Fix process.Foreground for BSDs, add openbsd implementation

process/process_darwin.go

@@ -251,7 +251,7 @@ func (p *Process) ForegroundWithContext(ctx context.Context) (bool, error) {
 	if err != nil {
 		return false, err
 	}
-	out, err := invoke.CommandWithContext(ctx, ps, "-o", "stat=", "-p", string(pid))
+	out, err := invoke.CommandWithContext(ctx, ps, "-o", "stat=", "-p", strconv.Itoa(int(pid)))
 	if err != nil {
 		return false, err
 	}

process/process_freebsd.go

@@ -181,7 +181,7 @@ func (p *Process) ForegroundWithContext(ctx context.Context) (bool, error) {
 	if err != nil {
 		return false, err
 	}
-	out, err := invoke.CommandWithContext(ctx, ps, "-o", "stat=", "-p", string(pid))
+	out, err := invoke.CommandWithContext(ctx, ps, "-o", "stat=", "-p", strconv.Itoa(int(pid)))
 	if err != nil {
 		return false, err
 	}

process/process_openbsd.go

@@ -162,6 +162,23 @@ func (p *Process) StatusWithContext(ctx context.Context) (string, error) {
 
 	return s, nil
 }
+func (p *Process) Foreground() (bool, error) {
+	return p.ForegroundWithContext(context.Background())
+}
+
+func (p *Process) ForegroundWithContext(ctx context.Context) (bool, error) {
+	// see https://github.com/shirou/gopsutil/issues/596#issuecomment-432707831 for implementation details
+	pid := p.Pid
+	ps, err := exec.LookPath("ps")
+	if err != nil {
+		return false, err
+	}
+	out, err := invoke.CommandWithContext(ctx, ps, "-o", "stat=", "-p", strconv.Itoa(int(pid)))
+	if err != nil {
+		return false, err
+	}
+	return strings.IndexByte(string(out), '+') != -1, nil
+}
 func (p *Process) Uids() ([]int32, error) {
 	return p.UidsWithContext(context.Background())
 }