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// Copyright 2017 The Crashpad Authors
//
// 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.
#include "snapshot/posix/timezone.h"
#include <stddef.h>
#include <time.h>
#include <iterator>
#include "base/check.h"
#include "base/logging.h"
#include "build/build_config.h"
namespace crashpad {
namespace internal {
void TimeZone(const timeval& snapshot_time,
SystemSnapshot::DaylightSavingTimeStatus* dst_status,
int* standard_offset_seconds,
int* daylight_offset_seconds,
std::string* standard_name,
std::string* daylight_name) {
tzset();
tm local;
PCHECK(localtime_r(&snapshot_time.tv_sec, &local)) << "localtime_r";
*standard_name = tzname[0];
bool found_transition = false;
long probe_gmtoff = local.tm_gmtoff;
#if BUILDFLAG(IS_ANDROID)
// Some versions of the timezone database on Android have incorrect
// information (e.g. Asia/Kolkata and Pacific/Honolulu). These timezones set
// daylight to a non-zero value and return incorrect, >= 0 values for tm_isdst
// in the probes below. If tzname[1] is set to a bogus value, assume the
// timezone does not actually use daylight saving time.
if (daylight && strncmp(tzname[1], "_TZif", 5) != 0) {
#else
if (daylight) {
#endif
// Scan forward and backward, one month at a time, looking for an instance
// when the observance of daylight saving time is different than it is in
// |local|. It’s possible that no such instance will be found even with
// |daylight| set. This can happen in locations where daylight saving time
// was once observed or is expected to be observed in the future, but where
// no transitions to or from daylight saving time occurred or will occur
// within a year of the current date. Arizona, which last observed daylight
// saving time in 1967, is an example.
static constexpr int kMonthDeltas[] =
{0, 1, -1, 2, -2, 3, -3, 4, -4, 5, -5, 6, -6,
7, -7, 8, -8, 9, -9, 10, -10, 11, -11, 12, -12};
for (size_t index = 0; index < std::size(kMonthDeltas) && !found_transition;
++index) {
// Look at a day of each month at local noon. Set tm_isdst to -1 to avoid
// giving mktime() any hints about whether to consider daylight saving
// time in effect. mktime() accepts values of tm_mon that are outside of
// its normal range and behaves as expected: if tm_mon is -1, it
// references December of the preceding year, and if it is 12, it
// references January of the following year.
tm probe_tm = {};
probe_tm.tm_hour = 12;
probe_tm.tm_mday = std::min(local.tm_mday, 28);
probe_tm.tm_mon = local.tm_mon + kMonthDeltas[index];
probe_tm.tm_year = local.tm_year;
probe_tm.tm_isdst = -1;
if (mktime(&probe_tm) == -1) {
PLOG(WARNING) << "mktime";
continue;
}
if (probe_tm.tm_isdst < 0 || local.tm_isdst < 0) {
LOG(WARNING) << "dst status not available";
continue;
}
if (probe_tm.tm_isdst != local.tm_isdst) {
found_transition = true;
probe_gmtoff = probe_tm.tm_gmtoff;
}
}
}
if (found_transition) {
*daylight_name = tzname[1];
if (!local.tm_isdst) {
*dst_status = SystemSnapshot::kObservingStandardTime;
*standard_offset_seconds = local.tm_gmtoff;
*daylight_offset_seconds = probe_gmtoff;
} else {
*dst_status = SystemSnapshot::kObservingDaylightSavingTime;
*standard_offset_seconds = probe_gmtoff;
*daylight_offset_seconds = local.tm_gmtoff;
}
} else {
*daylight_name = tzname[0];
*dst_status = SystemSnapshot::kDoesNotObserveDaylightSavingTime;
#if BUILDFLAG(IS_ANDROID)
// timezone is more reliably set correctly on Android.
*standard_offset_seconds = -timezone;
*daylight_offset_seconds = -timezone;
#else
*standard_offset_seconds = local.tm_gmtoff;
*daylight_offset_seconds = local.tm_gmtoff;
#endif // BUILDFLAG(IS_ANDROID)
}
}
} // namespace internal
} // namespace crashpad