time.c

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/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: d586b04422815e021df574fd81236570a3a4702e $
 *
 * @brief Platform independent time functions
 * @file lib/util/time.c
 *
 * @copyright 2016-2019 Alan DeKok (aland@freeradius.org)
 * @copyright 2019-2020 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
RCSID("$Id: d586b04422815e021df574fd81236570a3a4702e $")
 
#include <freeradius-devel/autoconf.h>
#include <freeradius-devel/util/time.h>
#include <freeradius-devel/util/skip.h>
 
int64_t const fr_time_multiplier_by_res[] = {
        [FR_TIME_RES_NSEC]      = 1,
        [FR_TIME_RES_USEC]      = NSEC / USEC,
        [FR_TIME_RES_MSEC]      = NSEC / MSEC,
        [FR_TIME_RES_CSEC]      = NSEC / CSEC,
        [FR_TIME_RES_SEC]       = NSEC,
        [FR_TIME_RES_MIN]       = (int64_t)NSEC * 60,
        [FR_TIME_RES_HOUR]      = (int64_t)NSEC * 3600,
        [FR_TIME_RES_DAY]       = (int64_t)NSEC * 86400,
        [FR_TIME_RES_WEEK]      = (int64_t)NSEC * 86400 * 7,
        [FR_TIME_RES_MONTH]     = FR_TIME_DUR_MONTH,
        [FR_TIME_RES_YEAR]      = FR_TIME_DUR_YEAR,
};
 
fr_table_num_ordered_t const fr_time_precision_table[] = {
        { L("microseconds"),    FR_TIME_RES_USEC },
        { L("us"),              FR_TIME_RES_USEC },
 
        { L("nanoseconds"),     FR_TIME_RES_NSEC },
        { L("ns"),              FR_TIME_RES_NSEC },
 
        { L("milliseconds"),    FR_TIME_RES_MSEC },
        { L("ms"),              FR_TIME_RES_MSEC },
 
        { L("centiseconds"),    FR_TIME_RES_CSEC },
        { L("cs"),              FR_TIME_RES_CSEC },
 
        { L("seconds"),         FR_TIME_RES_SEC },
        { L("s"),               FR_TIME_RES_SEC },
 
        { L("minutes"),         FR_TIME_RES_MIN },
        { L("m"),               FR_TIME_RES_MIN },
 
        { L("hours"),           FR_TIME_RES_HOUR },
        { L("h"),               FR_TIME_RES_HOUR },
 
        { L("days"),            FR_TIME_RES_DAY },
        { L("d"),               FR_TIME_RES_DAY },
 
        { L("weeks"),           FR_TIME_RES_WEEK },
        { L("w"),               FR_TIME_RES_WEEK },
 
        /*
         *      These use special values FR_TIME_DUR_MONTH and FR_TIME_DUR_YEAR
         */
        { L("months"),          FR_TIME_RES_MONTH },
        { L("M"),               FR_TIME_RES_MONTH },
 
        { L("years"),           FR_TIME_RES_YEAR },
        { L("y"),               FR_TIME_RES_YEAR },
 
};
size_t fr_time_precision_table_len = NUM_ELEMENTS(fr_time_precision_table);
 
int64_t                         fr_time_epoch;                                  //!< monotonic clock at boot, i.e. our epoch
_Atomic int64_t                 fr_time_monotonic_to_realtime;                  //!< difference between the two clocks
 
static char const               *tz_names[2] = { NULL, NULL };  //!< normal, DST, from localtime_r(), tm_zone
static long                     gmtoff[2] = {0, 0};             //!< from localtime_r(), tm_gmtoff
static bool                     isdst = false;                  //!< from localtime_r(), tm_is_dst
 
 
/** Get a new fr_time_monotonic_to_realtime value
 *
 * Should be done regularly to adjust for changes in system time.
 *
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int fr_time_sync(void)
{
        struct tm tm;
        time_t now;
 
        /*
         *      fr_time_monotonic_to_realtime is the difference in nano
         *
         *      So to convert a realtime timeval to fr_time we just subtract fr_time_monotonic_to_realtime from the timeval,
         *      which leaves the number of nanoseconds elapsed since our epoch.
         */
        struct timespec ts_realtime, ts_monotime;
 
        /*
         *      Call these consecutively to minimise drift...
         */
        if (clock_gettime(CLOCK_REALTIME, &ts_realtime) < 0) return -1;
        if (clock_gettime(CLOCK_MONOTONIC_RAW, &ts_monotime) < 0) return -1;
 
        atomic_store_explicit(&fr_time_monotonic_to_realtime,
                              fr_time_delta_unwrap(fr_time_delta_from_timespec(&ts_realtime)) -
                              (fr_time_delta_unwrap(fr_time_delta_from_timespec(&ts_monotime)) - fr_time_epoch),
                              memory_order_release);
 
        now = ts_realtime.tv_sec;
 
