Use the bootstrapProxy to load jars. Better bootstrap url algo

dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/DatadogClassLoader.java

@@ -34,7 +34,6 @@ public class DatadogClassLoader extends URLClassLoader {
   // As a workaround, we keep a reference to the bootstrap jar
   // to use only for resource lookups.
   private final BootstrapClassLoaderProxy bootstrapProxy;
-
   /**
    * Construct a new DatadogClassLoader
    *
@@ -44,25 +43,23 @@ public class DatadogClassLoader extends URLClassLoader {
    *     9+.
    */
   public DatadogClassLoader(
-      final URL bootstrapJarLocation,
+      final URL bootstrapJarLocation, final String internalJarFileName, final ClassLoader parent) {
-      final String internalJarFileName,
-      final ClassLoader classloaderForJarResource,
-      final ClassLoader parent) {
     super(new URL[] {}, parent);
     bootstrapProxy = new BootstrapClassLoaderProxy(new URL[] {bootstrapJarLocation});
 
-    if (classloaderForJarResource != null) { // Some tests pass null
+    if (internalJarFileName != null) { // some tests pass null
       try {
         // The fields of the URL are mostly dummy.  InternalJarURLHandler is the only important
         // field.  If extending this class from Classloader instead of URLClassloader required less
         // boilerplate it could be used and the need for dummy fields would be reduced
+
         final URL internalJarURL =
             new URL(
                 "x-internal-jar",
                 null,
                 0,
                 "/",
-                new InternalJarURLHandler(internalJarFileName, classloaderForJarResource));
+                new InternalJarURLHandler(internalJarFileName, bootstrapProxy));
 
         addURL(internalJarURL);
       } catch (final MalformedURLException e) {

dd-java-agent/agent-bootstrap/src/test/groovy/datadog/trace/bootstrap/DatadogClassLoaderTest.groovy

@@ -13,7 +13,7 @@ class DatadogClassLoaderTest extends Specification {
     def className1 = 'some/class/Name1'
     def className2 = 'some/class/Name2'
     final URL loc = getClass().getProtectionDomain().getCodeSource().getLocation()
-    final DatadogClassLoader ddLoader = new DatadogClassLoader(loc, null, null, null)
+    final DatadogClassLoader ddLoader = new DatadogClassLoader(loc, null, null)
     final Phaser threadHoldLockPhase = new Phaser(2)
     final Phaser acquireLockFromMainThreadPhase = new Phaser(2)
 

dd-java-agent/agent-tooling/src/test/groovy/datadog/trace/agent/test/ClassLoaderMatcherTest.groovy

@@ -16,7 +16,7 @@ class ClassLoaderMatcherTest extends Specification {
   def "skips agent classloader"() {
     setup:
     URL root = new URL("file://")
-    final URLClassLoader agentLoader = new DatadogClassLoader(root, null, null, null)
+    final URLClassLoader agentLoader = new DatadogClassLoader(root, null, null)
     expect:
     ClassLoaderMatcher.skipClassLoader().matches(agentLoader)
   }

dd-java-agent/src/main/java/datadog/trace/agent/TracingAgent.java

@@ -5,11 +5,14 @@ import java.io.File;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.lang.instrument.Instrumentation;
+import java.lang.management.ManagementFactory;
+import java.lang.management.RuntimeMXBean;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
+import java.security.CodeSource;
 import java.util.jar.JarFile;
 
 /** Entry point for initializing the agent. */
@@ -140,10 +143,34 @@ public class TracingAgent {
   private static synchronized void installBootstrapJar(final Instrumentation inst)
       throws Exception {
     if (BOOTSTRAP_URL == null) {
-      BOOTSTRAP_URL = TracingAgent.class.getProtectionDomain().getCodeSource().getLocation();
+      File bootstrapJarFile = null;
 
-      // bootstrap jar must be appended before agent classloader is created.
+      final CodeSource codeSource = TracingAgent.class.getProtectionDomain().getCodeSource();
-      inst.appendToBootstrapClassLoaderSearch(new JarFile(new File(BOOTSTRAP_URL.toURI())));
+
+      if (codeSource != null) {
+        BOOTSTRAP_URL = codeSource.getLocation();
+        bootstrapJarFile = new File(BOOTSTRAP_URL.toURI());
+      }
+
+      if (bootstrapJarFile == null || bootstrapJarFile.isDirectory()) {
+        // Certain tests (and when running with an IDE) have a folder as the CP
+        // Get the jar from the -javaagent parameter
+        final RuntimeMXBean runtimeMxBean = ManagementFactory.getRuntimeMXBean();
+        for (final String arg : runtimeMxBean.getInputArguments()) {
+          if (arg.startsWith("-javaagent")) {
+            BOOTSTRAP_URL = new URL("file:" + arg.substring(arg.indexOf(":") + 1));
+            bootstrapJarFile = new File(BOOTSTRAP_URL.toURI());
+            break;
+          }
+        }
+
+        if (bootstrapJarFile == null) {
+          throw new Exception(
+              "Unable to install bootstrap jar because agent is running from directory");
+        }
+      }
+
+      inst.appendToBootstrapClassLoaderSearch(new JarFile(bootstrapJarFile));
     }
   }
 
@@ -169,11 +196,8 @@ public class TracingAgent {
     final Class<?> loaderClass =
         ClassLoader.getSystemClassLoader().loadClass("datadog.trace.bootstrap.DatadogClassLoader");
     final Constructor constructor =
-        loaderClass.getDeclaredConstructor(
+        loaderClass.getDeclaredConstructor(URL.class, String.class, ClassLoader.class);
-            URL.class, String.class, ClassLoader.class, ClassLoader.class);
+    return (ClassLoader) constructor.newInstance(BOOTSTRAP_URL, innerJarFilename, agentParent);
-    return (ClassLoader)
-        constructor.newInstance(
-            BOOTSTRAP_URL, innerJarFilename, TracingAgent.class.getClassLoader(), agentParent);
   }
 
   private static ClassLoader getPlatformClassLoader()