localtime.c

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		rulep->r_type = DAY_OF_YEAR;
		strp = getnum(strp, &rulep->r_day, 0, DAYSPERLYEAR - 1);
	} else	return NULL;		/* invalid format */
	if (strp == NULL)
		return NULL;
	if (*strp == '/') {
		/*
		** Time specified.
		*/
		++strp;
		strp = getsecs(strp, &rulep->r_time);
	} else	rulep->r_time = 2 * SECSPERHOUR;	/* default = 2:00:00 */
	return strp;
}

/*
** Given the Epoch-relative time of January 1, 00:00:00 GMT, in a year, the
** year, a rule, and the offset from GMT at the time that rule takes effect,
** calculate the Epoch-relative time that rule takes effect.
*/

static time_t
transtime(janfirst, year, rulep, offset)
const time_t				janfirst;
const int				year;
register const struct rule * const	rulep;
const long				offset;
{
	register int	leapyear;
	register time_t	value;
	register int	i;
	int		d, m1, yy0, yy1, yy2, dow;

	INITIALIZE(value);
	leapyear = isleap(year);
	switch (rulep->r_type) {

	case JULIAN_DAY:
		/*
		** Jn - Julian day, 1 == January 1, 60 == March 1 even in leap
		** years.
		** In non-leap years, or if the day number is 59 or less, just
		** add SECSPERDAY times the day number-1 to the time of
		** January 1, midnight, to get the day.
		*/
		value = janfirst + (rulep->r_day - 1) * SECSPERDAY;
		if (leapyear && rulep->r_day >= 60)
			value += SECSPERDAY;
		break;

	case DAY_OF_YEAR:
		/*
		** n - day of year.
		** Just add SECSPERDAY times the day number to the time of
		** January 1, midnight, to get the day.
		*/
		value = janfirst + rulep->r_day * SECSPERDAY;
		break;

	case MONTH_NTH_DAY_OF_WEEK:
		/*
		** Mm.n.d - nth "dth day" of month m.
		*/
		value = janfirst;
		for (i = 0; i < rulep->r_mon - 1; ++i)
			value += mon_lengths[leapyear][i] * SECSPERDAY;

		/*
		** Use Zeller's Congruence to get day-of-week of first day of
		** month.
		*/
		m1 = (rulep->r_mon + 9) % 12 + 1;
		yy0 = (rulep->r_mon <= 2) ? (year - 1) : year;
		yy1 = yy0 / 100;
		yy2 = yy0 % 100;
		dow = ((26 * m1 - 2) / 10 +
			1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7;
		if (dow < 0)
			dow += DAYSPERWEEK;

		/*
		** "dow" is the day-of-week of the first day of the month.  Get
		** the day-of-month (zero-origin) of the first "dow" day of the
		** month.
		*/
		d = rulep->r_day - dow;
		if (d < 0)
			d += DAYSPERWEEK;
		for (i = 1; i < rulep->r_week; ++i) {
			if (d + DAYSPERWEEK >=
				mon_lengths[leapyear][rulep->r_mon - 1])
					break;
			d += DAYSPERWEEK;
		}

		/*
		** "d" is the day-of-month (zero-origin) of the day we want.
		*/
		value += d * SECSPERDAY;
		break;
	}

	/*
	** "value" is the Epoch-relative time of 00:00:00 GMT on the day in
	** question.  To get the Epoch-relative time of the specified local
	** time on that day, add the transition time and the current offset
	** from GMT.
	*/
	return value + rulep->r_time + offset;
}

/*
** Given a POSIX section 8-style TZ string, fill in the rule tables as
** appropriate.
*/

static int
tzparse(name, sp, lastditch)
const char *			name;
register struct state * const	sp;
const int			lastditch;
{
	const char *			stdname;
	const char *			dstname;
	size_t				stdlen;
	size_t				dstlen;
	long				stdoffset;
	long				dstoffset;
	register time_t *		atp;
	register unsigned char *	typep;
	register char *			cp;
	register int			load_result;

