Add forceListHidden dial option to force the use of 'LIST -a' command (#271)

This is useful for servers that do not offer up
hidden folders/files by default when using LIST/MLSD
commands.
Setting forceListHidden to true will force the use of
the 'LIST -a' command even when MLST support has
been detected.

client_test.go

@@ -295,6 +295,20 @@ func TestListCurrentDir(t *testing.T) {
 	mock.Wait()
 }
 
+func TestListCurrentDirWithForceListHidden(t *testing.T) {
+	mock, c := openConnExt(t, "127.0.0.1", "no-time", DialWithDisabledMLSD(true), DialWithForceListHidden(true))
+
+	assert.True(t, c.options.forceListHidden)
+	_, err := c.List("")
+	assert.NoError(t, err)
+	assert.Equal(t, "LIST -a", mock.lastFull, "LIST -a must not have a trailing whitespace")
+
+	err = c.Quit()
+	assert.NoError(t, err)
+
+	mock.Wait()
+}
+
 func TestTimeUnsupported(t *testing.T) {
 	mock, c := openConnExt(t, "127.0.0.1", "no-time")
 

ftp.go

@@ -72,18 +72,19 @@ type DialOption struct {
 
 // dialOptions contains all the options set by DialOption.setup
 type dialOptions struct {
-	context     context.Context
-	dialer      net.Dialer
-	tlsConfig   *tls.Config
-	explicitTLS bool
-	disableEPSV bool
-	disableUTF8 bool
-	disableMLSD bool
-	writingMDTM bool
-	location    *time.Location
-	debugOutput io.Writer
-	dialFunc    func(network, address string) (net.Conn, error)
-	shutTimeout time.Duration // time to wait for data connection closing status
+	context         context.Context
+	dialer          net.Dialer
+	tlsConfig       *tls.Config
+	explicitTLS     bool
+	disableEPSV     bool
+	disableUTF8     bool
+	disableMLSD     bool
+	writingMDTM     bool
+	forceListHidden bool
+	location        *time.Location
+	debugOutput     io.Writer
+	dialFunc        func(network, address string) (net.Conn, error)
+	shutTimeout     time.Duration // time to wait for data connection closing status
 }
 
 // Entry describes a file and is returned by List().
@@ -247,6 +248,16 @@ func DialWithWritingMDTM(enabled bool) DialOption {
 	}}
 }
 
+// DialWithForceListHidden returns a DialOption making ServerConn use LIST -a to include hidden files and folders in directory listings
+//
+// This is useful for servers that do not do this by default, but it forces the use of the LIST command
+// even if the server supports MLST.
+func DialWithForceListHidden(enabled bool) DialOption {
+	return DialOption{func(do *dialOptions) {
+		do.forceListHidden = enabled
+	}}
+}
+
 // DialWithLocation returns a DialOption that configures the ServerConn with specified time.Location
 // The location is used to parse the dates sent by the server which are in server's timezone
 func DialWithLocation(location *time.Location) DialOption {
@@ -650,11 +661,14 @@ func (c *ServerConn) List(path string) (entries []*Entry, err error) {
 	var cmd string
 	var parser parseFunc
 
-	if c.mlstSupported {
+	if c.mlstSupported && !c.options.forceListHidden {
 		cmd = "MLSD"
 		parser = parseRFC3659ListLine
 	} else {
 		cmd = "LIST"
+		if c.options.forceListHidden {
+			cmd += " -a"
+		}
 		parser = parseListLine
 	}
 

walker.go

@@ -4,7 +4,7 @@ import (
 	"path"
 )
 
-//Walker traverses the directory tree of a remote FTP server
+// Walker traverses the directory tree of a remote FTP server
 type Walker struct {
 	serverConn *ServerConn
 	root       string