libchromeos: Adding a generic signal handler.
This adds an AsynchronousSignalHandler allowing to handle signal when
using chrome run loops.
This class originates and is generalized from
login_manager::ChildExitHandler and login_manager::TerminationHandler
and CL:7589
BUG=None
TEST=asynchronous_signal_handler_unittest
Change-Id: Ie6ab1c475059d846867612d51bd4453b1f4de627
Reviewed-on: https://chromium-review.googlesource.com/207330
Reviewed-by: Benjamin Lerman <qsr@chromium.org>
Commit-Queue: Benjamin Lerman <qsr@chromium.org>
Tested-by: Benjamin Lerman <qsr@chromium.org>
diff --git a/chromeos/asynchronous_signal_handler.cc b/chromeos/asynchronous_signal_handler.cc
new file mode 100644
index 0000000..ca6f8fe
--- /dev/null
+++ b/chromeos/asynchronous_signal_handler.cc
@@ -0,0 +1,107 @@
+// 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 "chromeos/asynchronous_signal_handler.h"
+
+#include <signal.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <base/file_util.h>
+#include <base/logging.h>
+#include <base/message_loop/message_loop.h>
+
+#include "chromeos/utility.h"
+
+namespace {
+const int kInvalidDescriptor = -1;
+} // namespace
+
+namespace chromeos {
+
+AsynchronousSignalHandler::AsynchronousSignalHandler()
+ : fd_watcher_(new base::MessageLoopForIO::FileDescriptorWatcher),
+ descriptor_(kInvalidDescriptor) {
+ 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() {
+ if (descriptor_ != kInvalidDescriptor) {
+ fd_watcher_->StopWatchingFileDescriptor();
+
+ if (close(descriptor_) != 0)
+ PLOG(WARNING) << "Failed to close file descriptor";
+
+ descriptor_ = kInvalidDescriptor;
+ CHECK_EQ(0, sigprocmask(SIG_SETMASK, &saved_signal_mask_, NULL));
+ }
+}
+
+void AsynchronousSignalHandler::Init() {
+ CHECK_EQ(kInvalidDescriptor, descriptor_);
+ CHECK_EQ(0, sigprocmask(SIG_BLOCK, &signal_mask_, &saved_signal_mask_));
+ descriptor_ =
+ signalfd(descriptor_, &signal_mask_, SFD_CLOEXEC | SFD_NONBLOCK);
+ CHECK_NE(kInvalidDescriptor, descriptor_);
+ CHECK(base::MessageLoopForIO::current()->WatchFileDescriptor(
+ descriptor_, true, base::MessageLoopForIO::WATCH_READ, fd_watcher_.get(),
+ this))
+ << "Watching shutdown pipe 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()) {
+ registered_callbacks_.erase(callback_it);
+ ResetSignal(signal);
+ }
+}
+
+void AsynchronousSignalHandler::OnFileCanReadWithoutBlocking(int fd) {
+ struct signalfd_siginfo info;
+ while (base::ReadFromFD(fd, 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::OnFileCanWriteWithoutBlocking(int fd) {
+ NOTREACHED();
+}
+
+void AsynchronousSignalHandler::ResetSignal(int signal) {
+ CHECK_EQ(0, sigdelset(&signal_mask_, signal));
+ UpdateSignals();
+}
+
+void AsynchronousSignalHandler::UpdateSignals() {
+ if (descriptor_ != kInvalidDescriptor) {
+ CHECK_EQ(0, sigprocmask(SIG_SETMASK, &saved_signal_mask_, NULL));
+ CHECK_EQ(0, sigprocmask(SIG_BLOCK, &signal_mask_, NULL));
+ CHECK_EQ(descriptor_,
+ signalfd(descriptor_, &signal_mask_, SFD_CLOEXEC | SFD_NONBLOCK));
+ }
+}
+
+} // namespace chromeos