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/*
* Copyright (c) 2022, Tim Flynn <trflynn89@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/String.h>
#include <LibTimeZone/TimeZone.h>
#include <stdio.h>
#include <time.h>
namespace TimeZone {
// NOTE: Without ENABLE_TIME_ZONE_DATA LibTimeZone operates in a UTC-only mode and only recognizes
// the 'UTC' time zone, which is slightly more useful than a bunch of dummy functions that
// can't do anything. When we build with time zone data, these weakly linked functions are
// replaced with their proper counterparts.
#if !ENABLE_TIME_ZONE_DATA
enum class TimeZone : u16 {
UTC,
};
#endif
class TimeZoneFile {
public:
TimeZoneFile(char const* mode)
: m_file(fopen("/etc/timezone", mode))
{
if (m_file)
flockfile(m_file);
}
~TimeZoneFile()
{
if (m_file) {
funlockfile(m_file);
fclose(m_file);
}
}
ErrorOr<String> read_time_zone()
{
if (!m_file)
return Error::from_string_literal("Could not open /etc/timezone");
Array<u8, 128> buffer;
size_t bytes = fread(buffer.data(), 1, buffer.size(), m_file);
if (bytes == 0)
return Error::from_string_literal("Could not read time zone from /etc/timezone");
return String(buffer.span().slice(0, bytes)).trim_whitespace();
}
ErrorOr<void> write_time_zone(StringView time_zone)
{
if (!m_file)
return Error::from_string_literal("Could not open /etc/timezone");
auto bytes = fwrite(time_zone.characters_without_null_termination(), 1, time_zone.length(), m_file);
if (bytes != time_zone.length())
return Error::from_string_literal("Could not write new time zone to /etc/timezone");
return {};
}
private:
FILE* m_file { nullptr };
};
StringView system_time_zone()
{
TimeZoneFile time_zone_file("r");
// FIXME: Propagate the error to existing callers.
if (auto time_zone = time_zone_file.read_time_zone(); !time_zone.is_error())
return canonicalize_time_zone(time_zone.value()).value_or("UTC"sv);
return "UTC"sv;
}
StringView current_time_zone()
{
return canonicalize_time_zone(tzname[0]).value_or("UTC"sv);
}
ErrorOr<void> change_time_zone([[maybe_unused]] StringView time_zone)
{
#ifdef __serenity__
TimeZoneFile time_zone_file("w");
if (auto new_time_zone = canonicalize_time_zone(time_zone); new_time_zone.has_value())
return time_zone_file.write_time_zone(*new_time_zone);
return Error::from_string_literal("Provided time zone is not supported");
#else
// Do not even attempt to change the time zone of someone's host machine.
return {};
#endif
}
Span<StringView const> __attribute__((weak)) all_time_zones()
{
#if !ENABLE_TIME_ZONE_DATA
static constexpr auto utc = Array { "UTC"sv };
return utc;
#else
return {};
#endif
}
Optional<TimeZone> __attribute__((weak)) time_zone_from_string([[maybe_unused]] StringView time_zone)
{
#if !ENABLE_TIME_ZONE_DATA
if (time_zone.equals_ignoring_case("UTC"sv))
return TimeZone::UTC;
#endif
return {};
}
StringView __attribute__((weak)) time_zone_to_string([[maybe_unused]] TimeZone time_zone)
{
#if !ENABLE_TIME_ZONE_DATA
VERIFY(time_zone == TimeZone::UTC);
return "UTC"sv;
#else
return {};
#endif
}
Optional<StringView> canonicalize_time_zone(StringView time_zone)
{
auto maybe_time_zone = time_zone_from_string(time_zone);
if (!maybe_time_zone.has_value())
return {};
auto canonical_time_zone = time_zone_to_string(*maybe_time_zone);
if (canonical_time_zone.is_one_of("Etc/UTC"sv, "Etc/GMT"sv))
return "UTC"sv;
return canonical_time_zone;
}
Optional<DaylightSavingsRule> __attribute__((weak)) daylight_savings_rule_from_string(StringView) { return {}; }
StringView __attribute__((weak)) daylight_savings_rule_to_string(DaylightSavingsRule) { return {}; }
Optional<Offset> __attribute__((weak)) get_time_zone_offset([[maybe_unused]] TimeZone time_zone, AK::Time)
{
#if !ENABLE_TIME_ZONE_DATA
VERIFY(time_zone == TimeZone::UTC);
return Offset {};
#else
return {};
#endif
}
Optional<Offset> get_time_zone_offset(StringView time_zone, AK::Time time)
{
if (auto maybe_time_zone = time_zone_from_string(time_zone); maybe_time_zone.has_value())
return get_time_zone_offset(*maybe_time_zone, time);
return {};
}
Optional<Array<NamedOffset, 2>> __attribute__((weak)) get_named_time_zone_offsets([[maybe_unused]] TimeZone time_zone, AK::Time)
{
#if !ENABLE_TIME_ZONE_DATA
VERIFY(time_zone == TimeZone::UTC);
NamedOffset utc_offset {};
utc_offset.name = "UTC"sv;
return Array { utc_offset, utc_offset };
#else
return {};
#endif
}
Optional<Array<NamedOffset, 2>> get_named_time_zone_offsets(StringView time_zone, AK::Time time)
{
if (auto maybe_time_zone = time_zone_from_string(time_zone); maybe_time_zone.has_value())
return get_named_time_zone_offsets(*maybe_time_zone, time);
return {};
}
Optional<Location> __attribute__((weak)) get_time_zone_location(TimeZone) { return {}; }
Optional<Location> get_time_zone_location(StringView time_zone)
{
if (auto maybe_time_zone = time_zone_from_string(time_zone); maybe_time_zone.has_value())
return get_time_zone_location(*maybe_time_zone);
return {};
}
}
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