ART: Add GetClassModifiers

Add support for GetClassModifiers. Add a test.

Bug: 31684578
Test: m test-art-host-run-test-912-classes
Change-Id: Ia14276d3139503ce35f7684bd846b371e9eafa25
diff --git a/runtime/openjdkjvmti/OpenjdkJvmTi.cc b/runtime/openjdkjvmti/OpenjdkJvmTi.cc
index 5283919..75c314f 100644
--- a/runtime/openjdkjvmti/OpenjdkJvmTi.cc
+++ b/runtime/openjdkjvmti/OpenjdkJvmTi.cc
@@ -546,7 +546,7 @@
   }
 
   static jvmtiError GetClassModifiers(jvmtiEnv* env, jclass klass, jint* modifiers_ptr) {
-    return ERR(NOT_IMPLEMENTED);
+    return ClassUtil::GetClassModifiers(env, klass, modifiers_ptr);
   }
 
   static jvmtiError GetClassMethods(jvmtiEnv* env,
diff --git a/runtime/openjdkjvmti/ti_class.cc b/runtime/openjdkjvmti/ti_class.cc
index 415e258..76d070c 100644
--- a/runtime/openjdkjvmti/ti_class.cc
+++ b/runtime/openjdkjvmti/ti_class.cc
@@ -224,4 +224,40 @@
   return ClassIsT(jklass, test, is_array_class_ptr);
 }
 
+// Keep this in sync with Class.getModifiers().
+static uint32_t ClassGetModifiers(art::Thread* self, art::ObjPtr<art::mirror::Class> klass)
+    REQUIRES_SHARED(art::Locks::mutator_lock_) {
+  if (klass->IsArrayClass()) {
+    uint32_t component_modifiers = ClassGetModifiers(self, klass->GetComponentType());
+    if ((component_modifiers & art::kAccInterface) != 0) {
+      component_modifiers &= ~(art::kAccInterface | art::kAccStatic);
+    }
+    return art::kAccAbstract | art::kAccFinal | component_modifiers;
+  }
+
+  uint32_t modifiers = klass->GetAccessFlags() & art::kAccJavaFlagsMask;
+
+  art::StackHandleScope<1> hs(self);
+  art::Handle<art::mirror::Class> h_klass(hs.NewHandle(klass));
+  return art::mirror::Class::GetInnerClassFlags(h_klass, modifiers);
+}
+
+jvmtiError ClassUtil::GetClassModifiers(jvmtiEnv* env ATTRIBUTE_UNUSED,
+                                        jclass jklass,
+                                        jint* modifiers_ptr) {
+  art::ScopedObjectAccess soa(art::Thread::Current());
+  art::ObjPtr<art::mirror::Class> klass = soa.Decode<art::mirror::Class>(jklass);
+  if (klass == nullptr) {
+    return ERR(INVALID_CLASS);
+  }
+
+  if (modifiers_ptr == nullptr) {
+    return ERR(NULL_POINTER);
+  }
+
+  *modifiers_ptr = ClassGetModifiers(soa.Self(), klass);
+
+  return ERR(NONE);
+}
+
 }  // namespace openjdkjvmti
diff --git a/runtime/openjdkjvmti/ti_class.h b/runtime/openjdkjvmti/ti_class.h
index 838c94c..619f50e 100644
--- a/runtime/openjdkjvmti/ti_class.h
+++ b/runtime/openjdkjvmti/ti_class.h
@@ -49,6 +49,8 @@
                                     jint* method_count_ptr,
                                     jmethodID** methods_ptr);
 
+  static jvmtiError GetClassModifiers(jvmtiEnv* env, jclass klass, jint* modifiers_ptr);
+
   static jvmtiError GetClassSignature(jvmtiEnv* env,
                                       jclass klass,
                                       char** signature_ptr,
diff --git a/test/912-classes/classes.cc b/test/912-classes/classes.cc
index 6771d71..3383d04 100644
--- a/test/912-classes/classes.cc
+++ b/test/912-classes/classes.cc
@@ -87,6 +87,19 @@
   return is_array_class;
 }
 
+extern "C" JNIEXPORT jint JNICALL Java_Main_getClassModifiers(
+    JNIEnv* env ATTRIBUTE_UNUSED, jclass Main_klass ATTRIBUTE_UNUSED, jclass klass) {
+  jint mod;
+  jvmtiError result = jvmti_env->GetClassModifiers(klass, &mod);
+  if (result != JVMTI_ERROR_NONE) {
+    char* err;
+    jvmti_env->GetErrorName(result, &err);
+    printf("Failure running GetClassModifiers: %s\n", err);
+    return JNI_FALSE;
+  }
+  return mod;
+}
+
 extern "C" JNIEXPORT jobjectArray JNICALL Java_Main_getClassFields(
     JNIEnv* env, jclass Main_klass ATTRIBUTE_UNUSED, jclass klass) {
   jint count = 0;
diff --git a/test/912-classes/expected.txt b/test/912-classes/expected.txt
index 9999903..de23b7b 100644
--- a/test/912-classes/expected.txt
+++ b/test/912-classes/expected.txt
@@ -1,10 +1,17 @@
 [Ljava/lang/Object;, null]
+1
 [Ljava/lang/String;, null]
+11
 [Ljava/lang/Math;, null]
+11
 [Ljava/util/List;, null]
+601
 [L$Proxy0;, null]
+11
 [I, null]
+411
 [[D, null]
+411
 int interface=false array=false
 $Proxy0 interface=false array=false
 java.lang.Runnable interface=true array=false
diff --git a/test/912-classes/src/Main.java b/test/912-classes/src/Main.java
index fd9e31a..cbcfe71 100644
--- a/test/912-classes/src/Main.java
+++ b/test/912-classes/src/Main.java
@@ -82,6 +82,11 @@
   private static void testClass(Class<?> base) throws Exception {
     String[] result = getClassSignature(base);
     System.out.println(Arrays.toString(result));
+    int mod = getClassModifiers(base);
+    if (mod != base.getModifiers()) {
+      throw new RuntimeException("Unexpected modifiers: " + base.getModifiers() + " vs " + mod);
+    }
+    System.out.println(Integer.toHexString(mod));
   }
 
   private static void testClassType(Class<?> c) throws Exception {
@@ -107,6 +112,8 @@
   private static native boolean isInterface(Class<?> c);
   private static native boolean isArrayClass(Class<?> c);
 
+  private static native int getClassModifiers(Class<?> c);
+
   private static native Object[] getClassFields(Class<?> c);
   private static native Object[] getClassMethods(Class<?> c);