localtime.c

操作系统SunOS 4.1.3版本的源码

		if (lclptr == NULL) {
#ifdef S5EMUL
			settzname();	/* all we can do */
#endif
			return;
		}
	}
	if (tzload((char *) NULL, lclptr) != 0)
		gmtload(lclptr);
#ifdef S5EMUL
	settzname();
#endif
}

void
tzset()
{
	register const char *	name;

	name = getenv("TZ");
	if (name == NULL) {
		tzsetwall();
		return;
	}
	lcl_is_set = TRUE;
	if (lclptr == NULL) {
		lclptr = (struct state *) calloc(1, (unsigned)sizeof *lclptr);
		if (lclptr == NULL) {
#ifdef S5EMUL
			settzname();	/* all we can do */
#endif
			return;
		}
	}
	if (*name == '\0') {
		/*
		** User wants it fast rather than right.
		*/
		lclptr->timecnt = 0;
		lclptr->typecnt = 1;
		lclptr->charcnt = sizeof GMT;
		if (allocall(lclptr) < 0)
			return;
		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) tzparse(name, lclptr, TRUE);
#ifdef S5EMUL
	settzname();
#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.
*/

static struct tm	tm;

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

	if (!lcl_is_set)
		tzset();
	sp = lclptr;
	if (sp == NULL) {
		gmtsub(timep, offset, tmp);
		return;
	}
	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];
	timesub(&t, ttisp->tt_gmtoff, tmp);
	tmp->tm_isdst = ttisp->tt_isdst;
#ifdef S5EMUL
	tzname[tmp->tm_isdst] = (char *) &sp->chars[ttisp->tt_abbrind];
#endif /* S5EMUL */
	tmp->tm_zone = &sp->chars[ttisp->tt_abbrind];
}

struct tm *
localtime(timep)
const time_t * const	timep;
{
	localsub(timep, 0L, &tm);
	return &tm;
}

/*
** 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;
{
	if (!gmt_is_set) {
		gmt_is_set = TRUE;
		gmtptr = (struct state *) calloc(1, (unsigned)sizeof *gmtptr);
		if (gmtptr != NULL)
			gmtload(gmtptr);
	}
	timesub(timep, offset, tmp);
	/*
	** 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 {
		if (gmtptr == NULL)
			tmp->tm_zone = GMT;
		else	tmp->tm_zone = gmtptr->chars;
	}
}

struct tm *
gmtime(timep)
const time_t * const	timep;
{
	gmtsub(timep, 0L, &tm);
	return &tm;
}

struct tm *
offtime(timep, offset)
const time_t * const	timep;
const long		offset;
{
	gmtsub(timep, offset, &tm);
	return &tm;
}

static void
timesub(timep, offset, tmp)
const time_t * const			timep;
const long				offset;
register struct tm * const		tmp;
{
	register long			days;
	register long			rem;
	register int			y;
	register int			yleap;
	register const int *		ip;

	days = *timep / SECSPERDAY;
	rem = *timep % SECSPERDAY;
	rem += offset;
	while (rem < 0) {
		rem += SECSPERDAY;
		--days;
	}
	while (rem >= SECSPERDAY) {
		rem -= SECSPERDAY;
		++days;
	}
	tmp->tm_hour = (int) (rem / SECSPERHOUR);
	rem = rem % SECSPERHOUR;
	tmp->tm_min = (int) (rem / SECSPERMIN);
	tmp->tm_sec = (int) (rem % SECSPERMIN);
	tmp->tm_wday = (int) ((EPOCH_WDAY + days) % DAYSPERWEEK);
	if (tmp->tm_wday < 0)
		tmp->tm_wday += DAYSPERWEEK;
	y = EPOCH_YEAR;
	if (days >= 0)
		for ( ; ; ) {
			yleap = isleap(y);
			if (days < (long) year_lengths[yleap])
				break;
			++y;
			days = days - (long) year_lengths[yleap];
		}
	else do {
		--y;
		yleap = isleap(y);
		days = days + (long) year_lengths[yleap];
	} while (days < 0);
	tmp->tm_year = y - TM_YEAR_BASE;
	tmp->tm_yday = (int) days;
	ip = mon_lengths[yleap];
	for (tmp->tm_mon = 0; days >= (long) ip[tmp->tm_mon]; ++(tmp->tm_mon))
		days = days - (long) ip[tmp->tm_mon];
	tmp->tm_mday = (int) (days + 1);
	tmp->tm_isdst = 0;
	tmp->tm_gmtoff = offset;
}

