use `Files.createTempDirectory()` instead of `new File()` (#7713)

core/src/main/java/com/cloud/storage/JavaStorageLayer.java

@@ -22,8 +22,11 @@ package com.cloud.storage;
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.nio.file.attribute.FileAttribute;
 import java.nio.file.attribute.PosixFilePermission;
+import java.nio.file.attribute.PosixFilePermissions;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
@@ -186,8 +189,12 @@ public class JavaStorageLayer implements StorageLayer {
     @Override
     public File createUniqDir() throws IOException {
         String dirName = System.getProperty("java.io.tmpdir");
+        String subDirNamePrefix = "";
+        FileAttribute<Set<PosixFilePermission>> perms = PosixFilePermissions
+                .asFileAttribute(PosixFilePermissions.fromString("rwxrwx---"));
         if (dirName != null) {
-            File dir = new File(dirName);
+            Path p = Files.createTempDirectory(Path.of(dirName), subDirNamePrefix, perms);
+            File dir = p.toFile();
             if (dir.exists()) {
                 if (isWorldReadable(dir)) {
                     if (STD_TMP_DIR_PATH.equals(dir.getAbsolutePath())) {

core/src/test/java/com/cloud/storage/JavaStorageLayerTest.java

@@ -0,0 +1,46 @@
+//
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you 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 com.cloud.storage;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class JavaStorageLayerTest {
+
+    JavaStorageLayer jsl = new JavaStorageLayer();
+
+    @Test
+    public void createUniqDir() {
+
+        try {
+            File one = jsl.createUniqDir();
+            Assert.assertTrue(one.isDirectory());
+            Assert.assertTrue(one.canRead());
+            Assert.assertTrue(one.canWrite());
+            Assert.assertTrue(one.canExecute());
+        } catch (IOException e) {
+            Assert.fail("creation of a unique dir should succeed.");
+        }
+    }
+}
+