        /*
         *      Get local time zone name, daylight savings, and GMT
         *      offsets.
         */
        (void) localtime_r(&now, &tm);
 
        isdst = (tm.tm_isdst != 0);
        tz_names[isdst] = tm.tm_zone;
        gmtoff[isdst] = tm.tm_gmtoff * NSEC; /* they store seconds, we store nanoseconds */
 
        return 0;
}
 
/** Initialize the local time.
 *
 *  MUST be called when the program starts.  MUST NOT be called after
 *  that.
 *
 * @return
 *      - <0 on error
 *      - 0 on success
 */
int fr_time_start(void)
{
        struct timespec ts;
 
        tzset();        /* Populate timezone, daylight and tzname globals */
 
        if (clock_gettime(CLOCK_MONOTONIC_RAW, &ts) < 0) return -1;
        fr_time_epoch = fr_time_delta_unwrap(fr_time_delta_from_timespec(&ts));
 
        return fr_time_sync();
}
 
/** Return time delta from the time zone.
 *
 * Returns the delta between UTC and the timezone specified by tz
 *
 * @param[in] tz        time zone name
 * @param[out] delta    the time delta
 * @return
 *      - 0 converted OK
 *      - <0 on error
 *
 *  @note This function ONLY handles a limited number of time
 *  zones: local and gmt.  It is impossible in general to parse
 *  arbitrary time zone strings, as there are duplicates.
 */
int fr_time_delta_from_time_zone(char const *tz, fr_time_delta_t *delta)
{
        *delta = fr_time_delta_wrap(0);
 
        if ((strcmp(tz, "UTC") == 0) ||
            (strcmp(tz, "GMT") == 0)) {
                return 0;
        }
 
        /*
         *      Our local time zone OR time zone with daylight savings.
         */
        if (tz_names[0] && (strcmp(tz, tz_names[0]) == 0)) {
                *delta = fr_time_delta_wrap(gmtoff[0]);
                return 0;
        }
 
        if (tz_names[1] && (strcmp(tz, tz_names[1]) == 0)) {
                *delta = fr_time_delta_wrap(gmtoff[1]);
                return 0;
        }
 
        return -1;
}
 
/** Create fr_time_delta_t from a string
 *
 * @param[out] out              Where to write fr_time_delta_t
 * @param[in] in                String to parse.
 * @param[in] hint              scale for the parsing.  Default is "seconds".
 * @param[in] no_trailing       asserts that there should be a terminal sequence
 *                              after the time delta.  Allows us to produce
 *                              better errors.
 * @param[in] tt                terminal sequences.
 * @return
 *      - >= 0 on success.
 *      - <0 on failure.
 */
fr_slen_t fr_time_delta_from_substr(fr_time_delta_t *out, fr_sbuff_t *in, fr_time_res_t hint,
                                    bool no_trailing, fr_sbuff_term_t const *tt)
{
        fr_sbuff_t              our_in = FR_SBUFF(in);
        int64_t                 integer = 0;    /* Whole units */
        double                  f = 0.0;
        fr_time_res_t           res;
        bool                    do_float;
        bool                    negative;
        fr_sbuff_parse_error_t  sberr;
        bool                    overflow;
        size_t                  match_len;
 
        negative = fr_sbuff_is_char(&our_in, '-');
        do_float = false;
 
        if (fr_sbuff_is_char(&our_in, '.')) goto is_float;
 
        /*
         *      Look for:
         *
         *      <integer>[scale]
         */
        if (fr_sbuff_out(&sberr, &integer, &our_in) < 0) {
                char const *err;
 
        num_error:
                if (sberr != FR_SBUFF_PARSE_ERROR_NOT_FOUND) {
                        err = fr_table_str_by_value(sbuff_parse_error_table, sberr, "<INVALID>");
                } else {
                        err = "Invalid text, input should be a number";
                }
 
                fr_strerror_printf("Failed parsing time_delta: %s", err);
                FR_SBUFF_ERROR_RETURN(&our_in);
        }
 
        /*
         *      hh:mm:ss
         */
        if (fr_sbuff_next_if_char(&our_in, ':')) goto do_timestamp;
 
        /*
         *      If it's a fractional thing, then just parse it as a double.
         *
         *      <float>[scale]
         */
        if (fr_sbuff_is_char(&our_in, '.')) {
                our_in = FR_SBUFF(in);
 
        is_float:
                if (fr_sbuff_out(&sberr, &f, &our_in) < 0) goto num_error;
 
                do_float = true;
        }
 
        /*
         *      Now look for the time resolution.
         */
        fr_sbuff_out_by_longest_prefix(&match_len, &res, fr_time_precision_table, &our_in, FR_TIME_RES_INVALID);
 
        if (fr_sbuff_is_terminal(&our_in, tt)) {
                if (match_len == 0) res = hint;
 
        } else if (no_trailing) {
        fail_trailing_data:
                /* Got a qualifier but there is more text after it. */
                if (res != FR_TIME_RES_INVALID) {
                        fr_strerror_const("Trailing data after time_delta");
                        FR_SBUFF_ERROR_RETURN(&our_in);
                }
 
                fr_strerror_const("Invalid precision qualifier for time_delta");
                FR_SBUFF_ERROR_RETURN(&our_in);
 
        } else if (match_len == 0) {
                /*
                 *      There is trailing data, but we don't care about it.  Ensure that we have a time resolution.
                 */
                res = hint;
        }
 
        fr_assert(res != FR_TIME_RES_INVALID);
 
