portlist: move code around to avoid unused function warnings.

portlist/netstat.go

@@ -7,12 +7,9 @@
 package portlist
 
 import (
-	"fmt"
 	"sort"
 	"strconv"
 	"strings"
-
-	exec "tailscale.com/tempfork/osexec"
 )
 
 func parsePort(s string) int {
@@ -141,23 +138,3 @@ func parsePortsNetstat(output string) List {
 
 	return l
 }
-
-//lint:ignore U1000 function is only used on !linux, but we want the
-// unit test to run on linux, so we don't build-tag it away.
-func listPortsNetstat(arg string) (List, error) {
-	exe, err := exec.LookPath("netstat")
-	if err != nil {
-		return nil, fmt.Errorf("netstat: lookup: %v", err)
-	}
-	output, err := exec.Command(exe, arg).Output()
-	if err != nil {
-		xe, ok := err.(*exec.ExitError)
-		stderr := ""
-		if ok {
-			stderr = strings.TrimSpace(string(xe.Stderr))
-		}
-		return nil, fmt.Errorf("netstat: %v (%q)", err, stderr)
-	}
-
-	return parsePortsNetstat(string(output)), nil
-}

portlist/netstat_exec.go

@@ -0,0 +1,32 @@
+// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build windows freebsd openbsd darwin,amd64
+
+package portlist
+
+import (
+	"fmt"
+	"strings"
+
+	exec "tailscale.com/tempfork/osexec"
+)
+
+func listPortsNetstat(arg string) (List, error) {
+	exe, err := exec.LookPath("netstat")
+	if err != nil {
+		return nil, fmt.Errorf("netstat: lookup: %v", err)
+	}
+	output, err := exec.Command(exe, arg).Output()
+	if err != nil {
+		xe, ok := err.(*exec.ExitError)
+		stderr := ""
+		if ok {
+			stderr = strings.TrimSpace(string(xe.Stderr))
+		}
+		return nil, fmt.Errorf("netstat: %v (%q)", err, stderr)
+	}
+
+	return parsePortsNetstat(string(output)), nil
+}

portlist/portlist_windows.go

@@ -4,7 +4,9 @@
 
 package portlist
 
-import "time"
+import (
+	"time"
+)
 
 // Forking on Windows is insanely expensive, so don't do it too often.
 const pollInterval = 5 * time.Second