name: \"%s\"",
									tm->tm_zone)));
			}
		}
	}
	else
		tm->tm_isdst = -1;
#elif defined(HAVE_INT_TIMEZONE)
	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.
		 */
		if (HasCTZSet)
		{
			*tzp = CTimeZone;
			tm->tm_isdst = 0;
			if (tzn != NULL)
				*tzn = NULL;
		}
		else
		{
			*tzp = ((tm->tm_isdst > 0) ? (TIMEZONE_GLOBAL - 3600) : 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[tm->tm_isdst], MAXTZLEN + 1);
				if (strlen(tzname[tm->tm_isdst]) > MAXTZLEN)
					ereport(WARNING,
							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
							 errmsg("invalid time zone name: \"%s\"",
									tzname[tm->tm_isdst])));
			}
		}
	}
	else
		tm->tm_isdst = -1;
#else							/* not (HAVE_TM_ZONE || HAVE_INT_TIMEZONE) */
	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.
		 */
		if (HasCTZSet)
		{
			*tzp = CTimeZone;
			if (tzn != NULL)
				*tzn = NULL;
		}
		else
		{
			/* default to UTC */
			*tzp = 0;
			if (tzn != NULL)
				*tzn = NULL;
		}
	}
	else
		tm->tm_isdst = -1;
#endif
}


/* tm2abstime()
 * Convert a tm structure to abstime.
 * Note that tm has full year (not 1900-based) and 1-based month.
 */
static AbsoluteTime
tm2abstime(struct tm * tm, int tz)
{
	int			day;
	AbsoluteTime sec;

	/* validate, before going out of range on some members */
	if (tm->tm_year < 1901 || tm->tm_year > 2038
		|| tm->tm_mon < 1 || tm->tm_mon > 12
		|| tm->tm_mday < 1 || tm->tm_mday > 31
		|| tm->tm_hour < 0 || tm->tm_hour > 23
		|| tm->tm_min < 0 || tm->tm_min > 59
		|| tm->tm_sec < 0 || tm->tm_sec > 60)
		return INVALID_ABSTIME;

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

	/* check for time out of range */
	if ((day < MIN_DAYNUM) || (day > MAX_DAYNUM))
		return INVALID_ABSTIME;

	/* convert to seconds */
	sec = tm->tm_sec + tz + (tm->tm_min + (day * 24 + tm->tm_hour) * 60) * 60;

	/* check for overflow */
	if ((day == MAX_DAYNUM && sec < 0) ||
		(day == MIN_DAYNUM && sec > 0))
		return INVALID_ABSTIME;

	/* check for reserved values (e.g. "current" on edge of usual range */
	if (!AbsoluteTimeIsReal(sec))
		return INVALID_ABSTIME;

	return sec;
}


/* abstimein()
 * Decode date/time string and return abstime.
 */
Datum
abstimein(PG_FUNCTION_ARGS)
{
	char	   *str = PG_GETARG_CSTRING(0);
	AbsoluteTime result;
	fsec_t		fsec;
	int			tz = 0;
	struct tm	date,
			   *tm = &date;
	int			dterr;
	char	   *field[MAXDATEFIELDS];
	char		lowstr[MAXDATELEN + 1];
	int			dtype;
	int			nf,
				ftype[MAXDATEFIELDS];

	if (strlen(str) >= sizeof(lowstr))
		dterr = DTERR_BAD_FORMAT;
	else
		dterr = ParseDateTime(str, lowstr, field, ftype, MAXDATEFIELDS, &nf);
	if (dterr == 0)
		dterr = DecodeDateTime(field, ftype, nf, &dtype, tm, &fsec, &tz);
	if (dterr != 0)
		DateTimeParseError(dterr, str, "abstime");

	switch (dtype)
	{
		case DTK_DATE:
			result = tm2abstime(tm, tz);
			break;

		case DTK_EPOCH:

			/*
			 * Don't bother retaining this as a reserved value, but
			 * instead just set to the actual epoch time (1970-01-01)
			 */
			result = 0;
			break;

		case DTK_LATE:
			result = NOEND_ABSTIME;
			break;

		case DTK_EARLY:
			result = NOSTART_ABSTIME;
			break;

		case DTK_INVALID:
			result = INVALID_ABSTIME;
			break;

		default:
			elog(ERROR, "unexpected dtype %d while parsing abstime \"%s\"",
				 dtype, str);
			result = INVALID_ABSTIME;
			break;
	};

