Trim trailing whitespace from list commands

Listing a current directory (when the path argument is empty)
would send the command "LIST " with trailing whitespace to FTP
resulting in 500 errors with Solaris FTP server.
This patch fixes that.

client_test.go

@@ -7,6 +7,8 @@ import (
 	"strings"
 	"testing"
 	"time"
+
+	"github.com/stretchr/testify/assert"
 )
 
 const (
@@ -300,3 +302,20 @@ func TestMissingFolderDeleteDirRecur(t *testing.T) {
 	// Wait for the connection to close
 	mock.Wait()
 }
+
+func TestListCurrentDir(t *testing.T) {
+	mock, c := openConn(t, "127.0.0.1")
+
+	_, err := c.List("")
+	assert.NoError(t, err)
+	assert.Equal(t, "LIST", mock.lastFull, "LIST must not have a trailing whitespace")
+
+	_, err = c.NameList("")
+	assert.NoError(t, err)
+	assert.Equal(t, "NLST", mock.lastFull, "NLST must not have a trailing whitespace")
+
+	err = c.Quit()
+	assert.NoError(t, err)
+
+	mock.Wait()
+}

conn_test.go

@@ -18,6 +18,7 @@ type ftpMock struct {
 	listener *net.TCPListener
 	proto    *textproto.Conn
 	commands []string // list of received commands
+	lastFull string   // full last command
 	rest     int
 	fileCont *bytes.Buffer
 	dataConn *mockDataConn
@@ -66,6 +67,7 @@ func (mock *ftpMock) listen(t *testing.T) {
 
 	for {
 		fullCommand, _ := mock.proto.ReadLine()
+		mock.lastFull = fullCommand
 
 		cmdParts := strings.Split(fullCommand, " ")
 

ftp.go

@@ -539,7 +539,11 @@ func (c *ServerConn) cmdDataConnFrom(offset uint64, format string, args ...inter
 
 // NameList issues an NLST FTP command.
 func (c *ServerConn) NameList(path string) (entries []string, err error) {
-	conn, err := c.cmdDataConnFrom(0, "NLST %s", path)
+	space := " "
+	if path == "" {
+		space = ""
+	}
+	conn, err := c.cmdDataConnFrom(0, "NLST%s%s", space, path)
 	if err != nil {
 		return nil, err
 	}
@@ -570,7 +574,11 @@ func (c *ServerConn) List(path string) (entries []*Entry, err error) {
 		parser = parseListLine
 	}
 
-	conn, err := c.cmdDataConnFrom(0, "%s %s", cmd, path)
+	space := " "
+	if path == "" {
+		space = ""
+	}
+	conn, err := c.cmdDataConnFrom(0, "%s%s%s", cmd, space, path)
 	if err != nil {
 		return nil, err
 	}