1 files changed, 1038 insertions, 0 deletions

diff --git a/src/core/hle/service/time/time_zone_manager.cpp b/src/core/hle/service/time/time_zone_manager.cpp
new file mode 100644
index 000000000..c06ca538a
--- /dev/null
+++ b/src/core/hle/service/time/time_zone_manager.cpp
@@ -0,0 +1,1038 @@
+// Copyright 2019 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <climits>
+
+#include <boost/safe_numerics/safe_integer.hpp>
+
+#include "common/assert.h"
+#include "common/logging/log.h"
+#include "core/file_sys/content_archive.h"
+#include "core/file_sys/nca_metadata.h"
+#include "core/file_sys/registered_cache.h"
+#include "core/file_sys/romfs.h"
+#include "core/file_sys/system_archive/system_archive.h"
+#include "core/hle/service/time/time_zone_manager.h"
+
+namespace Service::Time::TimeZone {
+
+static constexpr s32 epoch_year{1970};
+static constexpr s32 year_base{1900};
+static constexpr s32 epoch_week_day{4};
+static constexpr s32 seconds_per_minute{60};
+static constexpr s32 minutes_per_hour{60};
+static constexpr s32 hours_per_day{24};
+static constexpr s32 days_per_week{7};
+static constexpr s32 days_per_normal_year{365};
+static constexpr s32 days_per_leap_year{366};
+static constexpr s32 months_per_year{12};
+static constexpr s32 seconds_per_hour{seconds_per_minute * minutes_per_hour};
+static constexpr s32 seconds_per_day{seconds_per_hour * hours_per_day};
+static constexpr s32 years_per_repeat{400};
+static constexpr s64 average_seconds_per_year{31556952};
+static constexpr s64 seconds_per_repeat{years_per_repeat * average_seconds_per_year};
+
+struct Rule {
+    enum class Type : u32 { JulianDay, DayOfYear, MonthNthDayOfWeek };
+    Type rule_type{};
+    s32 day{};
+    s32 week{};
+    s32 month{};
+    s32 transition_time{};
+};
+
+struct CalendarTimeInternal {
+    s64 year{};
+    s8 month{};
+    s8 day{};
+    s8 hour{};
+    s8 minute{};
+    s8 second{};
+    int Compare(const CalendarTimeInternal& other) const {
+        if (year != other.year) {
+            if (year < other.year) {
+                return -1;
+            }
+            return 1;
+        }
+        if (month != other.month) {
+            return month - other.month;
+        }
+        if (day != other.day) {
+            return day - other.day;
+        }
+        if (hour != other.hour) {
+            return hour - other.hour;
+        }
+        if (minute != other.minute) {
+            return minute - other.minute;
+        }
+        if (second != other.second) {
+            return second - other.second;
+        }
+        return {};
+    }
+};
+
+template <typename TResult, typename TOperand>
+static bool SafeAdd(TResult& result, TOperand op) {
+    const boost::safe_numerics::safe<TResult> safe_result{result};
+    const boost::safe_numerics::safe<TOperand> safe_op{op};
+    try {
+        result = safe_result + safe_op;
+    } catch (const std::exception&) {
+        return {}; // Failed with undefined behavior
+    }
+    return true;
+}
+
+template <typename TResult, typename TUnit, typename TBase>
+static bool SafeNormalize(TResult& result, TUnit& unit, TBase base) {
+    TUnit delta{};
+    if (unit >= 0) {
+        delta = unit / base;
+    } else {
+        delta = -1 - (-1 - unit) / base;
+    }
+    unit -= delta * base;
+    return SafeAdd(result, delta);
+}
+
+template <typename T>
+static constexpr bool IsLeapYear(T year) {
+    return ((year) % 4) == 0 && (((year) % 100) != 0 || ((year) % 400) == 0);
+}
+
+template <typename T>
+static constexpr T GetYearLengthInDays(T year) {
+    return IsLeapYear(year) ? days_per_leap_year : days_per_normal_year;
+}
+
+static constexpr s64 GetLeapDaysFromYearPositive(s64 year) {
+    return year / 4 - year / 100 + year / years_per_repeat;
+}
+
+static constexpr s64 GetLeapDaysFromYear(s64 year) {
+    if (year < 0) {
+        return -1 - GetLeapDaysFromYearPositive(-1 - year);
+    } else {
+        return GetLeapDaysFromYearPositive(year);
+    }
+}
+
+static constexpr int GetMonthLength(bool is_leap_year, int month) {
+    constexpr std::array<int, 12> month_lengths{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+    constexpr std::array<int, 12> month_lengths_leap{31, 29, 31, 30, 31, 30,
