diff options
Diffstat (limited to 'absl/time/internal/cctz/src/time_zone_format.cc')
| -rw-r--r-- | absl/time/internal/cctz/src/time_zone_format.cc | 848 |
1 files changed, 848 insertions, 0 deletions
diff --git a/absl/time/internal/cctz/src/time_zone_format.cc b/absl/time/internal/cctz/src/time_zone_format.cc new file mode 100644 index 000000000000..6d5ccba1ce49 --- /dev/null +++ b/absl/time/internal/cctz/src/time_zone_format.cc @@ -0,0 +1,848 @@ +// 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 +// +// http://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. + +#if !defined(HAS_STRPTIME) +# if !defined(_MSC_VER) +# define HAS_STRPTIME 1 // assume everyone has strptime() except windows +# endif +#endif + +#include "absl/time/internal/cctz/include/cctz/time_zone.h" + +#include <cctype> +#include <chrono> +#include <cstddef> +#include <cstdint> +#include <cstring> +#include <ctime> +#include <limits> +#include <string> +#include <vector> +#if !HAS_STRPTIME +#include <iomanip> +#include <sstream> +#endif + +#include "absl/time/internal/cctz/include/cctz/civil_time.h" +#include "time_zone_if.h" + +namespace absl { +namespace time_internal { +namespace cctz { +namespace detail { + +namespace { + +#if !HAS_STRPTIME +// Build a strptime() using C++11's std::get_time(). +char* strptime(const char* s, const char* fmt, std::tm* tm) { + std::istringstream input(s); + input >> std::get_time(tm, fmt); + if (input.fail()) return nullptr; + return const_cast<char*>(s) + + (input.eof() ? strlen(s) : static_cast<std::size_t>(input.tellg())); +} +#endif + +std::tm ToTM(const time_zone::absolute_lookup& al) { + std::tm tm{}; + tm.tm_sec = al.cs.second(); + tm.tm_min = al.cs.minute(); + tm.tm_hour = al.cs.hour(); + tm.tm_mday = al.cs.day(); + tm.tm_mon = al.cs.month() - 1; + + // Saturate tm.tm_year is cases of over/underflow. + if (al.cs.year() < std::numeric_limits<int>::min() + 1900) { + tm.tm_year = std::numeric_limits<int>::min(); + } else if (al.cs.year() - 1900 > std::numeric_limits<int>::max()) { + tm.tm_year = std::numeric_limits<int>::max(); + } else { + tm.tm_year = static_cast<int>(al.cs.year() - 1900); + } + + switch (get_weekday(civil_day(al.cs))) { + case weekday::sunday: + tm.tm_wday = 0; + break; + case weekday::monday: + tm.tm_wday = 1; + break; + case weekday::tuesday: + tm.tm_wday = 2; + break; + case weekday::wednesday: + tm.tm_wday = 3; + break; + case weekday::thursday: + tm.tm_wday = 4; + break; + case weekday::friday: + tm.tm_wday = 5; + break; + case weekday::saturday: + tm.tm_wday = 6; + break; + } + tm.tm_yday = get_yearday(civil_day(al.cs)) - 1; + tm.tm_isdst = al.is_dst ? 1 : 0; + return tm; +} + +const char kDigits[] = "0123456789"; + +// Formats a 64-bit integer in the given field width. Note that it is up +// to the caller of Format64() [and Format02d()/FormatOffset()] to ensure +// that there is sufficient space before ep to hold the conversion. +char* Format64(char* ep, int width, std::int_fast64_t v) { + bool neg = false; + if (v < 0) { + --width; + neg = true; + if (v == std::numeric_limits<std::int_fast64_t>::min()) { + // Avoid negating minimum value. + std::int_fast64_t last_digit = -(v % 10); + v /= 10; + if (last_digit < 0) { + ++v; + last_digit += 10; + } + --width; + *--ep = kDigits[last_digit]; + } + v = -v; + } + do { + --width; + *--ep = kDigits[v % 10]; + } while (v /= 10); + while (--width >= 0) *--ep = '0'; // zero pad + if (neg) *--ep = '-'; + return ep; +} + +// Formats [0 .. 