        /*
         *      For floating point numbers, we pre-multiply by the time resolution, and then override the time
         *      resolution to indicate that no further scaling is necessary.
         *
         *      We check for overflow prior to multiplication, as doubles have ~53 bits of precision, while
         *      int64_t has 64 bits of precision.  That way the comparison is more likely to be accurate.
         */
        if (do_float) {
                if (f < ((double) INT64_MIN) / (double) fr_time_multiplier_by_res[res])  goto fail_overflow;
                if (f > ((double) INT64_MAX) / (double) fr_time_multiplier_by_res[res]) goto fail_overflow;
 
                f *= fr_time_multiplier_by_res[res];
                res = FR_TIME_RES_NSEC;
                integer = f;
        }
 
        /*
         *      We have a valid time scale.  Let's use that.
         */
        *out = fr_time_delta_from_integer(&overflow, integer, res);
        if (overflow) {
        fail_overflow:
                fr_strerror_printf("time_delta would %s", negative ? "underflow" : "overflow");
                fr_sbuff_set_to_start(&our_in);
                FR_SBUFF_ERROR_RETURN(&our_in);
 
        }
        FR_SBUFF_SET_RETURN(in, &our_in);
 
do_timestamp:
        res = hint;
 
        /*
         *      We allow 2^15 hours, but much less than that in seconds/
         */
        if (integer < 0) {
                if (integer < INT16_MIN) goto fail_overflow;
        } else {
                if (integer > INT16_MAX) goto fail_overflow;
        }
 
        /*
         *      It's a timestamp format
         *
         *      [hours:]minutes:seconds
         */
        {
                uint64_t                hours, minutes, seconds;
                fr_sbuff_marker_t       m1;
 
                fr_sbuff_marker(&m1, &our_in);
 
                if (fr_sbuff_out(&sberr, &seconds, &our_in) < 0) goto num_error;
 
                /*
                 *      minutes:seconds
                 */
                if (!fr_sbuff_next_if_char(&our_in, ':')) {
                        hours = 0;
                        minutes = negative ? -integer : integer;
 
                } else {
                        /*
                         *      hours:minutes:seconds
                         *
                         *      The second number we read is the minutes,
                         *      and the seconds are the third number, read
                         *      below.  For the mm:ss form the second number
                         *      is already the seconds, so it must NOT be
                         *      re-read here.
                         */
                        hours = negative ? -integer : integer;
                        minutes = seconds;
 
                        if (fr_sbuff_out(&sberr, &seconds, &our_in) < 0) goto num_error;
                }
 
                if (minutes >= 60) {
                        fr_strerror_printf("minutes component of time_delta is too large");
                        FR_SBUFF_ERROR_RETURN(&m1);
                }
 
                if (seconds >= 60) {
                        fr_strerror_printf("seconds component of time_delta is too large");
                        FR_SBUFF_ERROR_RETURN(&m1);
                }
 
                if (no_trailing && !fr_sbuff_is_terminal(&our_in, tt)) goto fail_trailing_data;
 
                /*
                 *      Add all the components together...
                 */
                if (!fr_add(&integer, ((hours * 60) * 60) + (minutes * 60), seconds)) goto fail_overflow;
 
                /*
                 *      We can't have more than 64K hours plus a bit,
                 *      which limits the size of the integer that we
                 *      return.
                 */
                fr_assert(integer < ((int64_t) UINT16_MAX) * 3600 + 3600 + 60);
 
                /*
                 *      Flip the sign back to negative
                 */
                if (negative) integer = -(integer);
        }
 
        *out = fr_time_delta_from_sec(integer);
        FR_SBUFF_SET_RETURN(in, &our_in);
}
 
/** Create fr_time_delta_t from a string
 *
 * @param[out] out      Where to write fr_time_delta_t
 * @param[in] in        String to parse.
 * @param[in] inlen     Length of string.
 * @param[in] hint      scale for the parsing.  Default is "seconds"
 * @return
 *      - >0 on success.
 *      - <0 on failure.
 */
fr_slen_t fr_time_delta_from_str(fr_time_delta_t *out, char const *in, size_t inlen, fr_time_res_t hint)
{
        fr_slen_t slen;
 
        if (!*in) {
                fr_strerror_const("Empty input is invalid");
                return -1;
        }
 
        slen = fr_time_delta_from_substr(out, &FR_SBUFF_IN(in, inlen), hint, true, NULL);
        if (slen < 0) return slen;
        if (slen != (fr_slen_t)inlen) {
                fr_strerror_const("trailing data after time_delta");    /* Shouldn't happen with no_trailing */
                return -(inlen + 1);
        }
        return slen;
}
 
/** Print fr_time_delta_t to a string with an appropriate suffix
 *
 * @param[out] out              Where to write the string version of the time delta.
 * @param[in] delta             to print.
 * @param[in] res               to print resolution with.
 * @param[in] is_unsigned       whether the value should be printed unsigned.
 * @return
 *      - >0 the number of bytes written to out.
 *      - <0 how many additional bytes would have been required.
 */
fr_slen_t fr_time_delta_to_str(fr_sbuff_t *out, fr_time_delta_t delta, fr_time_res_t res, bool is_unsigned)
{
        fr_sbuff_t      our_out = FR_SBUFF(out);
        char            *q;
        char            *start;
        int64_t         lhs = 0;
        uint64_t        rhs = 0;
 
