diff options
Diffstat (limited to 'compat/timegm.c')
| -rw-r--r-- | compat/timegm.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/compat/timegm.c b/compat/timegm.c new file mode 100644 index 0000000..2658445 --- /dev/null +++ b/compat/timegm.c @@ -0,0 +1,220 @@ +/* + * ---------------------------------------------------------------------- + * 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; +} |