| // Copyright 2016 Google Inc. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // https://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| // This file implements the TimeZoneIf interface using the "zoneinfo" |
| // data provided by the IANA Time Zone Database (i.e., the only real game |
| // in town). |
| // |
| // TimeZoneInfo represents the history of UTC-offset changes within a time |
| // zone. Most changes are due to daylight-saving rules, but occasionally |
| // shifts are made to the time-zone's base offset. The database only attempts |
| // to be definitive for times since 1970, so be wary of local-time conversions |
| // before that. Also, rule and zone-boundary changes are made at the whim |
| // of governments, so the conversion of future times needs to be taken with |
| // a grain of salt. |
| // |
| // For more information see tzfile(5), http://www.iana.org/time-zones, or |
| // https://en.wikipedia.org/wiki/Zoneinfo. |
| // |
| // Note that we assume the proleptic Gregorian calendar and 60-second |
| // minutes throughout. |
| |
| #include "time_zone_info.h" |
| |
| #include <algorithm> |
| #include <cassert> |
| #include <chrono> |
| #include <cstdint> |
| #include <cstdio> |
| #include <cstdlib> |
| #include <cstring> |
| #include <functional> |
| #include <iostream> |
| #include <memory> |
| #include <sstream> |
| #include <string> |
| |
| #include "absl/time/internal/cctz/include/cctz/civil_time.h" |
| #include "time_zone_fixed.h" |
| #include "time_zone_posix.h" |
| |
| namespace absl { |
| inline namespace lts_2019_08_08 { |
| namespace time_internal { |
| namespace cctz { |
| |
| namespace { |
| |
| inline bool IsLeap(year_t year) { |
| return (year % 4) == 0 && ((year % 100) != 0 || (year % 400) == 0); |
| } |
| |
| // The number of days in non-leap and leap years respectively. |
| const std::int_least32_t kDaysPerYear[2] = {365, 366}; |
| |
| // The day offsets of the beginning of each (1-based) month in non-leap and |
| // leap years respectively (e.g., 335 days before December in a leap year). |
| const std::int_least16_t kMonthOffsets[2][1 + 12 + 1] = { |
| {-1, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365}, |
| {-1, 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366}, |
| }; |
| |
| // We reject leap-second encoded zoneinfo and so assume 60-second minutes. |
| const std::int_least32_t kSecsPerDay = 24 * 60 * 60; |
| |
| // 400-year chunks always have 146097 days (20871 weeks). |
| const std::int_least64_t kSecsPer400Years = 146097LL * kSecsPerDay; |
| |
| // Like kDaysPerYear[] but scaled up by a factor of kSecsPerDay. |
| const std::int_least32_t kSecsPerYear[2] = { |
| 365 * kSecsPerDay, |
| 366 * kSecsPerDay, |
| }; |
| |
| // Single-byte, unsigned numeric values are encoded directly. |
| inline std::uint_fast8_t Decode8(const char* cp) { |
| return static_cast<std::uint_fast8_t>(*cp) & 0xff; |
| } |
| |
| // Multi-byte, numeric values are encoded using a MSB first, |
| // twos-complement representation. These helpers decode, from |
| // the given address, 4-byte and 8-byte values respectively. |
| // Note: If int_fastXX_t == intXX_t and this machine is not |
| // twos complement, then there will be at least one input value |
| // we cannot represent. |
| std::int_fast32_t Decode32(const char* cp) { |
| std::uint_fast32_t v = 0; |
| for (int i = 0; i != (32 / 8); ++i) v = (v << 8) | Decode8(cp++); |
| const std::int_fast32_t s32max = 0x7fffffff; |
| const auto s32maxU = static_cast<std::uint_fast32_t>(s32max); |
| if (v <= s32maxU) return static_cast<std::int_fast32_t>(v); |
| return static_cast<std::int_fast32_t>(v - s32maxU - 1) - s32max - 1; |
| } |
| |
| std::int_fast64_t Decode64(const char* cp) { |
| std::uint_fast64_t v = 0; |
| for (int i = 0; i != (64 / 8); ++i) v = (v << 8) | Decode8(cp++); |
| const std::int_fast64_t s64max = 0x7fffffffffffffff; |
| const auto s64maxU = static_cast<std::uint_fast64_t>(s64max); |
| if (v <= s64maxU) return static_cast<std::int_fast64_t>(v); |
| return static_cast<std::int_fast64_t>(v - s64maxU - 1) - s64max - 1; |
| } |
| |
| // Generate a year-relative offset for a PosixTransition. |
| std::int_fast64_t TransOffset(bool leap_year, int jan1_weekday, |
| const PosixTransition& pt) { |
| std::int_fast64_t days = 0; |
| switch (pt.date.fmt) { |
| case PosixTransition::J: { |
| days = pt.date.j.day; |
| if (!leap_year || days < kMonthOffsets[1][3]) days -= 1; |
| break; |
| } |
| case PosixTransition::N: { |
| days = pt.date.n.day; |
| break; |
| } |
| case PosixTransition::M: { |
| const bool last_week = (pt.date.m.week == 5); |
| days = kMonthOffsets[leap_year][pt.date.m.month + last_week]; |
| const std::int_fast64_t weekday = (jan1_weekday + days) % 7; |
| if (last_week) { |
