/* Copyright (c) 2002-2003 Timo Sirainen */

 #include "lib.h"

 #include "utc-offset.h"

 #include <sys/time.h>

 int utc_offset(struct tm *tm, time_t t __attr_unused__)

 {

 #ifdef HAVE_TM_GMTOFF

 	return (int) (tm->tm_gmtoff/60);

 #else

 	struct tm ltm, gtm;

 	int offset;

 	/* gmtime() overwrites tm, so we need to copy it elsewhere */

 	ltm = *tm;

 	tm = gmtime(&t);

 	gtm = *tm;

 	/* max offset of 24 hours */

 	if ((ltm.tm_yday < gtm.tm_yday && ltm.tm_year == gtm.tm_year) ||

 	    ltm.tm_year < gtm.tm_year)

 		offset = -24 * 60;

 	else if ((ltm.tm_yday > gtm.tm_yday && ltm.tm_year == gtm.tm_year) ||

 		 ltm.tm_year > gtm.tm_year)

 		offset = 24 * 60;

 	else

 		offset = 0;

 	offset += (ltm.tm_hour - gtm.tm_hour) * 60;

 	offset += (ltm.tm_min - gtm.tm_min);

 	/* restore overwritten tm */

 	*tm = ltm;

 	return offset;

 #endif

 }