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// Copyright 2014 The Chromium OS 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 "brillo/asynchronous_signal_handler.h"
#include <signal.h>
#include <sys/types.h>
#include <unistd.h>
#include <base/bind.h>
#include <base/files/file_util.h>
#include <base/logging.h>
namespace brillo {
AsynchronousSignalHandler::AsynchronousSignalHandler() {
CHECK_EQ(sigemptyset(&signal_mask_), 0) << "Failed to initialize signal mask";
CHECK_EQ(sigemptyset(&saved_signal_mask_), 0)
<< "Failed to initialize signal mask";
}
AsynchronousSignalHandler::~AsynchronousSignalHandler() {
fd_watcher_ = nullptr;
if (!descriptor_.is_valid())
return;
// Close FD before restoring sigprocmask.
descriptor_.reset();
CHECK_EQ(0, sigprocmask(SIG_SETMASK, &saved_signal_mask_, nullptr));
}
void AsynchronousSignalHandler::Init() {
// Making sure it is not yet initialized.
CHECK(!descriptor_.is_valid());
// Set sigprocmask before creating signalfd.
CHECK_EQ(0, sigprocmask(SIG_BLOCK, &signal_mask_, &saved_signal_mask_));
// Creating signalfd, and start watching it.
descriptor_.reset(signalfd(-1, &signal_mask_, SFD_CLOEXEC | SFD_NONBLOCK));
CHECK(descriptor_.is_valid());
fd_watcher_ = base::FileDescriptorWatcher::WatchReadable(
descriptor_.get(),
base::BindRepeating(&AsynchronousSignalHandler::OnReadable,
base::Unretained(this)));
CHECK(fd_watcher_) << "Watching signalfd failed.";
}
void AsynchronousSignalHandler::RegisterHandler(int signal,
const SignalHandler& callback) {
registered_callbacks_[signal] = callback;
CHECK_EQ(0, sigaddset(&signal_mask_, signal));
UpdateSignals();
}
void AsynchronousSignalHandler::UnregisterHandler(int signal) {
Callbacks::iterator callback_it = registered_callbacks_.find(signal);
if (callback_it == registered_callbacks_.end())
return;
registered_callbacks_.erase(callback_it);
CHECK_EQ(0, sigdelset(&signal_mask_, signal));
UpdateSignals();
}
void AsynchronousSignalHandler::OnReadable() {
struct signalfd_siginfo info;
while (base::ReadFromFD(descriptor_.get(),
reinterpret_cast<char*>(&info), sizeof(info))) {
int signal = info.ssi_signo;
Callbacks::iterator callback_it = registered_callbacks_.find(signal);
if (callback_it == registered_callbacks_.end()) {
LOG(WARNING) << "Unable to find a signal handler for signal: " << signal;
// Can happen if a signal has been called multiple time, and the callback
// asked to be unregistered the first time.
continue;
}
const SignalHandler& callback = callback_it->second;
bool must_unregister = callback.Run(info);
if (must_unregister)
UnregisterHandler(signal);
}
}
void AsynchronousSignalHandler::UpdateSignals() {
if (!descriptor_.is_valid())
return;
sigset_t mask;
CHECK_EQ(0, sigorset(&mask, &signal_mask_, &saved_signal_mask_));
CHECK_EQ(0, sigprocmask(SIG_SETMASK, &mask, nullptr));
CHECK_EQ(
descriptor_.get(),
signalfd(descriptor_.get(), &signal_mask_, SFD_CLOEXEC | SFD_NONBLOCK));
}
} // namespace brillo
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