var (
	Interrupt Signal = syscall.Note("interrupt")
	Kill      Signal = syscall.Note("kill")
)

func startProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
	sysattr := &syscall.ProcAttr{
		Dir: attr.Dir,
		Env: attr.Env,
		Sys: attr.Sys,
	}

	sysattr.Files = make([]uintptr, 0, len(attr.Files))
	for _, f := range attr.Files {

	"math"
	. "os"
	"runtime"
	"syscall"
	"testing"
)

func TestErrProcessDone(t *testing.T) {
	testenv.MustHaveGoBuild(t)
	t.Parallel()

	p, err := StartProcess(testenv.GoToolPath(t), []string{"go"}, &ProcAttr{})
	if err != nil {
		t.Fatalf("starting test process: %v", err)
	}
	p.Wait()
	if got := p.Signal(Kill); got != ErrProcessDone {
		t.Errorf("got %v want %v", got, ErrProcessDone)
	}
}

	if err := os.CheckPidfdOnce(); err != nil {
		// Non-pidfd code paths tested in exec_unix_test.go.
		t.Skipf("skipping: pidfd not available: %v", err)
	}

	p, err := os.StartProcess(testenv.GoToolPath(t), []string{"go"}, &os.ProcAttr{})
	if err != nil {
		t.Fatalf("starting test process: %v", err)
	}
	p.Wait()

	// Use pid of a non-existing process.
	proc, err := os.FindProcess(p.Pid)
	// FindProcess should never return errors on Unix.

// sending a signal.
var (
	Interrupt Signal = syscall.SIGINT
	Kill      Signal = syscall.SIGKILL
)

func startProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
	// If there is no SysProcAttr (ie. no Chroot or changed
	// UID/GID), double-check existence of the directory we want
	// to chdir into. We can make the error clearer this way.

	r, w, err := os.Pipe()
	if err != nil {
		t.Fatalf("Pipe() got err %v, want nil", err)
	}
	defer r.Close()
	defer w.Close()

	p, err := os.StartProcess(testenv.GoToolPath(t), []string{"go"}, &os.ProcAttr{
		// N.B. On Windows, StartProcess requires exactly 3 Files. Pass
		// in a dummy pipe to avoid irrelevant output on the test stdout.
		Files: []*os.File{r, w, w},
	})
	if err != nil {

	// returning the wait status, while future calls error with "process
	// released" rather than "process done".
	p.state.CompareAndSwap(0, uint64(reason))
}

// 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

	childFiles = append(childFiles, stderr)
	childFiles = append(childFiles, c.ExtraFiles...)

	env, err := c.environ()
	if err != nil {
		return err
	}

	c.Process, err = os.StartProcess(lp, c.argv(), &os.ProcAttr{
		Dir:   c.Dir,
		Files: childFiles,
		Env:   env,
		Sys:   c.SysProcAttr,
	})
	if err != nil {
		return err
	}
	started = true