diff options
Diffstat (limited to 'third_party/abseil-cpp/absl/time/internal/cctz/src/time_zone_libc.cc')
| -rw-r--r-- | third_party/abseil-cpp/absl/time/internal/cctz/src/time_zone_libc.cc | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/third_party/abseil-cpp/absl/time/internal/cctz/src/time_zone_libc.cc b/third_party/abseil-cpp/absl/time/internal/cctz/src/time_zone_libc.cc new file mode 100644 index 0000000000..47cf84c663 --- /dev/null +++ b/third_party/abseil-cpp/absl/time/internal/cctz/src/time_zone_libc.cc @@ -0,0 +1,308 @@ +// Copyright 2016 Google Inc. All Rights Reserved. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#if defined(_WIN32) || defined(_WIN64) +#define _CRT_SECURE_NO_WARNINGS 1 +#endif + +#include "time_zone_libc.h" + +#include <chrono> +#include <ctime> +#include <limits> +#include <utility> + +#include "absl/base/config.h" +#include "absl/time/internal/cctz/include/cctz/civil_time.h" +#include "absl/time/internal/cctz/include/cctz/time_zone.h" + +namespace absl { +ABSL_NAMESPACE_BEGIN +namespace time_internal { +namespace cctz { + +namespace { + +#if defined(_WIN32) || defined(_WIN64) +// Uses the globals: '_timezone', '_dstbias' and '_tzname'. +auto tm_gmtoff(const std::tm& tm) -> decltype(_timezone + _dstbias) { + const bool is_dst = tm.tm_isdst > 0; + return _timezone + (is_dst ? _dstbias : 0); +} +auto tm_zone(const std::tm& tm) -> decltype(_tzname[0]) { + const bool is_dst = tm.tm_isdst > 0; + return _tzname[is_dst]; +} +#elif defined(__sun) +// Uses the globals: 'timezone', 'altzone' and 'tzname'. +auto tm_gmtoff(const std::tm& tm) -> decltype(timezone) { + const bool is_dst = tm.tm_isdst > 0; + return is_dst ? altzone : timezone; +} +auto tm_zone(const std::tm& tm) -> decltype(tzname[0]) { + const bool is_dst = tm.tm_isdst > 0; + return tzname[is_dst]; +} +#elif defined(__native_client__) || defined(__myriad2__) || \ + defined(__EMSCRIPTEN__) +// Uses the globals: 'timezone' and 'tzname'. +auto tm_gmtoff(const std::tm& tm) -> decltype(_timezone + 0) { + const bool is_dst = tm.tm_isdst > 0; + return _timezone + (is_dst ? 60 * 60 : 0); +} +auto tm_zone(const std::tm& tm) -> decltype(tzname[0]) { + const bool is_dst = tm.tm_isdst > 0; + return tzname[is_dst]; +} +#else +// Adapt to different spellings of the struct std::tm extension fields. +#if defined(tm_gmtoff) +auto tm_gmtoff(const std::tm& tm) -> decltype(tm.tm_gmtoff) { + return tm.tm_gmtoff; +} +#elif defined(__tm_gmtoff) +auto tm_gmtoff(const std::tm& tm) -> decltype(tm.__tm_gmtoff) { + return tm.__tm_gmtoff; +} +#else +template <typename T> +auto tm_gmtoff(const T& tm) -> decltype(tm.tm_gmtoff) { + return tm.tm_gmtoff; +} +template <typename T> +auto tm_gmtoff(const T& tm) -> decltype(tm.__tm_gmtoff) { + return tm.__tm_gmtoff; +} +#endif // tm_gmtoff +#if defined(tm_zone) +auto tm_zone(const std::tm& tm) -> decltype(tm.tm_zone) { return tm.tm_zone; } +#elif defined(__tm_zone) +auto tm_zone(const std::tm& tm) -> decltype(tm.__tm_zone) { + return tm.__tm_zone; +} +#else +template <typename T> +auto tm_zone(const T& tm) -> decltype(tm.tm_zone) { + return tm.tm_zone; +} +template <typename T> +auto tm_zone(const T& tm) -> decltype(tm.__tm_zone) { + return tm.