+                                                     31, 31, 30, 31, 30, 31};
+    return is_leap_year ? month_lengths_leap[month] : month_lengths[month];
+}
+
+static constexpr bool IsDigit(char value) {
+    return value >= '0' && value <= '9';
+}
+
+static constexpr int GetQZName(const char* name, int offset, char delimiter) {
+    while (name[offset] != '\0' && name[offset] != delimiter) {
+        offset++;
+    }
+    return offset;
+}
+
+static constexpr int GetTZName(const char* name, int offset) {
+    for (char value{name[offset]};
+         value != '\0' && !IsDigit(value) && value != ',' && value != '-' && value != '+';
+         offset++) {
+        value = name[offset];
+    }
+    return offset;
+}
+
+static constexpr bool GetInteger(const char* name, int& offset, int& value, int min, int max) {
+    value = 0;
+    char temp{name[offset]};
+    if (!IsDigit(temp)) {
+        return {};
+    }
+    do {
+        value = value * 10 + (temp - '0');
+        if (value > max) {
+            return {};
+        }
+        temp = name[offset];
+    } while (IsDigit(temp));
+
+    return value >= min;
+}
+
+static constexpr bool GetSeconds(const char* name, int& offset, int& seconds) {
+    seconds = 0;
+    int value{};
+    if (!GetInteger(name, offset, value, 0, hours_per_day * days_per_week - 1)) {
+        return {};
+    }
+    seconds = value * seconds_per_hour;
+
+    if (name[offset] == ':') {
+        offset++;
+        if (!GetInteger(name, offset, value, 0, minutes_per_hour - 1)) {
+            return {};
+        }
+        seconds += value * seconds_per_minute;
+        if (name[offset] == ':') {
+            offset++;
+            if (!GetInteger(name, offset, value, 0, seconds_per_minute)) {
+                return {};
+            }
+            seconds += value;
+        }
+    }
+    return true;
+}
+
+static constexpr bool GetOffset(const char* name, int& offset, int& value) {
+    bool is_negative{};
+    if (name[offset] == '-') {
+        is_negative = true;
+        offset++;
+    } else if (name[offset] == '+') {
+        offset++;
+    }
+    if (!GetSeconds(name, offset, value)) {
+        return {};
+    }
+    if (is_negative) {
+        value = -value;
+    }
+    return true;
+}
+
+static constexpr bool GetRule(const char* name, int& position, Rule& rule) {
+    bool is_valid{};
+    if (name[position] == 'J') {
+        position++;
+        rule.rule_type = Rule::Type::JulianDay;
+        is_valid = GetInteger(name, position, rule.day, 1, days_per_normal_year);
+    } else if (name[position] == 'M') {
+        position++;
+        rule.rule_type = Rule::Type::MonthNthDayOfWeek;
+        is_valid = GetInteger(name, position, rule.month, 1, months_per_year);
+        if (!is_valid) {
+            return {};
+        }
+        if (name[position++] != '.') {
+            return {};
+        }
+        is_valid = GetInteger(name, position, rule.week, 1, 5);
+        if (!is_valid) {
+            return {};
+        }
+        if (name[position++] != '.') {
+            return {};
+        }
+        is_valid = GetInteger(name, position, rule.day, 0, days_per_week - 1);
+    } else if (isdigit(name[position])) {
+        rule.rule_type = Rule::Type::DayOfYear;
+        is_valid = GetInteger(name, position, rule.day, 0, days_per_leap_year - 1);
+    } else {
+        return {};
+    }
+    if (!is_valid) {
+        return {};
+    }
+    if (name[position] == '/') {
+        position++;
+        return GetOffset(name, position, rule.transition_time);
+    } else {
+        rule.transition_time = 2 * seconds_per_hour;
+    }
+    return true;
+}
+
+static constexpr int TransitionTime(int year, Rule rule, int offset) {
+    int value{};
+    switch (rule.rule_type) {
+    case Rule::Type::JulianDay:
+        value = (rule.day - 1) * seconds_per_day;
+        if (IsLeapYear(year) && rule.day >= 60) {
+            value += seconds_per_day;
+        }
+        break;
+    case Rule::Type::DayOfYear:
+        value = rule.day * seconds_per_day;
+        break;
+    case Rule::Type::MonthNthDayOfWeek: {
+        // Use Zeller's Congruence (https://en.wikipedia.org/wiki/Zeller%27s_congruence) to
+        // calculate the day of the week for any Julian or Gregorian calendar date.
