memmap: opening empty path should be an error

lstater_test.go

@@ -73,7 +73,7 @@ func TestLstatIfPossible(t *testing.T) {
 	}
 
 	testLstat := func(l Lstater, pathFile, pathSymlink string) {
-		shouldLstat := pathSymlink != ""
+		shouldLstat := pathSymlink != FilePathSeparator
 		statRegular := checkLstat(l, pathFile, shouldLstat)
 		statSymlink := checkLstat(l, pathSymlink, shouldLstat)
 		if statRegular == nil || statSymlink == nil {
@@ -81,7 +81,7 @@ func TestLstatIfPossible(t *testing.T) {
 		}
 
 		symSym := statSymlink.Mode()&os.ModeSymlink == os.ModeSymlink
-		if symSym == (pathSymlink == "") {
+		if symSym == (pathSymlink == FilePathSeparator) {
 			t.Fatal("expected the FileInfo to describe the symlink")
 		}
 
@@ -95,8 +95,8 @@ func TestLstatIfPossible(t *testing.T) {
 	testLstat(overlayFs1, pathFile, pathSymlink)
 	testLstat(overlayFs2, pathFile, pathSymlink)
 	testLstat(basePathFs, "afero.txt", "symafero.txt")
-	testLstat(overlayFsMemOnly, pathFileMem, "")
+	testLstat(overlayFsMemOnly, pathFileMem, FilePathSeparator)
-	testLstat(basePathFsMem, "aferom.txt", "")
+	testLstat(basePathFsMem, "aferom.txt", FilePathSeparator)
 	testLstat(roFs, pathFile, pathSymlink)
-	testLstat(roFsMem, pathFileMem, "")
+	testLstat(roFsMem, pathFileMem, FilePathSeparator)
 }

memmap.go

@@ -159,6 +159,11 @@ func (m *MemMapFs) MkdirAll(path string, perm os.FileMode) error {
 
 // Handle some relative paths
 func normalizePath(path string) string {
+	// Cleaning an empty path would result in "."
+	if path == "" {
+		return path
+	}
+
 	path = filepath.Clean(path)
 
 	switch path {

memmap_test.go

@@ -449,3 +449,13 @@ func TestMemFsUnexpectedEOF(t *testing.T) {
 		t.Fatal("Expected ErrUnexpectedEOF")
 	}
 }
+
+func TestStatEmptyPath(t *testing.T) {
+	t.Parallel()
+
+	fs := NewMemMapFs()
+
+	if _, err := fs.Stat(""); !os.IsNotExist(err) {
+		t.Fatal(err)
+	}
+}