time_zone_manager: Implement go_ahead/go_back

Too many absolute values were causing mirrored time zones to resolve
as the same.

src/common/settings.cpp

@@ -1,12 +1,16 @@
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#if __cpp_lib_chrono >= 201907L
+#include <chrono>
+#endif
 #include <string_view>
 
 #include "common/assert.h"
 #include "common/fs/path_util.h"
 #include "common/logging/log.h"
 #include "common/settings.h"
+#include "common/time_zone.h"
 
 namespace Settings {
 
@@ -14,18 +18,23 @@ Values values;
 static bool configuring_global = true;
 
 std::string GetTimeZoneString() {
-    static constexpr std::array timezones{
-        "auto",      "default",   "CET", "CST6CDT", "Cuba",    "EET",    "Egypt",     "Eire",
-        "EST",       "EST5EDT",   "GB",  "GB-Eire", "GMT",     "GMT+0",  "GMT-0",     "GMT0",
-        "Greenwich", "Hongkong",  "HST", "Iceland", "Iran",    "Israel", "Jamaica",   "Japan",
-        "Kwajalein", "Libya",     "MET", "MST",     "MST7MDT", "Navajo", "NZ",        "NZ-CHAT",
-        "Poland",    "Portugal",  "PRC", "PST8PDT", "ROC",     "ROK",    "Singapore", "Turkey",
-        "UCT",       "Universal", "UTC", "W-SU",    "WET",     "Zulu",
-    };
-
     const auto time_zone_index = static_cast<std::size_t>(values.time_zone_index.GetValue());
-    ASSERT(time_zone_index < timezones.size());
-    return timezones[time_zone_index];
+    ASSERT(time_zone_index < Common::TimeZone::GetTimeZoneStrings().size());
+
+    std::string location_name;
+    if (time_zone_index == 0) { // Auto
+#if __cpp_lib_chrono >= 201907L
+        const struct std::chrono::tzdb& time_zone_data = std::chrono::get_tzdb();
+        const std::chrono::time_zone* current_zone = time_zone_data.current_zone();
+        std::string_view current_zone_name = current_zone->name();
+        location_name = current_zone_name;
+#else
+        location_name = Common::TimeZone::FindSystemTimeZone();
+#endif
+    } else {
+        location_name = Common::TimeZone::GetTimeZoneStrings()[time_zone_index];
+    }
+    return location_name;
 }
 
 void LogSettings() {

src/common/time_zone.cpp

@@ -4,12 +4,29 @@
 #include <chrono>
 #include <iomanip>
 #include <sstream>
+#include <fmt/chrono.h>
+#include <fmt/core.h>
 
 #include "common/logging/log.h"
+#include "common/settings.h"
 #include "common/time_zone.h"
 
 namespace Common::TimeZone {
 
+// Time zone strings
+constexpr std::array timezones{
+    "GMT",       "GMT",       "CET", "CST6CDT", "Cuba",    "EET",    "Egypt",     "Eire",
+    "EST",       "EST5EDT",   "GB",  "GB-Eire", "GMT",     "GMT+0",  "GMT-0",     "GMT0",
+    "Greenwich", "Hongkong",  "HST", "Iceland", "Iran",    "Israel", "Jamaica",   "Japan",
+    "Kwajalein", "Libya",     "MET", "MST",     "MST7MDT", "Navajo", "NZ",        "NZ-CHAT",
+    "Poland",    "Portugal",  "PRC", "PST8PDT", "ROC",     "ROK",    "Singapore", "Turkey",
+    "UCT",       "Universal", "UTC", "W-SU",    "WET",     "Zulu",
+};
+
+const std::array<const char*, 46>& GetTimeZoneStrings() {
+    return timezones;
+}
+
 std::string GetDefaultTimeZone() {
     return "GMT";
 }
@@ -18,10 +35,7 @@ static std::string GetOsTimeZoneOffset() {
     const std::time_t t{std::time(nullptr)};
     const std::tm tm{*std::localtime(&t)};
 
-    std::stringstream ss;
-    ss << std::put_time(&tm, "%z"); // Get the current timezone offset, e.g. "-400", as a string
-
-    return ss.str();
+    return fmt::format("{:%z}", tm);
 }
 
 static int ConvertOsTimeZoneOffsetToInt(const std::string& timezone) {
@@ -45,4 +59,57 @@ std::chrono::seconds GetCurrentOffsetSeconds() {
     return std::chrono::seconds{seconds};
 }
 