+        const int m1{(rule.month + 9) % 12 + 1};
+        const int yy0{(rule.month <= 2) ? (year - 1) : year};
+        const int yy1{yy0 / 100};
+        const int yy2{yy0 % 100};
+        int day_of_week{((26 * m1 - 2) / 10 + 1 + yy2 + yy2 / 4 + yy1 / 4 - 2 * yy1) % 7};
+
+        if (day_of_week < 0) {
+            day_of_week += days_per_week;
+        }
+        int day{rule.day - day_of_week};
+        if (day < 0) {
+            day += days_per_week;
+        }
+        for (int i{1}; i < rule.week; i++) {
+            if (day + days_per_week >= GetMonthLength(IsLeapYear(year), rule.month - 1)) {
+                break;
+            }
+            day += days_per_week;
+        }
+
+        value = day * seconds_per_day;
+        for (int index{}; index < rule.month - 1; ++index) {
+            value += GetMonthLength(IsLeapYear(year), index) * seconds_per_day;
+        }
+        break;
+    }
+    default:
+        UNREACHABLE();
+    }
+    return value + rule.transition_time + offset;
+}
+
+static bool ParsePosixName(const char* name, TimeZoneRule& rule) {
+    constexpr char default_rule[]{",M4.1.0,M10.5.0"};
+    const char* std_name{name};
+    int std_len{};
+    int offset{};
+    int std_offset{};
+
+    if (name[offset] == '<') {
+        offset++;
+        std_name = name + offset;
+        const int std_name_offset{offset};
+        offset = GetQZName(name, offset, '>');
+        if (name[offset] != '>') {
+            return {};
+        }
+        std_len = offset - std_name_offset;
+        offset++;
+    } else {
+        offset = GetTZName(name, offset);
+        std_len = offset;
+    }
+    if (!std_len) {
+        return {};
+    }
+    if (!GetOffset(name, offset, std_offset)) {
+        return {};
+    }
+
+    int char_count{std_len + 1};
+    int dest_len{};
+    int dest_offset{};
+    const char* dest_name{name + offset};
+    if (rule.chars.size() < char_count) {
+        return {};
+    }
+
+    if (name[offset] != '\0') {
+        if (name[offset] == '<') {
+            dest_name = name + (++offset);
+            const int dest_name_offset{offset};
+            offset = GetQZName(name, offset, '>');
+            if (name[offset] != '>') {
+                return {};
+            }
+            dest_len = offset - dest_name_offset;
+            offset++;
+        } else {
+            dest_name = name + (offset);
+            offset = GetTZName(name, offset);
+            dest_len = offset;
+        }
+        if (dest_len == 0) {
+            return {};
+        }
+        char_count += dest_len + 1;
+        if (rule.chars.size() < char_count) {
+            return {};
+        }
+        if (name[offset] != '\0' && name[offset] != ',' && name[offset] != ';') {
+            if (!GetOffset(name, offset, dest_offset)) {
+                return {};
+            }
+        } else {
+            dest_offset = std_offset - seconds_per_hour;
+        }
+        if (name[offset] == '\0') {
+            name = default_rule;
+            offset = 0;
+        }
+        if (name[offset] == ',' || name[offset] == ';') {
+            offset++;
+
+            Rule start{};
+            if (!GetRule(name, offset, start)) {
+                return {};
+            }
+            if (name[offset++] != ',') {
+                return {};
+            }
+
+            Rule end{};
+            if (!GetRule(name, offset, end)) {
+                return {};
+            }
+            if (name[offset] != '\0') {
+                return {};
+            }
+
+            rule.type_count = 2;
+            rule.ttis[0].gmt_offset = -dest_offset;
+            rule.ttis[0].is_dst = true;
+            rule.ttis[0].abbreviation_list_index = std_len + 1;
+            rule.ttis[1].gmt_offset = -std_offset;
+            rule.ttis[1].is_dst = false;
+            rule.ttis[1].abbreviation_list_index = 0;
+            rule.default_type = 0;
+
+            s64 jan_first{};
+            int time_count{};
+            int jan_offset{};
+            int year_beginning{epoch_year};
+            do {
+                const int year_seconds{GetYearLengthInDays(year_beginning - 1) * seconds_per_day};
+                year_beginning--;
+                if (!SafeAdd(jan_first, -year_seconds)) {
+                    jan_offset = -year_seconds;
+                    break;
+                }
+            } while (epoch_year - years_per_repeat / 2 < year_beginning);
+
+            int year_limit{year_beginning + years_per_repeat + 1};
+            int year{};
