kernels/linux-2.4.0/fs/isofs/util.c
/* 
 * We have to convert from a MM/DD/YY format to the Unix ctime format.
 * We have to take into account leap years and all of that good stuff.
 * Unfortunately, the kernel does not have the information on hand to
 * take into account daylight savings time, but it shouldn't matter.
 * The time stored should be localtime (with or without DST in effect),
 * and the timezone offset should hold the offset required to get back
 * to GMT.  Thus  we should always be correct.
 */
We have to convert from a MM/DD/YY format to the Unix ctime format.
We have to take into account leap years and all of that good stuff.
Unfortunately, the kernel does not have the information on hand to
take into account daylight savings time, but it shouldn't matter.
The time stored should be localtime (with or without DST in effect),
and the timezone offset should hold the offset required to get back
to GMT.  Thus  we should always be correct.
We have to convert from a MM / DD / YY format to the Unix ctime format . We have to take into account leap years and all of that good stuff . Unfortunately the kernel does not have the information on hand to take into account daylight savings time but it shouldn ' t matter . The time stored should be localtime ( with or without DST in effect ) and the timezone offset should hold the offset required to get back to GMT . Thus we should always be correct .
int iso_date(char * p, int flag)
{
	int year, month, day, hour, minute, second, tz;
	int crtime, days, i;
	year = p[0] - 70;
	month = p[1];
	day = p[2];
	hour = p[3];
	minute = p[4];
	second = p[5];
	if (flag == 0) tz = p[6]; 
	else tz = 0;
	if (year < 0) {
		crtime = 0;
	} else {
		int monlen[12] = {31,28,31,30,31,30,31,31,30,31,30,31};
		days = year * 365;
		if (year > 2)
			days += (year+1) / 4;
		for (i = 1; i < month; i++)
			days += monlen[i-1];
		if (((year+2) % 4) == 0 && month > 2)
			days++;
		days += day - 1;
		crtime = ((((days * 24) + hour) * 60 + minute) * 60)
			+ second;
		if (tz & 0x80)
			tz |= (-1 << 8);
		if (-52 <= tz && tz <= 52)
			crtime -= tz * 15 * 60;
	}
	return crtime;
}
int iso_date ( char * p , int flag ) { int year , month , day , hour , minute , second , tz ; int crtime , days , i ; year = p [ 0 ] - 70 ; month = p [ 1 ] ; day = p [ 2 ] ; hour = p [ 3 ] ; minute = p [ 4 ] ; second = p [ 5 ] ; if ( flag == 0 ) tz = p [ 6 ] ; else tz = 0 ; if ( year < 0 ) { crtime = 0 ; } else { int monlen [ 12 ] = { 31 , 28 , 31 , 30 , 31 , 30 , 31 , 31 , 30 , 31 , 30 , 31 } ; days = year * 365 ; if ( year > 2 ) days += ( year + 1 ) / 4 ; for ( i = 1 ; i < month ; i ++ ) days += monlen [ i - 1 ] ; if ( ( ( year + 2 ) % 4 ) == 0 && month > 2 ) days ++ ; days += day - 1 ; crtime = ( ( ( ( days * 24 ) + hour ) * 60 + minute ) * 60 ) + second ; if ( tz & 0x80 ) tz |= ( -1 << 8 ) ; if ( -52 <= tz && tz <= 52 ) crtime -= tz * 15 * 60 ; } return crtime ; }
We have to convert from a MM/DD/YY format to the Unix ctime format.
We have to convert from a MM / DD / YY format to the Unix ctime format .
/* High sierra has no time zone */ /* sign extend */ /* 
		 * The timezone offset is unreliable on some disks,
		 * so we make a sanity check.  In no case is it ever
		 * more than 13 hours from GMT, which is 52*15min.
		 * The time is always stored in localtime with the
		 * timezone offset being what get added to GMT to
		 * get to localtime.  Thus we need to subtract the offset
		 * to get to true GMT, which is what we store the time
		 * as internally.  On the local system, the user may set
		 * their timezone any way they wish, of course, so GMT
		 * gets converted back to localtime on the receiving
		 * system.
		 *
		 * NOTE: mkisofs in versions prior to mkisofs-1.10 had
		 * the sign wrong on the timezone offset.  This has now
		 * been corrected there too, but if you are getting screwy
		 * results this may be the explanation.  If enough people
		 * complain, a user configuration option could be added
		 * to add the timezone offset in with the wrong sign
		 * for 'compatibility' with older discs, but I cannot see how
		 * it will matter that much.
		 *
		 * Thanks to kuhlmav@elec.canterbury.ac.nz (Volker Kuhlmann)
		 * for pointing out the sign error.
		 */