99] as %02d. +char* Format02d(char* ep, int v) { + *--ep = kDigits[v % 10]; + *--ep = kDigits[(v / 10) % 10]; + return ep; +} + +// Formats a UTC offset, like +00:00. +char* FormatOffset(char* ep, int offset, const char* mode) { + char sign = '+'; + if (offset < 0) { + offset = -offset; // bounded by 24h so no overflow + sign = '-'; + } + char sep = mode[0]; + if (sep != '\0' && mode[1] == '*') { + ep = Format02d(ep, offset % 60); + *--ep = sep; + } + int minutes = offset / 60; + ep = Format02d(ep, minutes % 60); + if (sep != '\0') *--ep = sep; + ep = Format02d(ep, minutes / 60); + *--ep = sign; + return ep; +} + +// Formats a std::tm using strftime(3). +void FormatTM(std::string* out, const std::string& fmt, const std::tm& tm) { + // strftime(3) returns the number of characters placed in the output + // array (which may be 0 characters). It also returns 0 to indicate + // an error, like the array wasn't large enough. To accommodate this, + // the following code grows the buffer size from 2x the format std::string + // length up to 32x. + for (std::size_t i = 2; i != 32; i *= 2) { + std::size_t buf_size = fmt.size() * i; + std::vector<char> buf(buf_size); + if (std::size_t len = strftime(&buf[0], buf_size, fmt.c_str(), &tm)) { + out->append(&buf[0], len); + return; + } + } +} + +// Used for %E#S/%E#f specifiers and for data values in parse(). +template <typename T> +const char* ParseInt(const char* dp, int width, T min, T max, T* vp) { + if (dp != nullptr) { + const T kmin = std::numeric_limits<T>::min(); + bool erange = false; + bool neg = false; + T value = 0; + if (*dp == '-') { + neg = true; + if (width <= 0 || --width != 0) { + ++dp; + } else { + dp = nullptr; // width was 1 + } + } + if (const char* const bp = dp) { + while (const char* cp = strchr(kDigits, *dp)) { + int d = static_cast<int>(cp - kDigits); + if (d >= 10) break; + if (value < kmin / 10) { + erange = true; + break; + } + value *= 10; + if (value < kmin + d) { + erange = true; + break; + } + value -= d; + dp += 1; + if (width > 0 && --width == 0) break; + } + if (dp != bp && !erange && (neg || value != kmin)) { + if (!neg || value != 0) { + if (!neg) value = -value; // make positive + if (min <= value && value <= max) { + *vp = value; + } else { + dp = nullptr; + } + } else { + dp = nullptr; + } + } else { + dp = nullptr; + } + } + } + return dp; +} + +// The number of base-10 digits that can be represented by a signed 64-bit +// integer. That is, 10^kDigits10_64 <= 2^63 - 1 < 10^(kDigits10_64 + 1). +const int kDigits10_64 = 18; + +// 10^n for everything that can be represented by a signed 64-bit integer. +const std::int_fast64_t kExp10[kDigits10_64 + 1] = { + 1, + 10, + 100, + 1000, + 10000, + 100000, + 1000000, + 10000000, + 100000000, + 1000000000, + 10000000000, + 100000000000, + 1000000000000, + 10000000000000, + 100000000000000, + 1000000000000000, + 10000000000000000, + 100000000000000000, + 1000000000000000000, +}; + +} // namespace + +// Uses strftime(3) to format the given Time. The following extended format +// specifiers are also supported: +// +// - %Ez - RFC3339-compatible numeric UTC offset (+hh:mm or -hh:mm) +// - %E*z - Full-resolution numeric UTC offset (+hh:mm:ss or -hh:mm:ss) +// - %E#S - Seconds with # digits of fractional precision +// - %E*S - Seconds with full fractional precision (a literal '*') +// - %E4Y - Four-character years (-999 ... -001, 0000, 0001 ... 