/* *  linux/fs/isofs/util.c */#include "isofs.h"/*  * 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]; /* High sierra has no time zone */	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;		/* sign extend */		if (tz & 0x80)			tz |= (-1 << 8);				/* 		 * 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.		 */		if (-52 <= tz && tz <= 52)			crtime -= tz * 15 * 60;	}	return crtime;}