NIFI-10004: Allow loading .class files that are relative to the NAR directory, in addition to the .jar / .nar files

NIFI-10004: When determining classname from a file, consider File.separator instead of just /
Signed-off-by: Matthew Burgess <mattyb149@apache.org>

This closes #6026

nifi-stateless/nifi-stateless-bootstrap/pom.xml

@@ -74,4 +74,18 @@
             <optional>true</optional>
         </dependency>
     </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.rat</groupId>
+                <artifactId>apache-rat-plugin</artifactId>
+                <configuration>
+                    <excludes combine.children="append">
+                        <exclude>src/test/resources/FakeBootstrap.class</exclude>
+                    </excludes>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
 </project>

nifi-stateless/nifi-stateless-bootstrap/src/main/java/org/apache/nifi/stateless/bootstrap/StatelessBootstrap.java

@@ -158,6 +158,8 @@ public class StatelessBootstrap {
             filesAllowed.add(file.getName());
         }
 
+        findClassNamesInDirectory(narDirectory, narDirectory, classesAllowed, filesAllowed);
+
         final File java11Directory = new File(narDirectory, "java11");
         final File[] java11DirectoryFiles = java11Directory.listFiles();
         if (java11DirectoryFiles != null) {
@@ -174,7 +176,7 @@ public class StatelessBootstrap {
             javaHomeFilenames.add(file.getName());
         }
 
-        logger.debug("The following JAR files will be explicitly allowed to be loaded by Stateless Extensions ClassLoaders from parent {}: {}", parent, filesAllowed);
+        logger.debug("The following class/JAR files will be explicitly allowed to be loaded by Stateless Extensions ClassLoaders from parent {}: {}", parent, filesAllowed);
         logger.debug("The following JAR/JMOD files from ${JAVA_HOME} will be explicitly allowed to be loaded by Stateless Extensions ClassLoaders from parent {}: {}", parent, javaHomeFilenames);
         logger.debug("The final list of classes allowed to be loaded by Stateless Extension ClassLoaders from parent {}: {}", parent, classesAllowed);
 
@@ -258,6 +260,36 @@ public class StatelessBootstrap {
         }
     }
 
+    static void findClassNamesInDirectory(final File file, final File baseDirectory, final Set<String> classNames, final Set<String> fileNames) {
+        if (file.isDirectory()) {
+            final File[] children = file.listFiles();
+            if (children != null) {
+                for (final File child : children) {
+                    findClassNamesInDirectory(child, baseDirectory, classNames, fileNames);
+                }
+            }
+
+            return;
+        }
+
+        final String filename = file.getName();
+        if (filename.endsWith(".class")) {
+            final String absolutePath = file.getAbsolutePath();
+            final String baseDirectoryPath = baseDirectory.getAbsolutePath();
+            if (!absolutePath.startsWith(baseDirectoryPath)) {
+                return;
+            }
+
+            final File relativeFile = baseDirectory.toPath().relativize(file.toPath()).toFile();
+            final String relativePath = relativeFile.getPath();
+
+            final int lastIndex = relativePath.lastIndexOf(".class");
+            final String className = relativePath.substring(0, lastIndex).replace(File.separator, ".");
+            classNames.add(className);
+            fileNames.add(filename);
+        }
+    }
+
     private static void findClassesInJmod(final File file, final Set<String> classNames) throws IOException {
         if (!file.getName().endsWith(".jmod") || !file.isFile() || !file.exists()) {
             return;

nifi-stateless/nifi-stateless-bootstrap/src/test/java/org/apache/nifi/stateless/bootstrap/TestStatelessBootstrap.java

@@ -0,0 +1,45 @@
+/*
+ * 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.nifi.stateless.bootstrap;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.util.HashSet;
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class TestStatelessBootstrap {
+
+    @Test
+    public void testAllowsClassFiles() {
+        final File libDir = new File("src/test/resources/test-lib");
+
+        final Set<String> classNames = new HashSet<>();
+        final Set<String> fileNames = new HashSet<>();
+        StatelessBootstrap.findClassNamesInDirectory(libDir, libDir, classNames, fileNames);
+
+        assertEquals(1, classNames.size());
+        assertEquals(1, fileNames.size());
+        assertTrue(classNames.contains("org.apache.nifi.stateless.FakeBootstrap"));
+        assertTrue(fileNames.contains("FakeBootstrap.class"));
+    }
+
+}

nifi-stateless/nifi-stateless-bootstrap/src/test/resources/test-lib/org/apache/nifi/stateless/FakeBootstrap.class

@@ -0,0 +1,13 @@
+
+      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.