+std::string FindSystemTimeZone() {
+#if defined(MINGW)
+    // MinGW has broken strftime -- https://sourceforge.net/p/mingw-w64/bugs/793/
+    // e.g. fmt::format("{:%z}") -- returns "Eastern Daylight Time" when it should be "-0400"
+    return timezones[0];
+#else
+    // Time zone offset in seconds from GMT
+    constexpr std::array offsets{
+        0,     0,     3600,  -21600, -19768, 7200,   7509,   -1521, -18000, -18000, -75,    -75,
+        0,     0,     0,     0,      0,      27402,  -36000, -968,  12344,  8454,   -18430, 33539,
+        40160, 3164,  3600,  -25200, -25200, -25196, 41944,  44028, 5040,   -2205,  29143,  -28800,
+        29160, 30472, 24925, 6952,   0,      0,      0,      9017,  0,      0,
+    };
+
+    // If the time zone recognizes Daylight Savings Time
+    constexpr std::array dst{
+        false, false, true,  true,  true,  true,  true,  true,  false, true,  true, true,
+        false, false, false, false, false, true,  false, false, true,  true,  true, true,
+        false, true,  true,  false, true,  true,  true,  true,  true,  true,  true, true,
+        true,  true,  true,  true,  false, false, false, true,  true,  false,
+    };
+
+    static std::string system_time_zone_cached{};
+    if (!system_time_zone_cached.empty()) {
+        return system_time_zone_cached;
+    }
+
+    const auto now = std::time(nullptr);
+    const struct std::tm& local = *std::localtime(&now);
+
+    const s64 system_offset = GetCurrentOffsetSeconds().count() - (local.tm_isdst ? 3600 : 0);
+
+    int min = std::numeric_limits<int>::max();
+    int min_index = -1;
+    for (u32 i = 2; i < offsets.size(); i++) {
+        // Skip if system is celebrating DST but considered time zone does not
+        if (local.tm_isdst && !dst[i]) {
+            continue;
+        }
+
+        const auto offset = offsets[i];
+        const int difference = static_cast<int>(std::abs(offset - system_offset));
+        if (difference < min) {
+            min = difference;
+            min_index = i;
+        }
+    }
+
+    system_time_zone_cached = GetTimeZoneStrings()[min_index];
+    return system_time_zone_cached;
+#endif
+}
+
 } // namespace Common::TimeZone

src/common/time_zone.h

@@ -3,15 +3,21 @@
 
 #pragma once
 
+#include <array>
 #include <chrono>
 #include <string>
 
 namespace Common::TimeZone {
 
+[[nodiscard]] const std::array<const char*, 46>& GetTimeZoneStrings();
+
 /// Gets the default timezone, i.e. "GMT"
 [[nodiscard]] std::string GetDefaultTimeZone();
 
 /// Gets the offset of the current timezone (from the default), in seconds
 [[nodiscard]] std::chrono::seconds GetCurrentOffsetSeconds();
 
+/// Searches time zone offsets for the closest offset to the system time zone
+[[nodiscard]] std::string FindSystemTimeZone();
+
 } // namespace Common::TimeZone

src/core/hle/service/time/time_manager.cpp

@@ -22,10 +22,6 @@ s64 GetSecondsSinceEpoch() {
     return std::chrono::duration_cast<std::chrono::seconds>(time_since_epoch).count() +
            Settings::values.custom_rtc_differential;
 }
-
-s64 GetExternalRtcValue() {
-    return GetSecondsSinceEpoch() + TimeManager::GetExternalTimeZoneOffset();
-}
 } // Anonymous namespace
 
 struct TimeManager::Impl final {
@@ -43,7 +39,7 @@ struct TimeManager::Impl final {
               std::make_shared<Clock::EphemeralNetworkSystemClockContextWriter>()},
           time_zone_content_manager{system} {
 
-        const auto system_time{Clock::TimeSpanType::FromSeconds(GetExternalRtcValue())};
+        const auto system_time{Clock::TimeSpanType::FromSeconds(GetSecondsSinceEpoch())};
         SetupStandardSteadyClock(system, Common::UUID::MakeRandom(), system_time, {}, {});
         SetupStandardLocalSystemClock(system, {}, system_time.ToSeconds());
 
