Root/fs/udf/udftime.c

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). */
51static 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
62static 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
83extern struct timezone sys_tz;
84
85#define SECS_PER_HOUR (60 * 60)
86#define SECS_PER_DAY (SECS_PER_HOUR * 24)
87
88struct timespec *
89udf_disk_stamp_to_time(struct timespec *dest, struct timestamp src)
90{
91    int yday;
92    u16 typeAndTimezone = le16_to_cpu(src.typeAndTimezone);
93    u16 year = le16_to_cpu(src.year);
94    uint8_t type = typeAndTimezone >> 12;
95    int16_t offset;
96
97    if (type == 1) {
98        offset = typeAndTimezone << 4;
99        /* sign extent offset */
100        offset = (offset >> 4);
101        if (offset == -2047) /* unspecified offset */
102            offset = 0;
103    } else
104        offset = 0;
105
106    if ((year < EPOCH_YEAR) ||
107        (year >= EPOCH_YEAR + MAX_YEAR_SECONDS)) {
108        return NULL;
109    }
110    dest->tv_sec = year_seconds[year - EPOCH_YEAR];
111    dest->tv_sec -= offset * 60;
112
113    yday = ((__mon_yday[__isleap(year)][src.month - 1]) + src.day - 1);
114    dest->tv_sec += (((yday * 24) + src.hour) * 60 + src.minute) * 60 + src.second;
115    dest->tv_nsec = 1000 * (src.centiseconds * 10000 +
116            src.hundredsOfMicroseconds * 100 + src.microseconds);
117    return dest;
118}
119
120struct timestamp *
121udf_time_to_disk_stamp(struct timestamp *dest, struct timespec ts)
122{
123    long int days, rem, y;
124    const unsigned short int *ip;
125    int16_t offset;
126
127    offset = -sys_tz.tz_minuteswest;
128
129    if (!dest)
130        return NULL;
131
132    dest->typeAndTimezone = cpu_to_le16(0x1000 | (offset & 0x0FFF));
133
134    ts.tv_sec += offset * 60;
135    days = ts.tv_sec / SECS_PER_DAY;
136    rem = ts.tv_sec % SECS_PER_DAY;
137    dest->hour = rem / SECS_PER_HOUR;
138    rem %= SECS_PER_HOUR;
139    dest->minute = rem / 60;
140    dest->second = rem % 60;
141    y = 1970;
142
143#define DIV(a, b) ((a) / (b) - ((a) % (b) < 0))
144#define LEAPS_THRU_END_OF(y) (DIV (y, 4) - DIV (y, 100) + DIV (y, 400))
145
146    while (days < 0 || days >= (__isleap(y) ? 366 : 365)) {
147        long int yg = y + days / 365 - (days % 365 < 0);
148
149        /* Adjust DAYS and Y to match the guessed year. */
150        days -= ((yg - y) * 365
151             + LEAPS_THRU_END_OF(yg - 1)
152             - LEAPS_THRU_END_OF(y - 1));
153        y = yg;
154    }
155    dest->year = cpu_to_le16(y);
156    ip = __mon_yday[__isleap(y)];
157    for (y = 11; days < (long int)ip[y]; --y)
158        continue;
159    days -= ip[y];
160    dest->month = y + 1;
161    dest->day = days + 1;
162
163    dest->centiseconds = ts.tv_nsec / 10000000;
164    dest->hundredsOfMicroseconds = (ts.tv_nsec / 1000 -
165                    dest->centiseconds * 10000) / 100;
166    dest->microseconds = (ts.tv_nsec / 1000 - dest->centiseconds * 10000 -
167                  dest->hundredsOfMicroseconds * 100);
168    return dest;
169}
170
171/* EOF */
172

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