/*
 *      The % operator can return a _signed_ value.  This macro is
 *      correct for both positive and negative inputs.
 */
#define MOD(a,b) ((((a) < 0) ? -(uint64_t)(a) : (uint64_t)(a)) % (b))
 
        lhs = fr_time_delta_to_integer(delta, res);
        rhs = MOD(fr_time_delta_unwrap(delta), fr_time_multiplier_by_res[res]);
 
        if (!is_unsigned) {
                /*
                 *      0 is unsigned, but we want to print
                 *      "-0.1" if necessary.
                 */
                if ((lhs == 0) && fr_time_delta_isneg(delta)) {
                        FR_SBUFF_IN_CHAR_RETURN(&our_out, '-');
                }
 
                FR_SBUFF_IN_SPRINTF_RETURN(&our_out, "%" PRIi64 ".%09" PRIu64, lhs, rhs);
        } else {
                if (fr_time_delta_isneg(delta)) lhs = rhs = 0;
 
                FR_SBUFF_IN_SPRINTF_RETURN(&our_out, "%" PRIu64 ".%09" PRIu64, lhs, rhs);
        }
        /*
         *      If the sprintf wrote nothing there's nothing to trim.
         *      (Shouldn't happen for a non-zero format like %lu.%09lu, but
         *      guarding keeps us from walking behind the buffer if the sbuff
         *      ran out of room and no bytes were written.)
         */
        if (fr_sbuff_current(&our_out) == fr_sbuff_start(&our_out)) FR_SBUFF_SET_RETURN(out, &our_out);
 
        q = fr_sbuff_current(&our_out) - 1;
        start = fr_sbuff_start(&our_out);
 
        /*
         *      Truncate trailing zeros.  Don't walk past the start of the
         *      buffer - a bare "0" has no trailing zeros to strip.
         */
        while ((q > start) && (*q == '0')) *(q--) = '\0';
 
        /*
         *      If there's nothing after the decimal point,
         *      truncate the decimal point.  i.e. Don't print
         *      "5."
         */
        if (*q == '.') {
                *q = '\0';
        } else {
                q++;    /* to account for q-- above */
        }
 
        FR_SBUFF_SET_RETURN(out, q);
}
 
DIAG_OFF(format-nonliteral)
/** Copy a time string (local timezone) to an sbuff
 *
 * @note This function will attempt to extend the sbuff by double the length of
 *       the fmt string.  It is recommended to either pre-extend the sbuff before
 *       calling this function, or avoid using format specifiers that expand to
 *       character strings longer than 4 bytes.
 *
 * @param[in] out       Where to write the formatted time string.
 * @param[in] time      Internal server time to convert to wallclock
 *                      time and copy out as formatted string.
 * @param[in] fmt       Time format string.
 * @return
 *      - >0 the number of bytes written to the sbuff.
 *      - 0 if there's insufficient space in the sbuff.
 */
size_t fr_time_strftime_local(fr_sbuff_t *out, fr_time_t time, char const *fmt)
{
        struct tm       tm;
        time_t          utime = fr_time_to_sec(time);
        size_t          len;
 
        localtime_r(&utime, &tm);
 
        len = strftime(fr_sbuff_current(out), fr_sbuff_extend_lowat(NULL, out, strlen(fmt) * 2), fmt, &tm);
        if (len == 0) return 0;
 
        return fr_sbuff_advance(out, len);
}
 
/** Copy a time string (UTC) to an sbuff
 *
 * @note This function will attempt to extend the sbuff by double the length of
 *       the fmt string.  It is recommended to either pre-extend the sbuff before
 *       calling this function, or avoid using format specifiers that expand to
 *       character strings longer than 4 bytes.
 *
 * @param[in] out       Where to write the formatted time string.
 * @param[in] time      Internal server time to convert to wallclock
 *                      time and copy out as formatted string.
 * @param[in] fmt       Time format string.
 * @return
 *      - >0 the number of bytes written to the sbuff.
 *      - 0 if there's insufficient space in the sbuff.
 */
size_t fr_time_strftime_utc(fr_sbuff_t *out, fr_time_t time, char const *fmt)
{
        struct tm       tm;
        time_t          utime = fr_time_to_sec(time);
        size_t          len;
 
        gmtime_r(&utime, &tm);
 
        len = strftime(fr_sbuff_current(out), fr_sbuff_extend_lowat(NULL, out, strlen(fmt) * 2), fmt, &tm);
        if (len == 0) return 0;
 
        return fr_sbuff_advance(out, len);
}
DIAG_ON(format-nonliteral)
 
void fr_time_elapsed_update(fr_time_elapsed_t *elapsed, fr_time_t start, fr_time_t end)
{
        fr_time_delta_t delay;
 
        if (fr_time_gteq(start, end)) {
                delay = fr_time_delta_wrap(0);
        } else {
                delay = fr_time_sub(end, start);
        }
 
        if (fr_time_delta_lt(delay, fr_time_delta_wrap(1000))) { /* microseconds */
                elapsed->array[0]++;
 
