Ensure Win service bits only compile on Windows.

btcd.go

@@ -19,6 +19,10 @@ var (
 	shutdownChannel = make(chan bool)
 )
 
+// winServiceMain is only invoked on Windows.  It detect when btcd is running as
+// a service and reacts accordingly.
+var winServiceMain func() (bool, error)
+
 // btcdMain is the real main function for btcd.  It is necessary to work around
 // the fact that deferred functions do not run when os.Exit() is called.  The
 // optional serverChan parameter is mainly used by the service code to be
@@ -126,7 +130,7 @@ func main() {
 	// the return isService flag is true, exit now since we ran as a
 	// service.  Otherwise, just fall through to normal operation.
 	if runtime.GOOS == "windows" {
-		isService, err := serviceMain()
+		isService, err := winServiceMain()
 		if err != nil {
 			fmt.Println(err)
 			os.Exit(1)

config.go

@@ -43,6 +43,10 @@ var (
 	defaultLogFile     = filepath.Join(btcdHomeDir, "logs", "btcd.log")
 )
 
+// runServiceCommand is only set to a real function on Windows.  It is used
+// to parse and execute service commands specified via the -s flag.
+var runServiceCommand func(string) error
+
 // config defines the configuration options for btcd.
 //
 // See loadConfig for details on the configuration load process.
@@ -271,10 +275,6 @@ func loadConfig() (*config, []string, error) {
 
 	// Service options which are only added on Windows.
 	serviceOpts := serviceOptions{}
-	var runServiceCommand func(string) error
-	if runtime.GOOS == "windows" {
-		runServiceCommand = performServiceCommand
-	}
 
 	// Create the home directory if it doesn't already exist.
 	err := os.MkdirAll(btcdHomeDir, 0700)

service_windows.go

@@ -318,3 +318,9 @@ func serviceMain() (bool, error) {
 
 	return true, nil
 }
+
+// Set windows specific functions to real functions.
+func init() {
+	runServiceCommand = performServiceCommand
+	winServiceMain = serviceMain
+}