--- /dev/null
+/*
+ * Copyright © 2013 Canonical Ltd.
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authored by: Thomas Voß <thomas.voss@canonical.com>
+ */
+
+#ifndef CORE_POSIX_CHILD_PROCESS_H_
+#define CORE_POSIX_CHILD_PROCESS_H_
+
+#include <core/posix/process.h>
+#include <core/posix/standard_stream.h>
+#include <core/posix/visibility.h>
+
+#include <core/signal.h>
+
+#include <iosfwd>
+#include <functional>
+
+namespace core
+{
+namespace posix
+{
+/**
+ * @brief The Process class models a child process of this process.
+ *
+ * In addition to the functionality offered by the Process class, an instance
+ * of ChildProcess offers functionality to wait for status changes of the child
+ * process and to access the child process's standard streams if they have been
+ * redirected when forking or exec'ing.
+ */
+class CORE_POSIX_DLL_PUBLIC ChildProcess : public Process
+{
+public:
+ /**
+ * @brief The DeathObserver class observes child process' states and emits a signal when a monitored child has died.
+ *
+ * Please note that the name of this class is morbid for a reason: Listening
+ * for SIGCHLD is not enough to catch all dying children. Whenever a SIGCHLD is
+ * received, we have to wait for all the children of this process and reap all
+ * monitored ones. We are thus changing state and potentially race with other
+ * wait operations on children.
+ *
+ */
+ class DeathObserver
+ {
+ public:
+ /**
+ * @brief Creates the unique instance of class DeathObserver.
+ * @throw std::logic_error if the given SignalTrap instance does not trap Signal::sig_chld.
+ * @throw std::runtime_error if there already is an instance of the death observer.
+ */
+ static std::unique_ptr<DeathObserver> create_once_with_signal_trap(
+ std::shared_ptr<SignalTrap> trap);
+
+ DeathObserver(const DeathObserver&) = delete;
+ virtual ~DeathObserver() = default;
+
+ DeathObserver& operator=(const DeathObserver&) = delete;
+ bool operator==(const DeathObserver&) const = delete;
+
+ /**
+ * @brief add adds the specified child to the list of observed child processes.
+ * @param child The child to be observed.
+ * @return true iff the child has been added to the list of observed child processes.
+ */
+ virtual bool add(const ChildProcess& child) = 0;
+
+ /**
+ * @brief has checks whether the specified child is observed.
+ * @param child The child to check for.
+ * @return true iff the specified child is observed for state changes.
+ */
+ virtual bool has(const ChildProcess& child) const = 0;
+
+ /**
+ * @brief child_died is emitted whenever an observed child ceases to exist.
+ */
+ virtual const core::Signal<ChildProcess>& child_died() const = 0;
+
+ /**
+ * @brief Checks and reaps all child processes registered with the observer instance.
+ */
+ virtual void on_sig_child() = 0;
+
+ protected:
+ DeathObserver() = default;
+ };
+
+ /**
+ * @brief Creates an invalid ChildProcess.
+ * @return An invalid ChildProcess instance.
+ */
+ static ChildProcess invalid();
+
+ ~ChildProcess();
+
+ /**
+ * @brief Wait for the child process to change state.
+ * @param [in] flags Alters the behavior of the wait operation.
+ * @return Result of the wait operation, as well as information about the
+ * reasons for a child process's state change.
+ */
+ wait::Result wait_for(const wait::Flags& flags);
+
+ /**
+ * @brief Mark the child process to not to be killed when the ChildProcess
+ * instance goes away.
+ */
+ void dont_kill_on_cleanup();
+
+#ifndef ANDROID
+ /**
+ * @brief Access this process's stderr.
+ */
+ std::istream& cerr();
+
+ /**
+ * @brief Access this process's stdin.
+ */
+ std::ostream& cin();
+
+ /**
+ * @brief Access this process's stdout.
+ */
+ std::istream& cout();
+#endif
+
+private:
+ friend ChildProcess fork(const std::function<posix::exit::Status()>&, const StandardStream&);
+ friend ChildProcess vfork(const std::function<posix::exit::Status()>&, const StandardStream&);
+
+ class CORE_POSIX_DLL_LOCAL Pipe
+ {
+ public:
+ static Pipe invalid();
+
+ Pipe();
+ Pipe(const Pipe& rhs);
+ ~Pipe();
+
+ Pipe& operator=(const Pipe& rhs);
+
+ int read_fd() const;
+ void close_read_fd();
+
+ int write_fd() const;
+ void close_write_fd();
+
+ private:
+ Pipe(int fds[2]);
+ int fds[2];
+ };
+
+ CORE_POSIX_DLL_LOCAL ChildProcess(pid_t pid,
+ const Pipe& stdin,
+ const Pipe& stdout,
+ const Pipe& stderr);
+
+ struct CORE_POSIX_DLL_LOCAL Private;
+ std::shared_ptr<Private> d;
+};
+}
+}
+
+#endif // CORE_POSIX_CHILD_PROCESS_H_
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