| days -= (weekday + 7 - 1 - pt.date.m.weekday) % 7 + 1; |
| } else { |
| days += (pt.date.m.weekday + 7 - weekday) % 7; |
| days += (pt.date.m.week - 1) * 7; |
| } |
| break; |
| } |
| } |
| return (days * kSecsPerDay) + pt.time.offset; |
| } |
| |
| inline time_zone::civil_lookup MakeUnique(const time_point<seconds>& tp) { |
| time_zone::civil_lookup cl; |
| cl.kind = time_zone::civil_lookup::UNIQUE; |
| cl.pre = cl.trans = cl.post = tp; |
| return cl; |
| } |
| |
| inline time_zone::civil_lookup MakeUnique(std::int_fast64_t unix_time) { |
| return MakeUnique(FromUnixSeconds(unix_time)); |
| } |
| |
| inline time_zone::civil_lookup MakeSkipped(const Transition& tr, |
| const civil_second& cs) { |
| time_zone::civil_lookup cl; |
| cl.kind = time_zone::civil_lookup::SKIPPED; |
| cl.pre = FromUnixSeconds(tr.unix_time - 1 + (cs - tr.prev_civil_sec)); |
| cl.trans = FromUnixSeconds(tr.unix_time); |
| cl.post = FromUnixSeconds(tr.unix_time - (tr.civil_sec - cs)); |
| return cl; |
| } |
| |
| inline time_zone::civil_lookup MakeRepeated(const Transition& tr, |
| const civil_second& cs) { |
| time_zone::civil_lookup cl; |
| cl.kind = time_zone::civil_lookup::REPEATED; |
| cl.pre = FromUnixSeconds(tr.unix_time - 1 - (tr.prev_civil_sec - cs)); |
| cl.trans = FromUnixSeconds(tr.unix_time); |
| cl.post = FromUnixSeconds(tr.unix_time + (cs - tr.civil_sec)); |
| return cl; |
| } |
| |
| inline civil_second YearShift(const civil_second& cs, year_t shift) { |
| return civil_second(cs.year() + shift, cs.month(), cs.day(), |
| cs.hour(), cs.minute(), cs.second()); |
| } |
| |
| } // namespace |
| |
| // What (no leap-seconds) UTC+seconds zoneinfo would look like. |
| bool TimeZoneInfo::ResetToBuiltinUTC(const seconds& offset) { |
| transition_types_.resize(1); |
| TransitionType& tt(transition_types_.back()); |
| tt.utc_offset = static_cast<std::int_least32_t>(offset.count()); |
| tt.is_dst = false; |
| tt.abbr_index = 0; |
| |
| // We temporarily add some redundant, contemporary (2013 through 2023) |
| // transitions for performance reasons. See TimeZoneInfo::LocalTime(). |
| // TODO: Fix the performance issue and remove the extra transitions. |
| transitions_.clear(); |
| transitions_.reserve(12); |
| for (const std::int_fast64_t unix_time : { |
| -(1LL << 59), // BIG_BANG |
| 1356998400LL, // 2013-01-01T00:00:00+00:00 |
| 1388534400LL, // 2014-01-01T00:00:00+00:00 |
| 1420070400LL, // 2015-01-01T00:00:00+00:00 |
| 1451606400LL, // 2016-01-01T00:00:00+00:00 |
| 1483228800LL, // 2017-01-01T00:00:00+00:00 |
| 1514764800LL, // 2018-01-01T00:00:00+00:00 |
| 1546300800LL, // 2019-01-01T00:00:00+00:00 |
| 1577836800LL, // 2020-01-01T00:00:00+00:00 |
| 1609459200LL, // 2021-01-01T00:00:00+00:00 |
| 1640995200LL, // 2022-01-01T00:00:00+00:00 |
| 1672531200LL, // 2023-01-01T00:00:00+00:00 |
| 2147483647LL, // 2^31 - 1 |
| }) { |
| Transition& tr(*transitions_.emplace(transitions_.end())); |
| tr.unix_time = unix_time; |
| tr.type_index = 0; |
| tr.civil_sec = LocalTime(tr.unix_time, tt).cs; |
| tr.prev_civil_sec = tr.civil_sec - 1; |
| } |
| |
| default_transition_type_ = 0; |
| abbreviations_ = FixedOffsetToAbbr(offset); |
| abbreviations_.append(1, '\0'); // add NUL |
| future_spec_.clear(); // never needed for a fixed-offset zone |
| extended_ = false; |
| |
| tt.civil_max = LocalTime(seconds::max().count(), tt).cs; |
| tt.civil_min = LocalTime(seconds::min().count(), tt).cs; |
| |
| transitions_.shrink_to_fit(); |
| return true; |
| } |
| |
| // Builds the in-memory header using the raw bytes from the file. |
| bool TimeZoneInfo::Header::Build(const tzhead& tzh) { |
| std::int_fast32_t v; |
| if ((v = Decode32(tzh.tzh_timecnt)) < 0) return false; |
| timecnt = static_cast<std::size_t>(v); |
| if ((v = Decode32(tzh.tzh_typecnt)) < 0) return false; |
| typecnt = static_cast<std::size_t>(v); |
| if ((v = Decode32(tzh.tzh_charcnt)) < 0) return false; |
| charcnt = static_cast<std::size_t>(v); |
| if ((v = Decode32(tzh.tzh_leapcnt)) < 0) return false; |
| leapcnt = static_cast<std::size_t>(v); |
| if ((v = Decode32(tzh.tzh_ttisstdcnt)) < 0) return false; |
| ttisstdcnt = static_cast<std::size_t>(v); |
| if ((v = Decode32(tzh.tzh_ttisutcnt)) < 0) return false; |
| ttisutcnt = static_cast<std::size_t>(v); |
| return true; |
| } |
| |
| // How many bytes of data are associated with this header. The result |
| // depends upon whether this is a section with 4-byte or 8-byte times. |
| std::size_t TimeZoneInfo::Header::DataLength(std::size_t time_len) const { |
| std::size_t len = 0; |
| len += (time_len + 1) * timecnt; // unix_time + type_index |
| len += (4 + 1 + 1) * typecnt; // utc_offset + is_dst + abbr_index |
| len += 1 * charcnt; // abbreviations |
| len += (time_len + 4) * leapcnt; // leap-time + TAI-UTC |
| len += 1 * ttisstdcnt; // UTC/local indicators |
