xref: /openbmc/linux/fs/udf/udftime.c (revision 22246614)
1 /* Copyright (C) 1993, 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
2    This file is part of the GNU C Library.
3    Contributed by Paul Eggert (eggert@twinsun.com).
4 
5    The GNU C Library is free software; you can redistribute it and/or
6    modify it under the terms of the GNU Library General Public License as
7    published by the Free Software Foundation; either version 2 of the
8    License, or (at your option) any later version.
9 
10    The GNU C Library is distributed in the hope that it will be useful,
11    but WITHOUT ANY WARRANTY; without even the implied warranty of
12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13    Library General Public License for more details.
14 
15    You should have received a copy of the GNU Library General Public
16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18    Boston, MA 02111-1307, USA.  */
19 
20 /*
21  * dgb 10/02/98: ripped this from glibc source to help convert timestamps
22  *               to unix time
23  *     10/04/98: added new table-based lookup after seeing how ugly
24  *               the gnu code is
25  * blf 09/27/99: ripped out all the old code and inserted new table from
26  *		 John Brockmeyer (without leap second corrections)
27  *		 rewrote udf_stamp_to_time and fixed timezone accounting in
28  *		 udf_time_to_stamp.
29  */
30 
31 /*
32  * We don't take into account leap seconds. This may be correct or incorrect.
33  * For more NIST information (especially dealing with leap seconds), see:
34  * http://www.boulder.nist.gov/timefreq/pubs/bulletin/leapsecond.htm
35  */
36 
37 #include <linux/types.h>
38 #include <linux/kernel.h>
39 #include "udfdecl.h"
40 
41 #define EPOCH_YEAR 1970
42 
43 #ifndef __isleap
44 /* Nonzero if YEAR is a leap year (every 4 years,
45    except every 100th isn't, and every 400th is).  */
46 #define	__isleap(year)	\
47   ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
48 #endif
49 
50 /* How many days come before each month (0-12).  */
51 static const unsigned short int __mon_yday[2][13] = {
52 	/* Normal years.  */
53 	{0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365},
54 	/* Leap years.  */
55 	{0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366}
56 };
57 
58 #define MAX_YEAR_SECONDS	69
59 #define SPD			0x15180	/*3600*24 */
60 #define SPY(y, l, s)		(SPD * (365 * y + l) + s)
61 
62 static time_t year_seconds[MAX_YEAR_SECONDS] = {
63 /*1970*/ SPY(0,   0, 0), SPY(1,   0, 0), SPY(2,   0, 0), SPY(3,   1, 0),
64 /*1974*/ SPY(4,   1, 0), SPY(5,   1, 0), SPY(6,   1, 0), SPY(7,   2, 0),
65 /*1978*/ SPY(8,   2, 0), SPY(9,   2, 0), SPY(10,  2, 0), SPY(11,  3, 0),
66 /*1982*/ SPY(12,  3, 0), SPY(13,  3, 0), SPY(14,  3, 0), SPY(15,  4, 0),
67 /*1986*/ SPY(16,  4, 0), SPY(17,  4, 0), SPY(18,  4, 0), SPY(19,  5, 0),
68 /*1990*/ SPY(20,  5, 0), SPY(21,  5, 0), SPY(22,  5, 0), SPY(23,  6, 0),
69 /*1994*/ SPY(24,  6, 0), SPY(25,  6, 0), SPY(26,  6, 0), SPY(27,  7, 0),
70 /*1998*/ SPY(28,  7, 0), SPY(29,  7, 0), SPY(30,  7, 0), SPY(31,  8, 0),
71 /*2002*/ SPY(32,  8, 0), SPY(33,  8, 0), SPY(34,  8, 0), SPY(35,  9, 0),
72 /*2006*/ SPY(36,  9, 0), SPY(37,  9, 0), SPY(38,  9, 0), SPY(39, 10, 0),
