path: root/src/backend/utils/adt/date.c

/*-------------------------------------------------------------------------
 *
 * date.c--
 *    Functions for the built-in type "AbsoluteTime".
 *    Functions for the built-in type "RelativeTime".
 *    Functions for the built-in type "TimeInterval".
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /cvsroot/pgsql/src/backend/utils/adt/date.c,v 1.1.1.1 1996/07/09 06:22:03 scrappy Exp $
 *
 * NOTES
 *   This code is actually (almost) unused.
 *   It needs to be integrated with Time and struct trange.
 *
 * XXX	This code needs to be rewritten to work with the "new" definitions
 * XXX	in h/tim.h.  Look for int32's, int, long, etc. in the code.  The
 * XXX	definitions in h/tim.h may need to be rethought also.
 *
 * XXX  This code has been cleaned up some - avi 07/07/93
 *
 *-------------------------------------------------------------------------
 */
#include <ctype.h>
#include <stdio.h>
#include <time.h>
#include <sys/time.h>
#include <sys/types.h>
#include <string.h>

#include "postgres.h"
#include "miscadmin.h"
#include "access/xact.h"
#include "utils/builtins.h"	/* where function declarations go */
#include "utils/elog.h"
#include "utils/palloc.h"
#include "utils/nabstime.h"

#define	TM_YEAR_BASE	1900		/* compatible to UNIX time */
#define	EPOCH_YEAR	1970		/* compatible to UNIX time */
#define	YEAR_MAX	2038		/* otherwise overflow */
#define	YEAR_MIN	1902		/* otherwise overflow */
#define	DAYS_PER_LYEAR	366
#define	DAYS_PER_NYEAR	365
#define	HOURS_PER_DAY	24
#define	MINS_PER_HOUR	60
#define	SECS_PER_MIN	60
#define	MAX_LONG	2147483647	/* 2^31 */

/* absolute time definitions */
#define	TIME_NOW_STR		"now"	   /* represents time now */
#define	TIME_EPOCH_STR		"epoch"	   /* Jan 1 00:00:00 1970 GMT */
#define TIME_EPOCH_STR_LEN	(sizeof(TIME_EPOCH_STR)-1)

#define	INVALID_ABSTIME_STR 	"Undefined AbsTime"
#define	INVALID_ABSTIME_STR_LEN	(sizeof(INVALID_ABSTIME_STR)-1)

#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.
 */ 

#define	IsCharDigit(C)		isdigit(C)
#define	IsCharA_Z(C)		isalpha(C)		
#define	IsSpace(C)		((C) == ' ')
#define	IsNull(C)		((C) == NULL)

#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) abstimele((t1),(t2)) ? (t1) : (t2)
#define ABSTIMEMAX(t1, t2) abstimelt((t1),(t2)) ? (t2) : (t1)

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

static	char 	*unit_tab[] = {
	"second", "seconds", "minute", "minutes",
	"hour", "hours", "day", "days", "week", "weeks",
	"month", "months", "year", "years"};
#define UNITMAXLEN 7	/* max length of a unit name */
#define NUNITS 14	/* number of different units */

/* table of seconds per unit (month = 30 days, year = 365 days)  */
static	int	sec_tab[] = { 
	1,1, 60, 60,
	3600, 3600, 86400, 86400, 604800,  604800,
	2592000,  2592000,  31536000,  31536000 };

/* maximal values (in seconds) per unit which can be represented */
static	int	unit_max_quantity[] = {
	2144448000, 2144448000, 35740800, 35740800,
	595680, 595680, 24820, 24820, 3545, 3545,
	827, 827, 68, 68 };


struct timeb *TimeDifferenceFromGMT = NULL;
static bool TimeDiffIsInited = false;
static char *timezonename = NULL;

/*
 * Function prototypes -- internal to this file only
 */
static int correct_unit(char unit[], int *unptr);
static int correct_dir(char direction[], int *signptr);
static int istinterval(char *i_string, 
		       AbsoluteTime *i_start, 
		       AbsoluteTime *i_end);

