Refactor: pkg/util into sub-pkgs

pkg/util/file/file.go

@@ -0,0 +1,57 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+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 file
+
+import (
+	"os"
+)
+
+// FileExists checks if specified file exists.
+func FileExists(filename string) (bool, error) {
+	if _, err := os.Stat(filename); os.IsNotExist(err) {
+		return false, nil
+	} else if err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+// FileOrSymlinkExists checks if specified file or symlink exists.
+func FileOrSymlinkExists(filename string) (bool, error) {
+	if _, err := os.Lstat(filename); os.IsNotExist(err) {
+		return false, nil
+	} else if err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+// ReadDirNoStat returns a string of files/directories contained
+// in dirname without calling lstat on them.
+func ReadDirNoStat(dirname string) ([]string, error) {
+	if dirname == "" {
+		dirname = "."
+	}
+
+	f, err := os.Open(dirname)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	return f.Readdirnames(-1)
+}