+            for (year = year_beginning; year < year_limit; year++) {
+                int start_time{TransitionTime(year, start, std_offset)};
+                int end_time{TransitionTime(year, end, dest_offset)};
+                const int year_seconds{GetYearLengthInDays(year) * seconds_per_day};
+                const bool is_reversed{end_time < start_time};
+                if (is_reversed) {
+                    int swap{start_time};
+                    start_time = end_time;
+                    end_time = swap;
+                }
+
+                if (is_reversed ||
+                    (start_time < end_time &&
+                     (end_time - start_time < (year_seconds + (std_offset - dest_offset))))) {
+                    if (rule.ats.size() - 2 < time_count) {
+                        break;
+                    }
+
+                    rule.ats[time_count] = jan_first;
+                    if (SafeAdd(rule.ats[time_count], jan_offset + start_time)) {
+                        rule.types[time_count++] = is_reversed ? 1 : 0;
+                    } else if (jan_offset != 0) {
+                        rule.default_type = is_reversed ? 1 : 0;
+                    }
+
+                    rule.ats[time_count] = jan_first;
+                    if (SafeAdd(rule.ats[time_count], jan_offset + end_time)) {
+                        rule.types[time_count++] = is_reversed ? 0 : 1;
+                        year_limit = year + years_per_repeat + 1;
+                    } else if (jan_offset != 0) {
+                        rule.default_type = is_reversed ? 0 : 1;
+                    }
+                }
+                if (!SafeAdd(jan_first, jan_offset + year_seconds)) {
+                    break;
+                }
+                jan_offset = 0;
+            }
+            rule.time_count = time_count;
+            if (time_count == 0) {
+                rule.type_count = 1;
+            } else if (years_per_repeat < year - year_beginning) {
+                rule.go_back = true;
+                rule.go_ahead = true;
+            }
+        } else {
+            if (name[offset] == '\0') {
+                return {};
+            }
+
+            s64 their_std_offset{};
+            for (int index{}; index < rule.time_count; ++index) {
+                const s8 type{rule.types[index]};
+                if (rule.ttis[type].is_standard_time_daylight) {
+                    their_std_offset = -rule.ttis[type].gmt_offset;
+                }
+            }
+
+            s64 their_offset{their_std_offset};
+            for (int index{}; index < rule.time_count; ++index) {
+                const s8 type{rule.types[index]};
+                rule.types[index] = rule.ttis[type].is_dst ? 1 : 0;
+                if (!rule.ttis[type].is_gmt) {
+                    if (!rule.ttis[type].is_standard_time_daylight) {
+                        rule.ats[index] += dest_offset - their_std_offset;
+                    } else {
+                        rule.ats[index] += std_offset - their_std_offset;
+                    }
+                }
+                their_offset = -rule.ttis[type].gmt_offset;
+                if (!rule.ttis[type].is_dst) {
+                    their_std_offset = their_offset;
+                }
+            }
+            rule.ttis[0].gmt_offset = -std_offset;
+            rule.ttis[0].is_dst = false;
+            rule.ttis[0].abbreviation_list_index = 0;
+            rule.ttis[1].gmt_offset = -dest_offset;
+            rule.ttis[1].is_dst = true;
+            rule.ttis[1].abbreviation_list_index = std_len + 1;
+            rule.type_count = 2;
+            rule.default_type = 0;
+        }
+    } else {
+        // Default is standard time
+        rule.type_count = 1;
+        rule.time_count = 0;
+        rule.default_type = 0;
+        rule.ttis[0].gmt_offset = -std_offset;
+        rule.ttis[0].is_dst = false;
+        rule.ttis[0].abbreviation_list_index = 0;
+    }
+
+    rule.char_count = char_count;
+    for (int index{}; index < std_len; ++index) {
+        rule.chars[index] = std_name[index];
+    }
+
+    rule.chars[std_len++] = '\0';
+    if (dest_len != 0) {
+        for (int index{}; index < dest_len; ++index) {
+            rule.chars[std_len + index] = dest_name[index];
+        }
+        rule.chars[std_len + dest_len] = '\0';
+    }
+
+    return true;
+}
+
+static bool ParseTimeZoneBinary(TimeZoneRule& time_zone_rule, FileSys::VirtualFile& vfs_file) {
+    TzifHeader header{};
+    if (vfs_file->ReadObject<TzifHeader>(&header) != sizeof(TzifHeader)) {
