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b31c11bca5
It's expensive to determine the system time zone from disk each time it is requested. This makes LibUnicode cache the result, and provides an API to clear that cache. This will let us set up a monitor to watch for system time zone changes in platform-dependent ways.
151 lines
3.8 KiB
C++
151 lines
3.8 KiB
C++
/*
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* Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Array.h>
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#include <AK/NonnullOwnPtr.h>
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#include <AK/QuickSort.h>
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#include <LibUnicode/ICU.h>
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#include <LibUnicode/TimeZone.h>
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#include <unicode/timezone.h>
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#include <unicode/ucal.h>
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namespace Unicode {
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static Optional<String> cached_system_time_zone;
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String current_time_zone(UseTimeZoneCache)
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{
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if (cached_system_time_zone.has_value())
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return *cached_system_time_zone;
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UErrorCode status = U_ZERO_ERROR;
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auto time_zone = adopt_own_if_nonnull(icu::TimeZone::detectHostTimeZone());
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if (!time_zone)
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return "UTC"_string;
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icu::UnicodeString time_zone_id;
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time_zone->getID(time_zone_id);
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icu::UnicodeString time_zone_name;
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time_zone->getCanonicalID(time_zone_id, time_zone_name, status);
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if (icu_failure(status))
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return "UTC"_string;
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cached_system_time_zone = icu_string_to_string(time_zone_name);
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return *cached_system_time_zone;
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}
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void clear_system_time_zone_cache()
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{
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cached_system_time_zone.clear();
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}
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// https://github.com/unicode-org/icu/blob/main/icu4c/source/tools/tzcode/icuzones
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static constexpr bool is_legacy_non_iana_time_zone(StringView time_zone)
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{
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constexpr auto legacy_zones = to_array({
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"ACT"sv,
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"AET"sv,
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"AGT"sv,
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"ART"sv,
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"AST"sv,
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"BET"sv,
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"BST"sv,
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"Canada/East-Saskatchewan"sv,
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"CAT"sv,
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"CNT"sv,
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"CST"sv,
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"CTT"sv,
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"EAT"sv,
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"ECT"sv,
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"IET"sv,
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"IST"sv,
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"JST"sv,
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"MIT"sv,
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"NET"sv,
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"NST"sv,
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"PLT"sv,
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"PNT"sv,
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"PRT"sv,
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"PST"sv,
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"SST"sv,
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"US/Pacific-New"sv,
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"VST"sv,
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});
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if (time_zone.starts_with("SystemV/"sv))
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return true;
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return legacy_zones.contains_slow(time_zone);
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}
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static Vector<String> icu_available_time_zones(Optional<ByteString> const& region)
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{
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UErrorCode status = U_ZERO_ERROR;
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char const* icu_region = region.has_value() ? region->characters() : nullptr;
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auto time_zone_enumerator = adopt_own_if_nonnull(icu::TimeZone::createTimeZoneIDEnumeration(UCAL_ZONE_TYPE_ANY, icu_region, nullptr, status));
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if (icu_failure(status))
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return { "UTC"_string };
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auto time_zones = icu_string_enumeration_to_list(move(time_zone_enumerator), [](char const* zone) {
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return !is_legacy_non_iana_time_zone({ zone, strlen(zone) });
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});
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quick_sort(time_zones);
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return time_zones;
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}
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Vector<String> const& available_time_zones()
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{
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static auto time_zones = icu_available_time_zones({});
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return time_zones;
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}
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Vector<String> available_time_zones_in_region(StringView region)
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{
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return icu_available_time_zones(region);
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}
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Optional<String> resolve_primary_time_zone(StringView time_zone)
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{
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UErrorCode status = U_ZERO_ERROR;
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icu::UnicodeString iana_id;
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icu::TimeZone::getIanaID(icu_string(time_zone), iana_id, status);
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if (icu_failure(status))
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return {};
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return icu_string_to_string(iana_id);
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}
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Optional<TimeZoneOffset> time_zone_offset(StringView time_zone, UnixDateTime time)
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{
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UErrorCode status = U_ZERO_ERROR;
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auto icu_time_zone = adopt_own_if_nonnull(icu::TimeZone::createTimeZone(icu_string(time_zone)));
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if (!icu_time_zone || *icu_time_zone == icu::TimeZone::getUnknown())
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return {};
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i32 raw_offset = 0;
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i32 dst_offset = 0;
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icu_time_zone->getOffset(static_cast<UDate>(time.milliseconds_since_epoch()), 0, raw_offset, dst_offset, status);
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if (icu_failure(status))
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return {};
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return TimeZoneOffset {
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.offset = AK::Duration::from_milliseconds(raw_offset + dst_offset),
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.in_dst = dst_offset == 0 ? TimeZoneOffset::InDST::No : TimeZoneOffset::InDST::Yes,
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};
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}
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}
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