| // 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, sigemptyset(&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 |