/***************************************************************************** 
 *   USER I/O ROUTINES                                                       *
 *****************************************************************************/

/*
 *	reltimein	- converts a reltime string in an internal format
 */
int32	/* RelativeTime */
reltimein(char *timestring)
{
    int		error;
    int32 /* RelativeTime */	timeinsec;
    int		sign, unitnr;
    long		quantity;
    
    error = isreltime(timestring, &sign, &quantity, &unitnr);
    
#ifdef	DATEDEBUG
    elog(DEBUG, "reltimein: isreltime(%s) returns error=%d, %d, %d, %d",
	 timestring, error, sign, quantity, unitnr);
#endif	/* !DATEDEBUG */
    
    if (error != 1) {
	timeinsec = INVALID_RELTIME;  /*invalid time representation */
    } else {
	/* this check is necessary, while no control on overflow */
	if (quantity > unit_max_quantity[unitnr] || quantity < 0) {
#ifdef	DATEDEBUG
	    elog(DEBUG, "reltimein: illegal quantity %d (< %d)",
		 quantity, unit_max_quantity[unitnr]);
#endif	/* DATEDEBUG */
	    timeinsec = INVALID_RELTIME; /* illegal quantity */
	} else {
	    timeinsec = sign * quantity * sec_tab[unitnr];
#ifdef	DATEDEBUG
	    elog(DEBUG, "reltimein: computed timeinsec %d",
		 timeinsec);
#endif	/* DATEDEBUG */
	}
    }
    return(timeinsec);
}


/*
 *	reltimeout	- converts the internal format to a reltime string
 */
char *reltimeout(int32 timevalue)
{
    char		*timestring;
    long		quantity;
    register int	i;
    int		unitnr;
	
    timestring = (char *) palloc(Max(strlen(INVALID_RELTIME_STR),
				     UNITMAXLEN) + 1);
    if (timevalue == INVALID_RELTIME) {
	(void) strcpy(timestring,INVALID_RELTIME_STR);
	return(timestring);
    }
    if (timevalue == 0)
	i = 1;			/* unit = 'seconds' */
    else
	for (i = 12; i >= 0; i = i-2)
	    if ((timevalue % sec_tab[i]) == 0)
		break;		/* appropriate unit found */
    unitnr = i;
    quantity = (timevalue / sec_tab[unitnr]);
    if (quantity > 1 || quantity < -1)
	unitnr++;		/* adjust index for PLURAL of unit */
    if (quantity >= 0)
	(void) sprintf( timestring, "%c %lu %s", RELTIME_LABEL,
		       quantity, unit_tab[unitnr]);
    else
	(void) sprintf( timestring, "%c %lu %s %s", RELTIME_LABEL,
		       (quantity * -1), unit_tab[unitnr], RELTIME_PAST);
    return(timestring);
}


/*
 *	tintervalin	- converts an interval string to an internal format
 */
TimeInterval tintervalin(char *intervalstr)
{	
    int 		error;
    AbsoluteTime	i_start, i_end, t1, t2;
    TimeInterval	interval;
    
    interval = (TimeInterval) palloc(sizeof(TimeIntervalData));
    error = istinterval(intervalstr, &t1, &t2);
    if (error == 0)
	interval->status = T_INTERVAL_INVAL;
    if (t1 == INVALID_ABSTIME || t2 == INVALID_ABSTIME)
	interval->status = T_INTERVAL_INVAL;  /* undefined  */
    else {
	i_start = ABSTIMEMIN(t1, t2);
	i_end = ABSTIMEMAX(t1, t2);
	interval->data[0] = i_start;
	interval->data[1] = i_end;
	interval->status = T_INTERVAL_VALID;
    }
    return(interval);
}