+        return {};
+    }
+
+    constexpr s32 time_zone_max_leaps{50};
+    constexpr s32 time_zone_max_chars{50};
+    if (!(0 <= header.leap_count && header.leap_count < time_zone_max_leaps &&
+          0 < header.type_count && header.type_count < time_zone_rule.ttis.size() &&
+          0 <= header.time_count && header.time_count < time_zone_rule.ats.size() &&
+          0 <= header.char_count && header.char_count < time_zone_max_chars &&
+          (header.ttis_std_count == header.type_count || header.ttis_std_count == 0) &&
+          (header.ttis_gmt_count == header.type_count || header.ttis_gmt_count == 0))) {
+        return {};
+    }
+    time_zone_rule.time_count = header.time_count;
+    time_zone_rule.type_count = header.type_count;
+    time_zone_rule.char_count = header.char_count;
+
+    int time_count{};
+    u64 read_offset = sizeof(TzifHeader);
+    for (int index{}; index < time_zone_rule.time_count; ++index) {
+        s64_be at{};
+        vfs_file->ReadObject<s64_be>(&at, read_offset);
+        time_zone_rule.types[index] = 1;
+        if (time_count != 0 && at <= time_zone_rule.ats[time_count - 1]) {
+            if (at < time_zone_rule.ats[time_count - 1]) {
+                return {};
+            }
+            time_zone_rule.types[index - 1] = 0;
+            time_count--;
+        }
+        time_zone_rule.ats[time_count++] = at;
+        read_offset += sizeof(s64_be);
+    }
+    time_count = 0;
+    for (int index{}; index < time_zone_rule.time_count; ++index) {
+        const u8 type{*vfs_file->ReadByte(read_offset)};
+        read_offset += sizeof(u8);
+        if (time_zone_rule.time_count <= type) {
+            return {};
+        }
+        if (time_zone_rule.types[index] != 0) {
+            time_zone_rule.types[time_count++] = type;
+        }
+    }
+    time_zone_rule.time_count = time_count;
+    for (int index{}; index < time_zone_rule.type_count; ++index) {
+        TimeTypeInfo& ttis{time_zone_rule.ttis[index]};
+        u32_be gmt_offset{};
+        vfs_file->ReadObject<u32_be>(&gmt_offset, read_offset);
+        read_offset += sizeof(u32_be);
+        ttis.gmt_offset = gmt_offset;
+
+        const u8 dst{*vfs_file->ReadByte(read_offset)};
+        read_offset += sizeof(u8);
+        if (dst >= 2) {
+            return {};
+        }
+        ttis.is_dst = dst != 0;
+
+        const s32 abbreviation_list_index{*vfs_file->ReadByte(read_offset)};
+        read_offset += sizeof(u8);
+        if (abbreviation_list_index >= time_zone_rule.char_count) {
+            return {};
+        }
+        ttis.abbreviation_list_index = abbreviation_list_index;
+    }
+
+    vfs_file->ReadArray(time_zone_rule.chars.data(), time_zone_rule.char_count, read_offset);
+    time_zone_rule.chars[time_zone_rule.char_count] = '\0';
+    read_offset += time_zone_rule.char_count;
+    for (int index{}; index < time_zone_rule.type_count; ++index) {
+        if (header.ttis_std_count == 0) {
+            time_zone_rule.ttis[index].is_standard_time_daylight = false;
+        } else {
+            const u8 dst{*vfs_file->ReadByte(read_offset)};
+            read_offset += sizeof(u8);
+            if (dst >= 2) {
+                return {};
+            }
+            time_zone_rule.ttis[index].is_standard_time_daylight = dst != 0;
+        }
+    }
+
+    for (int index{}; index < time_zone_rule.type_count; ++index) {
+        if (header.ttis_std_count == 0) {
+            time_zone_rule.ttis[index].is_gmt = false;
+        } else {
+            const u8 dst{*vfs_file->ReadByte(read_offset)};
+            read_offset += sizeof(u8);
+            if (dst >= 2) {
+                return {};
+            }
+            time_zone_rule.ttis[index].is_gmt = dst != 0;
+        }
+    }
+
+    const u64 position{(read_offset - sizeof(TzifHeader))};
+    const std::size_t bytes_read{vfs_file->GetSize() - sizeof(TzifHeader) - position};
+    if (bytes_read < 0) {
+        return {};
+    }
+    constexpr s32 time_zone_name_max{255};
+    if (bytes_read > (time_zone_name_max + 1)) {
+        return {};
+    }
+
+    std::array<char, time_zone_name_max + 1> temp_name{};
+    vfs_file->ReadArray(temp_name.data(), bytes_read, read_offset);
+    if (bytes_read > 2 && temp_name[0] == '\n' && temp_name[bytes_read - 1] == '\n' &&
+        time_zone_rule.type_count + 2 <= time_zone_rule.ttis.size()) {
+        temp_name[bytes_read - 1] = '\0';
+
+        std::array<char, time_zone_name_max> name{};
+        std::memcpy(name.data(), temp_name.data() + 1, bytes_read - 1);
