remove ByteCounter from rootfs

internal/cmdrootfs/cmdrootfs.go

@@ -13,7 +13,11 @@ import (
 )
 
 type (
-	rootfsFactory func(io.ReadSeeker) io.WriterTo
+	flattener interface {
+		Flatten(io.Writer) error
+	}
+
+	rootfsFactory func(io.ReadSeeker) flattener
 
 	// Command is "rootfs" command
 	Command struct {
@@ -55,10 +59,7 @@ func (c *Command) Execute(args []string) (err error) {
 		out = outf
 	}
 
-	if _, err := c.rootfsNew(rd).WriteTo(out); err != nil {
-		return err
-	}
-	return nil
+	return c.rootfsNew(rd).Flatten(out)
 }
 
 // init() initializes Command with the default options.
@@ -67,7 +68,7 @@ func (c *Command) Execute(args []string) (err error) {
 // command will initialize itself.
 func (c *Command) init() {
 	c.BaseCommand.Init()
-	c.rootfsNew = func(r io.ReadSeeker) io.WriterTo {
+	c.rootfsNew = func(r io.ReadSeeker) flattener {
 		return rootfs.New(r)
 	}
 }

internal/cmdrootfs/cmdrootfs_test.go

@@ -67,7 +67,7 @@ func TestExecute(t *testing.T) {
 			inf := filepath.Join(dir, tt.infile)
 			c.PositionalArgs.Infile = goflags.Filename(inf)
 			c.PositionalArgs.Outfile = tt.outfile
-			c.rootfsNew = func(r io.ReadSeeker) io.WriterTo {
+			c.rootfsNew = func(r io.ReadSeeker) flattener {
 				return &passthrough{r}
 			}
 
@@ -92,4 +92,7 @@ func TestExecute(t *testing.T) {
 
 type passthrough struct{ r io.Reader }
 
-func (p *passthrough) WriteTo(w io.Writer) (int64, error) { return io.Copy(w, p.r) }
+func (p *passthrough) Flatten(w io.Writer) error {
+	_, err := io.Copy(w, p.r)
+	return err
+}