LibJS+LibUnicode: Port retrieving the system time zone to ICU

Author: https://github.com/trflynn89
Commit: https://github.com/LadybirdBrowser/ladybird/commit/d3e809bcd4
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/281

Tests/LibUnicode/CMakeLists.txt

@@ -4,6 +4,7 @@ set(TEST_SOURCES
     TestIDNA.cpp
     TestLocale.cpp
     TestSegmenter.cpp
+    TestTimeZone.cpp
     TestUnicodeCharacterTypes.cpp
     TestUnicodeNormalization.cpp
 )

Tests/LibUnicode/TestTimeZone.cpp

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibTest/TestCase.h>
+
+#include <AK/StringView.h>
+#include <LibCore/Environment.h>
+#include <LibUnicode/TimeZone.h>
+
+class TimeZoneGuard {
+public:
+    explicit TimeZoneGuard(StringView time_zone)
+        : m_time_zone(Core::Environment::get("TZ"sv))
+    {
+        MUST(Core::Environment::set("TZ"sv, time_zone, Core::Environment::Overwrite::Yes));
+    }
+
+    ~TimeZoneGuard()
+    {
+        if (m_time_zone.has_value())
+            MUST(Core::Environment::set("TZ"sv, *m_time_zone, Core::Environment::Overwrite::Yes));
+        else
+            MUST(Core::Environment::unset("TZ"sv));
+    }
+
+private:
+    Optional<StringView> m_time_zone;
+};
+
+TEST_CASE(current_time_zone)
+{
+    {
+        TimeZoneGuard guard { "America/New_York"sv };
+        EXPECT_EQ(Unicode::current_time_zone(), "America/New_York"sv);
+    }
+    {
+        TimeZoneGuard guard { "ladybird"sv };
+        EXPECT_EQ(Unicode::current_time_zone(), "UTC"sv);
+    }
+}

Userland/Libraries/LibJS/Runtime/Date.cpp

@@ -13,6 +13,7 @@
 #include <LibJS/Runtime/GlobalObject.h>
 #include <LibJS/Runtime/Temporal/ISO8601.h>
 #include <LibTimeZone/TimeZone.h>
+#include <LibUnicode/TimeZone.h>
 #include <time.h>
 
 namespace JS {
@@ -464,9 +465,9 @@ Vector<TimeZoneIdentifier> available_named_time_zone_identifiers()
 }
 
 // 21.4.1.24 SystemTimeZoneIdentifier ( ), https://tc39.es/ecma262/#sec-systemtimezoneidentifier
-StringView system_time_zone_identifier()
+String system_time_zone_identifier()
 {
-    return TimeZone::current_time_zone();
+    return Unicode::current_time_zone();
 }
 
 // 21.4.1.25 LocalTime ( t ), https://tc39.es/ecma262/#sec-localtime

Userland/Libraries/LibJS/Runtime/Date.h

@@ -76,7 +76,7 @@ Crypto::SignedBigInteger get_utc_epoch_nanoseconds(i32 year, u8 month, u8 day, u
 Vector<Crypto::SignedBigInteger> get_named_time_zone_epoch_nanoseconds(StringView time_zone_identifier, i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond);
 i64 get_named_time_zone_offset_nanoseconds(StringView time_zone_identifier, Crypto::SignedBigInteger const& epoch_nanoseconds);
 Vector<TimeZoneIdentifier> available_named_time_zone_identifiers();
-StringView system_time_zone_identifier();
+String system_time_zone_identifier();
 double local_time(double time);
 double utc_time(double time);
 double make_time(double hour, double min, double sec, double ms);

Userland/Libraries/LibJS/Runtime/DatePrototype.cpp

@@ -27,6 +27,7 @@
 #include <LibTimeZone/TimeZone.h>
 #include <LibUnicode/DisplayNames.h>
 #include <LibUnicode/Locale.h>
+#include <LibUnicode/TimeZone.h>
 
 namespace JS {
 
@@ -1159,7 +1160,7 @@ ByteString time_zone_string(double time)
         if (auto name = Unicode::time_zone_display_name(Unicode::default_locale(), tz_name, maybe_offset->in_dst, time); name.has_value())
             tz_name = name.release_value();
     } else {
-        tz_name = MUST(String::from_utf8(TimeZone::current_time_zone()));
+        tz_name = Unicode::current_time_zone();
     }
 
     // 10. Return the string-concatenation of offsetSign, offsetHour, offsetMin, and tzName.

