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105 lines
3.9 KiB
C++
105 lines
3.9 KiB
C++
// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
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// SPDX-License-Identifier: GPL-2.0-or-later
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#include <chrono>
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#include <exception>
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#include <iomanip>
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#include <map>
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#include <sstream>
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#include <stdexcept>
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#include <fmt/chrono.h>
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#include <fmt/core.h>
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#include "common/logging/log.h"
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#include "common/time_zone.h"
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namespace Common::TimeZone {
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// Time zone strings
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constexpr std::array timezones{
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"GMT", "GMT", "CET", "CST6CDT", "Cuba", "EET", "Egypt", "Eire",
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"EST", "EST5EDT", "GB", "GB-Eire", "GMT", "GMT+0", "GMT-0", "GMT0",
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"Greenwich", "Hongkong", "HST", "Iceland", "Iran", "Israel", "Jamaica", "Japan",
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"Kwajalein", "Libya", "MET", "MST", "MST7MDT", "Navajo", "NZ", "NZ-CHAT",
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"Poland", "Portugal", "PRC", "PST8PDT", "ROC", "ROK", "Singapore", "Turkey",
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"UCT", "Universal", "UTC", "W-SU", "WET", "Zulu",
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};
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const std::array<const char*, 46>& GetTimeZoneStrings() {
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return timezones;
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}
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std::string GetDefaultTimeZone() {
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return "GMT";
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}
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// Results are not comparable to seconds since Epoch
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static std::time_t TmSpecToSeconds(const struct std::tm& spec) {
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const int year = spec.tm_year - 1; // Years up to now
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const int leap_years = year / 4 - year / 100;
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std::time_t cumulative = spec.tm_year;
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cumulative = cumulative * 365 + leap_years + spec.tm_yday; // Years to days
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cumulative = cumulative * 24 + spec.tm_hour; // Days to hours
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cumulative = cumulative * 60 + spec.tm_min; // Hours to minutes
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cumulative = cumulative * 60 + spec.tm_sec; // Minutes to seconds
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return cumulative;
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}
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std::chrono::seconds GetCurrentOffsetSeconds() {
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const std::time_t t{std::time(nullptr)};
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const std::tm local{*std::localtime(&t)};
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const std::tm gmt{*std::gmtime(&t)};
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// gmt_seconds is a different offset than time(nullptr)
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const auto gmt_seconds = TmSpecToSeconds(gmt);
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const auto local_seconds = TmSpecToSeconds(local);
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const auto seconds_offset = local_seconds - gmt_seconds;
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return std::chrono::seconds{seconds_offset};
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}
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// Key is [Hours * 100 + Minutes], multiplied by 100 if DST
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const static std::map<s64, const char*> off_timezones = {
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{530, "Asia/Calcutta"}, {930, "Australia/Darwin"}, {845, "Australia/Eucla"},
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{103000, "Australia/Adelaide"}, {1030, "Australia/Lord_Howe"}, {630, "Indian/Cocos"},
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{1245, "Pacific/Chatham"}, {134500, "Pacific/Chatham"}, {-330, "Canada/Newfoundland"},
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{-23000, "Canada/Newfoundland"}, {430, "Asia/Kabul"}, {330, "Asia/Tehran"},
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{43000, "Asia/Tehran"}, {545, "Asia/Kathmandu"}, {-930, "Asia/Marquesas"},
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};
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std::string FindSystemTimeZone() {
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const s64 seconds = static_cast<s64>(GetCurrentOffsetSeconds().count());
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const s64 minutes = seconds / 60;
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const s64 hours = minutes / 60;
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const s64 minutes_off = minutes - hours * 60;
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if (minutes_off != 0) {
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const auto the_time = std::time(nullptr);
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const struct std::tm& local = *std::localtime(&the_time);
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const bool is_dst = local.tm_isdst != 0;
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const s64 tz_index = (hours * 100 + minutes_off) * (is_dst ? 100 : 1);
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try {
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return off_timezones.at(tz_index);
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} catch (std::out_of_range&) {
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LOG_ERROR(Common, "Time zone {} not handled, defaulting to hour offset.", tz_index);
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}
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}
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// For some reason the Etc/GMT times are reversed. GMT+6 contains -21600 as its offset,
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// -6 hours instead of +6 hours, so these signs are purposefully reversed to fix it.
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std::string postfix{""};
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if (hours > 0) {
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postfix = fmt::format("-{:d}", std::abs(hours));
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} else if (hours < 0) {
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postfix = fmt::format("+{:d}", std::abs(hours));
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}
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return fmt::format("Etc/GMT{:s}", postfix);
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}
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} // namespace Common::TimeZone
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