/*
 *	tintervalout	- converts an internal interval format to a string
 *
 */
char *tintervalout(TimeInterval interval)
{
    char	*i_str, *p;
    
    i_str = (char	*) palloc( T_INTERVAL_LEN );  /* ['...' '...'] */
    (void) strcpy(i_str,"['");
    if (interval->status == T_INTERVAL_INVAL)
	(void) strcat(i_str,INVALID_INTERVAL_STR);
    else {
	p = nabstimeout(interval->data[0]);
	(void) strcat(i_str,p);
	pfree(p);
	(void) strcat(i_str,"' '");
	p = nabstimeout(interval->data[1]);
	(void) strcat(i_str,p);
	pfree(p);
    }
    (void) strcat(i_str,"']\0");
    return(i_str);
}


/***************************************************************************** 
 *   PUBLIC ROUTINES                                                         *
 *****************************************************************************/

/*
 *	mktinterval	- creates a time interval with endpoints t1 and t2
 */
TimeInterval mktinterval(AbsoluteTime t1, AbsoluteTime t2)
{
    AbsoluteTime	tstart = ABSTIMEMIN(t1, t2), tend = ABSTIMEMAX(t1, t2);
    TimeInterval interval;
    
    interval = (TimeInterval) palloc(sizeof(TimeIntervalData));
    if (t1 == INVALID_ABSTIME || t2 == INVALID_ABSTIME)
	interval->status = T_INTERVAL_INVAL;
    else {
	interval->status = T_INTERVAL_VALID;
	interval->data[0] = tstart;
	interval->data[1] = tend;
    }
    
    return interval;
}

/*
 *	timepl, timemi and abstimemi use the formula
 *		abstime + reltime = abstime
 *	so	abstime - reltime = abstime
 *	and	abstime - abstime = reltime
 */

/*
 *	timepl		- returns the value of (abstime t1 + relime t2)
 */
AbsoluteTime timepl(AbsoluteTime t1, RelativeTime t2)
{
    if (t1 == CURRENT_ABSTIME)
	t1 = GetCurrentTransactionStartTime();
    
    if (AbsoluteTimeIsReal(t1) &&
	RelativeTimeIsValid(t2) &&
	((t2 > 0) ? (t1 < NOEND_ABSTIME - t2)
	 : (t1 > NOSTART_ABSTIME - t2))) 	/* prevent overflow */
	return (t1 + t2);
    
    return(INVALID_ABSTIME);
}


/*
 *	timemi		- returns the value of (abstime t1 - reltime t2)
 */
AbsoluteTime timemi(AbsoluteTime t1, RelativeTime t2)
{
    if (t1 == CURRENT_ABSTIME)
	t1 = GetCurrentTransactionStartTime();
    
    if (AbsoluteTimeIsReal(t1) &&
	RelativeTimeIsValid(t2) &&
	((t2 > 0) ? (t1 > NOSTART_ABSTIME + t2)
	 : (t1 < NOEND_ABSTIME + t2))) 	/* prevent overflow */
	return (t1 - t2);
    
    return(INVALID_ABSTIME);
}


/*
 *	abstimemi	- returns the value of (abstime t1 - abstime t2)
 */
static RelativeTime abstimemi(AbsoluteTime t1, AbsoluteTime t2)
{
    if (t1 == CURRENT_ABSTIME)
	t1 = GetCurrentTransactionStartTime();
    if (t2 == CURRENT_ABSTIME)
	t2 = GetCurrentTransactionStartTime();
    
    if (AbsoluteTimeIsReal(t1) &&
	AbsoluteTimeIsReal(t2))
	return (t1 - t2);
    
    return(INVALID_RELTIME);
}


/*
 *	ininterval	- returns 1, iff absolute date is in the interval
 */
int ininterval(AbsoluteTime t, TimeInterval interval)
{
    if (interval->status == T_INTERVAL_VALID && t != INVALID_ABSTIME)
	return (abstimege(t, interval->data[0]) &&
		abstimele(t, interval->data[1]));
    return(0);
}