        } else if (fr_time_delta_lt(delay, fr_time_delta_wrap(10000))) {
                elapsed->array[1]++;
 
        } else if (fr_time_delta_lt(delay, fr_time_delta_wrap(100000))) {
                elapsed->array[2]++;
 
        } else if (fr_time_delta_lt(delay, fr_time_delta_wrap(1000000))) { /* milliseconds */
                elapsed->array[3]++;
 
        } else if (fr_time_delta_lt(delay, fr_time_delta_wrap(10000000))) {
                elapsed->array[4]++;
 
        } else if (fr_time_delta_lt(delay, fr_time_delta_wrap(100000000))) {
                elapsed->array[5]++;
 
        } else if (fr_time_delta_lt(delay, fr_time_delta_wrap(1000000000))) { /* seconds */
                elapsed->array[6]++;
 
        } else {                /* tens of seconds or more */
                elapsed->array[7]++;
 
        }
}
 
static const char *names[8] = {
        "1us", "10us", "100us",
        "1ms", "10ms", "100ms",
        "1s", "10s"
};
 
static char const *tab_string = "\t\t\t\t\t\t\t\t\t\t\t\t\t\t";
 
void fr_time_elapsed_fprint(FILE *fp, fr_time_elapsed_t const *elapsed, char const *prefix, int tab_offset)
{
        int i;
        size_t prefix_len;
 
        if (!prefix) prefix = "elapsed";
 
        prefix_len = strlen(prefix);
 
        for (i = 0; i < 8; i++) {
                size_t len;
 
                if (!elapsed->array[i]) continue;
 
                len = prefix_len + 1 + strlen(names[i]);
 
                if (len >= (size_t) (tab_offset * 8)) {
                        fprintf(fp, "%s.%s %" PRIu64 "\n",
                                prefix, names[i], elapsed->array[i]);
 
                } else {
                        int tabs;
 
                        tabs = ((tab_offset * 8) - len);
                        if ((tabs & 0x07) != 0) tabs += 7;
                        tabs >>= 3;
 
                        fprintf(fp, "%s.%s%.*s%" PRIu64 "\n",
                                prefix, names[i], tabs, tab_string, elapsed->array[i]);
                }
        }
}
 
/*
 *      Based on https://blog.reverberate.org/2020/05/12/optimizing-date-algorithms.html
 */
fr_unix_time_t fr_unix_time_from_tm(struct tm *tm)
{
        static const uint16_t month_yday[12] = {0,   31,  59,  90,  120, 151,
                                                181, 212, 243, 273, 304, 334};
 
        uint32_t year_adj;
        uint32_t febs;
        uint32_t leap_days;
        uint32_t days;
 
        /* Prevent crash if tm->tm_mon is invalid - seen in clusterfuzz */
        if (unlikely(tm->tm_mon >= (__typeof__(tm->tm_mon))NUM_ELEMENTS(month_yday))) return fr_unix_time_min();
 
        if (unlikely(tm->tm_year > 10000)) return fr_unix_time_min();
 
        year_adj = tm->tm_year + 4800 + 1900;  /* Ensure positive year, multiple of 400. */
        febs = year_adj - (tm->tm_mon < 2 ? 1 : 0);  /* Februaries since base. tm_mon is 0 - 11 */
        leap_days = 1 + (febs / 4) - (febs / 100) + (febs / 400);
 
        days = 365 * year_adj + leap_days + month_yday[tm->tm_mon] + tm->tm_mday - 1;
 
#define CHECK(_x, _max) if ((tm->tm_ ## _x < 0) || (tm->tm_ ## _x >= _max)) tm->tm_ ## _x = _max - 1
 
        CHECK(sec, 60);
        CHECK(min, 60);
        CHECK(hour, 24);
        CHECK(mday, 32);
        CHECK(mon, 12);
        CHECK(year, 3000);
        CHECK(wday, 7);
        CHECK(mon, 12);
        CHECK(yday, 366);
        /* don't check gmtoff, it can be negative */
 
        /*
         *      2472692 adjusts the days for Unix epoch.  It is calculated as
         *      (365.2425 * (4800 + 1970))
         *
         *      We REMOVE the time zone offset in order to get internal unix times in UTC.
         */
        return fr_unix_time_from_sec((((days - 2472692) * 86400) + (tm->tm_hour * 3600) +
                                     (tm->tm_min * 60) + tm->tm_sec) - tm->tm_gmtoff);
}
 
/** Scale an input time to NSEC, clamping it at max / min.
 *
 * @param t     input time / time delta
 * @param hint  time resolution hint
 * @return
 *      - INT64_MIN on underflow
 *      - 0 on invalid hint
 *      - INT64_MAX on overflow
 *      - otherwise a valid number, multiplied by the relevant scale,
 *        so that the result is in nanoseconds.
 */
int64_t fr_time_scale(int64_t t, fr_time_res_t hint)
{
        int64_t scale;
 
        switch (hint) {
        case FR_TIME_RES_SEC:
                scale = NSEC;
                break;
 
        case FR_TIME_RES_MSEC:
                scale = 1000000;
                break;
 
        case FR_TIME_RES_USEC:
                scale = 1000;
                break;
 