| len += 1 * ttisutcnt; // standard/wall indicators |
| return len; |
| } |
| |
| // Check that the TransitionType has the expected offset/is_dst/abbreviation. |
| void TimeZoneInfo::CheckTransition(const std::string& name, |
| const TransitionType& tt, |
| std::int_fast32_t offset, bool is_dst, |
| const std::string& abbr) const { |
| if (tt.utc_offset != offset || tt.is_dst != is_dst || |
| &abbreviations_[tt.abbr_index] != abbr) { |
| std::clog << name << ": Transition" |
| << " offset=" << tt.utc_offset << "/" |
| << (tt.is_dst ? "DST" : "STD") |
| << "/abbr=" << &abbreviations_[tt.abbr_index] |
| << " does not match POSIX spec '" << future_spec_ << "'\n"; |
| } |
| } |
| |
| // zic(8) can generate no-op transitions when a zone changes rules at an |
| // instant when there is actually no discontinuity. So we check whether |
| // two transitions have equivalent types (same offset/is_dst/abbr). |
| bool TimeZoneInfo::EquivTransitions(std::uint_fast8_t tt1_index, |
| std::uint_fast8_t tt2_index) const { |
| if (tt1_index == tt2_index) return true; |
| const TransitionType& tt1(transition_types_[tt1_index]); |
| const TransitionType& tt2(transition_types_[tt2_index]); |
| if (tt1.is_dst != tt2.is_dst) return false; |
| if (tt1.utc_offset != tt2.utc_offset) return false; |
| if (tt1.abbr_index != tt2.abbr_index) return false; |
| return true; |
| } |
| |
| // Use the POSIX-TZ-environment-variable-style string to handle times |
| // in years after the last transition stored in the zoneinfo data. |
| void TimeZoneInfo::ExtendTransitions(const std::string& name, |
| const Header& hdr) { |
| extended_ = false; |
| bool extending = !future_spec_.empty(); |
| |
| PosixTimeZone posix; |
| if (extending && !ParsePosixSpec(future_spec_, &posix)) { |
| std::clog << name << ": Failed to parse '" << future_spec_ << "'\n"; |
| extending = false; |
| } |
| |
| if (extending && posix.dst_abbr.empty()) { // std only |
| // The future specification should match the last/default transition, |
| // and that means that handling the future will fall out naturally. |
| std::uint_fast8_t index = default_transition_type_; |
| if (hdr.timecnt != 0) index = transitions_[hdr.timecnt - 1].type_index; |
| const TransitionType& tt(transition_types_[index]); |
| CheckTransition(name, tt, posix.std_offset, false, posix.std_abbr); |
| extending = false; |
| } |
| |
| if (extending && hdr.timecnt < 2) { |
| std::clog << name << ": Too few transitions for POSIX spec\n"; |
| extending = false; |
| } |
| |
| if (!extending) { |
| // Ensure that there is always a transition in the second half of the |
| // time line (the BIG_BANG transition is in the first half) so that the |
| // signed difference between a civil_second and the civil_second of its |
| // previous transition is always representable, without overflow. |
| const Transition& last(transitions_.back()); |
| if (last.unix_time < 0) { |
| const std::uint_fast8_t type_index = last.type_index; |
| Transition& tr(*transitions_.emplace(transitions_.end())); |
| tr.unix_time = 2147483647; // 2038-01-19T03:14:07+00:00 |
| tr.type_index = type_index; |
| } |
| return; // last transition wins |
| } |
| |
| // Extend the transitions for an additional 400 years using the |
| // future specification. Years beyond those can be handled by |
| // mapping back to a cycle-equivalent year within that range. |
| // zic(8) should probably do this so that we don't have to. |
| // TODO: Reduce the extension by the number of compatible |
| // transitions already in place. |
| transitions_.reserve(hdr.timecnt + 400 * 2 + 1); |
| transitions_.resize(hdr.timecnt + 400 * 2); |
| extended_ = true; |
| |
| // The future specification should match the last two transitions, |
| // and those transitions should have different is_dst flags. Note |
| // that nothing says the UTC offset used by the is_dst transition |
| // must be greater than that used by the !is_dst transition. (See |
| // Europe/Dublin, for example.) |
| const Transition* tr0 = &transitions_[hdr.timecnt - 1]; |
| const Transition* tr1 = &transitions_[hdr.timecnt - 2]; |
| const TransitionType* tt0 = &transition_types_[tr0->type_index]; |
| const TransitionType* tt1 = &transition_types_[tr1->type_index]; |
| const TransitionType& dst(tt0->is_dst ? *tt0 : *tt1); |
| const TransitionType& std(tt0->is_dst ? *tt1 : *tt0); |
| CheckTransition(name, dst, posix.dst_offset, true, posix.dst_abbr); |
| CheckTransition(name, std, posix.std_offset, false, posix.std_abbr); |
| |
| // Add the transitions to tr1 and back to tr0 for each extra year. |
| last_year_ = LocalTime(tr0->unix_time, *tt0).cs.year(); |
| bool leap_year = IsLeap(last_year_); |
| const civil_day jan1(last_year_, 1, 1); |
| std::int_fast64_t jan1_time = civil_second(jan1) - civil_second(); |