@@ -123,14 +119,6 @@ struct TimeManager::Impl final {
         time_zone_content_manager.GetTimeZoneManager().MarkAsInitialized();
     }
 
-    static s64 GetExternalTimeZoneOffset() {
-        // With "auto" timezone setting, we use the external system's timezone offset
-        if (Settings::GetTimeZoneString() == "auto") {
-            return Common::TimeZone::GetCurrentOffsetSeconds().count();
-        }
-        return 0;
-    }
-
     void SetupStandardSteadyClock(Core::System& system_, Common::UUID clock_source_id,
                                   Clock::TimeSpanType setup_value,
                                   Clock::TimeSpanType internal_offset, bool is_rtc_reset_detected) {
@@ -301,13 +289,4 @@ void TimeManager::SetupTimeZoneManager(std::string location_name,
     impl->SetupTimeZoneManager(location_name, time_zone_updated_time_point,
                                total_location_name_count, time_zone_rule_version, vfs_file);
 }
-
-/*static*/ s64 TimeManager::GetExternalTimeZoneOffset() {
-    // With "auto" timezone setting, we use the external system's timezone offset
-    if (Settings::GetTimeZoneString() == "auto") {
-        return Common::TimeZone::GetCurrentOffsetSeconds().count();
-    }
-    return 0;
-}
-
 } // namespace Service::Time

src/core/hle/service/time/time_manager.h

@@ -64,8 +64,6 @@ public:
                               std::size_t total_location_name_count, u128 time_zone_rule_version,
                               FileSys::VirtualFile& vfs_file);
 
-    static s64 GetExternalTimeZoneOffset();
-
 private:
     Core::System& system;
 

src/core/hle/service/time/time_zone_content_manager.cpp

@@ -1,6 +1,7 @@
 // SPDX-FileCopyrightText: Copyright 2019 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include <chrono>
 #include <sstream>
 
 #include "common/logging/log.h"
@@ -12,7 +13,11 @@
 #include "core/file_sys/registered_cache.h"
 #include "core/file_sys/romfs.h"
 #include "core/file_sys/system_archive/system_archive.h"
+#include "core/file_sys/vfs.h"
+#include "core/file_sys/vfs_types.h"
+#include "core/hle/result.h"
 #include "core/hle/service/filesystem/filesystem.h"
+#include "core/hle/service/time/errors.h"
 #include "core/hle/service/time/time_manager.h"
 #include "core/hle/service/time/time_zone_content_manager.h"
 
@@ -71,20 +76,14 @@ TimeZoneContentManager::TimeZoneContentManager(Core::System& system_)
     : system{system_}, location_name_cache{BuildLocationNameCache(system)} {}
 
 void TimeZoneContentManager::Initialize(TimeManager& time_manager) {
-    std::string location_name;
     const auto timezone_setting = Settings::GetTimeZoneString();
-    if (timezone_setting == "auto" || timezone_setting == "default") {
-        location_name = Common::TimeZone::GetDefaultTimeZone();
-    } else {
-        location_name = timezone_setting;
-    }
 
     if (FileSys::VirtualFile vfs_file;
-        GetTimeZoneInfoFile(location_name, vfs_file) == ResultSuccess) {
+        GetTimeZoneInfoFile(timezone_setting, vfs_file) == ResultSuccess) {
         const auto time_point{
             time_manager.GetStandardSteadyClockCore().GetCurrentTimePoint(system)};
-        time_manager.SetupTimeZoneManager(location_name, time_point, location_name_cache.size(), {},
-                                          vfs_file);
+        time_manager.SetupTimeZoneManager(timezone_setting, time_point, location_name_cache.size(),
+                                          {}, vfs_file);
     } else {
         time_zone_manager.MarkAsInitialized();
     }
@@ -126,8 +125,15 @@ Result TimeZoneContentManager::GetTimeZoneInfoFile(const std::string& location_n
 
     vfs_file = zoneinfo_dir->GetFileRelative(location_name);
     if (!vfs_file) {
-        LOG_ERROR(Service_Time, "{:016X} has no file \"{}\"! Using default timezone.",
-                  time_zone_binary_titleid, location_name);
+        LOG_WARNING(Service_Time, "{:016X} has no file \"{}\"! Using system timezone.",
+                    time_zone_binary_titleid, location_name);
+        const std::string system_time_zone{Common::TimeZone::FindSystemTimeZone()};
+        vfs_file = zoneinfo_dir->GetFile(system_time_zone);
+    }
+
+    if (!vfs_file) {
+        LOG_WARNING(Service_Time, "{:016X} has no file \"{}\"! Using default timezone.",
+                    time_zone_binary_titleid, location_name);
         vfs_file = zoneinfo_dir->GetFile(Common::TimeZone::GetDefaultTimeZone());
     }
 

src/core/hle/service/time/time_zone_manager.cpp

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <climits>
+#include <limits>
 