	INITIALIZE(dstname);
	stdname = name;
	if (lastditch) {
		stdlen = strlen(name);	/* length of standard zone name */
		name += stdlen;
		if (stdlen >= sizeof sp->chars)
			stdlen = (sizeof sp->chars) - 1;
		stdoffset = 0;
	} else {
		name = getzname(name);
		stdlen = name - stdname;
		if (stdlen < 3)
			return -1;
		if (*name == '\0')
			return -1;	/* was "stdoffset = 0;" */
		else {
			name = getoffset(name, &stdoffset);
			if (name == NULL)
				return -1;
		}
	}
	load_result = tzload(TZDEFRULES, sp);
	if (load_result != 0)
		sp->leapcnt = 0;		/* so, we're off a little */
	if (*name != '\0') {
		dstname = name;
		name = getzname(name);
		dstlen = name - dstname;	/* length of DST zone name */
		if (dstlen < 3)
			return -1;
		if (*name != '\0' && *name != ',' && *name != ';') {
			name = getoffset(name, &dstoffset);
			if (name == NULL)
				return -1;
		} else	dstoffset = stdoffset - SECSPERHOUR;
		if (*name == ',' || *name == ';') {
			struct rule	start;
			struct rule	end;
			register int	year;
			register time_t	janfirst;
			time_t		starttime;
			time_t		endtime;

			++name;
			if ((name = getrule(name, &start)) == NULL)
				return -1;
			if (*name++ != ',')
				return -1;
			if ((name = getrule(name, &end)) == NULL)
				return -1;
			if (*name != '\0')
				return -1;
			sp->typecnt = 2;	/* standard time and DST */
			/*
			** Two transitions per year, from EPOCH_YEAR to 2037.
			*/
			sp->timecnt = 2 * (2037 - EPOCH_YEAR + 1);
			if (sp->timecnt > TZ_MAX_TIMES)
				return -1;
			sp->ttis[0].tt_gmtoff = -dstoffset;
			sp->ttis[0].tt_isdst = 1;
			sp->ttis[0].tt_abbrind = stdlen + 1;
			sp->ttis[1].tt_gmtoff = -stdoffset;
			sp->ttis[1].tt_isdst = 0;
			sp->ttis[1].tt_abbrind = 0;
			atp = sp->ats;
			typep = sp->types;
			janfirst = 0;
			for (year = EPOCH_YEAR; year <= 2037; ++year) {
				starttime = transtime(janfirst, year, &start,
					stdoffset);
				endtime = transtime(janfirst, year, &end,
					dstoffset);
				if (starttime > endtime) {
					*atp++ = endtime;
					*typep++ = 1;	/* DST ends */
					*atp++ = starttime;
					*typep++ = 0;	/* DST begins */
				} else {
					*atp++ = starttime;
					*typep++ = 0;	/* DST begins */
					*atp++ = endtime;
					*typep++ = 1;	/* DST ends */
				}
				janfirst += year_lengths[isleap(year)] *
					SECSPERDAY;
			}
		} else {
			register long	theirstdoffset;
			register long	theirdstoffset;
			register long	theiroffset;
			register int	isdst;
			register int	i;
			register int	j;

			if (*name != '\0')
				return -1;
			if (load_result != 0)
				return -1;
			/*
			** Initial values of theirstdoffset and theirdstoffset.
			*/
			theirstdoffset = 0;
			for (i = 0; i < sp->timecnt; ++i) {
				j = sp->types[i];
				if (!sp->ttis[j].tt_isdst) {
					theirstdoffset =
						-sp->ttis[j].tt_gmtoff;
					break;
				}
			}
			theirdstoffset = 0;
			for (i = 0; i < sp->timecnt; ++i) {
				j = sp->types[i];
				if (sp->ttis[j].tt_isdst) {
					theirdstoffset =
						-sp->ttis[j].tt_gmtoff;
					break;
				}
			}
			/*
			** Initially we're assumed to be in standard time.
			*/
			isdst = FALSE;
			theiroffset = theirstdoffset;
			/*
			** Now juggle transition times and types
			** tracking offsets as you do.
			*/
			for (i = 0; i < sp->timecnt; ++i) {
				j = sp->types[i];
				sp->types[i] = sp->ttis[j].tt_isdst;
				if (sp->ttis[j].tt_ttisgmt) {
					/* No adjustment to transition time */
				} else {
					/*
					** If summer time is in effect, and the
					** transition time was not specified as
					** standard time, add the summer time
					** offset to the transition time;
					** otherwise, add the standard time
					** offset to the transition time.
					*/
					/*
					** Transitions from DST to DDST
					** will effectively disappear since
					** POSIX provides for only one DST
					** offset.
					*/
					if (isdst && !sp->ttis[j].tt_ttisstd) {
						sp->ats[i] += dstoffset -
							theirdstoffset;
					} else {
						sp->ats[i] += stdoffset -
							theirstdoffset;
					}
				}
				theiroffset = -sp->ttis[j].tt_gmtoff;
				if (sp->ttis[j].tt_isdst)
					theirdstoffset = theiroffset;
				else	theirstdoffset = theiroffset;
			}
			/*
			** Finally, fill in ttis.
			** ttisstd and ttisgmt need not be handled.
			*/
			sp->ttis[0].tt_gmtoff = -stdoffset;
			sp->ttis[0].tt_isdst = FALSE;
			sp->ttis[0].tt_abbrind = 0;
			sp->ttis[1].tt_gmtoff = -dstoffset;
			sp->ttis[1].tt_isdst = TRUE;
			sp->ttis[1].tt_abbrind = stdlen + 1;
		}
	} else {
		dstlen = 0;
		sp->typecnt = 1;		/* only standard time */
		sp->timecnt = 0;
		sp->ttis[0].tt_gmtoff = -stdoffset;
		sp->ttis[0].tt_isdst = 0;
		sp->ttis[0].tt_abbrind = 0;
	}
	sp->charcnt = stdlen + 1;
	if (dstlen != 0)
		sp->charcnt += dstlen + 1;
	if (sp->charcnt > sizeof sp->chars)
		return -1;
	cp = sp->chars;
	(void) strncpy(cp, stdname, stdlen);
	cp += stdlen;
	*cp++ = '\0';
	if (dstlen != 0) {
		(void) strncpy(cp, dstname, dstlen);
		*(cp + dstlen) = '\0';
	}
	return 0;
}

