wip macOS port

1 files changed, 91 insertions, 0 deletions

diff --git a/nihil.posix/process.ccm b/nihil.posix/process.ccm
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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