| int jan1_weekday = (static_cast<int>(get_weekday(jan1)) + 1) % 7; |
| Transition* tr = &transitions_[hdr.timecnt]; // next trans to fill |
| if (LocalTime(tr1->unix_time, *tt1).cs.year() != last_year_) { |
| // Add a single extra transition to align to a calendar year. |
| transitions_.resize(transitions_.size() + 1); |
| assert(tr == &transitions_[hdr.timecnt]); // no reallocation |
| const PosixTransition& pt1(tt0->is_dst ? posix.dst_end : posix.dst_start); |
| std::int_fast64_t tr1_offset = TransOffset(leap_year, jan1_weekday, pt1); |
| tr->unix_time = jan1_time + tr1_offset - tt0->utc_offset; |
| tr++->type_index = tr1->type_index; |
| tr0 = &transitions_[hdr.timecnt]; |
| tr1 = &transitions_[hdr.timecnt - 1]; |
| tt0 = &transition_types_[tr0->type_index]; |
| tt1 = &transition_types_[tr1->type_index]; |
| } |
| const PosixTransition& pt1(tt0->is_dst ? posix.dst_end : posix.dst_start); |
| const PosixTransition& pt0(tt0->is_dst ? posix.dst_start : posix.dst_end); |
| for (const year_t limit = last_year_ + 400; last_year_ < limit;) { |
| last_year_ += 1; // an additional year of generated transitions |
| jan1_time += kSecsPerYear[leap_year]; |
| jan1_weekday = (jan1_weekday + kDaysPerYear[leap_year]) % 7; |
| leap_year = !leap_year && IsLeap(last_year_); |
| std::int_fast64_t tr1_offset = TransOffset(leap_year, jan1_weekday, pt1); |
| tr->unix_time = jan1_time + tr1_offset - tt0->utc_offset; |
| tr++->type_index = tr1->type_index; |
| std::int_fast64_t tr0_offset = TransOffset(leap_year, jan1_weekday, pt0); |
| tr->unix_time = jan1_time + tr0_offset - tt1->utc_offset; |
| tr++->type_index = tr0->type_index; |
| } |
| assert(tr == &transitions_[0] + transitions_.size()); |
| } |
| |
| bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) { |
| // Read and validate the header. |
| tzhead tzh; |
| if (zip->Read(&tzh, sizeof(tzh)) != sizeof(tzh)) |
| return false; |
| if (strncmp(tzh.tzh_magic, TZ_MAGIC, sizeof(tzh.tzh_magic)) != 0) |
| return false; |
| Header hdr; |
| if (!hdr.Build(tzh)) |
| return false; |
| std::size_t time_len = 4; |
| if (tzh.tzh_version[0] != '\0') { |
| // Skip the 4-byte data. |
| if (zip->Skip(hdr.DataLength(time_len)) != 0) |
| return false; |
| // Read and validate the header for the 8-byte data. |
| if (zip->Read(&tzh, sizeof(tzh)) != sizeof(tzh)) |
| return false; |
| if (strncmp(tzh.tzh_magic, TZ_MAGIC, sizeof(tzh.tzh_magic)) != 0) |
| return false; |
| if (tzh.tzh_version[0] == '\0') |
| return false; |
| if (!hdr.Build(tzh)) |
| return false; |
| time_len = 8; |
| } |
| if (hdr.typecnt == 0) |
| return false; |
| if (hdr.leapcnt != 0) { |
| // This code assumes 60-second minutes so we do not want |
| // the leap-second encoded zoneinfo. We could reverse the |
| // compensation, but the "right" encoding is rarely used |
| // so currently we simply reject such data. |
| return false; |
| } |
| if (hdr.ttisstdcnt != 0 && hdr.ttisstdcnt != hdr.typecnt) |
| return false; |
| if (hdr.ttisutcnt != 0 && hdr.ttisutcnt != hdr.typecnt) |
| return false; |
| |
| // Read the data into a local buffer. |
| std::size_t len = hdr.DataLength(time_len); |
| std::vector<char> tbuf(len); |
| if (zip->Read(tbuf.data(), len) != len) |
| return false; |
| const char* bp = tbuf.data(); |
| |
| // Decode and validate the transitions. |
| transitions_.reserve(hdr.timecnt + 2); // We might add a couple. |
| transitions_.resize(hdr.timecnt); |
| for (std::size_t i = 0; i != hdr.timecnt; ++i) { |
| transitions_[i].unix_time = (time_len == 4) ? Decode32(bp) : Decode64(bp); |
| bp += time_len; |
| if (i != 0) { |
| // Check that the transitions are ordered by time (as zic guarantees). |
| if (!Transition::ByUnixTime()(transitions_[i - 1], transitions_[i])) |
| return false; // out of order |
| } |
| } |
| bool seen_type_0 = false; |
| for (std::size_t i = 0; i != hdr.timecnt; ++i) { |
| transitions_[i].type_index = Decode8(bp++); |
| if (transitions_[i].type_index >= hdr.typecnt) |
| return false; |
| if (transitions_[i].type_index == 0) |
| seen_type_0 = true; |
| } |
| |
| // Decode and validate the transition types. |
| transition_types_.resize(hdr.typecnt); |
| for (std::size_t i = 0; i != hdr.typecnt; ++i) { |
| transition_types_[i].utc_offset = |
| static_cast<std::int_least32_t>(Decode32(bp)); |
| if (transition_types_[i].utc_offset >= kSecsPerDay || |
| transition_types_[i].utc_offset <= -kSecsPerDay) |
| return false; |
| bp += 4; |
| transition_types_[i].is_dst = (Decode8(bp++) != 0); |
| transition_types_[i].abbr_index = Decode8(bp++); |
| if (transition_types_[i].abbr_index >= hdr.charcnt) |
| return false; |
| } |
| |
| // Determine the before-first-transition type. |
| default_transition_type_ = 0; |
| if (seen_type_0 && hdr.timecnt != 0) { |
| std::uint_fast8_t index = 0; |
