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// 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.
#include "time_zone_posix.h"
#include <cstddef>
#include <cstring>
#include <limits>
#include <string>
namespace cctz {
namespace {
const char kDigits[] = "0123456789";
const char* ParseInt(const char* p, int min, int max, int* vp) {
int value = 0;
const char* op = p;
const int kMaxInt = std::numeric_limits<int>::max();
for (; const char* dp = strchr(kDigits, *p); ++p) {
int d = static_cast<int>(dp - kDigits);
if (d >= 10) break; // '\0'
if (value > kMaxInt / 10) return nullptr;
value *= 10;
if (value > kMaxInt - d) return nullptr;
value += d;
}
if (p == op || value < min || value > max) return nullptr;
*vp = value;
return p;
}
// abbr = <.*?> | [^-+,\d]{3,}
const char* ParseAbbr(const char* p, std::string* abbr) {
const char* op = p;
if (*p == '<') { // special zoneinfo <...> form
while (*++p != '>') {
if (*p == '\0') return nullptr;
}
abbr->assign(op + 1, static_cast<std::size_t>(p - op) - 1);
return ++p;
}
while (*p != '\0') {
if (strchr("-+,", *p)) break;
if (strchr(kDigits, *p)) break;
++p;
}
if (p - op < 3) return nullptr;
abbr->assign(op, static_cast<std::size_t>(p - op));
return p;
}
// offset = [+|-]hh[:mm[:ss]] (aggregated into single seconds value)
const char* ParseOffset(const char* p, int min_hour, int max_hour, int sign,
std::int_fast32_t* offset) {
if (p == nullptr) return nullptr;
if (*p == '+' || *p == '-') {
if (*p++ == '-') sign = -sign;
}
int hours = 0;
int minutes = 0;
int seconds = 0;
p = ParseInt(p, min_hour, max_hour, &hours);
if (p == nullptr) return nullptr;
if (*p == ':') {
p = ParseInt(p + 1, 0, 59, &minutes);
if (p == nullptr) return nullptr;
if (*p == ':') {
p = ParseInt(p + 1, 0, 59, &seconds);
if (p == nullptr) return nullptr;
}
}
*offset = sign * ((((hours * 60) + minutes) * 60) + seconds);
return p;
}
// datetime = ( Jn | n | Mm.w.d ) [ / offset ]
const char* ParseDateTime(const char* p, PosixTransition* res) {
if (p != nullptr && *p == ',') {
if (*++p == 'M') {
int month = 0;
if ((p = ParseInt(p + 1, 1, 12, &month)) != nullptr && *p == '.') {
int week = 0;
if ((p = ParseInt(p + 1, 1, 5, &week)) != nullptr && *p == '.') {
int weekday = 0;
if ((p = ParseInt(p + 1, 0, 6, &weekday)) != nullptr) {
res->date.fmt = PosixTransition::M;
res->date.m.month = static_cast<std::int_fast8_t>(month);
res->date.m.week = static_cast<std::int_fast8_t>(week);
res->date.m.weekday = static_cast<std::int_fast8_t>(weekday);
}
}
}
} else if (*p == 'J') {
int day = 0;
if ((p = ParseInt(p + 1, 1, 365, &day)) != nullptr) {
res->date.fmt = PosixTransition::J;
res->date.j.day = static_cast<std::int_fast16_t>(day);
}
} else {
int day = 0;
if ((p = ParseInt(p, 0, 365, &day)) != nullptr) {
res->date.fmt = PosixTransition::N;
res->date.n.day = static_cast<std::int_fast16_t>(day);
}
}
}
if (p != nullptr) {
res->time.offset = 2 * 60 * 60; // default offset is 02:00:00
if (*p == '/') p = ParseOffset(p + 1, -167, 167, 1, &res->time.offset);
}
return p;
}
} // namespace
// spec = std offset [ dst [ offset ] , datetime , datetime ]
bool ParsePosixSpec(const std::string& spec, PosixTimeZone* res) {
const char* p = spec.c_str();
if (*p == ':') return false;
p = ParseAbbr(p, &res->std_abbr);
p = ParseOffset(p, 0, 24, -1, &res->std_offset);
if (p == nullptr) return false;
if (*p == '\0') return true;
p = ParseAbbr(p, &res->dst_abbr);
if (p == nullptr) return false;
res->dst_offset = res->std_offset + (60 * 60); // default
if (*p != ',') p = ParseOffset(p, 0, 24, -1, &res->dst_offset);
p = ParseDateTime(p, &res->dst_start);
p = ParseDateTime(p, &res->dst_end);
return p != nullptr && *p == '\0';
}
} // namespace cctz
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