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abseil-cpp
Commit d65595c8 by Gennadiy Rozental Committed by Copybara-Service
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Import of CCTZ from GitHub. 

PiperOrigin-RevId: 543896343
Change-Id: Ia91b3e082b764b750bbbe9a3ce63192263d51438
parent e6c09ae4
Showing with 361 additions and 326 deletions
absl/time/internal/cctz/include/cctz/time_zone.h
......@@ -23,6 +23,7 @@
#include <chrono>
#include <cstdint>
#include <limits>
#include <ratio> // NOLINT: We use std::ratio in this header
#include <string>
#include <utility>
......
absl/time/internal/cctz/src/time_zone_format.cc
......@@ -14,15 +14,13 @@
#if !defined(HAS_STRPTIME)
#if !defined(_MSC_VER) && !defined(__MINGW32__) && !defined(__VXWORKS__)
#define HAS_STRPTIME \
1 // assume everyone has strptime() except windows
// and VxWorks
#define HAS_STRPTIME 1 // Assume everyone else has strptime().
#endif
#endif
#if defined(HAS_STRPTIME) && HAS_STRPTIME
#if !defined(_XOPEN_SOURCE) && !defined(__OpenBSD__)
#define _XOPEN_SOURCE // Definedness suffices for strptime.
#define _XOPEN_SOURCE // Definedness suffices for strptime().
#endif
#endif
......
absl/time/internal/cctz/src/time_zone_if.cc
......@@ -23,19 +23,19 @@ ABSL_NAMESPACE_BEGIN
namespace time_internal {
namespace cctz {
std::unique_ptr<TimeZoneIf> TimeZoneIf::Load(const std::string& name) {
std::unique_ptr<TimeZoneIf> TimeZoneIf::UTC() { return TimeZoneInfo::UTC(); }
std::unique_ptr<TimeZoneIf> TimeZoneIf::Make(const std::string& name) {
// Support "libc:localtime" and "libc:*" to access the legacy
// localtime and UTC support respectively from the C library.
// NOTE: The "libc:*" zones are internal, test-only interfaces, and
// are subject to change/removal without notice. Do not use them.
if (name.compare(0, 5, "libc:") == 0) {
return std::unique_ptr<TimeZoneIf>(new TimeZoneLibC(name.substr(5)));
return TimeZoneLibC::Make(name.substr(5));
}
// Otherwise use the "zoneinfo" implementation by default.
std::unique_ptr<TimeZoneInfo> tz(new TimeZoneInfo);
if (!tz->Load(name)) tz.reset();
return std::unique_ptr<TimeZoneIf>(tz.release());
// Otherwise use the "zoneinfo" implementation.
return TimeZoneInfo::Make(name);
}
// Defined out-of-line to avoid emitting a weak vtable in all TUs.
......
absl/time/internal/cctz/src/time_zone_if.h
......@@ -33,8 +33,9 @@ namespace cctz {
// Subclasses implement the functions for civil-time conversions in the zone.
class TimeZoneIf {
public:
// A factory function for TimeZoneIf implementations.
static std::unique_ptr<TimeZoneIf> Load(const std::string& name);
// Factory functions for TimeZoneIf implementations.
static std::unique_ptr<TimeZoneIf> UTC(); // never fails
static std::unique_ptr<TimeZoneIf> Make(const std::string& name);
virtual ~TimeZoneIf();
......@@ -51,7 +52,9 @@ class TimeZoneIf {
virtual std::string Description() const = 0;
protected:
TimeZoneIf() {}
TimeZoneIf() = default;
TimeZoneIf(const TimeZoneIf&) = delete;
TimeZoneIf& operator=(const TimeZoneIf&) = delete;
};
// Convert between time_point<seconds> and a count of seconds since the
......
absl/time/internal/cctz/src/time_zone_impl.cc
......@@ -99,11 +99,13 @@ void time_zone::Impl::ClearTimeZoneMapTestOnly() {
}
}
time_zone::Impl::Impl() : name_("UTC"), zone_(TimeZoneIf::UTC()) {}
time_zone::Impl::Impl(const std::string& name)
: name_(name), zone_(TimeZoneIf::Load(name_)) {}
: name_(name), zone_(TimeZoneIf::Make(name_)) {}
const time_zone::Impl* time_zone::Impl::UTCImpl() {
static const Impl* utc_impl = new Impl("UTC"); // never fails
static const Impl* utc_impl = new Impl;
return utc_impl;
}
......
