linux/fs/udf/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 (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 "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).  */
  52static 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
  63static 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
  84extern struct timezone sys_tz;
  85
  86#define SECS_PER_HOUR   (60 * 60)
  87#define SECS_PER_DAY    (SECS_PER_HOUR * 24)
  88
  89struct timespec *
  90udf_disk_stamp_to_time(struct timespec *dest, struct timestamp src)
  91{
  92        int yday;
  93        u16 typeAndTimezone = le16_to_cpu(src.typeAndTimezone);
  94        u16 year = le16_to_cpu(src.year);
  95        uint8_t type = typeAndTimezone >> 12;
  96        int16_t offset;
  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
 121struct timestamp *
 122udf_time_to_disk_stamp(struct timestamp *dest, struct timespec ts)
 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 */
 173
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