diff options
Diffstat (limited to 'libcxx/src/tzdb.cpp')
| -rw-r--r-- | libcxx/src/tzdb.cpp | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/libcxx/src/tzdb.cpp b/libcxx/src/tzdb.cpp index 0307f754..2c82a4a 100644 --- a/libcxx/src/tzdb.cpp +++ b/libcxx/src/tzdb.cpp @@ -15,6 +15,7 @@ #include <stdexcept> #include <string> +#include "include/tzdb/leap_second_private.h" #include "include/tzdb/time_zone_link_private.h" #include "include/tzdb/time_zone_private.h" #include "include/tzdb/types_private.h" @@ -622,6 +623,36 @@ static void __parse_tzdata(tzdb& __db, __tz::__rules_storage_type& __rules, istr } } +static void __parse_leap_seconds(vector<leap_second>& __leap_seconds, istream&& __input) { + // The file stores dates since 1 January 1900, 00:00:00, we want + // seconds since 1 January 1970. + constexpr auto __offset = sys_days{1970y / January / 1} - sys_days{1900y / January / 1}; + + while (true) { + switch (__input.peek()) { + case istream::traits_type::eof(): + return; + + case ' ': + case '\t': + case '\n': + __input.get(); + continue; + + case '#': + chrono::__skip_line(__input); + continue; + } + + sys_seconds __date = sys_seconds{seconds{chrono::__parse_integral(__input, false)}} - __offset; + chrono::__skip_mandatory_whitespace(__input); + seconds __value{chrono::__parse_integral(__input, false)}; + chrono::__skip_line(__input); + + __leap_seconds.emplace_back(leap_second::__constructor_tag{}, __date, __value); + } +} + void __init_tzdb(tzdb& __tzdb, __tz::__rules_storage_type& __rules) { filesystem::path __root = chrono::__libcpp_tzdb_directory(); ifstream __tzdata{__root / "tzdata.zi"}; @@ -631,7 +662,69 @@ void __init_tzdb(tzdb& __tzdb, __tz::__rules_storage_type& __rules) { std::ranges::sort(__tzdb.zones); std::ranges::sort(__tzdb.links); std::ranges::sort(__rules, {}, [](const auto& p) { return p.first; }); + + // There are two files with the leap second information + // - leapseconds as specified by zic + // - leap-seconds.list the source data + // The latter is much easier to parse, it seems Howard shares that + // opinion. + chrono::__parse_leap_seconds(__tzdb.leap_seconds, ifstream{__root / "leap-seconds.list"}); + // The Standard requires the leap seconds to be sorted. The file + // leap-seconds.list usually provides them in sorted order, but that is not + // guaranteed so we ensure it here. + std::ranges::sort(__tzdb.leap_seconds); +} + +#ifdef _WIN32 +[[nodiscard]] static const time_zone* __current_zone_windows(const tzdb& tzdb) { + // TODO TZDB Implement this on Windows. + std::__throw_runtime_error("unknown time zone"); +} +#else // ifdef _WIN32 +[[nodiscard]] static const time_zone* __current_zone_posix(const tzdb& tzdb) { + // On POSIX systems there are several ways to configure the time zone. + // In order of priority they are: + // - TZ environment variable + // https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08 + // The documentation is unclear whether or not it's allowed to + // change time zone information. For example the TZ string + // MST7MDT + // this is an entry in tzdata.zi. The value + // MST + // is also an entry. Is it allowed to use the following? + // MST-3 + // Even when this is valid there is no time_zone record in the + // database. Since the library would need to return a valid pointer, + // this means the library needs to allocate and leak a pointer. + // + // - The time zone name is the target of the symlink /etc/localtime + // relative to /usr/share/zoneinfo/ + + // The algorithm is like this: + // - If the environment variable TZ is set and points to a valid + // record use this value. + // - Else use the name based on the `/etc/localtime` symlink. + + if (const char* __tz = getenv("TZ")) + if (const time_zone* __result = tzdb.__locate_zone(__tz)) + return __result; + + filesystem::path __path = "/etc/localtime"; + if (!std::filesystem::exists(__path)) + std::__throw_runtime_error("tzdb: the symlink '/etc/localtime' does not exist"); + + if (!std::filesystem::is_symlink(__path)) + std::__throw_runtime_error("tzdb: the path '/etc/localtime' is not a symlink"); + + filesystem::path __tz = filesystem::read_symlink(__path); + string __name = filesystem::relative(__tz, "/usr/share/zoneinfo/"); + + if (const time_zone* __result = tzdb.__locate_zone(__name)) + return __result; + + std::__throw_runtime_error(("tzdb: the time zone '" + __name + "' is not found in the database").c_str()); } +#endif // ifdef _WIN32 //===----------------------------------------------------------------------===// // Public API @@ -642,6 +735,14 @@ _LIBCPP_NODISCARD_EXT _LIBCPP_AVAILABILITY_TZDB _LIBCPP_EXPORTED_FROM_ABI tzdb_l return __result; } +[[nodiscard]] _LIBCPP_AVAILABILITY_TZDB _LIBCPP_EXPORTED_FROM_ABI const time_zone* tzdb::__current_zone() const { +#ifdef _WIN32 + return chrono::__current_zone_windows(*this); +#else + return chrono::__current_zone_posix(*this); +#endif +} + _LIBCPP_AVAILABILITY_TZDB _LIBCPP_EXPORTED_FROM_ABI const tzdb& reload_tzdb() { if (chrono::remote_version() == chrono::get_tzdb().version) return chrono::get_tzdb(); |