dir2config: switch to includes instead of ad-hoc defaults

cmd/dkl-dir2config/fs.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"io"
+	iofs "io/fs"
+)
+
+type FS interface {
+	Open(path string) (io.ReadCloser, error)
+	List(path string) ([]string, error)
+}
+
+type fsFS struct{ iofs.FS }
+
+func (fs fsFS) Open(path string) (io.ReadCloser, error) {
+	return fs.FS.Open(path)
+}
+
+func (fs fsFS) List(path string) (entries []string, err error) {
+	dirEnts, err := iofs.ReadDir(fs.FS, path)
+	if err != nil {
+		return
+	}
+
+	entries = make([]string, 0, len(dirEnts))
+	for _, ent := range dirEnts {
+		if ent.IsDir() {
+			continue
+		}
+		entries = append(entries, ent.Name())
+	}
+
+	return
+}