[net-next-2.6.git] / fs / isofs / util.c

/*
 *  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;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/isofs/util.c
	3	*/
	4
94f2f715	5	#include "isofs.h"
1da177e4 LT	6
	7	/*
	8	* We have to convert from a MM/DD/YY format to the Unix ctime format.
	9	* We have to take into account leap years and all of that good stuff.
	10	* Unfortunately, the kernel does not have the information on hand to
	11	* take into account daylight savings time, but it shouldn't matter.
	12	* The time stored should be localtime (with or without DST in effect),
	13	* and the timezone offset should hold the offset required to get back
	14	* to GMT. Thus we should always be correct.
	15	*/
	16
	17	int iso_date(char * p, int flag)
	18	{
	19	int year, month, day, hour, minute, second, tz;
	20	int crtime, days, i;
	21
	22	year = p[0] - 70;
	23	month = p[1];
	24	day = p[2];
	25	hour = p[3];
	26	minute = p[4];
	27	second = p[5];
	28	if (flag == 0) tz = p[6]; /* High sierra has no time zone */
	29	else tz = 0;
	30
	31	if (year < 0) {
	32	crtime = 0;
	33	} else {
	34	int monlen[12] = {31,28,31,30,31,30,31,31,30,31,30,31};
	35
	36	days = year * 365;
	37	if (year > 2)
	38	days += (year+1) / 4;
	39	for (i = 1; i < month; i++)
	40	days += monlen[i-1];
	41	if (((year+2) % 4) == 0 && month > 2)
	42	days++;
	43	days += day - 1;
	44	crtime = ((((days * 24) + hour) * 60 + minute) * 60)
	45	+ second;
	46
	47	/* sign extend */
	48	if (tz & 0x80)
	49	tz \|= (-1 << 8);
	50
	51	/*
	52	* The timezone offset is unreliable on some disks,
	53	* so we make a sanity check. In no case is it ever
	54	* more than 13 hours from GMT, which is 52*15min.
	55	* The time is always stored in localtime with the
	56	* timezone offset being what get added to GMT to
	57	* get to localtime. Thus we need to subtract the offset
	58	* to get to true GMT, which is what we store the time
	59	* as internally. On the local system, the user may set
	60	* their timezone any way they wish, of course, so GMT
	61	* gets converted back to localtime on the receiving
	62	* system.
	63	*
	64	* NOTE: mkisofs in versions prior to mkisofs-1.10 had
	65	* the sign wrong on the timezone offset. This has now
	66	* been corrected there too, but if you are getting screwy
	67	* results this may be the explanation. If enough people
	68	* complain, a user configuration option could be added
	69	* to add the timezone offset in with the wrong sign
70	* for 'compatibility' with older discs, but I cannot see how
71	* it will matter that much.
72	*
73	* Thanks to kuhlmav@elec.canterbury.ac.nz (Volker Kuhlmann)
74	* for pointing out the sign error.
75	*/
76	if (-52 <= tz && tz <= 52)
77	crtime -= tz * 15 * 60;
78	}
79	return crtime;
80	}