| if (transition_types_[0].is_dst) { |
| index = transitions_[0].type_index; |
| while (index != 0 && transition_types_[index].is_dst) |
| --index; |
| } |
| while (index != hdr.typecnt && transition_types_[index].is_dst) |
| ++index; |
| if (index != hdr.typecnt) |
| default_transition_type_ = index; |
| } |
| |
| // Copy all the abbreviations. |
| abbreviations_.assign(bp, hdr.charcnt); |
| bp += hdr.charcnt; |
| |
| // Skip the unused portions. We've already dispensed with leap-second |
| // encoded zoneinfo. The ttisstd/ttisgmt indicators only apply when |
| // interpreting a POSIX spec that does not include start/end rules, and |
| // that isn't the case here (see "zic -p"). |
| bp += (8 + 4) * hdr.leapcnt; // leap-time + TAI-UTC |
| bp += 1 * hdr.ttisstdcnt; // UTC/local indicators |
| bp += 1 * hdr.ttisutcnt; // standard/wall indicators |
| assert(bp == tbuf.data() + tbuf.size()); |
| |
| future_spec_.clear(); |
| if (tzh.tzh_version[0] != '\0') { |
| // Snarf up the NL-enclosed future POSIX spec. Note |
| // that version '3' files utilize an extended format. |
| auto get_char = [](ZoneInfoSource* azip) -> int { |
| unsigned char ch; // all non-EOF results are positive |
| return (azip->Read(&ch, 1) == 1) ? ch : EOF; |
| }; |
| if (get_char(zip) != '\n') |
| return false; |
| for (int c = get_char(zip); c != '\n'; c = get_char(zip)) { |
| if (c == EOF) |
| return false; |
| future_spec_.push_back(static_cast<char>(c)); |
| } |
| } |
| |
| // We don't check for EOF so that we're forwards compatible. |
| |
| // If we did not find version information during the standard loading |
| // process (as of tzh_version '3' that is unsupported), then ask the |
| // ZoneInfoSource for any out-of-bound version std::string it may be privy to. |
| if (version_.empty()) { |
| version_ = zip->Version(); |
| } |
| |
| // Trim redundant transitions. zic may have added these to work around |
| // differences between the glibc and reference implementations (see |
| // zic.c:dontmerge) and the Qt library (see zic.c:WORK_AROUND_QTBUG_53071). |
| // For us, they just get in the way when we do future_spec_ extension. |
| while (hdr.timecnt > 1) { |
| if (!EquivTransitions(transitions_[hdr.timecnt - 1].type_index, |
| transitions_[hdr.timecnt - 2].type_index)) { |
| break; |
| } |
| hdr.timecnt -= 1; |
| } |
| transitions_.resize(hdr.timecnt); |
| |
| // Ensure that there is always a transition in the first half of the |
| // time line (the second half is handled in ExtendTransitions()) so that |
| // the signed difference between a civil_second and the civil_second of |
| // its previous transition is always representable, without overflow. |
| // A contemporary zic will usually have already done this for us. |
| if (transitions_.empty() || transitions_.front().unix_time >= 0) { |
| Transition& tr(*transitions_.emplace(transitions_.begin())); |
| tr.unix_time = -(1LL << 59); // see tz/zic.c "BIG_BANG" |
| tr.type_index = default_transition_type_; |
| hdr.timecnt += 1; |
| } |
| |
| // Extend the transitions using the future specification. |
| ExtendTransitions(name, hdr); |
| |
| // Compute the local civil time for each transition and the preceding |
| // second. These will be used for reverse conversions in MakeTime(). |
| const TransitionType* ttp = &transition_types_[default_transition_type_]; |
| for (std::size_t i = 0; i != transitions_.size(); ++i) { |
| Transition& tr(transitions_[i]); |
| tr.prev_civil_sec = LocalTime(tr.unix_time, *ttp).cs - 1; |
| ttp = &transition_types_[tr.type_index]; |
| tr.civil_sec = LocalTime(tr.unix_time, *ttp).cs; |
| if (i != 0) { |
| // Check that the transitions are ordered by civil time. Essentially |
| // this means that an offset change cannot cross another such change. |
| // No one does this in practice, and we depend on it in MakeTime(). |
| if (!Transition::ByCivilTime()(transitions_[i - 1], tr)) |
| return false; // out of order |
| } |
| } |
| |
| // Compute the maximum/minimum civil times that can be converted to a |
| // time_point<seconds> for each of the zone's transition types. |
| for (auto& tt : transition_types_) { |
| tt.civil_max = LocalTime(seconds::max().count(), tt).cs; |
| tt.civil_min = LocalTime(seconds::min().count(), tt).cs; |
| } |
| |
| transitions_.shrink_to_fit(); |
| return true; |
| } |
| |
| namespace { |
| |
| // fopen(3) adaptor. |
| inline FILE* FOpen(const char* path, const char* mode) { |
| #if defined(_MSC_VER) |
| FILE* fp; |
| if (fopen_s(&fp, path, mode) != 0) fp = nullptr; |
| return fp; |
| #else |
| return fopen(path, mode); // TODO: Enable the close-on-exec flag. |
| #endif |
| } |
| |
| // A stdio(3)-backed implementation of ZoneInfoSource. |
| class FileZoneInfoSource : public ZoneInfoSource { |
| public: |
| static std::unique_ptr<ZoneInfoSource> Open(const std::string& name); |