/*
 *	intervalrel	- returns  relative time corresponding to interval
 */
RelativeTime intervalrel(TimeInterval interval)
{
    if (interval->status == T_INTERVAL_VALID)
	return(abstimemi(interval->data[1], interval->data[0]));
    else
	return(INVALID_RELTIME);
}

/*
 *	timenow		- returns  time "now", internal format
 *
 *      Now AbsoluteTime is time since Jan 1 1970 -mer 7 Feb 1992
 */
AbsoluteTime timenow()
{
    time_t sec;
    if (time(&sec) < 0)
	return(INVALID_ABSTIME);
    return((AbsoluteTime) sec);
}

/*
 *	reltimeeq	- returns 1, iff arguments are equal
 *	reltimene	- returns 1, iff arguments are not equal
 *	reltimelt	- returns 1, iff t1 less than t2
 *	reltimegt	- returns 1, iff t1 greater than t2
 *	reltimele	- returns 1, iff t1 less than or equal to t2
 *	reltimege	- returns 1, iff t1 greater than or equal to t2
 */
int32 reltimeeq(RelativeTime t1, RelativeTime t2)
{
    if (t1 == INVALID_RELTIME || t2 == INVALID_RELTIME)
	return 0;
    return(t1 == t2);
}

int32 reltimene(RelativeTime t1, RelativeTime t2)
{
    if (t1 == INVALID_RELTIME || t2 == INVALID_RELTIME)
	return 0;
    return(t1 != t2);
}

int32 reltimelt(RelativeTime t1, RelativeTime t2)
{
    if (t1 == INVALID_RELTIME || t2 == INVALID_RELTIME)
	return 0;
    return(t1 < t2);
}

int32 reltimegt(RelativeTime t1, RelativeTime t2)
{
    if (t1 == INVALID_RELTIME || t2 == INVALID_RELTIME)
	return 0;
    return(t1 > t2);
}

int32 reltimele(RelativeTime t1, RelativeTime t2)
{
    if (t1 == INVALID_RELTIME || t2 == INVALID_RELTIME)
	return 0;
    return(t1 <= t2);
}

int32 reltimege(RelativeTime t1, RelativeTime t2)
{
    if (t1 == INVALID_RELTIME || t2 == INVALID_RELTIME)
	return 0;
    return(t1 >= t2);
}


/*
 *	intervaleq	- returns 1, iff interval i1 is equal to interval i2
 */
int32 intervaleq(TimeInterval i1, TimeInterval i2)
{
    if (i1->status == T_INTERVAL_INVAL || i2->status == T_INTERVAL_INVAL)
	return(0);	/* invalid interval */
    return(abstimeeq(i1->data[0], i2->data[0]) &&
	   abstimeeq(i1->data[1], i2->data[1]));
}

/*
 *	intervalleneq	- returns 1, iff length of interval i is equal to
 *				reltime t
 */
int32 intervalleneq(TimeInterval i, RelativeTime t)
{
    RelativeTime rt;
    
    if ((i->status == T_INTERVAL_INVAL) || (t == INVALID_RELTIME))
	return(0);
    rt = intervalrel(i);
    return (rt != INVALID_RELTIME && rt == t);
}

/*
 *	intervallenne	- returns 1, iff length of interval i is not equal
 *				to reltime t
 */
int32 intervallenne(TimeInterval i, RelativeTime t)
{
    RelativeTime rt;
    
    if ((i->status == T_INTERVAL_INVAL) || (t == INVALID_RELTIME))
	return(0);
    rt = intervalrel(i);
    return (rt != INVALID_RELTIME && rt != t);
}

/*
 *	intervallenlt	- returns 1, iff length of interval i is less than
 *				reltime t
 */
int32 intervallenlt(TimeInterval i, RelativeTime t)
{
    RelativeTime rt;
    
    if ((i->status == T_INTERVAL_INVAL) || (t == INVALID_RELTIME))
	return(0);
    rt = intervalrel(i);
    return (rt != INVALID_RELTIME && rt < t);
}

