some doc + fic Components

pkg/layerfs/doc.go

@@ -16,7 +16,7 @@
  *  limitations under the License.
  */
 
-// Package layerfs provides a virtual filesystem supporting a filesytem layer
+// Package layerfs provides a virtual filesystem supporting a filesystem layer
 // on top of a base filesystem, that is used to keep track of all changes
 // done to the filesystem. Thereby the root filesystem is not changed.
 package layerfs

pkg/vfs/doc.go

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2022 Mandelsoft. All rights reserved.
+ *  This file is licensed under the Apache Software License, v. 2 except as noted
+ *  otherwise in the LICENSE file
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+// Package vfs provides a virtual filesystem for GO. It is the main package
+// providing the abstract interfaces and implementation-agnostic
+// utility functions wrapped together with an implementation into a
+// comprehensive user interface VFS.
+// (see https://pkg.go.dev/github.com/mandelsoft/vfs)
+package vfs

pkg/vfs/utils.go

@@ -268,7 +268,14 @@ func Abs(fs FileSystem, path string) (string, error) {
 	return Join(fs, p, path), nil
 }
 
+// Rel determines the relative path from a source folder
+// to a target file.
 func Rel(fs FileSystem, src, tgt string) (string, error) {
+	if ok, _ := Exists(fs, src); ok {
+		if ok, _ := IsDir(fs, src); !ok {
+			return "", ErrNotDir
+		}
+	}
 	s, err := Canonical(fs, src, false)
 	if err != nil {
 		return "", fmt.Errorf("%s: %w", src, err)
@@ -305,13 +312,15 @@ func Rel(fs FileSystem, src, tgt string) (string, error) {
 	return Join(fs, sseq[is:]...), nil
 }
 
+// Components splits a path into its volume part and a list
+// of path components.
 func Components(fs FileSystem, p string) (string, []string) {
 	var seq []string
 	var b string
 
 	v, p := SplitVolume(fs, p)
 
-	for !IsRoot(fs, p) {
+	for p != "" && !IsRoot(fs, p) {
 		p, b = Split(fs, p)
 		seq = append(seq, b)
 	}