// Copyright 2014 The Chromium OS Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "brillo/asynchronous_signal_handler.h"
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#include <signal.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <base/bind.h>
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#include <base/files/file_util.h>
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#include <base/logging.h>
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#include <base/message_loop/message_loop.h>
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#include <base/posix/eintr_wrapper.h>
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namespace {
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const int kInvalidDescriptor = -1;
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} // namespace
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namespace brillo {
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AsynchronousSignalHandler::AsynchronousSignalHandler()
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: descriptor_(kInvalidDescriptor) {
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CHECK_EQ(sigemptyset(&signal_mask_), 0) << "Failed to initialize signal mask";
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CHECK_EQ(sigemptyset(&saved_signal_mask_), 0)
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<< "Failed to initialize signal mask";
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}
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AsynchronousSignalHandler::~AsynchronousSignalHandler() {
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if (descriptor_ != kInvalidDescriptor) {
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MessageLoop::current()->CancelTask(fd_watcher_task_);
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if (IGNORE_EINTR(close(descriptor_)) != 0)
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PLOG(WARNING) << "Failed to close file descriptor";
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descriptor_ = kInvalidDescriptor;
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CHECK_EQ(0, sigprocmask(SIG_SETMASK, &saved_signal_mask_, nullptr));
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}
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}
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void AsynchronousSignalHandler::Init() {
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CHECK_EQ(kInvalidDescriptor, descriptor_);
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CHECK_EQ(0, sigprocmask(SIG_BLOCK, &signal_mask_, &saved_signal_mask_));
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descriptor_ =
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signalfd(descriptor_, &signal_mask_, SFD_CLOEXEC | SFD_NONBLOCK);
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CHECK_NE(kInvalidDescriptor, descriptor_);
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fd_watcher_task_ = MessageLoop::current()->WatchFileDescriptor(
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FROM_HERE,
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descriptor_,
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MessageLoop::WatchMode::kWatchRead,
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true,
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base::Bind(&AsynchronousSignalHandler::OnFileCanReadWithoutBlocking,
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base::Unretained(this)));
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CHECK(fd_watcher_task_ != MessageLoop::kTaskIdNull)
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<< "Watching shutdown pipe failed.";
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}
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void AsynchronousSignalHandler::RegisterHandler(int signal,
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const SignalHandler& callback) {
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registered_callbacks_[signal] = callback;
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CHECK_EQ(0, sigaddset(&signal_mask_, signal));
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UpdateSignals();
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}
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void AsynchronousSignalHandler::UnregisterHandler(int signal) {
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Callbacks::iterator callback_it = registered_callbacks_.find(signal);
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if (callback_it != registered_callbacks_.end()) {
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registered_callbacks_.erase(callback_it);
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ResetSignal(signal);
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}
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}
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void AsynchronousSignalHandler::OnFileCanReadWithoutBlocking() {
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struct signalfd_siginfo info;
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while (base::ReadFromFD(descriptor_,
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reinterpret_cast<char*>(&info), sizeof(info))) {
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int signal = info.ssi_signo;
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Callbacks::iterator callback_it = registered_callbacks_.find(signal);
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if (callback_it == registered_callbacks_.end()) {
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LOG(WARNING) << "Unable to find a signal handler for signal: " << signal;
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// Can happen if a signal has been called multiple time, and the callback
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// asked to be unregistered the first time.
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continue;
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}
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const SignalHandler& callback = callback_it->second;
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bool must_unregister = callback.Run(info);
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if (must_unregister) {
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UnregisterHandler(signal);
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}
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}
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}
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void AsynchronousSignalHandler::ResetSignal(int signal) {
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CHECK_EQ(0, sigdelset(&signal_mask_, signal));
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UpdateSignals();
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}
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void AsynchronousSignalHandler::UpdateSignals() {
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if (descriptor_ != kInvalidDescriptor) {
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CHECK_EQ(0, sigprocmask(SIG_SETMASK, &saved_signal_mask_, nullptr));
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CHECK_EQ(0, sigprocmask(SIG_BLOCK, &signal_mask_, nullptr));
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CHECK_EQ(descriptor_,
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signalfd(descriptor_, &signal_mask_, SFD_CLOEXEC | SFD_NONBLOCK));
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}
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}
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} // namespace brillo
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