Refactor the flag management for main

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

pkg/libcontainer/nsinit/exec.go

@@ -44,18 +44,14 @@ func Exec(container *libcontainer.Container, tty bool, args []string) (int, erro
 	system.UsetCloseOnExec(r.Fd())
 
 	command := createCommand(container, console, r.Fd(), args)
-
 	if !tty {
-		inPipe, err = command.StdinPipe()
+		if inPipe, err = command.StdinPipe(); err != nil {
-		if err != nil {
 			return -1, err
 		}
-		outPipe, err = command.StdoutPipe()
+		if outPipe, err = command.StdoutPipe(); err != nil {
-		if err != nil {
 			return -1, err
 		}
-		errPipe, err = command.StderrPipe()
+		if errPipe, err = command.StderrPipe(); err != nil {
-		if err != nil {
 			return -1, err
 		}
 	}
@@ -63,7 +59,6 @@ func Exec(container *libcontainer.Container, tty bool, args []string) (int, erro
 	if err := command.Start(); err != nil {
 		return -1, err
 	}
-
 	if err := writePidFile(command); err != nil {
 		command.Process.Kill()
 		return -1, err
@@ -94,6 +89,7 @@ func Exec(container *libcontainer.Container, tty bool, args []string) (int, erro
 	if tty {
 		go io.Copy(os.Stdout, master)
 		go io.Copy(master, os.Stdin)
+
 		state, err := setupWindow(master)
 		if err != nil {
 			command.Process.Kill()
@@ -114,7 +110,6 @@ func Exec(container *libcontainer.Container, tty bool, args []string) (int, erro
 			return -1, err
 		}
 	}
-
 	return command.ProcessState.Sys().(syscall.WaitStatus).ExitStatus(), nil
 }
 

pkg/libcontainer/nsinit/init.go

@@ -173,7 +173,6 @@ func setupVethNetwork(config *libcontainer.Network, tempVethName string) error {
 // has been created and setup
 func getVethName(pipe io.ReadCloser) (string, error) {
 	defer pipe.Close()
-
 	data, err := ioutil.ReadAll(pipe)
 	if err != nil {
 		return "", fmt.Errorf("error reading from stdin %s", err)

pkg/libcontainer/nsinit/nsinit/main.go

@@ -12,27 +12,34 @@ import (
 	"strconv"
 )
 
+var (
+	console string
+	tty     bool
+	pipeFd  int
+)
+
 var (
 	ErrUnsupported    = errors.New("Unsupported method")
 	ErrWrongArguments = errors.New("Wrong argument count")
 )
 
-func main() {
+func init() {
-	var (
+	flag.StringVar(&console, "console", "", "console (pty slave) path")
-		console = flag.String("console", "", "Console (pty slave) name")
+	flag.BoolVar(&tty, "tty", false, "create a tty")
-		tty     = flag.Bool("tty", false, "Create a tty")
+	flag.IntVar(&pipeFd, "pipe", 0, "sync pipe fd")
-		pipeFd  = flag.Int("pipe", 0, "sync pipe fd")
-	)
-	flag.Parse()
 
+	flag.Parse()
+}
+
+func main() {
 	container, err := loadContainer()
 	if err != nil {
 		log.Fatal(err)
 	}
-
 	if flag.NArg() < 1 {
 		log.Fatal(ErrWrongArguments)
 	}
+
 	switch flag.Arg(0) {
 	case "exec": // this is executed outside of the namespace in the cwd
 		var exitCode int
@@ -45,7 +52,7 @@ func main() {
 		if nspid > 0 {
 			exitCode, err = nsinit.ExecIn(container, nspid, flag.Args()[1:])
 		} else {
-			exitCode, err = nsinit.Exec(container, *tty, flag.Args()[1:])
+			exitCode, err = nsinit.Exec(container, tty, flag.Args()[1:])
 		}
 		if err != nil {
 			log.Fatal(err)
@@ -55,7 +62,7 @@ func main() {
 		if flag.NArg() < 2 {
 			log.Fatal(ErrWrongArguments)
 		}
-		if err := nsinit.Init(container, *console, os.NewFile(uintptr(*pipeFd), "pipe"), flag.Args()[1:]); err != nil {
+		if err := nsinit.Init(container, console, os.NewFile(uintptr(pipeFd), "pipe"), flag.Args()[1:]); err != nil {
 			log.Fatal(err)
 		}
 	default: