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/*
* This source code is released into the public domain.
*/
module;
#include <expected>
#include <optional>
#include <system_error>
#include <utility>
#include <sys/types.h>
export module nihil.posix:process;
import nihil.error;
namespace nihil {
/*
* wait_result: the exit status of a process.
*/
export struct wait_result final {
// Return true if the process exited normally with an exit code of
// zero, otherwise false.
[[nodiscard]] auto okay(this wait_result const &self) -> bool;
[[nodiscard]] explicit operator bool(this wait_result const &self);
// Return the exit status, if any.
[[nodiscard]] auto status(this wait_result const &self)
-> std::optional<int>;
// Return the exit signal, if any.
[[nodiscard]] auto signal(this wait_result const &self)
-> std::optional<int>;
private:
friend struct process;
int _status;
// Construct a new wait_result from the output of waitpid().
wait_result(int status);
};
/*
* process: represents a process we created, which can be waited for.
*/
export struct process final {
process() = delete;
/*
* Create a new process from a pid, which must be a child of the
* current process.
*/
process(::pid_t pid);
// When destroyed, we automatically wait for the process to
// avoid creating zombie processes.
~process();
// Movable.
process(process &&) noexcept;
auto operator=(this process &, process &&) noexcept -> process &;
// Not copyable.
process(process const &) = delete;
auto operator=(this process &, process const &) -> process & = delete;
// Get the child's process id.
[[nodiscard]] auto pid(this process const &self) noexcept -> ::pid_t;
/*
* Wait for this process to exit (by calling waitpid()) and return
* its exit status. This destroys the process state, leaving this
* object in a moved-from state.
*/
[[nodiscard]] auto wait(this process &&self)
-> std::expected<wait_result, error>;
/*
* Release this process so we won't try to wait for it when
* destroying this object.
*/
[[nodiscard]] auto release(this process &&self) -> ::pid_t;
private:
::pid_t m_pid;
};
} // namespace nihil
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