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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 "absl/time/internal/cctz/include/cctz/time_zone.h"
#if defined(__ANDROID__)
#include <sys/system_properties.h>
#if __ANDROID_API__ >= 21
#include <dlfcn.h>
#endif
#endif
#if defined(__APPLE__)
#include <CoreFoundation/CFTimeZone.h>
#include <vector>
#endif
#include <cstdlib>
#include <cstring>
#include <string>
#include "time_zone_fixed.h"
#include "time_zone_impl.h"
namespace absl {
namespace time_internal {
namespace cctz {
#if defined(__ANDROID__) && __ANDROID_API__ >= 21
namespace {
// Android 'L' removes __system_property_get() from the NDK, however
// it is still a hidden symbol in libc so we use dlsym() to access it.
// See Chromium's base/sys_info_android.cc for a similar example.
using property_get_func = int (*)(const char*, char*);
property_get_func LoadSystemPropertyGet() {
int flag = RTLD_LAZY | RTLD_GLOBAL;
#if defined(RTLD_NOLOAD)
flag |= RTLD_NOLOAD; // libc.so should already be resident
#endif
if (void* handle = dlopen("libc.so", flag)) {
void* sym = dlsym(handle, "__system_property_get");
dlclose(handle);
return reinterpret_cast<property_get_func>(sym);
}
return nullptr;
}
int __system_property_get(const char* name, char* value) {
static property_get_func system_property_get = LoadSystemPropertyGet();
return system_property_get ? system_property_get(name, value) : -1;
}
} // namespace
#endif
std::string time_zone::name() const {
return effective_impl().Name();
}
time_zone::absolute_lookup time_zone::lookup(
const time_point<seconds>& tp) const {
return effective_impl().BreakTime(tp);
}
time_zone::civil_lookup time_zone::lookup(const civil_second& cs) const {
return effective_impl().MakeTime(cs);
}
bool time_zone::next_transition(const time_point<seconds>& tp,
civil_transition* trans) const {
return effective_impl().NextTransition(tp, trans);
}
bool time_zone::prev_transition(const time_point<seconds>& tp,
civil_transition* trans) const {
return effective_impl().PrevTransition(tp, trans);
}
std::string time_zone::version() const {
return effective_impl().Version();
}
std::string time_zone::description() const {
return effective_impl().Description();
}
const time_zone::Impl& time_zone::effective_impl() const {
if (impl_ == nullptr) {
// Dereferencing an implicit-UTC time_zone is expected to be
// rare, so we don't mind paying a small synchronization cost.
return *time_zone::Impl::UTC().impl_;
}
return *impl_;
}
bool load_time_zone(const std::string& name, time_zone* tz) {
return time_zone::Impl::LoadTimeZone(name, tz);
}
time_zone utc_time_zone() {
return time_zone::Impl::UTC(); // avoid name lookup
}
time_zone fixed_time_zone(const seconds& offset) {
time_zone tz;
load_time_zone(FixedOffsetToName(offset), &tz);
return tz;
}
time_zone local_time_zone() {
const char* zone = ":localtime";
#if defined(__ANDROID__)
char sysprop[PROP_VALUE_MAX];
if (__system_property_get("persist.sys.timezone", sysprop) > 0) {
zone = sysprop;
}
#endif
#if defined(__APPLE__)
std::vector<char> buffer;
CFTimeZoneRef tz_default = CFTimeZoneCopyDefault();
if (CFStringRef tz_name = CFTimeZoneGetName(tz_default)) {
CFStringEncoding encoding = kCFStringEncodingUTF8;
CFIndex length = CFStringGetLength(tz_name);
buffer.resize(CFStringGetMaximumSizeForEncoding(length, encoding) + 1);
if (CFStringGetCString(tz_name, &buffer[0], buffer.size(), encoding)) {
zone = &buffer[0];
}
}
CFRelease(tz_default);
#endif
// Allow ${TZ} to override to default zone.
char* tz_env = nullptr;
#if defined(_MSC_VER)
_dupenv_s(&tz_env, nullptr, "TZ");
#else
tz_env = std::getenv("TZ");
#endif
if (tz_env) zone = tz_env;
// We only support the "[:]<zone-name>" form.
if (*zone == ':') ++zone;
// Map "localtime" to a system-specific name, but
// allow ${LOCALTIME} to override the default name.
char* localtime_env = nullptr;
if (strcmp(zone, "localtime") == 0) {
#if defined(_MSC_VER)
// System-specific default is just "localtime".
_dupenv_s(&localtime_env, nullptr, "LOCALTIME");
#else
zone = "/etc/localtime"; // System-specific default.
localtime_env = std::getenv("LOCALTIME");
#endif
if (localtime_env) zone = localtime_env;
}
const std::string name = zone;
#if defined(_MSC_VER)
free(localtime_env);
free(tz_env);
#endif
time_zone tz;
load_time_zone(name, &tz); // Falls back to UTC.
// TODO: Follow the RFC3339 "Unknown Local Offset Convention" and
// arrange for %z to generate "-0000" when we don't know the local
// offset because the load_time_zone() failed and we're using UTC.
return tz;
}
} // namespace cctz
} // namespace time_internal
} // namespace absl
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