/*
 *	intervallengt	- returns 1, iff length of interval i is greater than
 *				reltime t
 */
int32 intervallengt(TimeInterval i, RelativeTime t)
{
    RelativeTime rt;
    
    if ((i->status == T_INTERVAL_INVAL) || (t == INVALID_RELTIME))
	return(0);
    rt = intervalrel(i);
    return (rt != INVALID_RELTIME && rt > t);
}

/*
 *	intervallenle	- returns 1, iff length of interval i is less or equal
 *				    than reltime t
 */
int32 intervallenle(TimeInterval i, RelativeTime t)
{	
    RelativeTime rt;
    
    if ((i->status == T_INTERVAL_INVAL) || (t == INVALID_RELTIME))
	return(0);
    rt = intervalrel(i);
    return (rt != INVALID_RELTIME && rt <= t);
}

/*
 *	intervallenge	- returns 1, iff length of interval i is greater or
 * 				equal than reltime t
 */
int32 intervallenge(TimeInterval i, RelativeTime t)
{
    RelativeTime rt;
    
    if ((i->status == T_INTERVAL_INVAL) || (t == INVALID_RELTIME))
	return(0);
    rt = intervalrel(i);
    return (rt != INVALID_RELTIME && rt >= t);
}

/*
 *	intervalct	- returns 1, iff interval i1 contains interval i2
 */
int32 intervalct(TimeInterval i1, TimeInterval i2)
{
    if (i1->status == T_INTERVAL_INVAL || i2->status == T_INTERVAL_INVAL)
	return(0);
    return(abstimele(i1->data[0], i2->data[0]) &&
	   abstimege(i1->data[1], i2->data[1]));
}

/*
 *	intervalov	- returns 1, iff interval i1 (partially) overlaps i2
 */
int32 intervalov(TimeInterval i1, TimeInterval i2)
{
    if (i1->status == T_INTERVAL_INVAL || i2->status == T_INTERVAL_INVAL)
	return(0);
    return(! (abstimelt(i1->data[1], i2->data[0]) ||
	      abstimegt(i1->data[0], i2->data[1])));
}

/*
 *	intervalstart	- returns  the start of interval i
 */
AbsoluteTime intervalstart(TimeInterval i)
{
    if (i->status == T_INTERVAL_INVAL)
	return INVALID_ABSTIME;
    return(i->data[0]);
}

/*
 *	intervalend	- returns  the end of interval i
 */
AbsoluteTime intervalend(TimeInterval i)
{
    if (i->status == T_INTERVAL_INVAL)
	return INVALID_ABSTIME;
    return(i->data[1]);
}


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

/*
 *	isreltime	- returns 1, iff datestring is of type reltime
 *				  2, iff datestring is 'invalid time' identifier
 *				  0, iff datestring contains a syntax error
 *
 *	output parameter:
 *		sign = -1, iff direction is 'ago'
 *			       else sign = 1.
 *		quantity   : quantity of unit
 *		unitnr     :	0 or 1 ... sec
 *				2 or 3 ... min
 *				4 or 5 ... hour
 *				6 or 7 ... day
 *				8 or 9 ... week
 *			       10 or 11... month
 *			       12 or 13... year
 *			  
 *
 *	Relative time:
 *
 *	`@' ` ' Quantity ` ' Unit [ ` ' Direction]
 *
 *	OR  `Undefined RelTime' 	(see also INVALID_RELTIME_STR)
 *
 *	where
 *	Quantity is	`1', `2', ...
 *	Unit is		`second', `minute', `hour', `day', `week',
 *			`month' (30-days), or `year' (365-days),
 *     			or PLURAL of these units.
 *	Direction is	`ago'
 *
 *	VALID time  less or equal   `@ 68 years' 
 *
 */
int isreltime(char *timestring, int *sign, long *quantity, int *unitnr)
{
    register char	*p;
    register char	c;
    int		i;
    char		unit[UNITMAXLEN] ;
    char		direction[DIRMAXLEN];
    int		localSign;
    int		localUnitNumber;
    long		localQuantity;
    