absl/time/internal/cctz/src/time_zone_impl.h
......@@ -78,7 +78,11 @@ class time_zone::Impl {
std::string Description() const { return zone_->Description(); }
private:
Impl();
explicit Impl(const std::string& name);
Impl(const Impl&) = delete;
Impl& operator=(const Impl&) = delete;
static const Impl* UTCImpl();
const std::string name_;
......
absl/time/internal/cctz/src/time_zone_info.cc
......@@ -134,6 +134,49 @@ std::int_fast64_t Decode64(const char* cp) {
return static_cast<std::int_fast64_t>(v - s64maxU - 1) - s64max - 1;
}
struct Header { // counts of:
std::size_t timecnt; // transition times
std::size_t typecnt; // transition types
std::size_t charcnt; // zone abbreviation characters
std::size_t leapcnt; // leap seconds (we expect none)
std::size_t ttisstdcnt; // UTC/local indicators (unused)
std::size_t ttisutcnt; // standard/wall indicators (unused)
bool Build(const tzhead& tzh);
std::size_t DataLength(std::size_t time_len) const;
};
// Builds the in-memory header using the raw bytes from the file.
bool 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 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;
}
// Does the rule for future transitions call for year-round daylight time?
// See tz/zic.c:stringzone() for the details on how such rules are encoded.
bool AllYearDST(const PosixTimeZone& posix) {
......@@ -217,98 +260,6 @@ inline civil_second YearShift(const civil_second& cs, year_t shift) {
} // 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 (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), // 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
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
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;
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');
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;
}
// 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.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,
......@@ -341,6 +292,20 @@ bool TimeZoneInfo::GetTransitionType(std::int_fast32_t utc_offset, bool is_dst,
return true;
}
// 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.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;
}
// Use the POSIX-TZ-environment-variable-style string to handle times
// in years after the last transition stored in the zoneinfo data.
bool TimeZoneInfo::ExtendTransitions() {
......@@ -394,206 +359,19 @@ bool TimeZoneInfo::ExtendTransitions() {
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_ + 1);
}
return true;
}
bool TimeZoneInfo::Load(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);
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_.reserve(hdr.typecnt + 2);
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_.reserve(hdr.charcnt + 10);
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 += (time_len + 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) or to avoid bugs in old readers. 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 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); // -18267312070-10-26T17:01:52+00:00
tr.type_index = default_transition_type_;
}
// Extend the transitions using the future specification.
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().
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
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_ + 1);
}
// 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;
}
......@@ -795,6 +573,240 @@ std::unique_ptr<ZoneInfoSource> FuchsiaZoneInfoSource::Open(
} // 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 (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), // 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
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
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;
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');
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;
}
bool TimeZoneInfo::Load(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);
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_.reserve(hdr.typecnt + 2);
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_.reserve(hdr.charcnt + 10);
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 += (time_len + 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) or to avoid bugs in old readers. 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 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); // -18267312070-10-26T17:01:52+00:00
tr.type_index = default_transition_type_;
}
// Extend the transitions using the future specification.
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().
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;
}
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
......@@ -816,6 +828,18 @@ bool TimeZoneInfo::Load(const std::string& name) {
return zip != nullptr && Load(zip.get());
}
std::unique_ptr<TimeZoneInfo> TimeZoneInfo::UTC() {
auto tz = std::unique_ptr<TimeZoneInfo>(new TimeZoneInfo);
tz->ResetToBuiltinUTC(seconds::zero());
return tz;
}
std::unique_ptr<TimeZoneInfo> TimeZoneInfo::Make(const std::string& name) {
auto tz = std::unique_ptr<TimeZoneInfo>(new TimeZoneInfo);
if (!tz->Load(name)) tz.reset(); // fallback to UTC
return tz;
}
// BreakTime() translation for a particular transition type.
time_zone::absolute_lookup TimeZoneInfo::LocalTime(
std::int_fast64_t unix_time, const TransitionType& tt) const {
......
absl/time/internal/cctz/src/time_zone_info.h
......@@ -18,6 +18,7 @@
#include <atomic>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <string>
#include <vector>
......@@ -64,12 +65,9 @@ struct TransitionType {
// A time zone backed by the IANA Time Zone Database (zoneinfo).
class TimeZoneInfo : public TimeZoneIf {
public:
TimeZoneInfo() = default;
TimeZoneInfo(const TimeZoneInfo&) = delete;
TimeZoneInfo& operator=(const TimeZoneInfo&) = delete;
// Loads the zoneinfo for the given name, returning true if successful.
bool Load(const std::string& name);
// Factories.