| |
| std::size_t Read(void* ptr, std::size_t size) override { |
| size = std::min(size, len_); |
| std::size_t nread = fread(ptr, 1, size, fp_.get()); |
| len_ -= nread; |
| return nread; |
| } |
| int Skip(std::size_t offset) override { |
| offset = std::min(offset, len_); |
| int rc = fseek(fp_.get(), static_cast<long>(offset), SEEK_CUR); |
| if (rc == 0) len_ -= offset; |
| return rc; |
| } |
| std::string Version() const override { |
| // TODO: It would nice if the zoneinfo data included the tzdb version. |
| return std::string(); |
| } |
| |
| protected: |
| explicit FileZoneInfoSource( |
| FILE* fp, std::size_t len = std::numeric_limits<std::size_t>::max()) |
| : fp_(fp, fclose), len_(len) {} |
| |
| private: |
| std::unique_ptr<FILE, int(*)(FILE*)> fp_; |
| std::size_t len_; |
| }; |
| |
| std::unique_ptr<ZoneInfoSource> FileZoneInfoSource::Open( |
| const std::string& name) { |
| // Use of the "file:" prefix is intended for testing purposes only. |
| if (name.compare(0, 5, "file:") == 0) return Open(name.substr(5)); |
| |
| // Map the time-zone name to a path name. |
| std::string path; |
| if (name.empty() || name[0] != '/') { |
| const char* tzdir = "/usr/share/zoneinfo"; |
| char* tzdir_env = nullptr; |
| #if defined(_MSC_VER) |
| _dupenv_s(&tzdir_env, nullptr, "TZDIR"); |
| #else |
| tzdir_env = std::getenv("TZDIR"); |
| #endif |
| if (tzdir_env && *tzdir_env) tzdir = tzdir_env; |
| path += tzdir; |
| path += '/'; |
| #if defined(_MSC_VER) |
| free(tzdir_env); |
| #endif |
| } |
| path += name; |
| |
| // Open the zoneinfo file. |
| FILE* fp = FOpen(path.c_str(), "rb"); |
| if (fp == nullptr) return nullptr; |
| std::size_t length = 0; |
| if (fseek(fp, 0, SEEK_END) == 0) { |
| long pos = ftell(fp); |
| if (pos >= 0) { |
| length = static_cast<std::size_t>(pos); |
| } |
| rewind(fp); |
| } |
| return std::unique_ptr<ZoneInfoSource>(new FileZoneInfoSource(fp, length)); |
| } |
| |
| class AndroidZoneInfoSource : public FileZoneInfoSource { |
| public: |
| static std::unique_ptr<ZoneInfoSource> Open(const std::string& name); |
| std::string Version() const override { return version_; } |
| |
| private: |
| explicit AndroidZoneInfoSource(FILE* fp, std::size_t len, const char* vers) |
| : FileZoneInfoSource(fp, len), version_(vers) {} |
| std::string version_; |
| }; |
| |
| std::unique_ptr<ZoneInfoSource> AndroidZoneInfoSource::Open( |
| const std::string& name) { |
| // Use of the "file:" prefix is intended for testing purposes only. |
| if (name.compare(0, 5, "file:") == 0) return Open(name.substr(5)); |
| |
| // See Android's libc/tzcode/bionic.cpp for additional information. |
| for (const char* tzdata : {"/data/misc/zoneinfo/current/tzdata", |
| "/system/usr/share/zoneinfo/tzdata"}) { |
| std::unique_ptr<FILE, int (*)(FILE*)> fp(FOpen(tzdata, "rb"), fclose); |
| if (fp.get() == nullptr) continue; |
| |
| char hbuf[24]; // covers header.zonetab_offset too |
| if (fread(hbuf, 1, sizeof(hbuf), fp.get()) != sizeof(hbuf)) continue; |
| if (strncmp(hbuf, "tzdata", 6) != 0) continue; |
| const char* vers = (hbuf[11] == '\0') ? hbuf + 6 : ""; |
| const std::int_fast32_t index_offset = Decode32(hbuf + 12); |
| const std::int_fast32_t data_offset = Decode32(hbuf + 16); |
| if (index_offset < 0 || data_offset < index_offset) continue; |
| if (fseek(fp.get(), static_cast<long>(index_offset), SEEK_SET) != 0) |
| continue; |
| |
| char ebuf[52]; // covers entry.unused too |
| const std::size_t index_size = |
| static_cast<std::size_t>(data_offset - index_offset); |
| const std::size_t zonecnt = index_size / sizeof(ebuf); |
| if (zonecnt * sizeof(ebuf) != index_size) continue; |
| for (std::size_t i = 0; i != zonecnt; ++i) { |
| if (fread(ebuf, 1, sizeof(ebuf), fp.get()) != sizeof(ebuf)) break; |
| const std::int_fast32_t start = data_offset + Decode32(ebuf + 40); |
| const std::int_fast32_t length = Decode32(ebuf + 44); |
| if (start < 0 || length < 0) break; |
| ebuf[40] = '\0'; // ensure zone name is NUL terminated |
| if (strcmp(name.c_str(), ebuf) == 0) { |
| if (fseek(fp.get(), static_cast<long>(start), SEEK_SET) != 0) break; |
| return std::unique_ptr<ZoneInfoSource>(new AndroidZoneInfoSource( |
| fp.release(), static_cast<std::size_t>(length), vers)); |
| } |
| } |
| } |
| |
| return nullptr; |
| } |
| |
| } // namespace |
| |
| bool TimeZoneInfo::Load(const std::string& name) { |
| // We can ensure that the loading of UTC or any other fixed-offset |
| // zone never fails because the simple, fixed-offset state can be |
| // internally generated. Note that this depends on our choice to not |
| // accept leap-second encoded ("right") zoneinfo. |
| auto offset = seconds::zero(); |
| if (FixedOffsetFromName(name, &offset)) { |
| return ResetToBuiltinUTC(offset); |
| } |