        case FR_TIME_RES_NSEC:
                return t;
 
        default:
                return 0;
        }
 
        if (t < 0) {
                if (t < (INT64_MIN / scale)) {
                        return INT64_MIN;
                }
        } else if (t > 0) {
                if (t > (INT64_MAX / scale)) {
                        return INT64_MAX;
                }
        }
 
        return t * scale;
}
 
 
/*
 *      Sort of strtok/strsep function.
 */
static char *mystrtok(char **ptr, char const *sep)
{
        char    *res;
 
        if (**ptr == '\0') return NULL;
 
        while (**ptr && strchr(sep, **ptr)) (*ptr)++;
 
        if (**ptr == '\0') return NULL;
 
        res = *ptr;
        while (**ptr && strchr(sep, **ptr) == NULL) (*ptr)++;
 
        if (**ptr != '\0') *(*ptr)++ = '\0';
 
        return res;
}
 
/*
 *      Helper function to get a 2-digit date. With a maximum value,
 *      and a terminating character.
 */
static int get_part(char **str, int *date, int min, int max, char term, char const *name)
{
        char *p = *str;
 
        if (!isdigit((uint8_t) *p) || !isdigit((uint8_t) p[1])) return -1;
        *date = (p[0] - '0') * 10  + (p[1] - '0');
 
        if (*date < min) {
                fr_strerror_printf("Invalid %s (too small)", name);
                return -1;
        }
 
        if (*date > max) {
                fr_strerror_printf("Invalid %s (too large)", name);
                return -1;
        }
 
        p += 2;
        if (!term) {
                *str = p;
                return 0;
        }
 
        if (*p != term) {
                fr_strerror_printf("Expected '%c' after %s, got '%c'",
                                   term, name, *p);
                return -1;
        }
        p++;
 
        *str = p;
        return 0;
}
 
static char const *months[] = {
        "jan", "feb", "mar", "apr", "may", "jun",
        "jul", "aug", "sep", "oct", "nov", "dec" };
 
 
/** Convert string in various formats to a fr_unix_time_t
 *
 * @param date_str input date string.
 * @param date time_t to write result to.
 * @param[in] hint      scale for the parsing.  Default is "seconds"
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int fr_unix_time_from_str(fr_unix_time_t *date, char const *date_str, fr_time_res_t hint)
{
        int             i;
        int64_t         tmp;
        struct tm       *tm, s_tm;
        char            buf[64];
        char            *p;
        char            *f[4];
        char            *tail = NULL;
        unsigned long   l;
        fr_time_delta_t gmt_delta = fr_time_delta_wrap(0);
 
        if (!*date_str) {
                fr_strerror_const("Empty input is invalid");
                return -1;
        }
 
        /*
         *      Test for unix timestamp, which is just a number and
         *      nothing else.
         */
        tmp = strtoul(date_str, &tail, 10);
        if (*tail == '\0') {
                *date = fr_unix_time_from_nsec(fr_time_scale(tmp, hint));
                return 0;
        }
 
        tm = &s_tm;
        memset(tm, 0, sizeof(*tm));
        tm->tm_isdst = -1;      /* don't know, and don't care about DST */
 
        /*
         *      Check for RFC 3339 dates.  Note that we only support
         *      dates in a ~1000 year period.  If the server is being
         *      used after 3000AD, someone can patch it then.
         *
         *      %Y-%m-%dT%H:%M:%S
         *      [.%d] sub-seconds
         *      Z | (+/-)%H:%M time zone offset
         *
         */
        if ((tmp > 1900) && (tmp < 3000) && *tail == '-') {
                unsigned long subseconds;
                int tz, tz_hour, tz_min;
 
                p = tail + 1;
                s_tm.tm_year = tmp - 1900; /* 'struct tm' starts years in 1900 */
 
                if (get_part(&p, &s_tm.tm_mon, 1, 12, '-', "month") < 0) return -1;
                s_tm.tm_mon--;  /* ISO is 1..12, where 'struct tm' is 0..11 */
 
                if (get_part(&p, &s_tm.tm_mday, 1, 31, 'T', "day") < 0) return -1;
                if (get_part(&p, &s_tm.tm_hour, 0, 23, ':', "hour") < 0) return -1;
                if (get_part(&p, &s_tm.tm_min, 0, 59, ':', "minute") < 0) return -1;
                if (get_part(&p, &s_tm.tm_sec, 0, 60, '\0', "seconds") < 0) return -1;
 
                if (*p == '.') {
                        p++;
                        subseconds = strtoul(p, &tail, 10);
                        if (subseconds > NSEC) {
                                fr_strerror_const("Invalid nanosecond specifier");
                                return -1;
                        }
 
                        /*
                         *      Scale subseconds to nanoseconds by how
                         *      many digits were parsed/
                         */
                        if ((tail - p) < 9) {
                                for (i = 0; i < 9 - (tail -p); i++) {
                                        subseconds *= 10;
                                }
                        }
 
                        p = tail;
                } else {
                        subseconds = 0;
                }
 
