mirror of
git://git.musl-libc.org/musl
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1cc81f5cb0
this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
81 lines
1.8 KiB
C
81 lines
1.8 KiB
C
#include "time_impl.h"
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#include <limits.h>
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/* 2000-03-01 (mod 400 year, immediately after feb29 */
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#define LEAPOCH (946684800LL + 86400*(31+29))
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#define DAYS_PER_400Y (365*400 + 97)
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#define DAYS_PER_100Y (365*100 + 24)
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#define DAYS_PER_4Y (365*4 + 1)
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int __secs_to_tm(long long t, struct tm *tm)
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{
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long long days, secs;
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int remdays, remsecs, remyears;
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int qc_cycles, c_cycles, q_cycles;
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int years, months;
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int wday, yday, leap;
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static const char days_in_month[] = {31,30,31,30,31,31,30,31,30,31,31,29};
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/* Reject time_t values whose year would overflow int */
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if (t < INT_MIN * 31622400LL || t > INT_MAX * 31622400LL)
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return -1;
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secs = t - LEAPOCH;
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days = secs / 86400;
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remsecs = secs % 86400;
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if (remsecs < 0) {
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remsecs += 86400;
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days--;
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}
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wday = (3+days)%7;
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if (wday < 0) wday += 7;
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qc_cycles = days / DAYS_PER_400Y;
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remdays = days % DAYS_PER_400Y;
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if (remdays < 0) {
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remdays += DAYS_PER_400Y;
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qc_cycles--;
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}
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c_cycles = remdays / DAYS_PER_100Y;
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if (c_cycles == 4) c_cycles--;
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remdays -= c_cycles * DAYS_PER_100Y;
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q_cycles = remdays / DAYS_PER_4Y;
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if (q_cycles == 25) q_cycles--;
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remdays -= q_cycles * DAYS_PER_4Y;
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remyears = remdays / 365;
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if (remyears == 4) remyears--;
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remdays -= remyears * 365;
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leap = !remyears && (q_cycles || !c_cycles);
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yday = remdays + 31 + 28 + leap;
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if (yday >= 365+leap) yday -= 365+leap;
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years = remyears + 4*q_cycles + 100*c_cycles + 400*qc_cycles;
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for (months=0; days_in_month[months] <= remdays; months++)
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remdays -= days_in_month[months];
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if (years+100 > INT_MAX || years+100 < INT_MIN)
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return -1;
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tm->tm_year = years + 100;
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tm->tm_mon = months + 2;
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if (tm->tm_mon >= 12) {
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tm->tm_mon -=12;
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tm->tm_year++;
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}
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tm->tm_mday = remdays + 1;
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tm->tm_wday = wday;
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tm->tm_yday = yday;
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tm->tm_hour = remsecs / 3600;
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tm->tm_min = remsecs / 60 % 60;
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tm->tm_sec = remsecs % 60;
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return 0;
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}
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