Fix reading dirs from a MergeFS

utils/merge_fs.go

@@ -90,7 +90,7 @@ type mergedDir struct {
 	pos     int
 }
 
-func (d mergedDir) Readdir(count int) ([]os.FileInfo, error) {
+func (d *mergedDir) Readdir(count int) ([]os.FileInfo, error) {
 	if d.pos >= len(d.entries) && count > 0 {
 		return nil, io.EOF
 	}
@@ -102,12 +102,12 @@ func (d mergedDir) Readdir(count int) ([]os.FileInfo, error) {
 	return e, nil
 }
 
-func (d mergedDir) Close() error               { return nil }
-func (d mergedDir) Stat() (os.FileInfo, error) { return d.info, nil }
-func (d mergedDir) Read(p []byte) (n int, err error) {
+func (d *mergedDir) Close() error               { return nil }
+func (d *mergedDir) Stat() (os.FileInfo, error) { return d.info, nil }
+func (d *mergedDir) Read(p []byte) (n int, err error) {
 	return 0, fmt.Errorf("cannot Read from directory %s", d.name)
 }
-func (d mergedDir) Seek(offset int64, whence int) (int64, error) {
+func (d *mergedDir) Seek(offset int64, whence int) (int64, error) {
 	if offset == 0 && whence == io.SeekStart {
 		d.pos = 0
 		return 0, nil

utils/merge_fs_test.go

@@ -1,6 +1,7 @@
 package utils_test
 
 import (
+	"io"
 	"io/ioutil"
 	"net/http"
 	"os"
@@ -73,6 +74,27 @@ var _ = Describe("mergeFS", func() {
 		Expect(list[0].Name()).To(Equal("1111.txt"))
 		Expect(list[1].Name()).To(Equal("2222.json"))
 	})
+
+	It("allows to seek to the beginning of the directory", func() {
+		_f(baseName, "1111")
+		_f(baseName, "2222")
+		_f(baseName, "3333")
+
+		dir, err := mergedDir.Open(".")
+		Expect(err).To(BeNil())
+
+		list, _ := dir.Readdir(2)
+		Expect(list).To(HaveLen(2))
+		Expect(list[0].Name()).To(Equal("1111"))
+		Expect(list[1].Name()).To(Equal("2222"))
+
+		Expect(dir.Seek(0, io.SeekStart)).To(Equal(int64(0)))
+
+		list, _ = dir.Readdir(2)
+		Expect(list).To(HaveLen(2))
+		Expect(list[0].Name()).To(Equal("1111"))
+		Expect(list[1].Name()).To(Equal("2222"))
+	})
 })
 
 func _f(dir, name string, content ...string) string {