| |
| // Find and use a ZoneInfoSource to load the named zone. |
| auto zip = cctz_extension::zone_info_source_factory( |
| name, [](const std::string& name) -> std::unique_ptr<ZoneInfoSource> { |
| if (auto zip = FileZoneInfoSource::Open(name)) return zip; |
| if (auto zip = AndroidZoneInfoSource::Open(name)) return zip; |
| return nullptr; |
| }); |
| return zip != nullptr && Load(name, zip.get()); |
| } |
| |
| // BreakTime() translation for a particular transition type. |
| time_zone::absolute_lookup TimeZoneInfo::LocalTime( |
| std::int_fast64_t unix_time, const TransitionType& tt) const { |
| // A civil time in "+offset" looks like (time+offset) in UTC. |
| // Note: We perform two additions in the civil_second domain to |
| // sidestep the chance of overflow in (unix_time + tt.utc_offset). |
| return {(civil_second() + unix_time) + tt.utc_offset, |
| tt.utc_offset, tt.is_dst, &abbreviations_[tt.abbr_index]}; |
| } |
| |
| // BreakTime() translation for a particular transition. |
| time_zone::absolute_lookup TimeZoneInfo::LocalTime( |
| std::int_fast64_t unix_time, const Transition& tr) const { |
| const TransitionType& tt = transition_types_[tr.type_index]; |
| // Note: (unix_time - tr.unix_time) will never overflow as we |
| // have ensured that there is always a "nearby" transition. |
| return {tr.civil_sec + (unix_time - tr.unix_time), // TODO: Optimize. |
| tt.utc_offset, tt.is_dst, &abbreviations_[tt.abbr_index]}; |
| } |
| |
| // MakeTime() translation with a conversion-preserving +N * 400-year shift. |
| time_zone::civil_lookup TimeZoneInfo::TimeLocal(const civil_second& cs, |
| year_t c4_shift) const { |
| assert(last_year_ - 400 < cs.year() && cs.year() <= last_year_); |
| time_zone::civil_lookup cl = MakeTime(cs); |
| if (c4_shift > seconds::max().count() / kSecsPer400Years) { |
| cl.pre = cl.trans = cl.post = time_point<seconds>::max(); |
| } else { |
| const auto offset = seconds(c4_shift * kSecsPer400Years); |
| const auto limit = time_point<seconds>::max() - offset; |
| for (auto* tp : {&cl.pre, &cl.trans, &cl.post}) { |
| if (*tp > limit) { |
| *tp = time_point<seconds>::max(); |
| } else { |
| *tp += offset; |
| } |
| } |
| } |
| return cl; |
| } |
| |
| time_zone::absolute_lookup TimeZoneInfo::BreakTime( |
| const time_point<seconds>& tp) const { |
| std::int_fast64_t unix_time = ToUnixSeconds(tp); |
| const std::size_t timecnt = transitions_.size(); |
| assert(timecnt != 0); // We always add a transition. |
| |
| if (unix_time < transitions_[0].unix_time) { |
| return LocalTime(unix_time, transition_types_[default_transition_type_]); |
| } |
| if (unix_time >= transitions_[timecnt - 1].unix_time) { |
| // After the last transition. If we extended the transitions using |
| // future_spec_, shift back to a supported year using the 400-year |
| // cycle of calendaric equivalence and then compensate accordingly. |
| if (extended_) { |
| const std::int_fast64_t diff = |
| unix_time - transitions_[timecnt - 1].unix_time; |
| const year_t shift = diff / kSecsPer400Years + 1; |
| const auto d = seconds(shift * kSecsPer400Years); |
| time_zone::absolute_lookup al = BreakTime(tp - d); |
| al.cs = YearShift(al.cs, shift * 400); |
| return al; |
| } |
| return LocalTime(unix_time, transitions_[timecnt - 1]); |
| } |
| |
| const std::size_t hint = local_time_hint_.load(std::memory_order_relaxed); |
| if (0 < hint && hint < timecnt) { |
| if (transitions_[hint - 1].unix_time <= unix_time) { |
| if (unix_time < transitions_[hint].unix_time) { |
| return LocalTime(unix_time, transitions_[hint - 1]); |
| } |
| } |
| } |
| |
| const Transition target = {unix_time, 0, civil_second(), civil_second()}; |
| const Transition* begin = &transitions_[0]; |
| const Transition* tr = std::upper_bound(begin, begin + timecnt, target, |
| Transition::ByUnixTime()); |
| local_time_hint_.store(static_cast<std::size_t>(tr - begin), |
| std::memory_order_relaxed); |
| return LocalTime(unix_time, *--tr); |
| } |
| |
| time_zone::civil_lookup TimeZoneInfo::MakeTime(const civil_second& cs) const { |
| const std::size_t timecnt = transitions_.size(); |
| assert(timecnt != 0); // We always add a transition. |
| |
| // Find the first transition after our target civil time. |
| const Transition* tr = nullptr; |
| const Transition* begin = &transitions_[0]; |
| const Transition* end = begin + timecnt; |
| if (cs < begin->civil_sec) { |
| tr = begin; |
| } else if (cs >= transitions_[timecnt - 1].civil_sec) { |
| tr = end; |
| } else { |
| const std::size_t hint = time_local_hint_.load(std::memory_order_relaxed); |
| if (0 < hint && hint < timecnt) { |
| if (transitions_[hint - 1].civil_sec <= cs) { |
| if (cs < transitions_[hint].civil_sec) { |
| tr = begin + hint; |
| } |
| } |
| } |
| if (tr == nullptr) { |
