[ISSUE #11461] Handle relative copy targets without a parent

common/src/main/java/org/apache/rocketmq/common/utils/IOTinyUtils.java

@@ -81,7 +81,10 @@ static public void copyFile(String source, String target) throws IOException {
             throw new IllegalArgumentException("source file does not exist.");
         }
         File tf = new File(target);
-        tf.getParentFile().mkdirs();
+        File parent = tf.getParentFile();
+        if (parent != null) {
+            parent.mkdirs();
+        }
         if (!tf.exists() && !tf.createNewFile()) {
             throw new RuntimeException("failed to create target file.");
         }

common/src/test/java/org/apache/rocketmq/common/utils/IOTinyUtilsRelativePathTest.java

@@ -0,0 +1,91 @@
+/*
+ * 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 org.apache.rocketmq.common.utils;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.UUID;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertThrows;
+
+public class IOTinyUtilsRelativePathTest {
+
+    @Rule
+    public TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+    @Test
+    public void testCopyToRelativeFileName() throws IOException {
+        copyToRelativeFile(false);
+    }
+
+    @Test
+    public void testOverwriteRelativeFileName() throws IOException {
+        copyToRelativeFile(true);
+    }
+
+    @Test
+    public void testNestedTargetDirectoriesAreStillCreated() throws IOException {
+        Path source = temporaryFolder.newFile().toPath();
+        byte[] content = "source-content".getBytes(StandardCharsets.UTF_8);
+        Files.write(source, content);
+        Path target = temporaryFolder.getRoot().toPath().resolve("nested/copy.bin");
+        IOTinyUtils.copyFile(source.toString(), target.toString());
+        assertArrayEquals(content, Files.readAllBytes(target));
+    }
+
+    @Test
+    public void testMissingSourceDoesNotOverwriteExistingTarget() throws IOException {
+        Path target = relativeTarget();
+        byte[] original = "keep-existing".getBytes(StandardCharsets.UTF_8);
+        try {
+            Files.write(target, original);
+            String missingSource = temporaryFolder.getRoot().toPath().resolve("missing").toString();
+            assertThrows(IllegalArgumentException.class, () -> IOTinyUtils.copyFile(missingSource, target.toString()));
+            assertArrayEquals(original, Files.readAllBytes(target));
+        } finally {
+            Files.deleteIfExists(target);
+        }
+    }
+
+    private void copyToRelativeFile(boolean existing) throws IOException {
+        Path source = temporaryFolder.newFile().toPath();
+        byte[] content = "copied-content".getBytes(StandardCharsets.UTF_8);
+        Files.write(source, content);
+        Path target = relativeTarget();
+        try {
+            if (existing) {
+                Files.write(target, "old-content-is-longer".getBytes(StandardCharsets.UTF_8));
+            }
+            IOTinyUtils.copyFile(source.toString(), target.toString());
+            assertArrayEquals(content, Files.readAllBytes(target));
+        } finally {
+            Files.deleteIfExists(target);
+        }
+    }
+
+    private Path relativeTarget() {
+        return Paths.get("iotiny-copy-" + UUID.randomUUID() + ".tmp");
+    }
+}