nativelibc/time/tzset.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 <string.h>
#include <stdlib.h>
#include <windows.h>
#include <nt.h>

#ifndef TZDEFAULT
#define TZDEFAULT "localtime"
#endif

char *tzname[2];
long int timezone;
int daylight;

static void tzset_utc() {
	tzname[0] = tzname[1] = (char *)"UTC";
	timezone = 0;
	daylight = 0;
}

void tzset() {
	//static int initialized = 0;
	//if(initialized) return;
	//initialized = 1;

	//const char *tz = getenv("TZ");
	const char *tz = NULL;		// TODO: implement the getenv
	if(tz && !*tz) tz = "Universal";
	else if(tz && *tz == ':') tz++;
	else if(!tz) tz = TZDEFAULT;

	//free(old_tz);
	//old_tz = tz ? strdup(tz) : NULL;

	if(!tz || strcmp(tz, "localtime") == 0) {
		static char _tzname[64];
		TIME_ZONE_INFORMATION tzi;
		long int status = RtlQueryTimeZoneInformation(&tzi);
		if(status < 0) {
			tzset_utc();
			return;
		}
		wcstombs(_tzname, tzi.StandardName, sizeof _tzname);
		tzname[0] = _tzname;
		timezone = tzi.Bias * 60;
		daylight = tzi.DaylightBias;
	} else tzset_utc();
}