    if (!PointerIsValid(sign)) {
	sign = &localSign;
    }
    if (!PointerIsValid(unitnr)) {
	unitnr = &localUnitNumber;
    }
    if (!PointerIsValid(quantity)) {
	quantity = &localQuantity;
    }
    unit[0] = '\0';
    direction[0] = '\0';
    p = timestring;
    /* skip leading blanks */
    while ((c = *p) != '\0') {
	if (c != ' ')
	    break;
	p++;
    }
    /* Test whether 'invalid time' identifier or not */
    if (!strncmp(INVALID_RELTIME_STR,p,strlen(INVALID_RELTIME_STR) + 1))
	return(2);	/* correct 'invalid time' identifier found */
    
    /* handle label of relative time */
    if (c != RELTIME_LABEL)
	return(0);	/*syntax error*/
    c = *++p;
    if (c != ' ')	return(0);	/*syntax error*/
    p++;
    /* handle the quantity */
    *quantity = 0;
    for (;;) {
	c = *p;
	if (isdigit(c)) {
	    *quantity = *quantity * 10 + (c -'0');
	    p++;
	} else {
	    if (c == ' ' )
		break; 		/* correct quantity found */
	    else
		return(0); 	/* syntax error */
	}
    }
    /* handle unit */
    p++;
    i = 0;
    for (;;) {
	c = *p;
	if (c >= 'a' && c <= 'z' && i <= (UNITMAXLEN - 1)) {
	    unit[i] = c;
	    p++;
	    i++;
	} else {
	    if ((c == ' ' || c == '\0')
		&& correct_unit(unit, unitnr))
		break;		/* correct unit found */
	    else
		return(0);	/* syntax error */
	}
    }
    /* handle optional direction */
    if (c == ' ')
	p++;
    i = 0;
    *sign = 1;
    for (;;) {
	c = *p;
	if (c >= 'a' && c <= 'z' && i <= (DIRMAXLEN - 1)) {
	    direction[i] = c;
	    p++;
	    i++;
	} else {
	    if ((c == ' ' || c == '\0') && i == 0) {
		*sign = 1;
		break;  /* no direction specified */
	    }
	    if ((c == ' ' || c == '\0') && i != 0)
		{
		    direction[i] = '\0';
		    correct_dir(direction, sign);
		    break;	  /* correct direction found */
		}
	    else
		return(0); 	/* syntax error*/
	}
    }
    return(1);
}

/*
 *	correct_unit	- returns 1, iff unit is a correct unit description
 *
 *	output parameter:
 *		unptr: points to an integer which is the appropriate unit number
 *		       (see function isreltime())
 */
static int correct_unit(char unit[], int *unptr)
{
    int	j = 0;
    
    while (j < NUNITS) {
	if (strncmp(unit, unit_tab[j], strlen(unit_tab[j])) == 0) {
	    *unptr = j;
	    return(1);
	}
	j++;
    }
    return (0); /* invalid unit descriptor */
}

/*
 *	correct_dir	- returns 1, iff direction is a correct identifier
 *
 *	output parameter:
 *		signptr: points to -1 if dir corresponds to past tense
 *			 else  to 1
 */
static int correct_dir(char direction[], int *signptr)
{	
    *signptr = 1;
    if (strncmp(RELTIME_PAST, direction, strlen(RELTIME_PAST)+1) == 0)
	{
	    *signptr = -1;
	    return(1);
	} else
	    return (0);  /* invalid direction descriptor */
}


