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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/time_zone_monitor.h"
#include <stdlib.h>
#include <vector>
#include "base/basictypes.h"
#include "base/bind.h"
#include "base/files/file_path.h"
#include "base/files/file_path_watcher.h"
#include "base/memory/ref_counted.h"
#include "base/stl_util.h"
#include "content/public/browser/browser_thread.h"
#if !defined(OS_CHROMEOS)
namespace content {
namespace {
class TimeZoneMonitorLinuxImpl;
} // namespace
class TimeZoneMonitorLinux : public TimeZoneMonitor {
public:
TimeZoneMonitorLinux();
~TimeZoneMonitorLinux() override;
void NotifyRenderersFromImpl() {
NotifyRenderers();
}
private:
scoped_refptr<TimeZoneMonitorLinuxImpl> impl_;
DISALLOW_COPY_AND_ASSIGN(TimeZoneMonitorLinux);
};
namespace {
// FilePathWatcher needs to run on the FILE thread, but TimeZoneMonitor runs
// on the UI thread. TimeZoneMonitorLinuxImpl is the bridge between these
// threads.
class TimeZoneMonitorLinuxImpl
: public base::RefCountedThreadSafe<TimeZoneMonitorLinuxImpl> {
public:
explicit TimeZoneMonitorLinuxImpl(TimeZoneMonitorLinux* owner)
: base::RefCountedThreadSafe<TimeZoneMonitorLinuxImpl>(),
file_path_watchers_(),
owner_(owner) {
DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
BrowserThread::PostTask(
BrowserThread::FILE,
FROM_HERE,
base::Bind(&TimeZoneMonitorLinuxImpl::StartWatchingOnFileThread, this));
}
void StopWatching() {
DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
owner_ = NULL;
BrowserThread::PostTask(
BrowserThread::FILE,
FROM_HERE,
base::Bind(&TimeZoneMonitorLinuxImpl::StopWatchingOnFileThread, this));
}
private:
friend class base::RefCountedThreadSafe<TimeZoneMonitorLinuxImpl>;
~TimeZoneMonitorLinuxImpl() {
DCHECK(!owner_);
STLDeleteElements(&file_path_watchers_);
}
void StartWatchingOnFileThread() {
DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
// There is no true standard for where time zone information is actually
// stored. glibc uses /etc/localtime, uClibc uses /etc/TZ, and some older
// systems store the name of the time zone file within /usr/share/zoneinfo
// in /etc/timezone. Different libraries and custom builds may mean that
// still more paths are used. Just watch all three of these paths, because
// false positives are harmless, assuming the false positive rate is
// reasonable.
const char* kFilesToWatch[] = {
"/etc/localtime",
"/etc/timezone",
"/etc/TZ",
};
for (size_t index = 0; index < arraysize(kFilesToWatch); ++index) {
file_path_watchers_.push_back(new base::FilePathWatcher());
file_path_watchers_.back()->Watch(
base::FilePath(kFilesToWatch[index]),
false,
base::Bind(&TimeZoneMonitorLinuxImpl::OnTimeZoneFileChanged, this));
}
}
void StopWatchingOnFileThread() {
DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
STLDeleteElements(&file_path_watchers_);
}
void OnTimeZoneFileChanged(const base::FilePath& path, bool error) {
DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
BrowserThread::PostTask(
BrowserThread::UI,
FROM_HERE,
base::Bind(&TimeZoneMonitorLinuxImpl::OnTimeZoneFileChangedOnUIThread,
this));
}
void OnTimeZoneFileChangedOnUIThread() {
DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
if (owner_) {
owner_->NotifyRenderersFromImpl();
}
}
std::vector<base::FilePathWatcher*> file_path_watchers_;
TimeZoneMonitorLinux* owner_;
DISALLOW_COPY_AND_ASSIGN(TimeZoneMonitorLinuxImpl);
};
} // namespace
TimeZoneMonitorLinux::TimeZoneMonitorLinux()
: TimeZoneMonitor(),
impl_() {
// If the TZ environment variable is set, its value specifies the time zone
// specification, and it's pointless to monitor any files in /etc for
// changes because such changes would have no effect on the TZ environment
// variable and thus the interpretation of the local time zone in the
// or renderer processes.
//
// The system-specific format for the TZ environment variable beginning with
// a colon is implemented by glibc as the path to a time zone data file, and
// it would be possible to monitor this file for changes if a TZ variable of
// this format was encountered, but this is not necessary: when loading a
// time zone specification in this way, glibc does not reload the file when
// it changes, so it's pointless to respond to a notification that it has
// changed.
if (!getenv("TZ")) {
impl_ = new TimeZoneMonitorLinuxImpl(this);
}
}
TimeZoneMonitorLinux::~TimeZoneMonitorLinux() {
if (impl_.get()) {
impl_->StopWatching();
}
}
// static
scoped_ptr<TimeZoneMonitor> TimeZoneMonitor::Create() {
return scoped_ptr<TimeZoneMonitor>(new TimeZoneMonitorLinux());
}
} // namespace content
#endif // !OS_CHROMEOS
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