diff options
Diffstat (limited to 'third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.cc')
| -rw-r--r-- | third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.cc | 958 |
1 files changed, 0 insertions, 958 deletions
diff --git a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.cc b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.cc deleted file mode 100644 index 665fb424fe..0000000000 --- a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.cc +++ /dev/null @@ -1,958 +0,0 @@ -// 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/base/config.h" -#include "absl/time/internal/cctz/include/cctz/civil_time.h" -#include "time_zone_fixed.h" -#include "time_zone_posix.h" - -namespace absl { -ABSL_NAMESPACE_BEGIN -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 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. - const std::size_t pos = (name.compare(0, 5, "file:") == 0) ? 5 : 0; - - // Map the time-zone name to a path name. - std::string path; - if (pos == name.size() || name[pos] != '/') { - 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.append(name, pos, std::string::npos); - - // 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 offset = ftell(fp); - if (offset >= 0) { - length = static_cast<std::size_t>(offset); - } - 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. - const std::size_t pos = (name.compare(0, 5, "file:") == 0) ? 5 : 0; - - // 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() + pos, 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 -ABSL_NAMESPACE_END -} // namespace absl |