fs: Add helper functions ReadDir/ReadDirNames

internal/fs/fs_helpers.go

@@ -0,0 +1,45 @@
+package fs
+
+import "os"
+
+// ReadDir reads the directory named by dirname within fs and returns a list of
+// directory entries.
+func ReadDir(fs FS, dirname string) ([]os.FileInfo, error) {
+	f, err := fs.Open(dirname)
+	if err != nil {
+		return nil, err
+	}
+
+	entries, err := f.Readdir(-1)
+	if err != nil {
+		return nil, err
+	}
+
+	err = f.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	return entries, nil
+}
+
+// ReadDirNames reads the directory named by dirname within fs and returns a
+// list of entry names.
+func ReadDirNames(fs FS, dirname string) ([]string, error) {
+	f, err := fs.Open(dirname)
+	if err != nil {
+		return nil, err
+	}
+
+	entries, err := f.Readdirnames(-1)
+	if err != nil {
+		return nil, err
+	}
+
+	err = f.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	return entries, nil
+}