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Diffstat (limited to 'absl/time/internal/cctz/src/time_zone_info.cc')
-rw-r--r--absl/time/internal/cctz/src/time_zone_info.cc265
1 files changed, 136 insertions, 129 deletions
diff --git a/absl/time/internal/cctz/src/time_zone_info.cc b/absl/time/internal/cctz/src/time_zone_info.cc
index f1697cdf..8039353e 100644
--- a/absl/time/internal/cctz/src/time_zone_info.cc
+++ b/absl/time/internal/cctz/src/time_zone_info.cc
@@ -40,7 +40,6 @@
#include <cstdlib>
#include <cstring>
#include <functional>
-#include <iostream>
#include <memory>
#include <sstream>
#include <string>
@@ -83,6 +82,27 @@ const std::int_least32_t kSecsPerYear[2] = {
366 * kSecsPerDay,
};
+// Convert a cctz::weekday to a POSIX TZ weekday number (0==Sun, ..., 6=Sat).
+inline int ToPosixWeekday(weekday wd) {
+ switch (wd) {
+ case weekday::sunday:
+ return 0;
+ case weekday::monday:
+ return 1;
+ case weekday::tuesday:
+ return 2;
+ case weekday::wednesday:
+ return 3;
+ case weekday::thursday:
+ return 4;
+ case weekday::friday:
+ return 5;
+ case weekday::saturday:
+ return 6;
+ }
+ return 0; /*NOTREACHED*/
+}
+
// 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;
@@ -188,15 +208,13 @@ bool TimeZoneInfo::ResetToBuiltinUTC(const seconds& offset) {
tt.is_dst = false;
tt.abbr_index = 0;
- // We temporarily add some redundant, contemporary (2013 through 2023)
+ // We temporarily add some redundant, contemporary (2015 through 2025)
// 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
+ -(1LL << 59), // a "first half" transition
1420070400LL, // 2015-01-01T00:00:00+00:00
1451606400LL, // 2016-01-01T00:00:00+00:00
1483228800LL, // 2017-01-01T00:00:00+00:00
@@ -206,7 +224,8 @@ bool TimeZoneInfo::ResetToBuiltinUTC(const seconds& offset) {
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
+ 1704067200LL, // 2024-01-01T00:00:00+00:00
+ 1735689600LL, // 2025-01-01T00:00:00+00:00
}) {
Transition& tr(*transitions_.emplace(transitions_.end()));
tr.unix_time = unix_time;
@@ -217,8 +236,8 @@ bool TimeZoneInfo::ResetToBuiltinUTC(const seconds& offset) {
default_transition_type_ = 0;
abbreviations_ = FixedOffsetToAbbr(offset);
- abbreviations_.append(1, '\0'); // add NUL
- future_spec_.clear(); // never needed for a fixed-offset zone
+ abbreviations_.append(1, '\0');
+ future_spec_.clear(); // never needed for a fixed-offset zone
extended_ = false;
tt.civil_max = LocalTime(seconds::max().count(), tt).cs;
@@ -259,21 +278,6 @@ std::size_t TimeZoneInfo::Header::DataLength(std::size_t time_len) const {
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).
@@ -282,117 +286,108 @@ bool TimeZoneInfo::EquivTransitions(std::uint_fast8_t tt1_index,
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.is_dst != tt2.is_dst) return false;
if (tt1.abbr_index != tt2.abbr_index) return false;
return true;
}
+// Find/make a transition type with these attributes.
+bool TimeZoneInfo::GetTransitionType(std::int_fast32_t utc_offset, bool is_dst,
+ const std::string& abbr,
+ std::uint_least8_t* index) {
+ std::size_t type_index = 0;
+ std::size_t abbr_index = abbreviations_.size();
+ for (; type_index != transition_types_.size(); ++type_index) {
+ const TransitionType& tt(transition_types_[type_index]);
+ const char* tt_abbr = &abbreviations_[tt.abbr_index];
+ if (tt_abbr == abbr) abbr_index = tt.abbr_index;
+ if (tt.utc_offset == utc_offset && tt.is_dst == is_dst) {
+ if (abbr_index == tt.abbr_index) break; // reuse
+ }
+ }
+ if (type_index > 255 || abbr_index > 255) {
+ // No index space (8 bits) available for a new type or abbreviation.
+ return false;
+ }
+ if (type_index == transition_types_.size()) {
+ TransitionType& tt(*transition_types_.emplace(transition_types_.end()));
+ tt.utc_offset = static_cast<std::int_least32_t>(utc_offset);
+ tt.is_dst = is_dst;
+ if (abbr_index == abbreviations_.size()) {
+ abbreviations_.append(abbr);
+ abbreviations_.append(1, '\0');
+ }
+ tt.abbr_index = static_cast<std::uint_least8_t>(abbr_index);
+ }
+ *index = static_cast<std::uint_least8_t>(type_index);
+ 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) {
+bool TimeZoneInfo::ExtendTransitions() {
extended_ = false;
- bool extending = !future_spec_.empty();
+ if (future_spec_.empty()) return true; // last transition prevails
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
+ if (!ParsePosixSpec(future_spec_, &posix)) return false;
+
+ // Find transition type for the future std specification.