/*
** Adapted from code provided by Robert Elz, who writes:
**	The "best" way to do mktime I think is based on an idea of Bob
**	Kridle's (so its said...) from a long time ago. (mtxinu!kridle now).
**	It does a binary search of the time_t space.  Since time_t's are
**	just 32 bits, its a max of 32 iterations (even at 64 bits it
**	would still be very reasonable).
*/

#ifndef WRONG
#define WRONG	(-1)
#endif /* !defined WRONG */

static void
normalize(tensptr, unitsptr, base)
int * const	tensptr;
int * const	unitsptr;
const int	base;
{
	if (*unitsptr >= base) {
		*tensptr += *unitsptr / base;
		*unitsptr %= base;
	} else if (*unitsptr < 0) {
		--*tensptr;
		*unitsptr += base;
		if (*unitsptr < 0) {
			*tensptr -= 1 + (-*unitsptr) / base;
			*unitsptr = base - (-*unitsptr) % base;
		}
	}
}

static int
tmcomp(atmp, btmp)
register const struct tm * const atmp;
register const struct tm * const btmp;
{
	register int	result;

	if ((result = (atmp->tm_year - btmp->tm_year)) == 0 &&
		(result = (atmp->tm_mon - btmp->tm_mon)) == 0 &&
		(result = (atmp->tm_mday - btmp->tm_mday)) == 0 &&
		(result = (atmp->tm_hour - btmp->tm_hour)) == 0 &&
		(result = (atmp->tm_min - btmp->tm_min)) == 0)
			result = atmp->tm_sec - btmp->tm_sec;
	return result;
}

static time_t
time2(tmp, funcp, offset, okayp)
struct tm * const	tmp;
void (* const		funcp)();
const long		offset;
int * const		okayp;
{
	register const struct state *	sp;
	register int			dir;
	register int			bits;
	register int			i, j ;
	register int			saved_seconds;
	time_t				newt;
	time_t				t;
	struct tm			yourtm, mytm;