static void
gmtload(sp)
struct state * const	sp;
{
	if (tzload(gmt, sp) != 0)
		(void) tzparse(gmt, sp, TRUE);
}

#ifndef STD_INSPIRED
/*
** A non-static declaration of tzsetwall in a system header file
** may cause a warning about this upcoming static declaration...
*/
static
#endif /* !defined STD_INSPIRED */
#ifdef	_THREAD_SAFE
void
tzsetwall_basic P((void))
#else
void
tzsetwall P((void))
#endif
{
	if (lcl_is_set < 0)
		return;
	lcl_is_set = -1;

#ifdef ALL_STATE
	if (lclptr == NULL) {
		lclptr = (struct state *) malloc(sizeof *lclptr);
		if (lclptr == NULL) {
			settzname();	/* all we can do */
			return;
		}
	}
#endif /* defined ALL_STATE */
	if (tzload((char *) NULL, lclptr) != 0)
		gmtload(lclptr);
	settzname();
}

#ifdef	_THREAD_SAFE
void
tzsetwall P((void))
{
	pthread_mutex_lock(&lcl_mutex);
	tzsetwall_basic();
	pthread_mutex_unlock(&lcl_mutex);
}
#endif

#ifdef	_THREAD_SAFE
static void
tzset_basic P((void))
#else
void
tzset P((void))
#endif
{
	register const char *	name;

	name = getenv("TZ");
	if (name == NULL) {
		tzsetwall();
		return;
	}

	if (lcl_is_set > 0  &&  strcmp(lcl_TZname, name) == 0)
		return;
	lcl_is_set = (strlen(name) < sizeof(lcl_TZname));
	if (lcl_is_set)
		(void) strcpy(lcl_TZname, name);

#ifdef ALL_STATE
	if (lclptr == NULL) {
		lclptr = (struct state *) malloc(sizeof *lclptr);
		if (lclptr == NULL) {
			settzname();	/* all we can do */
			return;
		}
	}
#endif /* defined ALL_STATE */
	if (*name == '\0') {
		/*
		** User wants it fast rather than right.
		*/
		lclptr->leapcnt = 0;		/* so, we're off a little */
		lclptr->timecnt = 0;
		lclptr->ttis[0].tt_gmtoff = 0;
		lclptr->ttis[0].tt_abbrind = 0;
		(void) strcpy(lclptr->chars, gmt);
	} else if (tzload(name, lclptr) != 0)
		if (name[0] == ':' || tzparse(name, lclptr, FALSE) != 0)
			(void) gmtload(lclptr);
	settzname();
}

#ifdef	_THREAD_SAFE
void
tzset P((void))
{
	pthread_mutex_lock(&lcl_mutex);
	tzset_basic();
	pthread_mutex_unlock(&lcl_mutex);
}
#endif

/*
** The easy way to behave "as if no library function calls" localtime
** is to not call it--so we drop its guts into "localsub", which can be
** freely called.  (And no, the PANS doesn't require the above behavior--
** but it *is* desirable.)
**
** The unused offset argument is for the benefit of mktime variants.
*/

