nativelibc/time/localtime.c

/*	A part of the Native C Library for Windows NT
	Copyright 2007-2015 PC GO Ld.

	This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
*/

#include <time.h>
#include <errno.h>
#include <windows.h>
#include <nt.h>

struct tm *localtime_r(const time_t *timep, struct tm *tp) {
	if(!timep) {
		errno = EINVAL;
		return NULL;
	}

	TIME_ZONE_INFORMATION tzi;
	long int status = RtlQueryTimeZoneInformation(&tzi);
	if(status < 0) {
		__set_errno_from_ntstatus(status);
		return NULL;
	}
	// tzi.Bias is minute based
	time_t lt = *timep - tzi.Bias * 60;
	return gmtime_r(&lt, tp) ? tp : NULL;
}

struct tm *localtime(const time_t *timep) {
	static struct tm buffer;
	return localtime_r(timep, &buffer);
}