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https://github.com/zephyrproject-rtos/zephyr
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55ace13c32
The algorithm for converting broken-down civil time to seconds in the POSIX epoch time scale would produce undefined behavior on a toolchain that uses a 32-bit time_t in cases where the referenced time could not be represented exactly. However, there are use cases in Zephyr for civil time conversions outside the 32-bit representable range of 1901-12-13T20:45:52Z through 2038-01-19T03:14:07Z inclusive. Add new API that specifically returns a 64-bit signed seconds count, and revise the existing API to detect out-of-range values and convert them to a diagnosible error. Closes #18465 Signed-off-by: Peter A. Bigot <pab@pabigot.com>
71 lines
1.7 KiB
C
71 lines
1.7 KiB
C
/*
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* Copyright (c) 2019 Peter Bigot Consulting, LLC
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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/*
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* The time_days_from_civil function is derived directly from public
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* domain content written by Howard Hinnant and available at:
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* http://howardhinnant.github.io/date_algorithms.html#days_from_civil
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*/
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#include <zephyr/types.h>
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#include <errno.h>
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#include <sys/timeutil.h>
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/** Convert a civil (proleptic Gregorian) date to days relative to
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* 1970-01-01.
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*
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* @param y the calendar year
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* @param m the calendar month, in the range [1, 12]
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* @param d the day of the month, in the range [1, last_day_of_month(y, m)]
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*
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* @return the signed number of days between the specified day and
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* 1970-01-01
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*
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* @see http://howardhinnant.github.io/date_algorithms.html#days_from_civil
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*/
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static s64_t time_days_from_civil(s64_t y,
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unsigned int m,
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unsigned int d)
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{
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y -= m <= 2;
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s64_t era = (y >= 0 ? y : y - 399) / 400;
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unsigned int yoe = y - era * 400;
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unsigned int doy = (153U * (m + (m > 2 ? -3 : 9)) + 2U) / 5U + d;
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unsigned int doe = yoe * 365U + yoe / 4U - yoe / 100U + doy;
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return era * 146097 + (time_t)doe - 719468;
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}
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s64_t timeutil_timegm64(const struct tm *tm)
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{
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s64_t y = 1900 + (s64_t)tm->tm_year;
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unsigned int m = tm->tm_mon + 1;
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unsigned int d = tm->tm_mday - 1;
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s64_t ndays = time_days_from_civil(y, m, d);
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s64_t time = tm->tm_sec;
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time += 60LL * (tm->tm_min + 60LL * tm->tm_hour);
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time += 86400LL * ndays;
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return time;
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}
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time_t timeutil_timegm(const struct tm *tm)
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{
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s64_t time = timeutil_timegm64(tm);
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time_t rv = (time_t)time;
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errno = 0;
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if ((sizeof(rv) == sizeof(s32_t))
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&& ((time < (s64_t)INT32_MIN)
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|| (time > (s64_t)INT32_MAX))) {
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errno = ERANGE;
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rv = -1;
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}
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return rv;
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}
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