content: /*
   * Copyright The OpenTelemetry Authors
   * SPDX-License-Identifier: Apache-2.0
   */
  
  package io.opentelemetry.javaagent.instrumentation.internal.classloader;
  
  import static io.opentelemetry.javaagent.extension.matcher.AgentElementMatchers.extendsClass;
  import static io.opentelemetry.javaagent.instrumentation.internal.classloader.AdviceUtil.applyInlineAdvice;
  import static net.bytebuddy.matcher.ElementMatchers.isMethod;
  import static net.bytebuddy.matcher.ElementMatchers.isProtected;
  import static net.bytebuddy.matcher.ElementMatchers.isPublic;
  import static net.bytebuddy.matcher.ElementMatchers.isStatic;
  import static net.bytebuddy.matcher.ElementMatchers.named;
  import static net.bytebuddy.matcher.ElementMatchers.not;
  import static net.bytebuddy.matcher.ElementMatchers.takesArgument;
  import static net.bytebuddy.matcher.ElementMatchers.takesArguments;
  
  import io.opentelemetry.javaagent.bootstrap.InjectedClassHelper;
  import io.opentelemetry.javaagent.extension.instrumentation.TypeInstrumentation;
  import io.opentelemetry.javaagent.extension.instrumentation.TypeTransformer;
  import net.bytebuddy.asm.Advice;
  import net.bytebuddy.description.method.MethodDescription;
  import net.bytebuddy.description.type.TypeDescription;
  import net.bytebuddy.matcher.ElementMatcher;
  
  /**
   * This instrumentation inserts loading of our injected helper classes at the start of {@code
   * ClassLoader.loadClass} method.
   */
  public class LoadInjectedClassInstrumentation implements TypeInstrumentation {
  
    @Override
    public ElementMatcher<TypeDescription> typeMatcher() {
      return extendsClass(named("java.lang.ClassLoader"));
    }
  
    @Override
    public void transform(TypeTransformer transformer) {
      ElementMatcher.Junction<MethodDescription> methodMatcher =
          isMethod()
              .and(named("loadClass"))
              .and(
                  takesArguments(1)
                      .and(takesArgument(0, String.class))
                      .or(
                          takesArguments(2)
                              .and(takesArgument(0, String.class))
                              .and(takesArgument(1, boolean.class))))
              .and(isPublic().or(isProtected()))
              .and(not(isStatic()));
      // Inline instrumentation to prevent problems with invokedynamic-recursion
      applyInlineAdvice(transformer, methodMatcher, this.getClass().getName() + "$LoadClassAdvice");
    }
  
    @SuppressWarnings("unused")
    public static class LoadClassAdvice {
  
      @Advice.OnMethodEnter(skipOn = Advice.OnNonDefaultValue.class)
      public static Class<?> onEnter(
          @Advice.This ClassLoader classLoader, @Advice.Argument(0) String name) {
        Class<?> helperClass = InjectedClassHelper.loadHelperClass(classLoader, name);
        if (helperClass != null) {
          return helperClass;
        }
  
        return null;
      }
  
      @Advice.OnMethodExit(onThrowable = Throwable.class)
      public static void onExit(
          @Advice.Return(readOnly = false) Class<?> result, @Advice.Enter Class<?> loadedClass) {
        if (loadedClass != null) {
          result = loadedClass;
        }
      }
    }
  }
  