| const Transition target = {0, 0, cs, civil_second()}; |
| tr = std::upper_bound(begin, end, target, Transition::ByCivilTime()); |
| time_local_hint_.store(static_cast<std::size_t>(tr - begin), |
| std::memory_order_relaxed); |
| } |
| } |
| |
| if (tr == begin) { |
| if (tr->prev_civil_sec >= cs) { |
| // Before first transition, so use the default offset. |
| const TransitionType& tt(transition_types_[default_transition_type_]); |
| if (cs < tt.civil_min) return MakeUnique(time_point<seconds>::min()); |
| return MakeUnique(cs - (civil_second() + tt.utc_offset)); |
| } |
| // tr->prev_civil_sec < cs < tr->civil_sec |
| return MakeSkipped(*tr, cs); |
| } |
| |
| if (tr == end) { |
| if (cs > (--tr)->prev_civil_sec) { |
| // After the last transition. If we extended the transitions using |
| // future_spec_, shift back to a supported year using the 400-year |
| // cycle of calendaric equivalence and then compensate accordingly. |
| if (extended_ && cs.year() > last_year_) { |
| const year_t shift = (cs.year() - last_year_ - 1) / 400 + 1; |
| return TimeLocal(YearShift(cs, shift * -400), shift); |
| } |
| const TransitionType& tt(transition_types_[tr->type_index]); |
| if (cs > tt.civil_max) return MakeUnique(time_point<seconds>::max()); |
| return MakeUnique(tr->unix_time + (cs - tr->civil_sec)); |
| } |
| // tr->civil_sec <= cs <= tr->prev_civil_sec |
| return MakeRepeated(*tr, cs); |
| } |
| |
| if (tr->prev_civil_sec < cs) { |
| // tr->prev_civil_sec < cs < tr->civil_sec |
| return MakeSkipped(*tr, cs); |
| } |
| |
| if (cs <= (--tr)->prev_civil_sec) { |
| // tr->civil_sec <= cs <= tr->prev_civil_sec |
| return MakeRepeated(*tr, cs); |
| } |
| |
| // In between transitions. |
| return MakeUnique(tr->unix_time + (cs - tr->civil_sec)); |
| } |
| |
| std::string TimeZoneInfo::Version() const { |
| return version_; |
| } |
| |
| std::string TimeZoneInfo::Description() const { |
| std::ostringstream oss; |
| oss << "#trans=" << transitions_.size(); |
| oss << " #types=" << transition_types_.size(); |
| oss << " spec='" << future_spec_ << "'"; |
| return oss.str(); |
| } |
| |
| bool TimeZoneInfo::NextTransition(const time_point<seconds>& tp, |
| time_zone::civil_transition* trans) const { |
| if (transitions_.empty()) return false; |
| const Transition* begin = &transitions_[0]; |
| const Transition* end = begin + transitions_.size(); |
| if (begin->unix_time <= -(1LL << 59)) { |
| // Do not report the BIG_BANG found in recent zoneinfo data as it is |
| // really a sentinel, not a transition. See tz/zic.c. |
| ++begin; |
| } |
| std::int_fast64_t unix_time = ToUnixSeconds(tp); |
| const Transition target = {unix_time, 0, civil_second(), civil_second()}; |
| const Transition* tr = std::upper_bound(begin, end, target, |
| Transition::ByUnixTime()); |
| for (; tr != end; ++tr) { // skip no-op transitions |
| std::uint_fast8_t prev_type_index = |
| (tr == begin) ? default_transition_type_ : tr[-1].type_index; |
| if (!EquivTransitions(prev_type_index, tr[0].type_index)) break; |
| } |
| // When tr == end we return false, ignoring future_spec_. |
| if (tr == end) return false; |
| trans->from = tr->prev_civil_sec + 1; |
| trans->to = tr->civil_sec; |
| return true; |
| } |
| |
| bool TimeZoneInfo::PrevTransition(const time_point<seconds>& tp, |
| time_zone::civil_transition* trans) const { |
| if (transitions_.empty()) return false; |
| const Transition* begin = &transitions_[0]; |
| const Transition* end = begin + transitions_.size(); |
| if (begin->unix_time <= -(1LL << 59)) { |
| // Do not report the BIG_BANG found in recent zoneinfo data as it is |
| // really a sentinel, not a transition. See tz/zic.c. |
| ++begin; |
| } |
| std::int_fast64_t unix_time = ToUnixSeconds(tp); |
| if (FromUnixSeconds(unix_time) != tp) { |
| if (unix_time == std::numeric_limits<std::int_fast64_t>::max()) { |
| if (end == begin) return false; // Ignore future_spec_. |
| trans->from = (--end)->prev_civil_sec + 1; |
| trans->to = end->civil_sec; |
| return true; |
| } |
| unix_time += 1; // ceils |
| } |
| const Transition target = {unix_time, 0, civil_second(), civil_second()}; |
| const Transition* tr = std::lower_bound(begin, end, target, |
| Transition::ByUnixTime()); |
| for (; tr != begin; --tr) { // skip no-op transitions |
| std::uint_fast8_t prev_type_index = |
| (tr - 1 == begin) ? default_transition_type_ : tr[-2].type_index; |
| if (!EquivTransitions(prev_type_index, tr[-1].type_index)) break; |
| } |
| // When tr == end we return the "last" transition, ignoring future_spec_. |
| if (tr == begin) return false; |
| trans->from = (--tr)->prev_civil_sec + 1; |
| trans->to = tr->civil_sec; |
| return true; |
| } |
| |
| } // namespace cctz |
| } // namespace time_internal |
| } // inline namespace lts_2019_08_08 |
| } // namespace absl |