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// Copyright 2015 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 LIBBRILLO_BRILLO_PROCESS_REAPER_H_
#define LIBBRILLO_BRILLO_PROCESS_REAPER_H_
#include <sys/wait.h>
#include <map>
#include <base/callback.h>
#include <base/location.h>
#include <base/macros.h>
#include <brillo/asynchronous_signal_handler.h>
namespace brillo {
class BRILLO_EXPORT ProcessReaper final {
public:
// The callback called when a child exits.
using ChildCallback = base::OnceCallback<void(const siginfo_t&)>;
ProcessReaper() = default;
~ProcessReaper();
// Register the ProcessReaper using either the provided
// brillo::AsynchronousSignalHandlerInterface. You can call Unregister() to
// remove this ProcessReapper or it will be called during shutdown.
// You can only register this ProcessReaper with one signal handler at a time.
void Register(AsynchronousSignalHandlerInterface* async_signal_handler);
// Unregisters the ProcessReaper from the
// brillo::AsynchronousSignalHandlerInterface passed in Register(). It
// doesn't do anything if not registered.
void Unregister();
// Watch for the child process |pid| to finish and call |callback| when the
// selected process exits or the process terminates for other reason. The
// |callback| receives the exit status and exit code of the terminated process
// as a siginfo_t. See wait(2) for details about siginfo_t.
bool WatchForChild(const base::Location& from_here,
pid_t pid,
ChildCallback callback);
// Stop watching child process |pid|. This is useful in situations
// where the child process may have been reaped outside of the signal
// handler, or the caller is no longer interested in being notified about
// this child process anymore. Returns true if a child was removed from
// the watchlist.
bool ForgetChild(pid_t pid);
private:
// SIGCHLD handler for the AsynchronousSignalHandler. Always returns false
// (meaning that the signal handler should not be unregistered).
bool HandleSIGCHLD(const signalfd_siginfo& sigfd_info);
struct WatchedProcess {
base::Location location;
ChildCallback callback;
};
std::map<pid_t, WatchedProcess> watched_processes_;
// The |async_signal_handler_| is owned by the caller and is |nullptr| when
// not registered.
AsynchronousSignalHandlerInterface* async_signal_handler_{nullptr};
DISALLOW_COPY_AND_ASSIGN(ProcessReaper);
};
} // namespace brillo
#endif // LIBBRILLO_BRILLO_PROCESS_REAPER_H_