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udftime.c
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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 ([email protected]).
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 "udfdecl.h"
38 
39 #include <linux/types.h>
40 #include <linux/kernel.h>
41 
42 #define EPOCH_YEAR 1970
43 
44 #ifndef __isleap
45 /* Nonzero if YEAR is a leap year (every 4 years,
46  except every 100th isn't, and every 400th is). */
47 #define __isleap(year) \
48  ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
49 #endif
50 
51 /* How many days come before each month (0-12). */
52 static const unsigned short int __mon_yday[2][13] = {
53  /* Normal years. */
54  {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365},
55  /* Leap years. */
56  {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366}
57 };
58 
59 #define MAX_YEAR_SECONDS 69
60 #define SPD 0x15180 /*3600*24 */
61 #define SPY(y, l, s) (SPD * (365 * y + l) + s)
62 
63 static time_t year_seconds[MAX_YEAR_SECONDS] = {
64 /*1970*/ SPY(0, 0, 0), SPY(1, 0, 0), SPY(2, 0, 0), SPY(3, 1, 0),
65 /*1974*/ SPY(4, 1, 0), SPY(5, 1, 0), SPY(6, 1, 0), SPY(7, 2, 0),
66 /*1978*/ SPY(8, 2, 0), SPY(9, 2, 0), SPY(10, 2, 0), SPY(11, 3, 0),
67 /*1982*/ SPY(12, 3, 0), SPY(13, 3, 0), SPY(14, 3, 0), SPY(15, 4, 0),
68 /*1986*/ SPY(16, 4, 0), SPY(17, 4, 0), SPY(18, 4, 0), SPY(19, 5, 0),
69 /*1990*/ SPY(20, 5, 0), SPY(21, 5, 0), SPY(22, 5, 0), SPY(23, 6, 0),
70 /*1994*/ SPY(24, 6, 0), SPY(25, 6, 0), SPY(26, 6, 0), SPY(27, 7, 0),
71 /*1998*/ SPY(28, 7, 0), SPY(29, 7, 0), SPY(30, 7, 0), SPY(31, 8, 0),
72 /*2002*/ SPY(32, 8, 0), SPY(33, 8, 0), SPY(34, 8, 0), SPY(35, 9, 0),
73 /*2006*/ SPY(36, 9, 0), SPY(37, 9, 0), SPY(38, 9, 0), SPY(39, 10, 0),
74 /*2010*/ SPY(40, 10, 0), SPY(41, 10, 0), SPY(42, 10, 0), SPY(43, 11, 0),
75 /*2014*/ SPY(44, 11, 0), SPY(45, 11, 0), SPY(46, 11, 0), SPY(47, 12, 0),
76 /*2018*/ SPY(48, 12, 0), SPY(49, 12, 0), SPY(50, 12, 0), SPY(51, 13, 0),
77 /*2022*/ SPY(52, 13, 0), SPY(53, 13, 0), SPY(54, 13, 0), SPY(55, 14, 0),
78 /*2026*/ SPY(56, 14, 0), SPY(57, 14, 0), SPY(58, 14, 0), SPY(59, 15, 0),
79 /*2030*/ SPY(60, 15, 0), SPY(61, 15, 0), SPY(62, 15, 0), SPY(63, 16, 0),
80 /*2034*/ SPY(64, 16, 0), SPY(65, 16, 0), SPY(66, 16, 0), SPY(67, 17, 0),
81 /*2038*/ SPY(68, 17, 0)
82 };
83 
84 extern struct timezone sys_tz;
85 
86 #define SECS_PER_HOUR (60 * 60)
87 #define SECS_PER_DAY (SECS_PER_HOUR * 24)
88 
89 struct timespec *
91 {
92  int yday;
94  u16 year = le16_to_cpu(src.year);
95  uint8_t type = typeAndTimezone >> 12;
97 
98  if (type == 1) {
99  offset = typeAndTimezone << 4;
100  /* sign extent offset */
101  offset = (offset >> 4);
102  if (offset == -2047) /* unspecified offset */
103  offset = 0;
104  } else
105  offset = 0;
106 
107  if ((year < EPOCH_YEAR) ||
108  (year >= EPOCH_YEAR + MAX_YEAR_SECONDS)) {
109  return NULL;
110  }
111  dest->tv_sec = year_seconds[year - EPOCH_YEAR];
112  dest->tv_sec -= offset * 60;
113 
114  yday = ((__mon_yday[__isleap(year)][src.month - 1]) + src.day - 1);
115  dest->tv_sec += (((yday * 24) + src.hour) * 60 + src.minute) * 60 + src.second;
116  dest->tv_nsec = 1000 * (src.centiseconds * 10000 +
117  src.hundredsOfMicroseconds * 100 + src.microseconds);
118  return dest;
119 }
120 
121 struct timestamp *
123 {
124  long int days, rem, y;
125  const unsigned short int *ip;
126  int16_t offset;
127 
128  offset = -sys_tz.tz_minuteswest;
129 
130  if (!dest)
131  return NULL;
132 
133  dest->typeAndTimezone = cpu_to_le16(0x1000 | (offset & 0x0FFF));
134 
135  ts.tv_sec += offset * 60;
136  days = ts.tv_sec / SECS_PER_DAY;
137  rem = ts.tv_sec % SECS_PER_DAY;
138  dest->hour = rem / SECS_PER_HOUR;
139  rem %= SECS_PER_HOUR;
140  dest->minute = rem / 60;
141  dest->second = rem % 60;
142  y = 1970;
143 
144 #define DIV(a, b) ((a) / (b) - ((a) % (b) < 0))
145 #define LEAPS_THRU_END_OF(y) (DIV (y, 4) - DIV (y, 100) + DIV (y, 400))
146 
147  while (days < 0 || days >= (__isleap(y) ? 366 : 365)) {
148  long int yg = y + days / 365 - (days % 365 < 0);
149 
150  /* Adjust DAYS and Y to match the guessed year. */
151  days -= ((yg - y) * 365
152  + LEAPS_THRU_END_OF(yg - 1)
153  - LEAPS_THRU_END_OF(y - 1));
154  y = yg;
155  }
156  dest->year = cpu_to_le16(y);
157  ip = __mon_yday[__isleap(y)];
158  for (y = 11; days < (long int)ip[y]; --y)
159  continue;
160  days -= ip[y];
161  dest->month = y + 1;
162  dest->day = days + 1;
163 
164  dest->centiseconds = ts.tv_nsec / 10000000;
165  dest->hundredsOfMicroseconds = (ts.tv_nsec / 1000 -
166  dest->centiseconds * 10000) / 100;
167  dest->microseconds = (ts.tv_nsec / 1000 - dest->centiseconds * 10000 -
168  dest->hundredsOfMicroseconds * 100);
169  return dest;
170 }
171 
172 /* EOF */