                /*
                 *      Time zone is GMT.  Leave well enough
                 *      alone.
                 */
                if (*p == 'Z') {
                        if (p[1] != '\0') {
                                fr_strerror_printf("Unexpected text '%c' after time zone", p[1]);
                                return -1;
                        }
                        tz = 0;
                        goto done;
                }
 
                if ((*p != '+') && (*p != '-')) {
                        fr_strerror_printf("Invalid time zone specifier '%c'", *p);
                        return -1;
                }
                tail = p;       /* remember sign for later */
                p++;
 
                if (get_part(&p, &tz_hour, 0, 23, ':', "hour in time zone") < 0) return -1;
                if (get_part(&p, &tz_min, 0, 59, '\0', "minute in time zone") < 0) return -1;
 
                if (*p != '\0') {
                        fr_strerror_printf("Unexpected text '%c' after time zone", *p);
                        return -1;
                }
 
                /*
                 *      We set the time zone, but the timegm()
                 *      function ignores it.  Note also that mktime()
                 *      ignores it too, and treats the time zone as
                 *      local.
                 *
                 *      We can't store this value in s_tm.gtmoff,
                 *      because the timegm() function helpfully zeros
                 *      it out.
                 *
                 *      So insyead of using stupid C library
                 *      functions, we just roll our own.
                 */
                tz = tz_hour * 3600 + tz_min * 60;
                if (*tail == '-') tz *= -1;
 
        done:
                /*
                 *      Set the gmt offset correctly, as
                 *      fr_unix_time_from_tm() will do the correction
                 *      to remove the time zone.
                 */
                tm->tm_gmtoff = tz;
                *date = fr_unix_time_add(fr_unix_time_from_tm(tm), fr_time_delta_wrap(subseconds));
                return 0;
        }
 
        /*
         *      Try to parse dates via locale-specific names,
         *      using the same format string as strftime().
         *
         *      If that fails, then we fall back to our parsing
         *      routine, which is much more forgiving.
         */
 
#ifdef __APPLE__
        /*
         *      OSX "man strptime" says it only accepts the local time zone, and GMT.
         *
         *      However, when printing dates via strftime(), it prints
         *      "UTC" instead of "GMT".  So... we have to fix it up
         *      for stupid nonsense.
         */
        {
                char const *tz = strstr(date_str, "UTC");
                if (tz) {
                        char *my_str;
 
                        my_str = talloc_strdup(NULL, date_str);
                        if (my_str) {
                                p = my_str + (tz - date_str);
                                memcpy(p, "GMT", 3);
 
                                p = strptime(my_str, "%b %e %Y %H:%M:%S %Z", tm);
                                if (p && (*p == '\0')) {
                                        talloc_free(my_str);
                                        *date = fr_unix_time_from_tm(tm);
                                        return 0;
                                }
                                talloc_free(my_str);
                        }
                }
        }
#endif
 
        p = strptime(date_str, "%b %e %Y %H:%M:%S %Z", tm);
        if (p && (*p == '\0')) {
                *date = fr_unix_time_from_tm(tm);
                return 0;
        }
 
        strlcpy(buf, date_str, sizeof(buf));
 
        p = buf;
        f[0] = mystrtok(&p, " \t");
        f[1] = mystrtok(&p, " \t");
        f[2] = mystrtok(&p, " \t");
        f[3] = mystrtok(&p, " \t"); /* may, or may not, be present */
        if (!f[0] || !f[1] || !f[2]) {
                fr_strerror_const("Too few fields");
                return -1;
        }
 
        /*
         *      Try to parse the time zone.  If it's GMT / UTC or a
         *      local time zone we're OK.
         *
         *      Otherwise, ignore errors and assume GMT.
         */
        if (*p != '\0') {
                fr_skip_whitespace(p);
                (void) fr_time_delta_from_time_zone(p, &gmt_delta);
        }
 
        /*
         *      The time has a colon, where nothing else does.
         *      So if we find it, bubble it to the back of the list.
         */
        if (f[3]) {
                for (i = 0; i < 3; i++) {
                        if (strchr(f[i], ':')) {
                                p = f[3];
                                f[3] = f[i];
                                f[i] = p;
                                break;
                        }
                }
        }
 
        /*
         *  The month is text, which allows us to find it easily.
         */
        tm->tm_mon = 12;
        for (i = 0; i < 3; i++) {
                if (isalpha((uint8_t) *f[i])) {
                        int j;
 
                        /*
                         *  Bubble the month to the front of the list
                         */
                        p = f[0];
                        f[0] = f[i];
                        f[i] = p;
 
                        for (j = 0; j < 12; j++) {
                                if (strncasecmp(months[j], f[0], 3) == 0) {
                                        tm->tm_mon = j;
                                        break;
                                }
                        }
                }
        }
 
        /* month not found? */
        if (tm->tm_mon == 12) {
                fr_strerror_const("No month found");
                return -1;
        }
 
        /*
         *      Check for invalid text, or invalid trailing text.
         */
        l = strtoul(f[1], &tail, 10);
        if ((l == ULONG_MAX) || (*tail != '\0')) {
                fr_strerror_const("Invalid year string");
                return -1;
        }
        tm->tm_year = l;
 
        l = strtoul(f[2], &tail, 10);
        if ((l == ULONG_MAX) || (*tail != '\0')) {
                fr_strerror_const("Invalid day of month string");
                return -1;
        }
        tm->tm_mday = l;
 
        if (tm->tm_year >= 1900) {
                tm->tm_year -= 1900;
 