73 /*2010*/ SPY(40, 10, 0), SPY(41, 10, 0), SPY(42, 10, 0), SPY(43, 11, 0),
74 /*2014*/ SPY(44, 11, 0), SPY(45, 11, 0), SPY(46, 11, 0), SPY(47, 12, 0),
75 /*2018*/ SPY(48, 12, 0), SPY(49, 12, 0), SPY(50, 12, 0), SPY(51, 13, 0),
76 /*2022*/ SPY(52, 13, 0), SPY(53, 13, 0), SPY(54, 13, 0), SPY(55, 14, 0),
77 /*2026*/ SPY(56, 14, 0), SPY(57, 14, 0), SPY(58, 14, 0), SPY(59, 15, 0),
78 /*2030*/ SPY(60, 15, 0), SPY(61, 15, 0), SPY(62, 15, 0), SPY(63, 16, 0),
79 /*2034*/ SPY(64, 16, 0), SPY(65, 16, 0), SPY(66, 16, 0), SPY(67, 17, 0),
80 /*2038*/ SPY(68, 17, 0)
81 };
82 
83 extern struct timezone sys_tz;
84 
85 #define SECS_PER_HOUR	(60 * 60)
86 #define SECS_PER_DAY	(SECS_PER_HOUR * 24)
87 
88 struct timespec *udf_disk_stamp_to_time(struct timespec *dest, timestamp src)
89 {
90 	int yday;
91 	u16 typeAndTimezone = le16_to_cpu(src.typeAndTimezone);
92 	u16 year = le16_to_cpu(src.year);
93 	uint8_t type = typeAndTimezone >> 12;
94 	int16_t offset;
95 
96 	if (type == 1) {
97 		offset = typeAndTimezone << 4;
98 		/* sign extent offset */
99 		offset = (offset >> 4);
100 		if (offset == -2047) /* unspecified offset */
101 			offset = 0;
102 	} else
103 		offset = 0;
104 
105 	if ((year < EPOCH_YEAR) ||
106 	    (year >= EPOCH_YEAR + MAX_YEAR_SECONDS)) {
107 		return NULL;
108 	}
109 	dest->tv_sec = year_seconds[year - EPOCH_YEAR];
110 	dest->tv_sec -= offset * 60;
111 
112 	yday = ((__mon_yday[__isleap(year)][src.month - 1]) + src.day - 1);
113 	dest->tv_sec += (((yday * 24) + src.hour) * 60 + src.minute) * 60 + src.second;
114 	dest->tv_nsec = 1000 * (src.centiseconds * 10000 +
115 			src.hundredsOfMicroseconds * 100 + src.microseconds);
116 	return dest;
117 }
118 
119 timestamp *udf_time_to_disk_stamp(timestamp *dest, struct timespec ts)
120 {
121 	long int days, rem, y;
122 	const unsigned short int *ip;
123 	int16_t offset;
124 
125 	offset = -sys_tz.tz_minuteswest;
126 
127 	if (!dest)
128 		return NULL;
129 
130 	dest->typeAndTimezone = cpu_to_le16(0x1000 | (offset & 0x0FFF));
131 
132 	ts.tv_sec += offset * 60;
133 	days = ts.tv_sec / SECS_PER_DAY;
134 	rem = ts.tv_sec % SECS_PER_DAY;
135 	dest->hour = rem / SECS_PER_HOUR;
136 	rem %= SECS_PER_HOUR;
137 	dest->minute = rem / 60;
138 	dest->second = rem % 60;
139 	y = 1970;
140 
141 #define DIV(a, b) ((a) / (b) - ((a) % (b) < 0))
142 #define LEAPS_THRU_END_OF(y) (DIV (y, 4) - DIV (y, 100) + DIV (y, 400))
143 
144 	while (days < 0 || days >= (__isleap(y) ? 366 : 365)) {
145 		long int yg = y + days / 365 - (days % 365 < 0);
146 
147 		/* Adjust DAYS and Y to match the guessed year.  */
148 		days -= ((yg - y) * 365
149 			 + LEAPS_THRU_END_OF(yg - 1)
150 			 - LEAPS_THRU_END_OF(y - 1));
151 		y = yg;
152 	}
153 	dest->year = cpu_to_le16(y);
154 	ip = __mon_yday[__isleap(y)];
155 	for (y = 11; days < (long int)ip[y]; --y)
156 		continue;
157 	days -= ip[y];
158 	dest->month = y + 1;
159 	dest->day = days + 1;
160 
161 	dest->centiseconds = ts.tv_nsec / 10000000;
162 	dest->hundredsOfMicroseconds = (ts.tv_nsec / 1000 -
163 					dest->centiseconds * 10000) / 100;
164 	dest->microseconds = (ts.tv_nsec / 1000 - dest->centiseconds * 10000 -
165 			      dest->hundredsOfMicroseconds * 100);
166 	return dest;
167 }
168 
169 /* EOF */
170