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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.
#ifndef LIBCHROMEOS_CHROMEOS_ASYNCHRONOUS_SIGNAL_HANDLER_H_
#define LIBCHROMEOS_CHROMEOS_ASYNCHRONOUS_SIGNAL_HANDLER_H_
#include <signal.h>
#include <sys/signalfd.h>
#include <map>
#include <base/callback.h>
#include <base/compiler_specific.h>
#include <base/macros.h>
#include <base/memory/scoped_ptr.h>
#include <base/message_loop/message_loop.h>
#include <chromeos/chromeos_export.h>
namespace chromeos {
// Sets up signal handlers for registered signals, and converts signal receipt
// into a write on a pipe. Watches that pipe for data and, when some appears,
// execute the associated callback.
class CHROMEOS_EXPORT AsynchronousSignalHandler
: public base::MessageLoopForIO::Watcher {
public:
AsynchronousSignalHandler();
~AsynchronousSignalHandler() override;
// The callback called when a signal is received.
typedef base::Callback<bool(const struct signalfd_siginfo&)> SignalHandler;
// Initialize the handler.
void Init();
// Register a new handler for the given |signal|, replacing any previously
// registered handler. |callback| will be called on the thread the
// |AsynchronousSignalHandler| is bound to when a signal is received. The
// received |signalfd_siginfo| will be passed to |callback|. |callback| must
// returns |true| if the signal handler must be unregistered, and |false|
// otherwise. Due to an implementation detail, you cannot set any sigaction
// flags you might be accustomed to using. This might matter if you hoped to
// use SA_NOCLDSTOP to avoid getting a SIGCHLD when a child process receives a
// SIGSTOP.
void RegisterHandler(int signal, const SignalHandler& callback);
// Unregister a previously registered handler for the given |signal|.
void UnregisterHandler(int signal);
// Implementation of base::MessageLoopForIO::Watcher
void OnFileCanReadWithoutBlocking(int fd) override;
void OnFileCanWriteWithoutBlocking(int fd) override;
private:
// Controller used to manage watching of signalling pipe.
scoped_ptr<base::MessageLoopForIO::FileDescriptorWatcher> fd_watcher_;
// The registered callbacks.
typedef std::map<int, SignalHandler> Callbacks;
Callbacks registered_callbacks_;
// File descriptor for accepting signals indicated by |signal_mask_|.
int descriptor_;
// A set of signals to be handled after the dispatcher is running.
sigset_t signal_mask_;
// A copy of the signal mask before the dispatcher starts, which will be
// used to restore to the original state when the dispatcher stops.
sigset_t saved_signal_mask_;
// Resets the given signal to its default behavior. Doesn't touch
// |registered_callbacks_|.
CHROMEOS_PRIVATE void ResetSignal(int signal);
// Updates the set of signals that this handler listens to.
CHROMEOS_PRIVATE void UpdateSignals();
DISALLOW_COPY_AND_ASSIGN(AsynchronousSignalHandler);
};
} // namespace chromeos
#endif // LIBCHROMEOS_CHROMEOS_ASYNCHRONOUS_SIGNAL_HANDLER_H_
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