ack/lang/cem/libcc.ansi/core/time/localtime.c

/*
 * localtime - convert a calendar time into broken down time
 */
/* $Id$ */

#include <time.h>
#include "loc_time.h"

/* We must be careful, since an int can't represent all the seconds in a day.
 * Hence the adjustment of minutes when adding timezone and dst information.
 * This assumes that both must be expressable in multiples of a minute.
 * Furthermore, it is assumed that both fit into an integer when expressed as
 * minutes (this is about 22 days, so this should not cause any problems). 
 */
struct tm*
localtime(const time_t* timer)
{
	struct tm* timep;
	unsigned dst;

	_tzset();
	timep = gmtime(timer); /* tm->tm_isdst == 0 */
	timep->tm_min -= _timezone / 60;
	timep->tm_sec -= _timezone % 60;
	mktime(timep);

	dst = _dstget(timep);
	if (dst)
	{
		timep->tm_min += dst / 60;
		timep->tm_sec += dst % 60;
		mktime(timep);
	}
	return timep;
}