/*ARGSUSED*/
static void
localsub(timep, offset, tmp)
const time_t * const	timep;
const long		offset;
struct tm * const	tmp;
{
	register struct state *		sp;
	register const struct ttinfo *	ttisp;
	register int			i;
	const time_t			t = *timep;

	sp = lclptr;
#ifdef ALL_STATE
	if (sp == NULL) {
		gmtsub(timep, offset, tmp);
		return;
	}
#endif /* defined ALL_STATE */
	if (sp->timecnt == 0 || t < sp->ats[0]) {
		i = 0;
		while (sp->ttis[i].tt_isdst)
			if (++i >= sp->typecnt) {
				i = 0;
				break;
			}
	} else {
		for (i = 1; i < sp->timecnt; ++i)
			if (t < sp->ats[i])
				break;
		i = sp->types[i - 1];
	}
	ttisp = &sp->ttis[i];
	/*
	** To get (wrong) behavior that's compatible with System V Release 2.0
	** you'd replace the statement below with
	**	t += ttisp->tt_gmtoff;
	**	timesub(&t, 0L, sp, tmp);
	*/
	timesub(&t, ttisp->tt_gmtoff, sp, tmp);
	tmp->tm_isdst = ttisp->tt_isdst;
	tzname[tmp->tm_isdst] = &sp->chars[ttisp->tt_abbrind];
#ifdef TM_ZONE
	tmp->TM_ZONE = &sp->chars[ttisp->tt_abbrind];
#endif /* defined TM_ZONE */
}

struct tm *
localtime_r(timep, p_tm)
const time_t * const	timep;
struct tm *p_tm;
{
#ifdef _THREAD_SAFE
	pthread_mutex_lock(&lcl_mutex);
#endif
	tzset();
	localsub(timep, 0L, p_tm);
#ifdef _THREAD_SAFE
	pthread_mutex_unlock(&lcl_mutex);
#endif
	return(p_tm);
}

struct tm *
localtime(timep)
const time_t * const	timep;
{
#ifdef	_THREAD_SAFE
	static struct pthread_mutex _localtime_mutex = PTHREAD_MUTEX_STATIC_INITIALIZER;
	static pthread_mutex_t localtime_mutex = &_localtime_mutex;
	static pthread_key_t localtime_key = -1;
	struct tm *p_tm;

	pthread_mutex_lock(&localtime_mutex);
	if (localtime_key < 0) {
		if (pthread_key_create(&localtime_key, free) < 0) {
			pthread_mutex_unlock(&localtime_mutex);
			return(NULL);
		}
	}
	pthread_mutex_unlock(&localtime_mutex);
	p_tm = pthread_getspecific(localtime_key);
	if (p_tm == NULL) {
		if ((p_tm = (struct tm *)malloc(sizeof(struct tm))) == NULL)
			return(NULL);
		pthread_setspecific(localtime_key, p_tm);
	}
	pthread_mutex_lock(&lcl_mutex);
	tzset();
	localsub(timep, 0L, p_tm);
	pthread_mutex_unlock(&lcl_mutex);
	return p_tm;
#else
	tzset();
	localsub(timep, 0L, &tm);
	return &tm;
#endif
}

/*
** gmtsub is to gmtime as localsub is to localtime.
*/

static void
gmtsub(timep, offset, tmp)
const time_t * const	timep;
const long		offset;
struct tm * const	tmp;
{
#ifdef	_THREAD_SAFE
	pthread_mutex_lock(&gmt_mutex);
#endif
	if (!gmt_is_set) {
		gmt_is_set = TRUE;
#ifdef ALL_STATE
		gmtptr = (struct state *) malloc(sizeof *gmtptr);
		if (gmtptr != NULL)
#endif /* defined ALL_STATE */
			gmtload(gmtptr);
	}
#ifdef	_THREAD_SAFE
	pthread_mutex_unlock(&gmt_mutex);
#endif
	timesub(timep, offset, gmtptr, tmp);
#ifdef TM_ZONE
	/*
	** Could get fancy here and deliver something such as
	** "GMT+xxxx" or "GMT-xxxx" if offset is non-zero,
	** but this is no time for a treasure hunt.
	*/
	if (offset != 0)
		tmp->TM_ZONE = wildabbr;
	else {
#ifdef ALL_STATE
		if (gmtptr == NULL)
			tmp->TM_ZONE = gmt;
		else	tmp->TM_ZONE = gmtptr->chars;
#endif /* defined ALL_STATE */
#ifndef ALL_STATE
		tmp->TM_ZONE = gmtptr->chars;
#endif /* State Farm */
	}
#endif /* defined TM_ZONE */
}