 #include "common/assert.h"
 #include "common/logging/log.h"
@@ -9,6 +10,7 @@
 #include "core/file_sys/nca_metadata.h"
 #include "core/file_sys/registered_cache.h"
 #include "core/hle/service/time/time_zone_manager.h"
+#include "core/hle/service/time/time_zone_types.h"
 
 namespace Service::Time::TimeZone {
 
@@ -142,6 +144,9 @@ static constexpr bool GetInteger(const char* name, int& offset, int& value, int
     if (!IsDigit(temp)) {
         return {};
     }
+    if (temp == '0') {
+        return {};
+    }
     do {
         value = value * 10 + (temp - '0');
         if (value > max) {
@@ -629,11 +634,47 @@ static bool ParseTimeZoneBinary(TimeZoneRule& time_zone_rule, FileSys::VirtualFi
             UNIMPLEMENTED();
         }
     }
+
+    const auto typesequiv = [](TimeZoneRule& rule, int a, int b) -> bool {
+        if (a < 0 || a >= rule.type_count || b < 0 || b >= rule.type_count) {
+            return {};
+        }
+
+        const struct TimeTypeInfo* ap = &rule.ttis[a];
+        const struct TimeTypeInfo* bp = &rule.ttis[b];
+
+        return (ap->gmt_offset == bp->gmt_offset && ap->is_dst == bp->is_dst &&
+                (std::strcmp(&rule.chars[ap->abbreviation_list_index],
+                             &rule.chars[bp->abbreviation_list_index]) == 0));
+    };
+
     if (time_zone_rule.type_count == 0) {
         return {};
     }
     if (time_zone_rule.time_count > 1) {
-        UNIMPLEMENTED();
+        if (time_zone_rule.ats[0] <= std::numeric_limits<s64>::max() - seconds_per_repeat) {
+            s64 repeatat = time_zone_rule.ats[0] + seconds_per_repeat;
+            int repeatattype = time_zone_rule.types[0];
+            for (int i = 1; i < time_zone_rule.time_count; ++i) {
+                if (time_zone_rule.ats[i] == repeatat &&
+                    typesequiv(time_zone_rule, time_zone_rule.types[i], repeatattype)) {
+                    time_zone_rule.go_back = true;
+                    break;
+                }
+            }
+        }
+        if (std::numeric_limits<s64>::min() + seconds_per_repeat <=
+            time_zone_rule.ats[time_zone_rule.time_count - 1]) {
+            s64 repeatat = time_zone_rule.ats[time_zone_rule.time_count - 1] - seconds_per_repeat;
+            int repeatattype = time_zone_rule.types[time_zone_rule.time_count - 1];
+            for (int i = time_zone_rule.time_count; i >= 0; --i) {
+                if (time_zone_rule.ats[i] == repeatat &&
+                    typesequiv(time_zone_rule, time_zone_rule.types[i], repeatattype)) {
+                    time_zone_rule.go_ahead = true;
+                    break;
+                }
+            }
+        }
     }
 
     s32 default_type{};

src/yuzu/configuration/configure_system.cpp

@@ -144,8 +144,7 @@ void ConfigureSystem::ApplyConfiguration() {
         if (ui->custom_rtc_checkbox->isChecked()) {
             Settings::values.custom_rtc = ui->custom_rtc_edit->dateTime().toSecsSinceEpoch();
             if (system.IsPoweredOn()) {
-                const s64 posix_time{*Settings::values.custom_rtc +
-                                     Service::Time::TimeManager::GetExternalTimeZoneOffset()};
+                const s64 posix_time{*Settings::values.custom_rtc};
                 system.GetTimeManager().UpdateLocalSystemClockTime(posix_time);
             }
         } else {