added cache only access server

pkg/fs/fs.go

@@ -128,11 +128,50 @@ func (fs *FS) RemoveDst(name string) error {
 	return os.Remove(dp)
 }
 
-func (fs *FS) statDst(name string) (fi stdfs.FileInfo, err error) {
+func (fs *FS) StatDst(name string) (fi stdfs.FileInfo, err error) {
+	fi, err = fs.sc.Get(name)
+	if err == nil {
+		return
+	}
+	return fs.statDst(name)
+}
+
+func (fs *FS) statDst(name string) (stdfs.FileInfo, error) {
 	_, dp := fs.paths(name)
 	return os.Stat(dp)
 }
 
+func (fs *FS) OpenDst(name string) (f http.File, err error) {
+	log := fs.log.WithValues("file", name)
+	_, dp := fs.paths(name)
+	fi, err := fs.StatDst(name)
+	if err != nil {
+		if !skipLog(name) {
+			log.Error(err, "error stat cache file")
+		}
+		return
+	}
+	file, err := os.Open(dp)
+	if err != nil {
+		if !skipLog(name) {
+			log.Error(err, "error opening cache file")
+		}
+		return
+	}
+	if fi.IsDir() {
+		f = &Dir{log: log.WithName("dir"), f: file, dc: fs.dc}
+		return
+	}
+	md := fs.metadata(name, fi.Size())
+	f = &File{
+		log:     log,
+		f:       file,
+		md:      md,
+		offline: true,
+	}
+	return
+}
+
 func (fs *FS) CancelPreload(name string) {
 	if cancel, ok := fs.pm[name]; ok {
 		cancel()