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/*
* ----------------------------------------------------------------------
* Copyright © 2005-2014 Rich Felker, et al.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
* ----------------------------------------------------------------------
*/
#include <errno.h>
#include <limits.h>
#include <time.h>
/* 2000-03-01 (mod 400 year, immediately after feb29 */
#define LEAPOCH (946684800LL + 86400*(31+29))
#define DAYS_PER_400Y (365*400 + 97)
#define DAYS_PER_100Y (365*100 + 24)
#define DAYS_PER_4Y (365*4 + 1)
static int __month_to_secs(int month, int is_leap)
{
static const int secs_through_month[] = {
0, 31*86400, 59*86400, 90*86400,
120*86400, 151*86400, 181*86400, 212*86400,
243*86400, 273*86400, 304*86400, 334*86400 };
int t = secs_through_month[month];
if (is_leap && month >= 2) t+=86400;
return t;
}
static long long __year_to_secs(long long year, int *is_leap)
{
if (year-2ULL <= 136) {
int y = year;
int leaps = (y-68)>>2;
if (!((y-68)&3)) {
leaps--;
if (is_leap) *is_leap = 1;
} else if (is_leap) *is_leap = 0;
return 31536000*(y-70) + 86400*leaps;
}
int cycles, centuries, leaps, rem;
if (!is_leap) is_leap = &(int){0};
cycles = (year-100) / 400;
rem = (year-100) % 400;
if (rem < 0) {
cycles--;
rem += 400;
}
if (!rem) {
*is_leap = 1;
centuries = 0;
leaps = 0;
} else {
if (rem >= 200) {
if (rem >= 300) centuries = 3, rem -= 300;
else centuries = 2, rem -= 200;
} else {
if (rem >= 100) centuries = 1, rem -= 100;
else centuries = 0;
}
if (!rem) {
*is_leap = 0;
leaps = 0;
} else {
leaps = rem / 4U;
rem %= 4U;
*is_leap = !rem;
}
}
leaps += 97*cycles + 24*centuries - *is_leap;
return (year-100) * 31536000LL + leaps * 86400LL + 946684800 + 86400;
}
static long long __tm_to_secs(const struct tm *tm)
{
int is_leap;
long long year = tm->tm_year;
int month = tm->tm_mon;
if (month >= 12 || month < 0) {
int adj = month / 12;
month %= 12;
if (month < 0) {
adj--;
month += 12;
}
year += adj;
}
long long t = __year_to_secs(year, &is_leap);
t += __month_to_secs(month, is_leap);
t += 86400LL * (tm->tm_mday-1);
t += 3600LL * tm->tm_hour;
t += 60LL * tm->tm_min;
t += tm->tm_sec;
return t;
}
static int __secs_to_tm(long long t, struct tm *tm)
{
long long days, secs;
int remdays, remsecs, remyears;
int qc_cycles, c_cycles, q_cycles;
int years, months;
int wday, yday, leap;
static const char days_in_month[] = {31,30,31,30,31,31,30,31,30,31,31,29};
/* Reject time_t values whose year would overflow int */
if (t < INT_MIN * 31622400LL || t > INT_MAX * 31622400LL)
return -1;
secs = t - LEAPOCH;
days = secs / 86400;
remsecs = secs % 86400;
if (remsecs < 0) {
remsecs += 86400;
days--;
}
wday = (3+days)%7;
if (wday < 0) wday += 7;
qc_cycles = days / DAYS_PER_400Y;
remdays = days % DAYS_PER_400Y;
if (remdays < 0) {
remdays += DAYS_PER_400Y;
qc_cycles--;
}
c_cycles = remdays / DAYS_PER_100Y;
if (c_cycles == 4) c_cycles--;
remdays -= c_cycles * DAYS_PER_100Y;
q_cycles = remdays / DAYS_PER_4Y;
if (q_cycles == 25) q_cycles--;
remdays -= q_cycles * DAYS_PER_4Y;
remyears = remdays / 365;
if (remyears == 4) remyears--;
remdays -= remyears * 365;
leap = !remyears && (q_cycles || !c_cycles);
yday = remdays + 31 + 28 + leap;
if (yday >= 365+leap) yday -= 365+leap;
years = remyears + 4*q_cycles + 100*c_cycles + 400*qc_cycles;
for (months=0; days_in_month[months] <= remdays; months++)
remdays -= days_in_month[months];
if (years+100 > INT_MAX || years+100 < INT_MIN)
return -1;
tm->tm_year = years + 100;
tm->tm_mon = months + 2;
if (tm->tm_mon >= 12) {
tm->tm_mon -=12;
tm->tm_year++;
}
tm->tm_mday = remdays + 1;
tm->tm_wday = wday;
tm->tm_yday = yday;
tm->tm_hour = remsecs / 3600;
tm->tm_min = remsecs / 60 % 60;
tm->tm_sec = remsecs % 60;
return 0;
}
#ifdef _WIN32
struct tm *__gmtime_r(const time_t *t, struct tm *tm)
{
if (__secs_to_tm(*t, tm) < 0) {
errno = EOVERFLOW;
return 0;
}
tm->tm_isdst = 0;
return tm;
}
#endif
time_t timegm(struct tm *tm)
{
struct tm new;
long long t = __tm_to_secs(tm);
if (__secs_to_tm(t, &new) < 0) {
errno = EOVERFLOW;
return -1;
}
#if SIZEOF_TIME_T != 8
if (t > (long long)INT_MAX || t < (long long)INT_MIN) {
errno = EOVERFLOW;
return -1;
}
#endif
*tm = new;
tm->tm_isdst = 0;
return t;
}
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