	PG_RETURN_ABSOLUTETIME(result);
}


/* abstimeout()
 * Given an AbsoluteTime return the English text version of the date
 */
Datum
abstimeout(PG_FUNCTION_ARGS)
{
	AbsoluteTime time = PG_GETARG_ABSOLUTETIME(0);
	char	   *result;
	int			tz;
	double		fsec = 0;
	struct tm	tt,
			   *tm = &tt;
	char		buf[MAXDATELEN + 1];
	char		zone[MAXDATELEN + 1],
			   *tzn = zone;

	switch (time)
	{
			/*
			 * Note that timestamp no longer supports 'invalid'. Retain
			 * 'invalid' for abstime for now, but dump it someday.
			 */
		case INVALID_ABSTIME:
			strcpy(buf, INVALID);
			break;
		case NOEND_ABSTIME:
			strcpy(buf, LATE);
			break;
		case NOSTART_ABSTIME:
			strcpy(buf, EARLY);
			break;
		default:
			abstime2tm(time, &tz, tm, &tzn);
			EncodeDateTime(tm, fsec, &tz, &tzn, DateStyle, buf);
			break;
	}

	result = pstrdup(buf);
	PG_RETURN_CSTRING(result);
}

/*
 *		abstimerecv			- converts external binary format to abstime
 */
Datum
abstimerecv(PG_FUNCTION_ARGS)
{
	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);

	PG_RETURN_ABSOLUTETIME((AbsoluteTime) pq_getmsgint(buf, sizeof(AbsoluteTime)));
}

/*
 *		abstimesend			- converts abstime to binary format
 */
Datum
abstimesend(PG_FUNCTION_ARGS)
{
	AbsoluteTime time = PG_GETARG_ABSOLUTETIME(0);
	StringInfoData buf;

	pq_begintypsend(&buf);
	pq_sendint(&buf, time, sizeof(time));
	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}


/* abstime_finite()
 */
Datum
abstime_finite(PG_FUNCTION_ARGS)
{
	AbsoluteTime abstime = PG_GETARG_ABSOLUTETIME(0);

	PG_RETURN_BOOL((abstime != INVALID_ABSTIME) &&
				   (abstime != NOSTART_ABSTIME) &&
				   (abstime != NOEND_ABSTIME));
}


/*
 * abstime comparison routines
 */
static int
abstime_cmp_internal(AbsoluteTime a, AbsoluteTime b)
{
	/*
	 * We consider all INVALIDs to be equal and larger than any non-INVALID.
	 * This is somewhat arbitrary; the important thing is to have a
	 * consistent sort order.
	 */
	if (a == INVALID_ABSTIME)
	{
		if (b == INVALID_ABSTIME)
			return 0;			/* INVALID = INVALID */
		else
			return 1;			/* INVALID > non-INVALID */
	}

	if (b == INVALID_ABSTIME)
		return -1;				/* non-INVALID < INVALID */

#if 0
	/* CURRENT is no longer stored internally... */
	/* XXX this is broken, should go away: */
	if (a == CURRENT_ABSTIME)
		a = GetCurrentTransactionStartTime();
	if (b == CURRENT_ABSTIME)
		b = GetCurrentTransactionStartTime();
#endif

	if (a > b)
		return 1;
	else if (a == b)
		return 0;
	else
		return -1;
}

Datum
abstimeeq(PG_FUNCTION_ARGS)
{
	AbsoluteTime t1 = PG_GETARG_ABSOLUTETIME(0);
	AbsoluteTime t2 = PG_GETARG_ABSOLUTETIME(1);

	PG_RETURN_BOOL(abstime_cmp_internal(t1, t2) == 0);
}

Datum
abstimene(PG_FUNCTION_ARGS)
{
	AbsoluteTime t1 = PG_GETARG_ABSOLUTETIME(0);
	AbsoluteTime t2 = PG_GETARG_ABSOLUTETIME(1);

	PG_RETURN_BOOL(abstime_cmp_internal(t1, t2) != 0);
}

Datum
abstimelt(PG_FUNCTION_ARGS)
{
	AbsoluteTime t1 = PG_GETARG_ABSOLUTETIME(0);
	AbsoluteTime t2 = PG_GETARG_ABSOLUTETIME(1);

	PG_RETURN_BOOL(abstime_cmp_internal(t1, t2) < 0);
}

Datum
abstimegt(PG_FUNCTION_ARGS)
{
	AbsoluteTime t1 = PG_GETARG_ABSOLUTETIME(0);
	AbsoluteTime t2 = PG_GETARG_ABSOLUTETIME(1);

	PG_RETURN_BOOL(abstime_cmp_internal(t1, t2) > 0);
}

Datum
abstimele(PG_FUNCTION_ARGS)
{
	AbsoluteTime t1 = PG_GETARG_ABSOLUTETIME(0);
	AbsoluteTime t2 = PG_GETARG_ABSOLUTETIME(1);

	PG_RETURN_BOOL(abstime_cmp_internal(t1, t2) <= 0);