+
+        TimeZoneRule temp_rule;
+        if (ParsePosixName(name.data(), temp_rule)) {
+            UNIMPLEMENTED();
+        }
+    }
+    if (time_zone_rule.type_count == 0) {
+        return {};
+    }
+    if (time_zone_rule.time_count > 1) {
+        UNIMPLEMENTED();
+    }
+
+    s32 default_type{};
+
+    for (default_type = 0; default_type < time_zone_rule.time_count; default_type++) {
+        if (time_zone_rule.types[default_type] == 0) {
+            break;
+        }
+    }
+
+    default_type = default_type < time_zone_rule.time_count ? -1 : 0;
+    if (default_type < 0 && time_zone_rule.time_count > 0 &&
+        time_zone_rule.ttis[time_zone_rule.types[0]].is_dst) {
+        default_type = time_zone_rule.types[0];
+        while (--default_type >= 0) {
+            if (!time_zone_rule.ttis[default_type].is_dst) {
+                break;
+            }
+        }
+    }
+    if (default_type < 0) {
+        default_type = 0;
+        while (time_zone_rule.ttis[default_type].is_dst) {
+            if (++default_type >= time_zone_rule.type_count) {
+                default_type = 0;
+                break;
+            }
+        }
+    }
+    time_zone_rule.default_type = default_type;
+    return true;
+}
+
+static ResultCode CreateCalendarTime(s64 time, int gmt_offset, CalendarTimeInternal& calendar_time,
+                                     CalendarAdditionalInfo& calendar_additional_info) {
+    s64 year{epoch_year};
+    s64 time_days{time / seconds_per_day};
+    s64 remaining_seconds{time % seconds_per_day};
+    while (time_days < 0 || time_days >= GetYearLengthInDays(year)) {
+        s64 delta = time_days / days_per_leap_year;
+        if (!delta) {
+            delta = time_days < 0 ? -1 : 1;
+        }
+        s64 new_year{year};
+        if (!SafeAdd(new_year, delta)) {
+            return ERROR_OUT_OF_RANGE;
+        }
+        time_days -= (new_year - year) * days_per_normal_year;
+        time_days -= GetLeapDaysFromYear(new_year - 1) - GetLeapDaysFromYear(year - 1);
+        year = new_year;
+    }
+
+    s64 day_of_year{time_days};
+    remaining_seconds += gmt_offset;
+    while (remaining_seconds < 0) {
+        remaining_seconds += seconds_per_day;
+        day_of_year--;
+    }
+
+    while (remaining_seconds >= seconds_per_day) {
+        remaining_seconds -= seconds_per_day;
+        day_of_year++;
+    }
+
+    while (day_of_year < 0) {
+        if (!SafeAdd(year, -1)) {
+            return ERROR_OUT_OF_RANGE;
+        }
+        day_of_year += GetYearLengthInDays(year);
+    }
+
+    while (day_of_year >= GetYearLengthInDays(year)) {
+        day_of_year -= GetYearLengthInDays(year);
+        if (!SafeAdd(year, 1)) {
+            return ERROR_OUT_OF_RANGE;
+        }
+    }
+
+    calendar_time.year = year;
+    calendar_additional_info.day_of_year = static_cast<u32>(day_of_year);
+    s64 day_of_week{
+        (epoch_week_day +
+         ((year - epoch_year) % days_per_week) * (days_per_normal_year % days_per_week) +
+         GetLeapDaysFromYear(year - 1) - GetLeapDaysFromYear(epoch_year - 1) + day_of_year) %
+        days_per_week};
+    if (day_of_week < 0) {
+        day_of_week += days_per_week;
+    }
+
+    calendar_additional_info.day_of_week = static_cast<u32>(day_of_week);
+    calendar_time.hour = static_cast<s8>((remaining_seconds / seconds_per_hour) % seconds_per_hour);
+    remaining_seconds %= seconds_per_hour;
+    calendar_time.minute = static_cast<s8>(remaining_seconds / seconds_per_minute);
+    calendar_time.second = static_cast<s8>(remaining_seconds % seconds_per_minute);
+
+    for (calendar_time.month = 0;
+         day_of_year >= GetMonthLength(IsLeapYear(year), calendar_time.month);
+         ++calendar_time.month) {
+        day_of_year -= GetMonthLength(IsLeapYear(year), calendar_time.month);
+    }
+
+    calendar_time.day = static_cast<s8>(day_of_year + 1);
+    calendar_additional_info.is_dst = false;
+    calendar_additional_info.gmt_offset = gmt_offset;
+
+    return RESULT_SUCCESS;
+}
+
+static ResultCode ToCalendarTimeInternal(const TimeZoneRule& rules, s64 time,
+                                         CalendarTimeInternal& calendar_time,
+                                         CalendarAdditionalInfo& calendar_additional_info) {
+    if ((rules.go_ahead && time < rules.ats[0]) ||
+        (rules.go_back && time > rules.ats[rules.time_count - 1])) {
+        s64 seconds{};
+        if (time < rules.ats[0]) {
+            seconds = rules.ats[0] - time;