9999) +// +// The standard specifiers from RFC3339_* (%Y, %m, %d, %H, %M, and %S) are +// handled internally for performance reasons. strftime(3) is slow due to +// a POSIX requirement to respect changes to ${TZ}. +// +// The TZ/GNU %s extension is handled internally because strftime() has +// to use mktime() to generate it, and that assumes the local time zone. +// +// We also handle the %z and %Z specifiers to accommodate platforms that do +// not support the tm_gmtoff and tm_zone extensions to std::tm. +// +// Requires that zero() <= fs < seconds(1). +std::string format(const std::string& format, const time_point<sys_seconds>& tp, + const detail::femtoseconds& fs, const time_zone& tz) { + std::string result; + result.reserve(format.size()); // A reasonable guess for the result size. + const time_zone::absolute_lookup al = tz.lookup(tp); + const std::tm tm = ToTM(al); + + // Scratch buffer for internal conversions. + char buf[3 + kDigits10_64]; // enough for longest conversion + char* const ep = buf + sizeof(buf); + char* bp; // works back from ep + + // Maintain three, disjoint subsequences that span format. + // [format.begin() ... pending) : already formatted into result + // [pending ... cur) : formatting pending, but no special cases + // [cur ... format.end()) : unexamined + // Initially, everything is in the unexamined part. + const char* pending = format.c_str(); // NUL terminated + const char* cur = pending; + const char* end = pending + format.length(); + + while (cur != end) { // while something is unexamined + // Moves cur to the next percent sign. + const char* start = cur; + while (cur != end && *cur != '%') ++cur; + + // If the new pending text is all ordinary, copy it out. + if (cur != start && pending == start) { + result.append(pending, static_cast<std::size_t>(cur - pending)); + pending = start = cur; + } + + // Span the sequential percent signs. + const char* percent = cur; + while (cur != end && *cur == '%') ++cur; + + // If the new pending text is all percents, copy out one + // percent for every matched pair, then skip those pairs. + if (cur != start && pending == start) { + std::size_t escaped = static_cast<std::size_t>(cur - pending) / 2; + result.append(pending, escaped); + pending += escaped * 2; + // Also copy out a single trailing percent. + if (pending != cur && cur == end) { + result.push_back(*pending++); + } + } + + // Loop unless we have an unescaped percent. + if (cur == end || (cur - percent) % 2 == 0) continue; + + // Simple specifiers that we handle ourselves. + if (strchr("YmdeHMSzZs%", *cur)) { + if (cur - 1 != pending) { + FormatTM(&result, std::string(pending, cur - 1), tm); + } + switch (*cur) { + case 'Y': + // This avoids the tm.tm_year overflow problem for %Y, however + // tm.tm_year will still be used by other specifiers like %D. + bp = Format64(ep, 0, al.cs.year()); + result.append(bp, static_cast<std::size_t>(ep - bp)); + break; + case 'm': + bp = Format02d(ep, al.cs.month()); + result.append(bp, static_cast<std::size_t>(ep - bp)); + break; + case 'd': + case 'e': + bp = Format02d(ep, al.cs.day()); + if (*cur == 'e' && *bp == '0') *bp = ' '; // for Windows + result.append(bp, static_cast<std::size_t>(ep - bp)); + break; + case 'H': + bp = Format02d(ep, al.cs.hour()); + result.append(bp, static_cast<std::size_t>(ep - bp)); + break; + case 'M': + bp = Format02d(ep, al.cs.minute()); + result.append(bp, static_cast<std::size_t>(ep - bp)); + break; + case 'S': + bp = Format02d(ep, al.cs.second()); + result.append(bp, static_cast<std::size_t>(ep - bp)); + break; + case 'z': + bp = FormatOffset(ep, al.offset, ""); + result.append(bp, static_cast<std::size_t>(ep - bp)); + break; + case 'Z': + result.append(al.abbr); + break; + case 's': + bp = Format64(ep, 0, ToUnixSeconds(tp)); + result.append(bp, static_cast<std::size_t>(ep - bp)); + break; + case '%': + result.push_back('%'); + break; + } + pending = ++cur; + continue; + } + + // Loop if there is no E modifier. + if (*cur != 'E' || ++cur == end) continue; + + // Format our extensions. + if (*cur == 'z') { + // Formats %Ez. + if (cur - 2 != pending) { + FormatTM(&result, std::string(pending, cur - 2), tm); + } + bp = FormatOffset(ep, al.offset, ":"); + result.append(bp, static_cast<std::size_t>(ep - bp)); + pending = ++cur; + } else if (*cur == '*' && cur + 1 != end && *(cur + 1) == 'z') { + // Formats %E*z. + if (cur - 2 != pending) { + FormatTM(&result, std::string(pending, cur - 2), tm); + } + bp = FormatOffset(ep, al.offset, ":*"); + result.append(bp, static_cast<std::size_t>(ep - bp)); + pending = cur += 2; + } else if (*cur == '*' && cur + 1 != end && + (*(cur + 1) == 'S' || *(cur + 1) == 'f')) { + // Formats %E*S or %E*F. + if (cur - 2 != pending) { + FormatTM(&result, std::string(pending, cur - 2), tm); + } + char* cp = ep; + bp = Format64(cp, 15, fs.count()); + while (cp != bp && cp[-1] == '0') --cp; + switch (*(cur + 1)) { + case 'S': + if (cp != bp) *--bp = '.'; + bp = Format02d(bp, al.cs.second()); + break; + case 'f': + if (cp == bp) *--bp = '0'; + break; + } + result.append(bp, static_cast<std::size_t>(cp - bp)); + pending = cur += 2; + } else if (*cur == '4' && cur + 1 != end && *(cur + 1) == 'Y') { + // Formats %E4Y. + if (cur - 2 != pending) { + FormatTM(&result, std::string(pending, cur - 2), tm); + } + bp = Format64(ep, 4, al.cs.year()); + result.append(bp, static_cast<std::size_t>(ep - bp)); + pending = cur += 2; + } else if (std::isdigit(*cur)) { + // Possibly found %E#S or %E#f. + int n = 0; + if (const char* np = ParseInt(cur, 0, 0, 1024, &n)) { + if (*np == 'S' || *np == 'f') { + // Formats %E#S or %E#f. + if (cur - 2 != pending) { + FormatTM(&result, std::string(pending, cur - 2), tm); + } + bp = ep; + if (n > 0) { + if (n > kDigits10_64) n = kDigits10_64; + bp = Format64(bp, n, (n > 15) ? fs.count() * kExp10[n - 15] + : fs.count() / kExp10[15 - n]); + if (*np == 'S') *--bp = '.'; + } + if (*np == 'S') bp = Format02d(bp, al.cs.second()); + result.append(bp, static_cast<std::size_t>(ep - bp)); + pending = cur = ++np; + } + } + } + } + + // Formats any remaining data. + if (end != pending) { + FormatTM(&result, std::string(pending, end), tm); + } + + return result; +} + +namespace { + +const char* ParseOffset(const char* dp, const char* mode, int* offset) { + if (dp != nullptr) { + const char first = *dp++; + if (first == '+' || first == '-') { + char sep = mode[0]; + int hours = 0; + int minutes = 0; + int seconds = 0; + const char* ap = ParseInt(dp, 2, 0, 23, &hours); + if (ap != nullptr && ap - dp == 2) { + dp = ap; + if (sep != '\0' && *ap == sep) ++ap; + const char* bp = ParseInt(ap, 2, 0, 59, &minutes); + if (bp != nullptr && bp - ap == 2) { + dp = bp; + if (sep != '\0' && *bp == sep) ++bp; + const char* cp = ParseInt(bp, 2, 0, 59, &seconds); + if (cp != nullptr && cp - bp == 2) dp = cp; + } + *offset = ((hours * 60 + minutes) * 60) + seconds; + if (first == '-') *offset = -*offset; + } else { + dp = nullptr; + } + } else if (first == 'Z') { // Zulu + *offset = 0; + } else { + dp = nullptr; + } + } + return dp; +} + +const char* ParseZone(const char* dp, std::string* zone) { + zone->clear(); + if (dp != nullptr) { + while (*dp != '\0' && !std::isspace(*dp)) zone->push_back(*dp++); + if (zone->empty()) dp = nullptr; + } + return dp; +} + +const char* ParseSubSeconds(const char* dp, detail::femtoseconds* subseconds) { + if (dp != nullptr) { + std::int_fast64_t v = 0; + std::int_fast64_t exp = 0; + const char* const bp = dp; + while (const char* cp = strchr(kDigits, *dp)) { + int d = static_cast<int>(cp - kDigits); + if (d >= 10) break; + if (exp < 15) { + exp += 1; + v *= 10; + v += d; + } + ++dp; + } + if (dp != bp) { + v *= kExp10[15 - exp]; + *subseconds = detail::femtoseconds(v); + } else { + dp = nullptr; + } + } + return dp; +} + +// Parses a std::string into a std::tm using strptime(3). +const char* ParseTM(const char* dp, const char* fmt, std::tm* tm) { + if (dp != nullptr) { + dp = strptime(dp, fmt, tm); + } + return dp; +} + +} // namespace + +// Uses strptime(3) to parse the given input. Supports the same extended +// format specifiers as format(), although %E#S and %E*S are treated +// identically (and similarly for %E#f and %E*f). %Ez and %E*z also accept +// the same inputs. +// +// The standard specifiers from RFC3339_* (%Y, %m, %d, %H, %M, and %S) are +// handled internally so that we can normally avoid strptime() altogether +// (which is particularly helpful when the native implementation is broken). +// +// The TZ/GNU %s extension is handled internally because strptime() has to +// use localtime_r() to generate it, and that assumes the local time zone. +// +// We also handle the %z specifier to accommodate platforms that do not +// support the tm_gmtoff extension to std::tm. %Z is parsed but ignored. +bool parse(const std::string& format, const std::string& input, + const time_zone& tz, time_point<sys_seconds>* sec, + detail::femtoseconds* fs, std::string* err) { + // The unparsed input. + const char* data = input.c_str(); // NUL terminated + + // Skips leading whitespace. + while (std::isspace(*data)) ++data; + + const year_t kyearmax = std::numeric_limits<year_t>::max(); + const year_t kyearmin = std::numeric_limits<year_t>::min(); + + // Sets default values for unspecified fields. + bool saw_year = false; + year_t year = 1970; + std::tm tm{}; + tm.tm_year = 1970 - 1900; + tm.tm_mon = 1 - 1; // Jan + tm.tm_mday = 1; + tm.tm_hour = 0; + tm.tm_min = 0; + tm.tm_sec = 0; + tm.tm_wday = 4; // Thu + tm.tm_yday = 0; + tm.tm_isdst = 0; + auto subseconds = detail::femtoseconds::zero(); + bool saw_offset = false; + int offset = 0; // No offset from passed tz. + std::string zone = "UTC"; + + const char* fmt = format.c_str(); // NUL terminated + bool twelve_hour = false; + bool afternoon = false; + + bool saw_percent_s = false; + std::int_fast64_t percent_s = 0; + + // Steps through format, one specifier at a time. + while (data != nullptr && *fmt != '\0') { + if (std::isspace(*fmt)) { + while (std::isspace(*data)) ++data; + while (std::isspace(*++fmt)) continue; + continue; + } + + if (*fmt != '%') { + if (*data == *fmt) { + ++data; + ++fmt; + } else { + data = nullptr; + } + continue; + } + + const char* percent = fmt; + if (*++fmt == '\0') { + data = nullptr; + continue; + } + switch (*fmt++) { + case 'Y': + // Symmetrically with FormatTime(), directly handing %Y avoids the + // tm.tm_year overflow problem. However, tm.tm_year will still be + // used by other specifiers like %D. + data = ParseInt(data, 0, kyearmin, kyearmax, &year); + if (data != nullptr) saw_year = true; + continue; + case 'm': + data = ParseInt(data, 2, 1, 12, &tm.tm_mon); + if (data != nullptr) tm.tm_mon -= 1; + continue; + case 'd': + case 'e': + data = ParseInt(data, 2, 1, 31, &tm.tm_mday); + continue; + case 'H': + data = ParseInt(data, 2, 0, 23, &tm.tm_hour); + twelve_hour = false; + continue; + case 'M': + data = ParseInt(data, 2, 0, 59, &tm.tm_min); + continue; + case 'S': + data = ParseInt(data, 2, 0, 60, &tm.tm_sec); + continue; + case 'I': + case 'l': + case 'r': // probably uses %I + twelve_hour = true; + break; + case 'R': // uses %H + case 'T': // uses %H + case 'c': // probably uses %H + case 'X': // probably uses %H + twelve_hour = false; + break; + case 'z': + data = ParseOffset(data, "", &offset); + if (data != nullptr) saw_offset = true; + continue; + case 'Z': // ignored; zone abbreviations are ambiguous + data = ParseZone(data, &zone); + continue; + case 's': + data = ParseInt(data, 0, + std::numeric_limits<std::int_fast64_t>::min(), + std::numeric_limits<std::int_fast64_t>::max(), + &percent_s); + if (data != nullptr) saw_percent_s = true; + continue; + case '%': + data = (*data == '%' ? data + 1 : nullptr); + continue; + case 'E': + if (*fmt == 'z' || (*fmt == '*' && *(fmt + 1) == 'z')) { + data = ParseOffset(data, ":", &offset); + if (data != nullptr) saw_offset = true; + fmt += (*fmt == 'z') ? 1 : 2; + continue; + } + if (*fmt == '*' && *(fmt + 1) == 'S') { + data = ParseInt(data, 2, 0, 60, &tm.tm_sec); + if (data != nullptr && *data == '.') { + data = ParseSubSeconds(data + 1, &subseconds); + } + fmt += 2; + continue; + } + if (*fmt == '*' && *(fmt + 1) == 'f') { + if (data != nullptr && std::isdigit(*data)) { + data = ParseSubSeconds(data, &subseconds); + } + fmt += 2; + continue; + } + if (*fmt == '4' && *(fmt + 1) == 'Y') { + const char* bp = data; + data = ParseInt(data, 4, year_t{-999}, year_t{9999}, &year); + if (data != nullptr) { + if (data - bp == 4) { + saw_year = true; + } else { + data = nullptr; // stopped too soon + } + } + fmt += 2; + continue; + } + if (std::isdigit(*fmt)) { + int n = 0; // value ignored + if (const char* np = ParseInt(fmt, 0, 0, 1024, &n)) { + if (*np == 'S') { + data = ParseInt(data, 2, 0, 60, &tm.tm_sec); + if (data != nullptr && *data == '.') { + data = ParseSubSeconds(data + 1, &subseconds); + } + fmt = ++np; + continue; + } + if (*np == 'f') { + if (data != nullptr && std::isdigit(*data)) { + data = ParseSubSeconds(data, &subseconds); + } + fmt = ++np; + continue; + } + } + } + if (*fmt == 'c') twelve_hour = false; // probably uses %H + if (*fmt == 'X') twelve_hour = false; // probably uses %H + if (*fmt != '\0') ++fmt; + break; + case 'O': + if (*fmt == 'H') twelve_hour = false; + if (*fmt == 'I') twelve_hour = true; + if (*fmt != '\0') ++fmt; + break; + } + + // Parses the current specifier. + const char* orig_data = data; + std::string