Fix VerifyError when using class-inject with -Xverify:all

class-inject/build.gradle.kts

@@ -6,6 +6,9 @@ plugins {
 dependencies {
   implementation(libs.asm)
   implementation(project(":utils"))
+
+  testImplementation(sourceSets["glue"].output)
+  testImplementation(libs.asm.util)
 }
 
 // class-inject generates glue bytecode at build-time to provide access to Unsafe.defineClass

class-inject/src/glue/java/datadog/instrument/glue/DefineClassGlueGenerator.java

@@ -116,7 +116,7 @@ public static void generateGlue(Path resourcePath, Path javaPath) throws IOExcep
    * @param unsafeNamespace which Unsafe to use for boot injection
    * @return glue to access {@code ClassLoader.defineClass}
    */
-  private static byte[] generateBytecode(String unsafeNamespace) {
+  static byte[] generateBytecode(String unsafeNamespace) {
 
     // use Unsafe to define boot classes that have no class-loader
     final String unsafeClass = unsafeNamespace + "/Unsafe";
@@ -172,6 +172,7 @@ private static byte[] generateBytecode(String unsafeNamespace) {
     final Label defineBootClass = new Label();
     final Label storeBootClass = new Label();
     final Label loadBootClass = new Label();
+    final Label lookupBootClass = new Label();
     final Label rethrowOriginal = new Label();
     final Label returnDefinedClasses = new Label();
 
@@ -199,7 +200,7 @@ private static byte[] generateBytecode(String unsafeNamespace) {
 
     // fall back and see if the boot class is already loaded if defining it fails
     mv.visitTryCatchBlock(defineBootClass, storeBootClass, loadBootClass, null);
-    mv.visitTryCatchBlock(loadBootClass, rethrowOriginal, rethrowOriginal, null);
+    mv.visitTryCatchBlock(lookupBootClass, rethrowOriginal, rethrowOriginal, null);
 
     // -------- SHARED SETUP CODE  --------
 
@@ -389,6 +390,8 @@ private static byte[] generateBytecode(String unsafeNamespace) {
     // see if the boot class has already been defined
     mv.visitLabel(loadBootClass);
     mv.visitVarInsn(ASTORE, originalError);
+    // must be after originalError is stored, or the handler can't rely on it being set
+    mv.visitLabel(lookupBootClass);
     mv.visitVarInsn(ALOAD, className);
     mv.visitInsn(ICONST_0); // initialize=false
     mv.visitInsn(ACONST_NULL);

class-inject/src/test/java/datadog/instrument/glue/DefineClassGlueGeneratorTest.java

@@ -0,0 +1,25 @@
+package datadog.instrument.glue;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.util.CheckClassAdapter;
+
+class DefineClassGlueGeneratorTest {
+
+  @ParameterizedTest
+  @ValueSource(strings = {"sun/misc", "jdk/internal/misc"})
+  void generatedBytecodePassesVerification(String unsafeNamespace) {
+    byte[] bytecode = DefineClassGlueGenerator.generateBytecode(unsafeNamespace);
+    StringWriter errors = new StringWriter();
+
+    // perform strict class verification, like -Xverify:all
+    CheckClassAdapter.verify(new ClassReader(bytecode), false, new PrintWriter(errors));
+
+    assertThat(errors.toString()).isEmpty();
+  }
+}

gradle/libs.versions.toml

@@ -13,6 +13,7 @@ jmh-plugin = "0.7.3"
 [libraries]
 asm = { module = "org.ow2.asm:asm", version.ref = "asm" }
 asm-commons = { module = "org.ow2.asm:asm-commons", version.ref = "asm" }
+asm-util = { module = "org.ow2.asm:asm-util", version.ref = "asm" }
 junit-jupiter = { module = "org.junit.jupiter:junit-jupiter", version.ref = "junit-jupiter" }
 junit-launcher = { module = "org.junit.platform:junit-platform-launcher", version.ref = "junit-platform" }
 assertj-core = { module = "org.assertj:assertj-core", version.ref = "assertj" }