Rename localtime64.[ch] to time64.[ch] to mirror change in y2038, and the file isn't about just localtime() anymore.

1 files changed, 481 insertions, 0 deletions

diff --git a/time64.c b/time64.c
new file mode 100644
index 0000000000..cb74b55000
--- /dev/null
+++ b/time64.c
@@ -0,0 +1,481 @@
+/*
+
+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 "time64.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;
+}