spec(percent, static_cast<std::size_t>(fmt - percent)); + data = ParseTM(data, spec.c_str(), &tm); + + // If we successfully parsed %p we need to remember whether the result + // was AM or PM so that we can adjust tm_hour before ConvertDateTime(). + // So reparse the input with a known AM hour, and check if it is shifted + // to a PM hour. + if (spec == "%p" && data != nullptr) { + std::string test_input = "1"; + test_input.append(orig_data, static_cast<std::size_t>(data - orig_data)); + const char* test_data = test_input.c_str(); + std::tm tmp{}; + ParseTM(test_data, "%I%p", &tmp); + afternoon = (tmp.tm_hour == 13); + } + } + + // Adjust a 12-hour tm_hour value if it should be in the afternoon. + if (twelve_hour && afternoon && tm.tm_hour < 12) { + tm.tm_hour += 12; + } + + if (data == nullptr) { + if (err != nullptr) *err = "Failed to parse input"; + return false; + } + + // Skip any remaining whitespace. + while (std::isspace(*data)) ++data; + + // parse() must consume the entire input std::string. + if (*data != '\0') { + if (err != nullptr) *err = "Illegal trailing data in input string"; + return false; + } + + // If we saw %s then we ignore anything else and return that time. + if (saw_percent_s) { + *sec = FromUnixSeconds(percent_s); + *fs = detail::femtoseconds::zero(); + return true; + } + + // If we saw %z, %Ez, or %E*z then we want to interpret the parsed fields + // in UTC and then shift by that offset. Otherwise we want to interpret + // the fields directly in the passed time_zone. + time_zone ptz = saw_offset ? utc_time_zone() : tz; + + // Allows a leap second of 60 to normalize forward to the following ":00". + if (tm.tm_sec == 60) { + tm.tm_sec -= 1; + offset -= 1; + subseconds = detail::femtoseconds::zero(); + } + + if (!saw_year) { + year = year_t{tm.tm_year}; + if (year > kyearmax - 1900) { + // Platform-dependent, maybe unreachable. + if (err != nullptr) *err = "Out-of-range year"; + return false; + } + year += 1900; + } + + const int month = tm.tm_mon + 1; + civil_second cs(year, month, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec); + + // parse() should not allow normalization. Due to the restricted field + // ranges above (see ParseInt()), the only possibility is for days to roll + // into months. That is, parsing "Sep 31" should not produce "Oct 1". + if (cs.month() != month || cs.day() != tm.tm_mday) { + if (err != nullptr) *err = "Out-of-range field"; + return false; + } + + // Accounts for the offset adjustment before converting to absolute time. + if ((offset < 0 && cs > civil_second::max() + offset) || + (offset > 0 && cs < civil_second::min() + offset)) { + if (err != nullptr) *err = "Out-of-range field"; + return false; + } + cs -= offset; + + const auto tp = ptz.lookup(cs).pre; + // Checks for overflow/underflow and returns an error as necessary. + if (tp == time_point<sys_seconds>::max()) { + const auto al = ptz.lookup(time_point<sys_seconds>::max()); + if (cs > al.cs) { + if (err != nullptr) *err = "Out-of-range field"; + return false; + } + } + if (tp == time_point<sys_seconds>::min()) { + const auto al = ptz.lookup(time_point<sys_seconds>::min()); + if (cs < al.cs) { + if (err != nullptr) *err = "Out-of-range field"; + return false; + } + } + + *sec = tp; + *fs = subseconds; + return true; +} + +} // namespace detail +} // namespace cctz +} // namespace time_internal +} // namespace absl |