/* Copyright (c) 2007-2008 Michael G Schwern This software originally derived from Paul Sheer's pivotal_gmtime_r.c. The MIT License: 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. */ /* Programmers who have available to them 64-bit time values as a 'long long' type can use localtime64_r() and gmtime64_r() which correctly converts the time even on 32-bit systems. Whether you have 64-bit time values will depend on the operating system. localtime64_r() is a 64-bit equivalent of localtime_r(). gmtime64_r() is a 64-bit equivalent of gmtime_r(). */ #include "localtime64.h" static const int days_in_month[2][12] = { {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}, {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}, }; static const int julian_days_by_month[2][12] = { {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334}, {0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335}, }; static const int length_of_year[2] = { 365, 366 }; /* Number of days in a 400 year Gregorian cycle */ static const int years_in_gregorian_cycle = 400; static const int days_in_gregorian_cycle = (365 * 400) + 100 - 4 + 1; /* 28 year calendar cycle between 2010 and 2037 */ static const int safe_years[28] = { 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025, 2026, 2027, 2028, 2029, 2030, 2031, 2032, 2033, 2034, 2035, 2036, 2037, 2010, 2011, 2012, 2013, 2014, 2015 }; #define SOLAR_CYCLE_LENGTH 28 static const int dow_year_start[SOLAR_CYCLE_LENGTH] = { 5, 0, 1, 2, /* 0 2016 - 2019 */ 3, 5, 6, 0, /* 4 */ 1, 3, 4, 5, /* 8 */ 6, 1, 2, 3, /* 12 */ 4, 6, 0, 1, /* 16 */ 2, 4, 5, 6, /* 20 2036, 2037, 2010, 2011 */ 0, 2, 3, 4 /* 24 2012, 2013, 2014, 2015 */ }; /* Let's assume people are going to be looking for dates in the future. Let's provide some cheats so you can skip ahead. This has a 4x speed boost when near 2008. */ /* Number of days since epoch on Jan 1st, 2008 GMT */ #define CHEAT_DAYS (1199145600 / 24 / 60 / 60) #define CHEAT_YEARS 108 #define IS_LEAP(n) ((!(((n) + 1900) % 400) || (!(((n) + 1900) % 4) && (((n) + 1900) % 100))) != 0) #define WRAP(a,b,m) ((a) = ((a) < 0 ) ? ((b)--, (a) + (m)) : (a)) #define SHOULD_USE_SYSTEM_LOCALTIME(a) ( \ USE_SYSTEM_LOCALTIME && \ (a) <= SYSTEM_LOCALTIME_MAX && \ (a) >= SYSTEM_LOCALTIME_MIN \ ) #define SHOULD_USE_SYSTEM_GMTIME(a) ( \ USE_SYSTEM_GMTIME && \ (a) <= SYSTEM_GMTIME_MAX && \ (a) >= SYSTEM_GMTIME_MIN \ ) int _is_exception_century(Int64 year) { int is_exception = ((year % 100 == 0) && !(year % 400 == 0)); /* printf("is_exception_century: %s\n", is_exception ? "yes" : "no"); */ return(is_exception); } /* timegm() is a GNU extension, so emulate it here if we need it */ #ifdef HAS_TIMEGM # define TIMEGM(n) timegm(n); #else # define TIMEGM(n) ((time_t)timegm64(n)); #endif Time64_T timegm64(struct tm *date) { int days = 0; Int64 seconds = 0; Int64 year; if( date->tm_year > 70 ) { year = 70; while( year < date->tm_year ) { days += length_of_year[IS_LEAP(year)]; year++; } } else if ( date->tm_year < 70 ) { year = 69; do { days -= length_of_year[IS_LEAP(year)]; year--; } while( year >= date->tm_year ); } days += julian_days_by_month[IS_LEAP(date->tm_year)][date->tm_mon]; days += date->tm_mday - 1; /* Avoid overflowing the days integer */ seconds = days; seconds = seconds * 60 * 60 * 24; seconds += date->tm_hour * 60 * 60; seconds += date->tm_min * 60; seconds += date->tm_sec; return((Time64_T)seconds); } int _check_tm(struct tm *tm) { /* Don't forget leap seconds */ assert(tm->tm_sec >= 0); assert(tm->tm_sec <= 61); assert(tm->tm_min >= 0); assert(tm->tm_min <= 59); assert(tm->tm_hour >= 0); assert(tm->tm_hour <= 23); assert(tm->tm_mday >= 1); assert(tm->tm_mday <= days_in_month[IS_LEAP(tm->tm_year)][tm->tm_mon]); assert(tm->tm_mon >= 0); assert(tm->tm_mon <= 11); assert(tm->tm_wday >= 0); assert(tm->tm_wday <= 6); assert(tm->tm_yday >= 0); assert(tm->tm_yday <= length_of_year[IS_LEAP(tm->tm_year)]); #ifdef HAS_TM_TM_GMTOFF assert(tm->tm_gmtoff >= -24 * 60 * 60); assert(tm->tm_gmtoff <= 24 * 60 * 60); #endif return 1; } /* The exceptional centuries without leap years cause the cycle to shift by 16 */ Year _cycle_offset(Year year) { const Year start_year = 2000; Year year_diff = year - start_year; Year exceptions; if( year > start_year ) year_diff--; exceptions = year_diff / 100; exceptions -= year_diff / 400; /* fprintf(stderr, "# year: %lld, exceptions: %lld, year_diff: %lld\n", year, exceptions, year_diff); */ return exceptions * 16; } /* For a given year after 2038, pick the latest possible matching year in the 28 year calendar cycle. A matching year... 1) Starts on the same day of the week. 2) Has the same leap year status. This is so the calendars match up. Also the previous year must match. When doing Jan 1st you might wind up on Dec 31st the previous year when doing a -UTC time zone. Finally, the next year must have the same start day of week. This is for Dec 31st with a +UTC time zone. It doesn't need the same leap year status since we only care about January 1st. */ int _safe_year(Year year) { int safe_year; Year year_cycle = year + _cycle_offset(year); /* Change non-leap xx00 years to an equivalent */ if( _is_exception_century(year) ) year_cycle += 11; /* Also xx01 years, since the previous year will be wrong */ if( _is_exception_century(year - 1) ) year_cycle += 17; year_cycle %= SOLAR_CYCLE_LENGTH; if( year_cycle < 0 ) year_cycle = SOLAR_CYCLE_LENGTH + year_cycle; assert( year_cycle >= 0 ); assert( year_cycle < SOLAR_CYCLE_LENGTH ); safe_year = safe_years[year_cycle]; assert(safe_year <= 2037 && safe_year >= 2010); /* printf("year: %d, year_cycle: %d, safe_year: %d\n", year, year_cycle, safe_year); */ return safe_year; } /* Simulate localtime_r() to the best of our ability */ struct tm * fake_localtime_r(const time_t *clock, struct tm *result) { const struct tm *static_result = localtime(clock); assert(result != NULL); if( static_result == NULL ) { memset(result, 0, sizeof(*result)); return NULL; } else { memcpy(result, static_result, sizeof(*result)); return result; } } /* Simulate gmtime_r() to the best of our ability */ struct tm * fake_gmtime_r(const time_t *clock, struct tm *result) { const struct tm *static_result = gmtime(clock); assert(result != NULL); if( static_result == NULL ) { memset(result, 0, sizeof(*result)); return NULL; } else { memcpy(result, static_result, sizeof(*result)); return result; } } struct tm *gmtime64_r (const Time64_T *in_time, struct tm *p) { int v_tm_sec, v_tm_min, v_tm_hour, v_tm_mon, v_tm_wday; Int64 v_tm_tday; int leap; Int64 m; Time64_T time = *in_time; Year year = 70; assert(p != NULL); /* Use the system gmtime() if time_t is small enough */ if( SHOULD_USE_SYSTEM_GMTIME(*in_time) ) { time_t safe_time = *in_time; GMTIME_R(&safe_time, p); assert(_check_tm(p)); return