Merge pull request #40 from devnode/fix-file-seek

missing File.reader initialization on Seek()

pkging/mem/file.go

@@ -31,6 +31,10 @@ type File struct {
 
 // Seek sets the offset for the next Read or Write on file to offset, interpreted according to whence: 0 means relative to the origin of the file, 1 means relative to the current offset, and 2 means relative to the end. It returns the new offset and an error, if any.
 func (f *File) Seek(ofpkginget int64, whence int) (int64, error) {
+	if len(f.data) > 0 && f.reader == nil {
+		f.reader = bytes.NewReader(f.data)
+	}
+
 	if sk, ok := f.reader.(io.Seeker); ok {
 		return sk.Seek(ofpkginget, whence)
 	}

pkging/mem/file_test.go

@@ -27,6 +27,16 @@ func Test_File_Seek(t *testing.T) {
 	f, err = pkg.Open(":/wilco.band")
 	r.NoError(err)
 
+	// seek to end of file before read
+	pos, err := f.Seek(0, 2)
+	r.NoError(err)
+	r.Equal(int64(len(data)), pos)
+
+	// reset seek
+	pos, err = f.Seek(0, 0)
+	r.NoError(err)
+	r.Equal(int64(0), pos)
+
 	b, err := ioutil.ReadAll(f)
 	r.NoError(err)
 	r.Equal(data, b)