Decouple shared functions between controllers (#8829)

* Decouple shared functions between controllers

* Apply suggestions from code review

Co-authored-by: Jintao Zhang <tao12345666333@163.com>

* Fix package names and fmt

Co-authored-by: Jintao Zhang <tao12345666333@163.com>

pkg/util/file/file_test.go

@@ -0,0 +1,53 @@
+/*
+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"
+	"testing"
+)
+
+func TestSHA1(t *testing.T) {
+	tests := []struct {
+		content []byte
+		sha     string
+	}{
+		{[]byte(""), "da39a3ee5e6b4b0d3255bfef95601890afd80709"},
+		{[]byte("hello world"), "2aae6c35c94fcfb415dbe95f408b9ce91ee846ed"},
+	}
+
+	for _, test := range tests {
+		f, err := os.CreateTemp("", "sha-test")
+		if err != nil {
+			t.Fatal(err)
+		}
+		f.Write(test.content)
+		f.Sync()
+
+		sha := SHA1(f.Name())
+		f.Close()
+
+		if sha != test.sha {
+			t.Fatalf("expected %v but returned %s", test.sha, sha)
+		}
+	}
+
+	sha := SHA1("")
+	if sha != "" {
+		t.Fatalf("expected an empty sha but returned %s", sha)
+	}
+}