	*okayp = FALSE;
	yourtm = *tmp;
	if (yourtm.tm_sec >= SECSPERMIN + 2 || yourtm.tm_sec < 0)
		normalize(&yourtm.tm_min, &yourtm.tm_sec, SECSPERMIN);
	normalize(&yourtm.tm_hour, &yourtm.tm_min, MINSPERHOUR);
	normalize(&yourtm.tm_mday, &yourtm.tm_hour, HOURSPERDAY);
	normalize(&yourtm.tm_year, &yourtm.tm_mon, MONSPERYEAR);
	while (yourtm.tm_mday <= 0) {
		--yourtm.tm_year;
		yourtm.tm_mday +=
			year_lengths[isleap(yourtm.tm_year + TM_YEAR_BASE)];
	}
	for ( ; ; ) {
		i = mon_lengths[isleap(yourtm.tm_year +
			TM_YEAR_BASE)][yourtm.tm_mon];
		if (yourtm.tm_mday <= i)
			break;
		yourtm.tm_mday -= i;
		if (++yourtm.tm_mon >= MONSPERYEAR) {
			yourtm.tm_mon = 0;
			++yourtm.tm_year;
		}
	}
	saved_seconds = yourtm.tm_sec;
	yourtm.tm_sec = 0;
	/*
	** Calculate the number of magnitude bits in a time_t
	** (this works regardless of whether time_t is
	** signed or unsigned, though lint complains if unsigned).
	*/
	for (bits = 0, t = 1; t > 0; ++bits, t <<= 1)
		;
	/*
	** If time_t is signed, then 0 is the median value,
	** if time_t is unsigned, then 1 << bits is median.
	*/
	t = (t < 0) ? 0 : ((time_t) 1 << bits);
	for ( ; ; ) {
		(*funcp)(&t, offset, &mytm);
		dir = tmcomp(&mytm, &yourtm);
		if (dir != 0) {
			if (bits-- < 0)
				return WRONG;
			if (bits < 0)
				--t;
			else if (dir > 0)
				t -= (time_t) 1 << bits;
			else	t += (time_t) 1 << bits;
			continue;
		}
		if (yourtm.tm_isdst < 0 || mytm.tm_isdst == yourtm.tm_isdst)
			break;
		/*
		** Right time, wrong type.
		** Hunt for right time, right type.
		** It's okay to guess wrong since the guess
		** gets checked.
		*/
		sp = (const struct state *)
			((funcp == localsub) ? lclptr : gmtptr);
		if (sp == NULL)
			return WRONG;
		for (i = 0; i < sp->typecnt; ++i) {
			if (sp->ttis[i].tt_isdst != yourtm.tm_isdst)
				continue;
			for (j = 0; j < sp->typecnt; ++j) {
				if (sp->ttis[j].tt_isdst == yourtm.tm_isdst)
					continue;
				newt = t + sp->ttis[j].tt_gmtoff -
					sp->ttis[i].tt_gmtoff;
				(*funcp)(&newt, offset, &mytm);
				if (tmcomp(&mytm, &yourtm) != 0)
					continue;
				if (mytm.tm_isdst != yourtm.tm_isdst)
					continue;
				/*
				** We have a match.
				*/
				t = newt;
				goto label;
			}
		}
		return WRONG;
	}
label:
	t += saved_seconds;
	(*funcp)(&t, offset, tmp);
	*okayp = TRUE;
	return t;
}

static time_t
time1(tmp, funcp, offset)
struct tm * const	tmp;
void (* const		funcp)();
const long		offset;
{
	register time_t			t;
	register const struct state *	sp;
	register int			samei, otheri;
	int				okay;

	
        if (tmp->tm_isdst > 1)
                tmp->tm_isdst = 1;
	t = time2(tmp, funcp, offset, &okay);
	if (okay || tmp->tm_isdst < 0)
		return t;
	/*
	** We're supposed to assume that somebody took a time of one type
	** and did some math on it that yielded a "struct tm" that's bad.
	** We try to divine the type they started from and adjust to the
	** type they need.
	*/
	sp = (const struct state *) ((funcp == localsub) ? lclptr : gmtptr);
	if (sp == NULL)
		return WRONG;
	for (samei = 0; samei < sp->typecnt; ++samei) {
		if (sp->ttis[samei].tt_isdst != tmp->tm_isdst)
			continue;
		for (otheri = 0; otheri < sp->typecnt; ++otheri) {
			if (sp->ttis[otheri].tt_isdst == tmp->tm_isdst)
				continue;
			tmp->tm_sec += sp->ttis[otheri].tt_gmtoff -
					sp->ttis[samei].tt_gmtoff;
			tmp->tm_isdst = !tmp->tm_isdst;
			t = time2(tmp, funcp, offset, &okay);
			if (okay)
				return t;
			tmp->tm_sec -= sp->ttis[otheri].tt_gmtoff -
					sp->ttis[samei].tt_gmtoff;
			tmp->tm_isdst = !tmp->tm_isdst;
		}
	}
	return WRONG;
}

time_t
mktime(tmp)
struct tm * const	tmp;
{
	return time1(tmp, localsub, 0L);
}

time_t
timelocal(tmp)
struct tm * const	tmp;
{
	tmp->tm_isdst = -1; 
	return mktime(tmp);
}

time_t
timegm(tmp)
struct tm * const	tmp;
{
	return time1(tmp, gmtsub, 0L);
}

time_t
timeoff(tmp, offset)
struct tm * const	tmp;
const long		offset;
{

	return time1(tmp, gmtsub, offset);
}