/*
 *	istinterval	- returns 1, iff i_string is a valid interval descr.
 *				  0, iff i_string is NOT a valid interval desc.
 *				  2, iff any time is INVALID_ABSTIME
 *
 *	output parameter:
 *		i_start, i_end: interval margins
 *
 *	Time interval:
 *	`[' {` '} `'' <AbsTime> `'' {` '} `'' <AbsTime> `'' {` '} `]'
 *
 *	OR  `Undefined Range'	(see also INVALID_INTERVAL_STR)
 *
 *	where <AbsTime> satisfies the syntax of absolute time.
 *
 *	e.g.  [  '  Jan 18 1902'   'Jan 1 00:00:00 1970']
 */
static int istinterval(char *i_string, 
		       AbsoluteTime *i_start, 
		       AbsoluteTime *i_end)
{
    register char		*p,*p1;
    register char		c;
    
    p = i_string;
    /* skip leading blanks up to '[' */
    while ((c = *p) != '\0') {
	if ( IsSpace(c))
	    p++;
	else if (c != '[')
	    return(0); /* syntax error */
	else
	    break;
    }
    p++;
    /* skip leading blanks up to "'" */
    while ((c = *p) != '\0') {
	if (IsSpace(c))
	    p++;
	else if (c != '"')
	    return (0);	/* syntax error */
	else
	    break;
    }
    p++;
    if (strncmp(INVALID_INTERVAL_STR,p,strlen(INVALID_INTERVAL_STR)) == 0)
	return(0);	/* undefined range, handled like a syntax err.*/
    /* search for the end of the first date and change it to a NULL*/
    p1 = p;
    while ((c = *p1) != '\0') {
	if ( c == '"') {
	    *p1 = '\0';
	    break;
	}
	p1++;
    }
    /* get the first date */
    *i_start = nabstimein(p);	/* first absolute date */
    /* rechange NULL at the end of the first date to a "'" */
    *p1 = '"';
    p = ++p1;
    /* skip blanks up to "'", beginning of second date*/
    while ((c = *p) != '\0') {
	if (IsSpace(c))
	    p++;
	else if (c != '"')
	    return (0);	/* syntax error */
	else
	    break;
    }	
    p++;
    /* search for the end of the second date and change it to a NULL*/
    p1 = p;
    while ((c = *p1) != '\0') {
	if ( c == '"') {
	    *p1 = '\0';
	    break;
	}
	p1++;
    }
    /* get the second date */
    *i_end = nabstimein(p);		/* second absolute date */
    /* rechange NULL at the end of the first date to a ''' */
    *p1 = '"';
    p = ++p1;
    /* skip blanks up to ']'*/
    while ((c = *p) != '\0') {
	if ( IsSpace(c))
	    p++;
	else if (c != ']')
	    return(0); /*syntax error */
	else
	    break;
    }
    p++;
    c = *p;
    if ( c != '\0' )
	return (0);	/* syntax error */
    /* it seems to be a valid interval */
    return(1);	
}


/*****************************************************************************
 *
 *****************************************************************************/

/*
 * timeofday -
 *     returns the current time as a text. similar to timenow() but returns
 *     seconds with more precision (up to microsecs). (I need this to compare
 *     the Wisconsin benchmark with Illustra whose TimeNow() shows current 
 *     time with precision up to microsecs.)              - ay 3/95
 */
text *
timeofday()
{

#ifndef WIN32
    struct timeval tp;
    struct timezone tpz;
#endif /* WIN32 */
    char templ[500];
    char buf[500];
    text *tm;
    int len = 0;

#ifndef WIN32
    gettimeofday(&tp, &tpz);
    (void) strftime(templ, sizeof(templ), "%a %b %d %H:%M:%S.%%d %Y %Z",
		    localtime((time_t *) &tp.tv_sec));
    sprintf(buf, templ, tp.tv_usec);

    len = VARHDRSZ + strlen(buf);
    tm = (text *)palloc(len);
    VARSIZE(tm) = len;
    strncpy(VARDATA(tm), buf, strlen(buf));
    return tm;
#else
    len = len / len;
    return tm;
#endif /* WIN32 */

}