__tm_zone; +} +#endif // tm_zone +#endif + +inline std::tm* gm_time(const std::time_t* timep, std::tm* result) { +#if defined(_WIN32) || defined(_WIN64) + return gmtime_s(result, timep) ? nullptr : result; +#else + return gmtime_r(timep, result); +#endif +} + +inline std::tm* local_time(const std::time_t* timep, std::tm* result) { +#if defined(_WIN32) || defined(_WIN64) + return localtime_s(result, timep) ? nullptr : result; +#else + return localtime_r(timep, result); +#endif +} + +// Converts a civil second and "dst" flag into a time_t and UTC offset. +// Returns false if time_t cannot represent the requested civil second. +// Caller must have already checked that cs.year() will fit into a tm_year. +bool make_time(const civil_second& cs, int is_dst, std::time_t* t, int* off) { + std::tm tm; + tm.tm_year = static_cast<int>(cs.year() - year_t{1900}); + tm.tm_mon = cs.month() - 1; + tm.tm_mday = cs.day(); + tm.tm_hour = cs.hour(); + tm.tm_min = cs.minute(); + tm.tm_sec = cs.second(); + tm.tm_isdst = is_dst; + *t = std::mktime(&tm); + if (*t == std::time_t{-1}) { + std::tm tm2; + const std::tm* tmp = local_time(t, &tm2); + if (tmp == nullptr || tmp->tm_year != tm.tm_year || + tmp->tm_mon != tm.tm_mon || tmp->tm_mday != tm.tm_mday || + tmp->tm_hour != tm.tm_hour || tmp->tm_min != tm.tm_min || + tmp->tm_sec != tm.tm_sec) { + // A true error (not just one second before the epoch). + return false; + } + } + *off = static_cast<int>(tm_gmtoff(tm)); + return true; +} + +// Find the least time_t in [lo:hi] where local time matches offset, given: +// (1) lo doesn't match, (2) hi does, and (3) there is only one transition. +std::time_t find_trans(std::time_t lo, std::time_t hi, int offset) { + std::tm tm; + while (lo + 1 != hi) { + const std::time_t mid = lo + (hi - lo) / 2; + if (std::tm* tmp = local_time(&mid, &tm)) { + if (tm_gmtoff(*tmp) == offset) { + hi = mid; + } else { + lo = mid; + } + } else { + // If std::tm cannot hold some result we resort to a linear search, + // ignoring all failed conversions. Slow, but never really happens. + while (++lo != hi) { + if (std::tm* tmp = local_time(&lo, &tm)) { + if (tm_gmtoff(*tmp) == offset) break; + } + } + return lo; + } + } + return hi; +} + +} // namespace + +TimeZoneLibC::TimeZoneLibC(const std::string& name) + : local_(name == "localtime") {} + +time_zone::absolute_lookup TimeZoneLibC::BreakTime( + const time_point<seconds>& tp) const { + time_zone::absolute_lookup al; + al.offset = 0; + al.is_dst = false; + al.abbr = "-00"; + + const std::int_fast64_t s = ToUnixSeconds(tp); + + // If std::time_t cannot hold the input we saturate the output. + if (s < std::numeric_limits<std::time_t>::min()) { + al.cs = civil_second::min(); + return al; + } + if (s > std::numeric_limits<std::time_t>::max()) { + al.cs = civil_second::max(); + return al; + } + + const std::time_t t = static_cast<std::time_t>(s); + std::tm tm; + std::tm* tmp = local_ ? local_time(&t, &tm) : gm_time(&t, &tm); + + // If std::tm cannot hold the result we saturate the output. + if (tmp == nullptr) { + al.cs = (s < 0) ? civil_second::min() : civil_second::max(); + return al; + } + + const year_t year = tmp->tm_year + year_t{1900}; + al.cs = civil_second(year, tmp->tm_mon + 1, tmp->tm_mday, tmp->tm_hour, + tmp->tm_min, tmp->tm_sec); + al.offset = static_cast<int>(tm_gmtoff(*tmp)); + al.abbr = local_ ? tm_zone(*tmp) : "UTC"; // as expected by cctz + al.is_dst = tmp->tm_isdst > 0; + return al; +} + +time_zone::civil_lookup TimeZoneLibC::MakeTime(const civil_second& cs) const { + if (!local_) { + // If time_point<seconds> cannot hold the result we saturate. + static const civil_second min_tp_cs = + civil_second() + ToUnixSeconds(time_point<seconds>::min()); + static const civil_second max_tp_cs = + civil_second() + ToUnixSeconds(time_point<seconds>::max()); + const time_point<seconds> tp = + (cs < min_tp_cs) + ? time_point<seconds>::min() + : (cs > max_tp_cs) ? time_point<seconds>::max() + : FromUnixSeconds(cs - civil_second()); + return {time_zone::civil_lookup::UNIQUE, tp, tp, tp}; + } + + // If tm_year cannot hold the requested year we saturate the result. + if (cs.year() < 0) { + if (cs.year() < std::numeric_limits<int>::min() + year_t{1900}) { + const time_point<seconds> tp = time_point<seconds>::min(); + return {time_zone::civil_lookup::UNIQUE, tp, tp, tp}; + } + } else { + if (cs.year() - year_t{1900} > std::numeric_limits<int>::max()) { + const time_point<seconds> tp = time_point<seconds>::max(); + return {time_zone::civil_lookup::UNIQUE, tp, tp, tp}; + } + } + + // We probe with "is_dst" values of 0 and 1 to try to distinguish unique + // civil seconds from skipped or repeated ones. This is not always possible + // however, as the "dst" flag does not change over some offset transitions. + // We are also subject to the vagaries of mktime() implementations. + std::time_t t0, t1; + int offset0, offset1; + if (make_time(cs, 0, &t0, &offset0) && make_time(cs, 1, &t1, &offset1)) { + if (t0 == t1) { + // The civil time was singular (pre == trans == post). + const time_point<seconds> tp = FromUnixSeconds(t0); + return {time_zone::civil_lookup::UNIQUE, tp, tp, tp}; + } + + if (t0 > t1) { + std::swap(t0, t1); + std::swap(offset0, offset1); + } + const std::time_t tt = find_trans(t0, t1, offset1); + const time_point<seconds> trans = FromUnixSeconds(tt); + + if (offset0 < offset1) { + // The civil time did not exist (pre >= trans > post). + const time_point<seconds> pre = FromUnixSeconds(t1); + const time_point<seconds> post = FromUnixSeconds(t0); + return {time_zone::civil_lookup::SKIPPED, pre, trans, post}; + } + + // The civil time was ambiguous (pre < trans <= post). + const time_point<seconds> pre = FromUnixSeconds(t0); + const time_point<seconds> post = FromUnixSeconds(t1); + return {time_zone::civil_lookup::REPEATED, pre, trans, post}; + } + + // make_time() failed somehow so we saturate the result. + const time_point<seconds> tp = (cs < civil_second()) + ? time_point<seconds>::min() + : time_point<seconds>::max(); + return {time_zone::civil_lookup::UNIQUE, tp, tp, tp}; +} + +bool TimeZoneLibC::NextTransition(const time_point<seconds>&, + time_zone::civil_transition*) const { + return false; +} + +bool TimeZoneLibC::PrevTransition(const time_point<seconds>&, + time_zone::civil_transition*) const { + return false; +} + +std::string TimeZoneLibC::Version() const { + return std::string(); // unknown +} + +std::string TimeZoneLibC::Description() const { + return local_ ? "localtime" : "UTC"; +} + +} // namespace cctz +} // namespace time_internal +ABSL_NAMESPACE_END +} // namespace absl |