+        } else {
+            seconds = time - rules.ats[rules.time_count - 1];
+        }
+        seconds--;
+
+        const s64 years{(seconds / seconds_per_repeat + 1) * years_per_repeat};
+        seconds = years * average_seconds_per_year;
+
+        s64 new_time{time};
+        if (time < rules.ats[0]) {
+            new_time += seconds;
+        } else {
+            new_time -= seconds;
+        }
+        if (new_time < rules.ats[0] && new_time > rules.ats[rules.time_count - 1]) {
+            return ERROR_TIME_NOT_FOUND;
+        }
+        if (const ResultCode result{
+                ToCalendarTimeInternal(rules, new_time, calendar_time, calendar_additional_info)};
+            result != RESULT_SUCCESS) {
+            return result;
+        }
+        if (time < rules.ats[0]) {
+            calendar_time.year -= years;
+        } else {
+            calendar_time.year += years;
+        }
+
+        return RESULT_SUCCESS;
+    }
+
+    s32 tti_index{};
+    if (rules.time_count == 0 || time < rules.ats[0]) {
+        tti_index = rules.default_type;
+    } else {
+        s32 low{1};
+        s32 high{rules.time_count};
+        while (low < high) {
+            s32 mid{(low + high) >> 1};
+            if (time < rules.ats[mid]) {
+                high = mid;
+            } else {
+                low = mid + 1;
+            }
+        }
+        tti_index = rules.types[low - 1];
+    }
+
+    if (const ResultCode result{CreateCalendarTime(time, rules.ttis[tti_index].gmt_offset,
+                                                   calendar_time, calendar_additional_info)};
+        result != RESULT_SUCCESS) {
+        return result;
+    }
+
+    calendar_additional_info.is_dst = rules.ttis[tti_index].is_dst;
+    const char* time_zone{&rules.chars[rules.ttis[tti_index].abbreviation_list_index]};
+    for (int index{}; time_zone[index] != '\0'; ++index) {
+        calendar_additional_info.timezone_name[index] = time_zone[index];
+    }
+    return RESULT_SUCCESS;
+}
+
+static ResultCode ToCalendarTimeImpl(const TimeZoneRule& rules, s64 time, CalendarInfo& calendar) {
+    CalendarTimeInternal calendar_time{};
+    const ResultCode result{
+        ToCalendarTimeInternal(rules, time, calendar_time, calendar.additiona_info)};
+    calendar.time.year = static_cast<s16>(calendar_time.year);
+    calendar.time.month = calendar_time.month;
+    calendar.time.day = calendar_time.day;
+    calendar.time.hour = calendar_time.hour;
+    calendar.time.minute = calendar_time.minute;
+    calendar.time.second = calendar_time.second;
+    return result;
+}
+
+TimeZoneManager::TimeZoneManager() = default;
+TimeZoneManager::~TimeZoneManager() = default;
+
+ResultCode TimeZoneManager::ToCalendarTime(const TimeZoneRule& rules, s64 time,
+                                           CalendarInfo& calendar) const {
+    return ToCalendarTimeImpl(rules, time, calendar);
+}
+
+ResultCode TimeZoneManager::SetDeviceLocationNameWithTimeZoneRule(const std::string& location_name,
+                                                                  FileSys::VirtualFile& vfs_file) {
+    TimeZoneRule rule{};
+    if (ParseTimeZoneBinary(rule, vfs_file)) {
+        device_location_name = location_name;
+        time_zone_rule = rule;
+        return RESULT_SUCCESS;
+    }
+    return ERROR_TIME_ZONE_CONVERSION_FAILED;
+}
+
+ResultCode TimeZoneManager::SetUpdatedTime(const Clock::SteadyClockTimePoint& value) {
+    time_zone_update_time_point = value;
+    return RESULT_SUCCESS;
+}
+
+ResultCode TimeZoneManager::ToCalendarTimeWithMyRules(s64 time, CalendarInfo& calendar) const {
+    if (is_initialized) {
+        return ToCalendarTime(time_zone_rule, time, calendar);
+    } else {
+        return ERROR_UNINITIALIZED_CLOCK;
+    }
+}
+
+ResultCode TimeZoneManager::ParseTimeZoneRuleBinary(TimeZoneRule& rules,
+                                                    FileSys::VirtualFile& vfs_file) const {
+    if (!ParseTimeZoneBinary(rules, vfs_file)) {
+        return ERROR_TIME_ZONE_CONVERSION_FAILED;
+    }
+    return RESULT_SUCCESS;
+}
+
+ResultCode TimeZoneManager::ToPosixTime(const TimeZoneRule& rules,
+                                        const CalendarTime& calendar_time, s64& posix_time) const {
+    posix_time = 0;
+
+    CalendarTimeInternal internal_time{};
+    internal_time.year = calendar_time.year;
+    internal_time.month = calendar_time.month;
+    internal_time.day = calendar_time.day;
+    internal_time.hour = calendar_time.hour;
+    internal_time.minute = calendar_time.minute;
