[process] implement ParentWithContext using PpidWithContext

Removes need for redundant ParentWithContext implementations. It had led
to it being unsupported on FreeBSD and OpenBSD even though
PpidWithContext was available for them, and different implementations
for getting the parent info used in ParentWithContext and
PpidWithContext on Darwin and Linux.

process/process.go

@@ -402,6 +402,15 @@ func (p *Process) Parent() (*Process, error) {
 	return p.ParentWithContext(context.Background())
 }
 
+// ParentWithContext returns parent Process of the process.
+func (p *Process) ParentWithContext(ctx context.Context) (*Process, error) {
+	ppid, err := p.PpidWithContext(ctx)
+	if err != nil {
+		return nil, err
+	}
+	return NewProcessWithContext(ctx, ppid)
+}
+
 // Status returns the process status.
 // Return value could be one of these.
 // R: Running S: Sleep T: Stop I: Idle

process/process_darwin.go

@@ -141,23 +141,6 @@ func (p *Process) createTimeWithContext(ctx context.Context) (int64, error) {
 	return start.Unix() * 1000, nil
 }
 
-func (p *Process) ParentWithContext(ctx context.Context) (*Process, error) {
-	out, err := common.CallLsofWithContext(ctx, invoke, p.Pid, "-FR")
-	if err != nil {
-		return nil, err
-	}
-	for _, line := range out {
-		if len(line) >= 1 && line[0] == 'R' {
-			v, err := strconv.Atoi(line[1:])
-			if err != nil {
-				return nil, err
-			}
-			return NewProcessWithContext(ctx, int32(v))
-		}
-	}
-	return nil, fmt.Errorf("could not find parent line")
-}
-
 func (p *Process) StatusWithContext(ctx context.Context) ([]string, error) {
 	r, err := callPsWithContext(ctx, "state", p.Pid, false, false)
 	if err != nil {

process/process_fallback.go

@@ -74,10 +74,6 @@ func (p *Process) CwdWithContext(ctx context.Context) (string, error) {
 	return "", common.ErrNotImplementedError
 }
 
-func (p *Process) ParentWithContext(ctx context.Context) (*Process, error) {
-	return nil, common.ErrNotImplementedError
-}
-
 func (p *Process) StatusWithContext(ctx context.Context) ([]string, error) {
 	return []string{""}, common.ErrNotImplementedError
 }

process/process_freebsd.go

@@ -118,10 +118,6 @@ func (p *Process) createTimeWithContext(ctx context.Context) (int64, error) {
 	return k.Start.Sec*1000 + k.Start.Usec/1000, nil
 }
 
-func (p *Process) ParentWithContext(ctx context.Context) (*Process, error) {
-	return nil, common.ErrNotImplementedError
-}
-
 func (p *Process) StatusWithContext(ctx context.Context) ([]string, error) {
 	k, err := p.getKProc()
 	if err != nil {

process/process_linux.go

@@ -123,17 +123,6 @@ func (p *Process) CwdWithContext(ctx context.Context) (string, error) {
 	return p.fillFromCwdWithContext()
 }
 
-func (p *Process) ParentWithContext(ctx context.Context) (*Process, error) {
-	err := p.fillFromStatusWithContext()
-	if err != nil {
-		return nil, err
-	}
-	if p.parent == 0 {
-		return nil, fmt.Errorf("wrong number of parents")
-	}
-	return NewProcessWithContext(ctx, p.parent)
-}
-
 func (p *Process) StatusWithContext(ctx context.Context) ([]string, error) {
 	err := p.fillFromStatusWithContext()
 	if err != nil {

process/process_openbsd.go

@@ -142,10 +142,6 @@ func (p *Process) createTimeWithContext(ctx context.Context) (int64, error) {
 	return 0, common.ErrNotImplementedError
 }
 
-func (p *Process) ParentWithContext(ctx context.Context) (*Process, error) {
-	return nil, common.ErrNotImplementedError
-}
-
 func (p *Process) StatusWithContext(ctx context.Context) ([]string, error) {
 	k, err := p.getKProc()
 	if err != nil {

process/process_plan9.go

@@ -74,10 +74,6 @@ func (p *Process) CwdWithContext(ctx context.Context) (string, error) {
 	return "", common.ErrNotImplementedError
 }
 
-func (p *Process) ParentWithContext(ctx context.Context) (*Process, error) {
-	return nil, common.ErrNotImplementedError
-}
-
 func (p *Process) StatusWithContext(ctx context.Context) ([]string, error) {
 	return []string{""}, common.ErrNotImplementedError
 }

process/process_solaris.go

@@ -88,10 +88,6 @@ func (p *Process) CwdWithContext(ctx context.Context) (string, error) {
 	return p.fillFromPathCwdWithContext(ctx)
 }
 
-func (p *Process) ParentWithContext(ctx context.Context) (*Process, error) {
-	return nil, common.ErrNotImplementedError
-}
-
 func (p *Process) StatusWithContext(ctx context.Context) ([]string, error) {
 	return []string{""}, common.ErrNotImplementedError
 }

process/process_windows.go

@@ -435,15 +435,6 @@ func (p *Process) CwdWithContext(_ context.Context) (string, error) {
 	return "", nil
 }
 
-func (p *Process) ParentWithContext(ctx context.Context) (*Process, error) {
-	ppid, err := p.PpidWithContext(ctx)
-	if err != nil {
-		return nil, fmt.Errorf("could not get ParentProcessID: %s", err)
-	}
-
-	return NewProcessWithContext(ctx, ppid)
-}
-
 func (p *Process) StatusWithContext(ctx context.Context) ([]string, error) {
 	return []string{""}, common.ErrNotImplementedError
 }