daemon: Clean up copyright headers and documentation

- Added copyright 2015-2018 CoreOS, Inc.
- Proper godoc package comment
- Got rid of named (but unused) return values

Fixes #83.

Author: muesli

daemon/sdnotify.go

@@ -1,4 +1,5 @@
 // Copyright 2014 Docker, Inc.
+// Copyright 2015-2018 CoreOS, Inc.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -13,7 +14,11 @@
 // limitations under the License.
 //
 
-// Code forked from Docker project
+// Package daemon provides a Go implementation of the sd_notify protocol.
+// It can be used to inform systemd of service start-up completion, watchdog
+// events, and other status changes.
+//
+// https://www.freedesktop.org/software/systemd/man/sd_notify.html#Description
 package daemon
 
 import (
@@ -29,7 +34,7 @@ import (
 // (false, nil) - notification not supported (i.e. NOTIFY_SOCKET is unset)
 // (false, err) - notification supported, but failure happened (e.g. error connecting to NOTIFY_SOCKET or while sending data)
 // (true, nil) - notification supported, data has been sent
-func SdNotify(unsetEnvironment bool, state string) (sent bool, err error) {
+func SdNotify(unsetEnvironment bool, state string) (bool, error) {
 	socketAddr := &net.UnixAddr{
 		Name: os.Getenv("NOTIFY_SOCKET"),
 		Net:  "unixgram",
@@ -41,10 +46,9 @@ func SdNotify(unsetEnvironment bool, state string) (sent bool, err error) {
 	}
 
 	if unsetEnvironment {
-		err = os.Unsetenv("NOTIFY_SOCKET")
-	}
-	if err != nil {
-		return false, err
+		if err := os.Unsetenv("NOTIFY_SOCKET"); err != nil {
+			return false, err
+		}
 	}
 
 	conn, err := net.DialUnix(socketAddr.Net, nil, socketAddr)
@@ -54,9 +58,7 @@ func SdNotify(unsetEnvironment bool, state string) (sent bool, err error) {
 	}
 	defer conn.Close()
 
-	_, err = conn.Write([]byte(state))
-	// Error sending the message
-	if err != nil {
+	if _, err = conn.Write([]byte(state)); err != nil {
 		return false, err
 	}
 	return true, nil