// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package os

import (

// ErrProcessDone indicates a Process has finished.
var ErrProcessDone = errors.New("os: process already finished")

// Process stores the information about a process created by StartProcess.
type Process struct {
	Pid    int
	handle uintptr      // handle is accessed atomically on Windows
	isdone atomic.Bool  // process has been successfully waited on
	sigMu  sync.RWMutex // avoid race between wait and signal

func newProcess( int,  uintptr) *Process {
	 := &Process{Pid: , handle: }
	runtime.SetFinalizer(, (*Process).Release)

func ( *Process) () {

func ( *Process) () bool {
	return .isdone.Load()

// ProcAttr holds the attributes that will be applied to a new process
// started by StartProcess.
type ProcAttr struct {
	// If Dir is non-empty, the child changes into the directory before
	// creating the process.
	Dir string
	// If Env is non-nil, it gives the environment variables for the
	// new process in the form returned by Environ.
	// If it is nil, the result of Environ will be used.
	Env []string
	// Files specifies the open files inherited by the new process. The
	// first three entries correspond to standard input, standard output, and
	// standard error. An implementation may support additional entries,
	// depending on the underlying operating system. A nil entry corresponds
	// to that file being closed when the process starts.
	// On Unix systems, StartProcess will change these File values
	// to blocking mode, which means that SetDeadline will stop working
	// and calling Close will not interrupt a Read or Write.
	Files []*File

	// Operating system-specific process creation attributes.
	// Note that setting this field means that your program
	// may not execute properly or even compile on some
	// operating systems.
	Sys *syscall.SysProcAttr

// A Signal represents an operating system signal.
// The usual underlying implementation is operating system-dependent:
// on Unix it is syscall.Signal.
type Signal interface {
	String() string
	Signal() // to distinguish from other Stringers

// Getpid returns the process id of the caller.
func () int { return syscall.Getpid() }

// Getppid returns the process id of the caller's parent.
func () int { return syscall.Getppid() }

// FindProcess looks for a running process by its pid.
// The Process it returns can be used to obtain information
// about the underlying operating system process.
// On Unix systems, FindProcess always succeeds and returns a Process
// for the given pid, regardless of whether the process exists. To test whether
// the process actually exists, see whether p.Signal(syscall.Signal(0)) reports
// an error.
func ( int) (*Process, error) {
	return findProcess()

// StartProcess starts a new process with the program, arguments and attributes
// specified by name, argv and attr. The argv slice will become os.Args in the
// new process, so it normally starts with the program name.
// If the calling goroutine has locked the operating system thread
// with runtime.LockOSThread and modified any inheritable OS-level
// thread state (for example, Linux or Plan 9 name spaces), the new
// process will inherit the caller's thread state.
// StartProcess is a low-level interface. The os/exec package provides
// higher-level interfaces.
// If there is an error, it will be of type *PathError.
func ( string,  []string,  *ProcAttr) (*Process, error) {
	return startProcess(, , )

// Release releases any resources associated with the Process p,
// rendering it unusable in the future.
// Release only needs to be called if Wait is not.
func ( *Process) () error {
	return .release()

// Kill causes the Process to exit immediately. Kill does not wait until
// the Process has actually exited. This only kills the Process itself,
// not any other processes it may have started.
func ( *Process) () error {
	return .kill()

// Wait waits for the Process to exit, and then returns a
// ProcessState describing its status and an error, if any.
// Wait releases any resources associated with the Process.
// On most operating systems, the Process must be a child
// of the current process or an error will be returned.
func ( *Process) () (*ProcessState, error) {
	return .wait()

// Signal sends a signal to the Process.
// Sending Interrupt on Windows is not implemented.
func ( *Process) ( Signal) error {
	return .signal()

// UserTime returns the user CPU time of the exited process and its children.
func ( *ProcessState) () time.Duration {
	return .userTime()

// SystemTime returns the system CPU time of the exited process and its children.
func ( *ProcessState) () time.Duration {
	return .systemTime()

// Exited reports whether the program has exited.
// On Unix systems this reports true if the program exited due to calling exit,
// but false if the program terminated due to a signal.
func ( *ProcessState) () bool {
	return .exited()

// Success reports whether the program exited successfully,
// such as with exit status 0 on Unix.
func ( *ProcessState) () bool {
	return .success()

// Sys returns system-dependent exit information about
// the process. Convert it to the appropriate underlying
// type, such as syscall.WaitStatus on Unix, to access its contents.
func ( *ProcessState) () any {
	return .sys()

// SysUsage returns system-dependent resource usage information about
// the exited process. Convert it to the appropriate underlying
// type, such as *syscall.Rusage on Unix, to access its contents.
// (On Unix, *syscall.Rusage matches struct rusage as defined in the
// getrusage(2) manual page.)
func ( *ProcessState) () any {
	return .sysUsage()