for i := 0; i < len(all); i++ {
		for j := 0; j < len(all)-i; j++ {
			buf := make([]byte, j)
			n, err := b.ReadAt(buf, int64(i))
			if err != nil || n != len(buf) {
				t.Errorf("ReadAt(%d, %d) = %d, %v; want %d, nil", i, j, n, err, len(buf))
			}
			if !bytes.Equal(buf, all[i:i+j]) {
				t.Errorf("ReadAt(%d, %d) = %q; want %q", i, j, buf, all[i:i+j])
			}
		}
	}
}

// findBodyOffset does the minimum work to verify the file has a header
// and returns the file body offset.
func (f *File) findBodyOffset() (int64, error) {
	var buf [fileHeaderLen]byte
	if _, err := f.zipr.ReadAt(buf[:], f.headerOffset); err != nil {
		return 0, err
	}
	b := readBuf(buf[:])
	if sig := b.uint32(); sig != fileHeaderSignature {
		return 0, ErrFormat
	}
	b = b[22:] // skip over most of the header

			minio.PutObjectOptions{DisableContentSha256: true},
		)
		return err
	}

	return NotImplemented{}
}

type listerAt []os.FileInfo

// Modeled after strings.Reader's ReadAt() implementation
func (f listerAt) ListAt(ls []os.FileInfo, offset int64) (int, error) {
	var n int
	if offset >= int64(len(f)) {
		return 0, io.EOF
	}
	n = copy(ls, f[offset:])
	if n < len(ls) {