+    internal_time.second = calendar_time.second;
+
+    s32 hour{internal_time.hour};
+    s32 minute{internal_time.minute};
+    if (!SafeNormalize(hour, minute, minutes_per_hour)) {
+        return ERROR_OVERFLOW;
+    }
+    internal_time.minute = static_cast<s8>(minute);
+
+    s32 day{internal_time.day};
+    if (!SafeNormalize(day, hour, hours_per_day)) {
+        return ERROR_OVERFLOW;
+    }
+    internal_time.day = static_cast<s8>(day);
+    internal_time.hour = static_cast<s8>(hour);
+
+    s64 year{internal_time.year};
+    s64 month{internal_time.month};
+    if (!SafeNormalize(year, month, months_per_year)) {
+        return ERROR_OVERFLOW;
+    }
+    internal_time.month = static_cast<s8>(month);
+
+    if (!SafeAdd(year, year_base)) {
+        return ERROR_OVERFLOW;
+    }
+
+    while (day <= 0) {
+        if (!SafeAdd(year, -1)) {
+            return ERROR_OVERFLOW;
+        }
+        s64 temp_year{year};
+        if (1 < internal_time.month) {
+            ++temp_year;
+        }
+        day += static_cast<s32>(GetYearLengthInDays(temp_year));
+    }
+
+    while (day > days_per_leap_year) {
+        s64 temp_year{year};
+        if (1 < internal_time.month) {
+            temp_year++;
+        }
+        day -= static_cast<s32>(GetYearLengthInDays(temp_year));
+        if (!SafeAdd(year, 1)) {
+            return ERROR_OVERFLOW;
+        }
+    }
+
+    while (true) {
+        const s32 month_length{GetMonthLength(IsLeapYear(year), internal_time.month)};
+        if (day <= month_length) {
+            break;
+        }
+        day -= month_length;
+        internal_time.month++;
+        if (internal_time.month >= months_per_year) {
+            internal_time.month = 0;
+            if (!SafeAdd(year, 1)) {
+                return ERROR_OVERFLOW;
+            }
+        }
+    }
+    internal_time.day = static_cast<s8>(day);
+
+    if (!SafeAdd(year, -year_base)) {
+        return ERROR_OVERFLOW;
+    }
+    internal_time.year = year;
+
+    s32 saved_seconds{};
+    if (internal_time.second >= 0 && internal_time.second < seconds_per_minute) {
+        saved_seconds = 0;
+    } else if (year + year_base < epoch_year) {
+        s32 second{internal_time.second};
+        if (!SafeAdd(second, 1 - seconds_per_minute)) {
+            return ERROR_OVERFLOW;
+        }
+        saved_seconds = second;
+        internal_time.second = 1 - seconds_per_minute;
+    } else {
+        saved_seconds = internal_time.second;
+        internal_time.second = 0;
+    }
+
+    s64 low{LLONG_MIN};
+    s64 high{LLONG_MAX};
+    while (true) {
+        s64 pivot{low / 2 + high / 2};
+        if (pivot < low) {
+            pivot = low;
+        } else if (pivot > high) {
+            pivot = high;
+        }
+        s32 direction{};
+        CalendarTimeInternal candidate_calendar_time{};
+        CalendarAdditionalInfo unused{};
+        if (ToCalendarTimeInternal(rules, pivot, candidate_calendar_time, unused) !=
+            RESULT_SUCCESS) {
+            if (pivot > 0) {
+                direction = 1;
+            } else {
+                direction = -1;
+            }
+        } else {
+            direction = candidate_calendar_time.Compare(internal_time);
+        }
+        if (!direction) {
+            const s64 time_result{pivot + saved_seconds};
+            if ((time_result < pivot) != (saved_seconds < 0)) {
+                return ERROR_OVERFLOW;
+            }
+            posix_time = time_result;
+            break;
+        } else {
+            if (pivot == low) {
+                if (pivot == LLONG_MAX) {
+                    return ERROR_TIME_NOT_FOUND;
+                }
+                pivot++;
+                low++;
+            } else if (pivot == high) {
+                if (pivot == LLONG_MIN) {
+                    return ERROR_TIME_NOT_FOUND;
+                }
+                pivot--;
+                high--;
+            }
+            if (low > high) {
+                return ERROR_TIME_NOT_FOUND;
+            }
+            if (direction > 0) {
+                high = pivot;
+            } else {
+                low = pivot;
+            }
+        }
+    }
+    return RESULT_SUCCESS;
+}
+
+ResultCode TimeZoneManager::GetDeviceLocationName(LocationName& value) const {
+    if (!is_initialized) {
+        return ERROR_UNINITIALIZED_CLOCK;
+    }
+    std::memcpy(value.data(), device_location_name.c_str(), device_location_name.size());
+    return RESULT_SUCCESS;
+}
+
+} // namespace Service::Time::TimeZone