+ std::uint_least8_t std_ti;
+ if (!GetTransitionType(posix.std_offset, false, posix.std_abbr, &std_ti))
+ return false;
+
+ if (posix.dst_abbr.empty()) { // std only
+ // The future specification should match the last transition, and
+ // that means that handling the future will fall out naturally.
+ return EquivTransitions(transitions_.back().type_index, std_ti);
}
+ // Find transition type for the future dst specification.
+ std::uint_least8_t dst_ti;
+ if (!GetTransitionType(posix.dst_offset, true, posix.dst_abbr, &dst_ti))
+ return false;
+
// 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);
+ // We may need two additional transitions for the current year.
+ transitions_.reserve(transitions_.size() + 400 * 2 + 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();
+ const Transition& last(transitions_.back());
+ const std::int_fast64_t last_time = last.unix_time;
+ const TransitionType& last_tt(transition_types_[last.type_index]);
+ last_year_ = LocalTime(last_time, last_tt).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
+ const civil_second jan1(last_year_);
+ std::int_fast64_t jan1_time = jan1 - civil_second();
+ int jan1_weekday = ToPosixWeekday(get_weekday(jan1));
+
+ Transition dst = {0, dst_ti, civil_second(), civil_second()};
+ Transition std = {0, std_ti, civil_second(), civil_second()};
+ for (const year_t limit = last_year_ + 400;; ++last_year_) {
+ auto dst_trans_off = TransOffset(leap_year, jan1_weekday, posix.dst_start);
+ auto std_trans_off = TransOffset(leap_year, jan1_weekday, posix.dst_end);
+ dst.unix_time = jan1_time + dst_trans_off - posix.std_offset;
+ std.unix_time = jan1_time + std_trans_off - posix.dst_offset;
+ const auto* ta = dst.unix_time < std.unix_time ? &dst : &std;
+ const auto* tb = dst.unix_time < std.unix_time ? &std : &dst;
+ if (last_time < tb->unix_time) {
+ if (last_time < ta->unix_time) transitions_.push_back(*ta);
+ transitions_.push_back(*tb);
+ }
+ if (last_year_ == limit) break;
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());
+ leap_year = !leap_year && IsLeap(last_year_ + 1);
+ }
+
+ return true;
}
-bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
+bool TimeZoneInfo::Load(ZoneInfoSource* zip) {
// Read and validate the header.
tzhead tzh;
if (zip->Read(&tzh, sizeof(tzh)) != sizeof(tzh)) return false;
@@ -430,7 +425,7 @@ bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
const char* bp = tbuf.data();
// Decode and validate the transitions.
- transitions_.reserve(hdr.timecnt + 2); // We might add a couple.
+ transitions_.reserve(hdr.timecnt + 2);
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);
@@ -449,6 +444,7 @@ bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
}
// Decode and validate the transition types.
+ transition_types_.reserve(hdr.typecnt + 2);
transition_types_.resize(hdr.typecnt);
for (std::size_t i = 0; i != hdr.typecnt; ++i) {
transition_types_[i].utc_offset =
@@ -475,6 +471,7 @@ bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
}
// Copy all the abbreviations.
+ abbreviations_.reserve(hdr.charcnt + 10);
abbreviations_.assign(bp, hdr.charcnt);
bp += hdr.charcnt;
@@ -506,7 +503,7 @@ bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
// 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.
+ // ZoneInfoSource for any out-of-bound version string it may be privy to.
if (version_.empty()) {
version_ = zip->Version();
}
@@ -525,19 +522,29 @@ bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
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.
+ // time line (the second half is handled below) so that the signed
+ // difference between a civil_second and the civil_second of its
+ // previous transition is always representable, without overflow.
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.unix_time = -(1LL << 59); // -18267312070-10-26T17:01:52+00:00
tr.type_index = default_transition_type_;
- hdr.timecnt += 1;
}
// Extend the transitions using the future specification.
- ExtendTransitions(name, hdr);
+ if (!ExtendTransitions()) return false;
+
+ // Ensure that there is always a transition in the second half of the
+ // time line (the first half is handled above) 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;
+ }
// Compute the local civil time for each transition and the preceding
// second. These will be used for reverse conversions in MakeTime().
@@ -718,12 +725,12 @@ bool TimeZoneInfo::Load(const std::string& name) {
// 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;
+ name, [](const std::string& n) -> std::unique_ptr<ZoneInfoSource> {
+ if (auto z = FileZoneInfoSource::Open(n)) return z;
+ if (auto z = AndroidZoneInfoSource::Open(n)) return z;
return nullptr;
});
- return zip != nullptr && Load(name, zip.get());
+ return zip != nullptr && Load(zip.get());
}
// BreakTime() translation for a particular transition type.
@@ -897,8 +904,8 @@ bool TimeZoneInfo::NextTransition(const time_point<seconds>& tp,
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.
+ // Do not report the BIG_BANG found in some zoneinfo data as it is
+ // really a sentinel, not a transition. See pre-2018f tz/zic.c.
++begin;
}
std::int_fast64_t unix_time = ToUnixSeconds(tp);
@@ -923,8 +930,8 @@ bool TimeZoneInfo::PrevTransition(const time_point<seconds>& tp,
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.
+ // Do not report the BIG_BANG found in some zoneinfo data as it is
+ // really a sentinel, not a transition. See pre-2018f tz/zic.c.
++begin;
}
std::int_fast64_t unix_time = ToUnixSeconds(tp);
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-04 12:18:46 +0000