Userland/Libraries/LibJS/Runtime/Intl/DateTimeFormatConstructor.cpp

@@ -197,7 +197,7 @@ ThrowCompletionOr<NonnullGCPtr<DateTimeFormat>> create_date_time_format(VM& vm,
     // 30. If timeZone is undefined, then
     if (time_zone_value.is_undefined()) {
         // a. Set timeZone to DefaultTimeZone().
-        time_zone = MUST(String::from_utf8(system_time_zone_identifier()));
+        time_zone = system_time_zone_identifier();
     }
     // 31. Else,
     else {

Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.cpp

@@ -687,7 +687,7 @@ ThrowCompletionOr<RelativeTo> to_relative_temporal_object(VM& vm, Object const&
             }
 
             // ii. Let timeZone be ! CreateTemporalTimeZone(timeZoneName).
-            time_zone = MUST_OR_THROW_OOM(create_temporal_time_zone(vm, *time_zone_name));
+            time_zone = MUST_OR_THROW_OOM(create_temporal_time_zone(vm, time_zone_name.release_value()));
 
             // iii. If result.[[TimeZone]].[[Z]] is true, then
             if (result.time_zone.z) {

Userland/Libraries/LibJS/Runtime/Temporal/Instant.cpp

@@ -279,7 +279,7 @@ ThrowCompletionOr<String> temporal_instant_to_string(VM& vm, Instant& instant, V
     // 4. If outputTimeZone is undefined, then
     if (output_time_zone.is_undefined()) {
         // a. Set outputTimeZone to ! CreateTemporalTimeZone("UTC").
-        output_time_zone = MUST_OR_THROW_OOM(create_temporal_time_zone(vm, "UTC"sv));
+        output_time_zone = MUST_OR_THROW_OOM(create_temporal_time_zone(vm, "UTC"_string));
     }
 
     // 5. Let isoCalendar be ! GetISO8601Calendar().

Userland/Libraries/LibJS/Runtime/Temporal/Now.cpp

@@ -158,7 +158,7 @@ TimeZone* system_time_zone(VM& vm)
 
     // 2. Return ! CreateTemporalTimeZone(identifier).
     // FIXME: Propagate possible OOM error
-    return MUST(create_temporal_time_zone(vm, identifier));
+    return MUST(create_temporal_time_zone(vm, move(identifier)));
 }
 
 // 2.3.2 SystemUTCEpochNanoseconds ( ), https://tc39.es/proposal-temporal/#sec-temporal-systemutcepochnanoseconds

Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp

@@ -61,7 +61,7 @@ ThrowCompletionOr<String> canonicalize_time_zone_name(VM& vm, StringView time_zo
 }
 
 // 11.6.1 CreateTemporalTimeZone ( identifier [ , newTarget ] ), https://tc39.es/proposal-temporal/#sec-temporal-createtemporaltimezone
-ThrowCompletionOr<TimeZone*> create_temporal_time_zone(VM& vm, StringView identifier, FunctionObject const* new_target)
+ThrowCompletionOr<TimeZone*> create_temporal_time_zone(VM& vm, String identifier, FunctionObject const* new_target)
 {
     auto& realm = *vm.current_realm();
 
@@ -89,7 +89,7 @@ ThrowCompletionOr<TimeZone*> create_temporal_time_zone(VM& vm, StringView identi
         VERIFY(MUST_OR_THROW_OOM(canonicalize_time_zone_name(vm, identifier)) == identifier);
 
         // b. Set object.[[Identifier]] to identifier.
-        object->set_identifier(TRY_OR_THROW_OOM(vm, String::from_utf8(identifier)));
+        object->set_identifier(move(identifier));
 
         // c. Set object.[[OffsetNanoseconds]] to undefined.
         // NOTE: No-op.
@@ -318,15 +318,15 @@ ThrowCompletionOr<Object*> to_temporal_time_zone(VM& vm, Value temporal_time_zon
         }
 
         // c. Return ! CreateTemporalTimeZone(name).
-        return MUST_OR_THROW_OOM(create_temporal_time_zone(vm, name));
+        return MUST_OR_THROW_OOM(create_temporal_time_zone(vm, move(name)));
     }
 
     // 5. If parseResult.[[Z]] is true, return ! CreateTemporalTimeZone("UTC").
     if (parse_result.z)
-        return MUST_OR_THROW_OOM(create_temporal_time_zone(vm, "UTC"sv));
+        return MUST_OR_THROW_OOM(create_temporal_time_zone(vm, "UTC"_string));
 
