Exclude Java agents from class loader created by PropertiesLauncher

PropertiesLauncher creates a ClassLoader that is used by the Launcher
to load an application’s classes. During the creation of this
ClassLoader URLs from its ClassLoader. This resulted resulting in Java
agents that are added to the system class loader via the -javaagent
launch option being available on both the system class loader and the
created class loader. Java agents are intended to always be loaded by
the system class loader. Making them available on another class loader
breaks this model.

This is the same problem that was in ExecutableArchiveLauncher and
that was fixed in ee08667 (see spring-projectsgh-863).

This commit updates PropertiesLauncher so that it skips the URLs of
any Java agents (found by examining the JVM’s input arguments) when
copying URLs over to the new ClassLoader, thereby ensuring that Java
agents are only ever loaded by the system class loader.

Closes spring-projectsgh-4911

Author: wilkinsona

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/PropertiesLauncher.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -72,6 +72,7 @@
  *
  * @author Dave Syer
  * @author Janne Valkealahti
+ * @author Andy Wilkinson
  */
 public class PropertiesLauncher extends Launcher {
 
@@ -132,18 +133,25 @@ public class PropertiesLauncher extends Launcher {
 
 	private final File home;
 
+	private final JavaAgentDetector javaAgentDetector;
+
 	private List<String> paths = new ArrayList<String>(DEFAULT_PATHS);
 
 	private final Properties properties = new Properties();
 
 	private Archive parent;
 
 	public PropertiesLauncher() {
+		this(new InputArgumentsJavaAgentDetector());
+	}
+
+	PropertiesLauncher(JavaAgentDetector javaAgentDetector) {
 		if (!isDebug()) {
 			this.logger.setLevel(Level.SEVERE);
 		}
 		try {
 			this.home = getHomeDirectory();
+			this.javaAgentDetector = javaAgentDetector;
 			initializeProperties(this.home);
 			initializePaths();
 			this.parent = createArchive();
@@ -517,21 +525,12 @@ private void addParentClassLoaderEntries(List<Archive> lib)
 		ClassLoader parentClassLoader = getClass().getClassLoader();
 		List<Archive> urls = new ArrayList<Archive>();
 		for (URL url : getURLs(parentClassLoader)) {
-			if (url.toString().endsWith(".jar") || url.toString().endsWith(".zip")) {
-				urls.add(new JarFileArchive(new File(url.toURI())));
-			}
-			else if (url.toString().endsWith("/*")) {
-				String name = url.getFile();
-				File dir = new File(name.substring(0, name.length() - 1));
-				if (dir.exists()) {
-					urls.add(new ExplodedArchive(
-							new File(name.substring(0, name.length() - 1)), false));
+			if (!this.javaAgentDetector.isJavaAgentJar(url)) {
+				Archive archive = createArchiveIfPossible(url);
+				if (archive != null) {
+					urls.add(archive);
 				}
 			}
-			else {
-				String filename = URLDecoder.decode(url.getFile(), "UTF-8");
-				urls.add(new ExplodedArchive(new File(filename)));
-			}
 		}
 		// The parent archive might have a "lib/" directory, meaning we are running from
 		// an executable JAR. We add nested entries from there with low priority (i.e. at
@@ -545,6 +544,26 @@ else if (url.toString().endsWith("/*")) {
 		}
 	}
 
+	private Archive createArchiveIfPossible(URL url)
+			throws IOException, URISyntaxException {
+		if (url.toString().endsWith(".jar") || url.toString().endsWith(".zip")) {
+			return new JarFileArchive(new File(url.toURI()));
+		}
+		else if (url.toString().endsWith("/*")) {
+			String name = url.getFile();
+			File dir = new File(name.substring(0, name.length() - 1));
+			if (dir.exists()) {
+				return new ExplodedArchive(new File(name.substring(0, name.length() - 1)),
+						false);
+			}
+		}
+		else {
+			String filename = URLDecoder.decode(url.getFile(), "UTF-8");
+			return new ExplodedArchive(new File(filename));
+		}
+		return null;
+	}
+
 	private void addNestedArchivesFromParent(List<Archive> urls) {
 		int index = findArchive(urls, this.parent);
 		if (index >= 0) {

spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/PropertiesLauncherTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2013 the original author or authors.
+ * Copyright 2012-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,32 +22,45 @@
 import java.net.URLClassLoader;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.List;
 
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
 
 import org.springframework.boot.loader.archive.Archive;
 import org.springframework.test.util.ReflectionTestUtils;
 
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.verify;
 
 /**
  * Tests for {@link PropertiesLauncher}.
  *
  * @author Dave Syer
+ * @author Andy Wilkinson
  */
 public class PropertiesLauncherTests {
 
+	@Mock
+	private JavaAgentDetector javaAgentDetector;
+
 	@Rule
 	public OutputCapture output = new OutputCapture();
 
 	@Before
 	public void setup() throws IOException {
+		MockitoAnnotations.initMocks(this);
 		System.setProperty("loader.home",
 				new File("src/test/resources").getAbsolutePath());
 	}
@@ -175,6 +188,22 @@ public void testArgsEnhanced() throws Exception {
 		assertEquals("[foo, bar]", Arrays.asList(launcher.getArgs("bar")).toString());
 	}
 
+	@Test
+	public void testJavaAgentJarsAreExcludedFromClasspath() throws Exception {
+		List<Archive> allArchives = new PropertiesLauncher().getClassPathArchives();
+		URL[] parentUrls = ((URLClassLoader) getClass().getClassLoader()).getURLs();
+		for (URL url : parentUrls) {
+			given(this.javaAgentDetector.isJavaAgentJar(url)).willReturn(true);
+		}
+		List<Archive> nonAgentArchives = new PropertiesLauncher(this.javaAgentDetector)
+				.getClassPathArchives();
+		assertThat(nonAgentArchives.size(),
+				is(equalTo(allArchives.size() - parentUrls.length)));
+		for (URL url : parentUrls) {
+			verify(this.javaAgentDetector).isJavaAgentJar(url);
+		}
+	}
+
 	private void waitFor(String value) throws Exception {
 		int count = 0;
 		boolean timeout = false;