static std::unique_ptr<TimeZoneInfo> UTC(); // never fails
static std::unique_ptr<TimeZoneInfo> Make(const std::string& name);
// TimeZoneIf implementations.
time_zone::absolute_lookup BreakTime(
......@@ -83,17 +81,9 @@ class TimeZoneInfo : public TimeZoneIf {
std::string Description() const override;
private:
struct Header { // counts of:
std::size_t timecnt; // transition times
std::size_t typecnt; // transition types
std::size_t charcnt; // zone abbreviation characters
std::size_t leapcnt; // leap seconds (we expect none)
std::size_t ttisstdcnt; // UTC/local indicators (unused)
std::size_t ttisutcnt; // standard/wall indicators (unused)
bool Build(const tzhead& tzh);
std::size_t DataLength(std::size_t time_len) const;
};
TimeZoneInfo() = default;
TimeZoneInfo(const TimeZoneInfo&) = delete;
TimeZoneInfo& operator=(const TimeZoneInfo&) = delete;
bool GetTransitionType(std::int_fast32_t utc_offset, bool is_dst,
const std::string& abbr, std::uint_least8_t* index);
......@@ -102,6 +92,7 @@ class TimeZoneInfo : public TimeZoneIf {
bool ExtendTransitions();
bool ResetToBuiltinUTC(const seconds& offset);
bool Load(const std::string& name);
bool Load(ZoneInfoSource* zip);
// Helpers for BreakTime() and MakeTime().
......
absl/time/internal/cctz/src/time_zone_libc.cc
......@@ -62,7 +62,7 @@ auto tm_zone(const std::tm& tm) -> decltype(tzname[0]) {
}
#elif defined(__native_client__) || defined(__myriad2__) || \
defined(__EMSCRIPTEN__)
// Uses the globals: 'timezone' and 'tzname'.
// Uses the globals: '_timezone' and 'tzname'.
auto tm_gmtoff(const std::tm& tm) -> decltype(_timezone + 0) {
const bool is_dst = tm.tm_isdst > 0;
return _timezone + (is_dst ? 60 * 60 : 0);
......@@ -193,8 +193,9 @@ std::time_t find_trans(std::time_t lo, std::time_t hi, tm_gmtoff_t offset) {
} // namespace
TimeZoneLibC::TimeZoneLibC(const std::string& name)
: local_(name == "localtime") {}
std::unique_ptr<TimeZoneLibC> TimeZoneLibC::Make(const std::string& name) {
return std::unique_ptr<TimeZoneLibC>(new TimeZoneLibC(name));
}
time_zone::absolute_lookup TimeZoneLibC::BreakTime(
const time_point<seconds>& tp) const {
......@@ -323,6 +324,9 @@ std::string TimeZoneLibC::Description() const {
return local_ ? "localtime" : "UTC";
}
TimeZoneLibC::TimeZoneLibC(const std::string& name)
: local_(name == "localtime") {}
} // namespace cctz
} // namespace time_internal
ABSL_NAMESPACE_END
......
absl/time/internal/cctz/src/time_zone_libc.h
......@@ -27,10 +27,10 @@ namespace cctz {
// A time zone backed by gmtime_r(3), localtime_r(3), and mktime(3),
// and which therefore only supports UTC and the local time zone.
// TODO: Add support for fixed offsets from UTC.
class TimeZoneLibC : public TimeZoneIf {
public:
explicit TimeZoneLibC(const std::string& name);
// Factory.
static std::unique_ptr<TimeZoneLibC> Make(const std::string& name);
// TimeZoneIf implementations.
time_zone::absolute_lookup BreakTime(
......@@ -44,6 +44,10 @@ class TimeZoneLibC : public TimeZoneIf {
std::string Description() const override;
private:
explicit TimeZoneLibC(const std::string& name);
TimeZoneLibC(const TimeZoneLibC&) = delete;
TimeZoneLibC& operator=(const TimeZoneLibC&) = delete;
const bool local_; // localtime or UTC
};
......
absl/time/internal/cctz/src/time_zone_lookup_test.cc
......@@ -734,6 +734,10 @@ TEST(TimeZone, UTC) {
time_zone loaded_utc0;
EXPECT_TRUE(load_time_zone("UTC0", &loaded_utc0));
EXPECT_EQ(loaded_utc0, utc);
time_zone loaded_bad;
EXPECT_FALSE(load_time_zone("Invalid/TimeZone", &loaded_bad));
EXPECT_EQ(loaded_bad, utc);
}
TEST(TimeZone, NamedTimeZones) {
......
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