     // 6. Return ! CreateTemporalTimeZone(parseResult.[[OffsetString]]).
-    return MUST_OR_THROW_OOM(create_temporal_time_zone(vm, *parse_result.offset_string));
+    return MUST_OR_THROW_OOM(create_temporal_time_zone(vm, parse_result.offset_string.release_value()));
 }
 
 // 11.5.19 GetOffsetNanosecondsFor ( timeZoneRec, instant ), https://tc39.es/proposal-temporal/#sec-temporal-getoffsetnanosecondsfor

Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h

@@ -39,7 +39,7 @@ private:
 
 bool is_available_time_zone_name(StringView time_zone);
 ThrowCompletionOr<String> canonicalize_time_zone_name(VM&, StringView time_zone);
-ThrowCompletionOr<TimeZone*> create_temporal_time_zone(VM&, StringView identifier, FunctionObject const* new_target = nullptr);
+ThrowCompletionOr<TimeZone*> create_temporal_time_zone(VM&, String identifier, FunctionObject const* new_target = nullptr);
 ISODateTime get_iso_parts_from_epoch(VM&, Crypto::SignedBigInteger const& epoch_nanoseconds);
 BigInt* get_named_time_zone_next_transition(VM&, StringView time_zone_identifier, BigInt const& epoch_nanoseconds);
 BigInt* get_named_time_zone_previous_transition(VM&, StringView time_zone_identifier, BigInt const& epoch_nanoseconds);

Userland/Libraries/LibJS/Runtime/Temporal/TimeZoneConstructor.cpp

@@ -65,7 +65,7 @@ ThrowCompletionOr<NonnullGCPtr<Object>> TimeZoneConstructor::construct(FunctionO
     }
 
     // 4. Return ? CreateTemporalTimeZone(identifier, NewTarget).
-    return *TRY(create_temporal_time_zone(vm, identifier, &new_target));
+    return *TRY(create_temporal_time_zone(vm, move(identifier), &new_target));
 }
 
 // 11.3.2 Temporal.TimeZone.from ( item ), https://tc39.es/proposal-temporal/#sec-temporal.timezone.from

Userland/Libraries/LibJS/Runtime/Temporal/ZonedDateTime.cpp

@@ -227,7 +227,7 @@ ThrowCompletionOr<ZonedDateTime*> to_temporal_zoned_date_time(VM& vm, Value item
         }
 
         // j. Let timeZone be ! CreateTemporalTimeZone(timeZoneName).
-        time_zone = MUST_OR_THROW_OOM(create_temporal_time_zone(vm, *time_zone_name));
+        time_zone = MUST_OR_THROW_OOM(create_temporal_time_zone(vm, time_zone_name.release_value()));
 
         // k. Let calendar be ? ToTemporalCalendarWithISODefault(result.[[Calendar]]).
         auto temporal_calendar_like = result.calendar.has_value()

Userland/Libraries/LibUnicode/CMakeLists.txt

@@ -17,6 +17,7 @@ set(SOURCES
     RelativeTimeFormat.cpp
     Segmenter.cpp
     String.cpp
+    TimeZone.cpp
     UnicodeKeywords.cpp
     ${UNICODE_DATA_SOURCES}
 )

Userland/Libraries/LibUnicode/TimeZone.cpp

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#define AK_DONT_REPLACE_STD
+
+#include <AK/NonnullOwnPtr.h>
+#include <LibUnicode/ICU.h>
+#include <LibUnicode/TimeZone.h>
+
+#include <unicode/timezone.h>
+
+namespace Unicode {
+
+String current_time_zone()
+{
+    UErrorCode status = U_ZERO_ERROR;
+
+    auto time_zone = adopt_own_if_nonnull(icu::TimeZone::detectHostTimeZone());
+    if (!time_zone)
+        return "UTC"_string;
+
+    icu::UnicodeString time_zone_id;
+    time_zone->getID(time_zone_id);
+
+    icu::UnicodeString time_zone_name;
+    time_zone->getCanonicalID(time_zone_id, time_zone_name, status);
+
+    if (icu_failure(status))
+        return "UTC"_string;
+
+    return icu_string_to_string(time_zone_name);
+}
+
+}

Userland/Libraries/LibUnicode/TimeZone.h

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/String.h>
+
+#pragma once
+
+namespace Unicode {
+
+String current_time_zone();
+
+}