        } else {
                /*
                 *  We can't use 2-digit years any more, they make it
                 *  impossible to tell what's the day, and what's the year.
                 */
                if (tm->tm_mday < 1900) {
                        fr_strerror_const("Invalid year < 1900");
                        return -1;
                }
 
                /*
                 *  Swap the year and the day.
                 */
                i = tm->tm_year;
                tm->tm_year = tm->tm_mday - 1900;
                tm->tm_mday = i;
        }
 
        if (tm->tm_year > 10000) {
                fr_strerror_const("Invalid value for year");
                return -1;
        }
 
        /*
         *      If the day is out of range, die.
         */
        if ((tm->tm_mday < 1) || (tm->tm_mday > 31)) {
                fr_strerror_const("Invalid value for day of month");
                return -1;
        }
 
        /*
         *      There may be %H:%M:%S.  Parse it in a hacky way.
         */
        if (f[3]) {
                f[0] = f[3];    /* HH */
                f[1] = strchr(f[0], ':'); /* find : separator */
                if (!f[1]) {
                        fr_strerror_const("No ':' after hour");
                        return -1;
                }
 
                *(f[1]++) = '\0'; /* nuke it, and point to MM:SS */
 
                f[2] = strchr(f[1], ':'); /* find : separator */
                if (f[2]) {
                        *(f[2]++) = '\0';       /* nuke it, and point to SS */
                        tm->tm_sec = atoi(f[2]);
                }                       /* else leave it as zero */
 
                tm->tm_hour = atoi(f[0]);
                tm->tm_min = atoi(f[1]);
        }
 
        *date = fr_unix_time_add(fr_unix_time_from_tm(tm), gmt_delta);
 
        return 0;
}
 
/** Convert unix time to string
 *
 * @param[out] out      Where to write the string.
 * @param[in] time      to convert.
 * @param[in] res       What base resolution to print the time as.
 * @param[in] utc       If true, use UTC, otherwise local time.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
fr_slen_t fr_unix_time_to_str(fr_sbuff_t *out, fr_unix_time_t time, fr_time_res_t res, bool utc)
{
        fr_sbuff_t      our_out = FR_SBUFF(out);
        int64_t         subseconds;
        time_t          t;
        struct tm       s_tm;
        size_t          len;
        char            buf[128];
 
        t = fr_unix_time_to_sec(time);
        if (utc) {
                (void) gmtime_r(&t, &s_tm);
        } else {
                (void) localtime_r(&t, &s_tm);
        }
 
        len = strftime(buf, sizeof(buf), "%Y-%m-%dT%H:%M:%S", &s_tm);
        FR_SBUFF_IN_BSTRNCPY_RETURN(&our_out, buf, len);
        subseconds = fr_unix_time_unwrap(time) % NSEC;
 
        /*
         *      Use RFC 3339 format, which is a
         *      profile of ISO8601.  The ISO standard
         *      allows a much more complex set of date
         *      formats.  The RFC is much stricter.
         */
        switch (res) {
        case FR_TIME_RES_INVALID:
        case FR_TIME_RES_YEAR:
        case FR_TIME_RES_MONTH:
        case FR_TIME_RES_WEEK:
        case FR_TIME_RES_DAY:
        case FR_TIME_RES_HOUR:
        case FR_TIME_RES_MIN:
        case FR_TIME_RES_SEC:
                break;
 
        case FR_TIME_RES_CSEC:
                subseconds /= (NSEC / CSEC);
                FR_SBUFF_IN_SPRINTF_RETURN(&our_out, ".%02" PRIi64, subseconds);
                break;
 
        case FR_TIME_RES_MSEC:
                subseconds /= (NSEC / MSEC);
                FR_SBUFF_IN_SPRINTF_RETURN(&our_out, ".%03" PRIi64, subseconds);
                break;
 
        case FR_TIME_RES_USEC:
                subseconds /= (NSEC / USEC);
                FR_SBUFF_IN_SPRINTF_RETURN(&our_out, ".%06" PRIi64, subseconds);
                break;
 
        case FR_TIME_RES_NSEC:
                FR_SBUFF_IN_SPRINTF_RETURN(&our_out, ".%09" PRIi64, subseconds);
                break;
        }
 
        /*
         *      And time zone.
         */
        if (s_tm.tm_gmtoff != 0) {
                int hours, minutes;
 
                hours = s_tm.tm_gmtoff / 3600;
                minutes = (s_tm.tm_gmtoff / 60) % 60;
 
                FR_SBUFF_IN_SPRINTF_RETURN(&our_out, "%+03d:%02u", hours, minutes);
        } else {
                FR_SBUFF_IN_CHAR_RETURN(&our_out, 'Z');
        }
 
        FR_SBUFF_SET_RETURN(out, &our_out);
}
 
/** Get the offset to gmt.
 *
 */
fr_time_delta_t fr_time_gmtoff(void)
{
        return fr_time_delta_wrap(gmtoff[isdst]);
}
 
/** Whether or not we're daylight savings.
 *
 */
bool fr_time_is_dst(void)
{
        return isdst;
}