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>
59 lines
1.5 KiB
C
59 lines
1.5 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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* @file
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* @brief Utilities supporting operation on time data structures.
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*
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* POSIX defines gmtime() to convert from time_t to struct tm, but all
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* inverse transformations are non-standard or require access to time
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* zone information. timeutil_timegm() implements the functionality
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* of the GNU extension timegm() function, but changes the error value
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* as @c EOVERFLOW is not a standard C error identifier.
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*
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* timeutil_timegm64() is provided to support full precision
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* conversion on platforms where @c time_t is limited to 32 bits.
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*/
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#ifndef ZEPHYR_INCLUDE_SYS_TIMEUTIL_H_
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#define ZEPHYR_INCLUDE_SYS_TIMEUTIL_H_
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#include <time.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Convert broken-down time to a POSIX epoch offset in seconds.
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*
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* @param tm pointer to broken down time.
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*
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* @return the corresponding time in the POSIX epoch time scale.
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*
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* @see http://man7.org/linux/man-pages/man3/timegm.3.html
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*/
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s64_t timeutil_timegm64(const struct tm *tm);
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/**
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* @brief Convert broken-down time to a POSIX epoch offset in seconds.
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*
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* @param tm pointer to broken down time.
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*
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* @return the corresponding time in the POSIX epoch time scale. If
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* the time cannot be represented then @c (time_t)-1 is returned and
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* @c errno is set to @c ERANGE`.
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*
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* @see http://man7.org/linux/man-pages/man3/timegm.3.html
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*/
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time_t timeutil_timegm(const struct tm *tm);
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#ifdef __cplusplus
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}
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#endif
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#endif /* ZEPHYR_INCLUDE_SYS_TIMEUTIL_H_ */
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