p; } #ifdef HAS_TM_TM_GMTOFF p->tm_gmtoff = 0; #endif p->tm_isdst = 0; #ifdef HAS_TM_TM_ZONE p->tm_zone = "UTC"; #endif v_tm_sec = (int)(time % 60); time /= 60; v_tm_min = (int)(time % 60); time /= 60; v_tm_hour = (int)(time % 24); time /= 24; v_tm_tday = time; WRAP (v_tm_sec, v_tm_min, 60); WRAP (v_tm_min, v_tm_hour, 60); WRAP (v_tm_hour, v_tm_tday, 24); v_tm_wday = (int)((v_tm_tday + 4) % 7); if (v_tm_wday < 0) v_tm_wday += 7; m = v_tm_tday; if (m >= CHEAT_DAYS) { year = CHEAT_YEARS; m -= CHEAT_DAYS; } if (m >= 0) { /* Gregorian cycles, this is huge optimization for distant times */ while (m >= (Time64_T) days_in_gregorian_cycle) { m -= (Time64_T) days_in_gregorian_cycle; year += years_in_gregorian_cycle; } /* Years */ leap = IS_LEAP (year); while (m >= (Time64_T) length_of_year[leap]) { m -= (Time64_T) length_of_year[leap]; year++; leap = IS_LEAP (year); } /* Months */ v_tm_mon = 0; while (m >= (Time64_T) days_in_month[leap][v_tm_mon]) { m -= (Time64_T) days_in_month[leap][v_tm_mon]; v_tm_mon++; } } else { year--; /* Gregorian cycles */ while (m < (Time64_T) -days_in_gregorian_cycle) { m += (Time64_T) days_in_gregorian_cycle; year -= years_in_gregorian_cycle; } /* Years */ leap = IS_LEAP (year); while (m < (Time64_T) -length_of_year[leap]) { m += (Time64_T) length_of_year[leap]; year--; leap = IS_LEAP (year); } /* Months */ v_tm_mon = 11; while (m < (Time64_T) -days_in_month[leap][v_tm_mon]) { m += (Time64_T) days_in_month[leap][v_tm_mon]; v_tm_mon--; } m += (Time64_T) days_in_month[leap][v_tm_mon]; } p->tm_year = year; if( p->tm_year != year ) { #ifdef EOVERFLOW errno = EOVERFLOW; #endif return NULL; } p->tm_mday = (int) m + 1; p->tm_yday = (int) julian_days_by_month[leap][v_tm_mon] + m; p->tm_sec = v_tm_sec, p->tm_min = v_tm_min, p->tm_hour = v_tm_hour, p->tm_mon = v_tm_mon, p->tm_wday = v_tm_wday; assert(_check_tm(p)); return p; } struct tm *localtime64_r (const Time64_T *time, struct tm *local_tm) { time_t safe_time; struct tm gm_tm; Year orig_year; int month_diff; assert(local_tm != NULL); /* Use the system localtime() if time_t is small enough */ if( SHOULD_USE_SYSTEM_LOCALTIME(*time) ) { safe_time = *time; LOCALTIME_R(&safe_time, local_tm); assert(_check_tm(local_tm)); return local_tm; } if( gmtime64_r(time, &gm_tm) == NULL ) return NULL; orig_year = gm_tm.tm_year; if (gm_tm.tm_year > (2037 - 1900) || gm_tm.tm_year < (1902 - 1900) ) { gm_tm.tm_year = _safe_year(gm_tm.tm_year + 1900) - 1900; } safe_time = TIMEGM(&gm_tm); if( LOCALTIME_R(&safe_time, local_tm) == NULL ) return NULL; local_tm->tm_year = orig_year; if( local_tm->tm_year != orig_year ) { #ifdef EOVERFLOW errno = EOVERFLOW; #endif return NULL; } month_diff = local_tm->tm_mon - gm_tm.tm_mon; /* When localtime is Dec 31st previous year and gmtime is Jan 1st next year. */ if( month_diff == 11 ) { local_tm->tm_year--; } /* When localtime is Jan 1st, next year and gmtime is Dec 31st, previous year. */ if( month_diff == -11 ) { local_tm->tm_year++; } /* GMT is Jan 1st, xx01 year, but localtime is still Dec 31st in a non-leap xx00. There is one point in the cycle we can't account for which the safe xx00 year is a leap year. So we need to correct for Dec 31st comming out as the 366th day of the year. */ if( !IS_LEAP(local_tm->tm_year) && local_tm->tm_yday == 365 ) local_tm->tm_yday--; assert(_check_tm(local_tm)); return local_tm; }