From d55b844e39c4d5eb1a56de6cb95c891659f8a27f Mon Sep 17 00:00:00 2001
From: Alex Light <allight@google.com>
Date: Tue, 15 Oct 2019 15:46:07 -0700
Subject: Add more standard structural redefinition entrypoints

Add structural redefinition extension function and event that mirror
the 'RedefineClasses' function and 'ClassFileLoadHook' event. The new
extension function is called
'com.android.art.class.structurally_redefine_classes' and the new
extension event is called
'com.android.art.class.structural_dex_file_load_hook'.

These extensions are the preferred way to use structural redefinition.
Like the standard 'RedefineClasses' multiple classes may be redefined
at a time.

The structural_dex_file_load_hook is triggered prior to the
can_retransform_classes ClassFileLoadHook. It is triggered on all
classes, even ones that cannot be structurally changed by
class-loading, class redefinition or by calling the RetransformClasses
function.

Calling 'structurally_redefine_classes' with new definitions that do
not require structural changes will fall back to non-structural
redefinition.

Test: ./test.py --host
Bug: 134162467
Change-Id: If4810930470c5c6509cf6db779910006e114b39f
---
 openjdkjvmti/transform.cc | 48 +++++++++++++++++++++++++++++------------------
 1 file changed, 30 insertions(+), 18 deletions(-)

(limited to 'openjdkjvmti/transform.cc')

diff --git a/openjdkjvmti/transform.cc b/openjdkjvmti/transform.cc
index aa37793e49..613368525e 100644
--- a/openjdkjvmti/transform.cc
+++ b/openjdkjvmti/transform.cc
@@ -255,13 +255,17 @@ void Transformer::TransformSingleClassDirect<ArtJvmtiEvent::kClassFileLoadHookNo
 template
 void Transformer::TransformSingleClassDirect<ArtJvmtiEvent::kClassFileLoadHookRetransformable>(
     EventHandler* event_handler, art::Thread* self, /*in-out*/ArtClassDefinition* def);
+template
+void Transformer::TransformSingleClassDirect<ArtJvmtiEvent::kStructuralDexFileLoadHook>(
+    EventHandler* event_handler, art::Thread* self, /*in-out*/ArtClassDefinition* def);
 
 template<ArtJvmtiEvent kEvent>
 void Transformer::TransformSingleClassDirect(EventHandler* event_handler,
                                              art::Thread* self,
                                              /*in-out*/ArtClassDefinition* def) {
   static_assert(kEvent == ArtJvmtiEvent::kClassFileLoadHookNonRetransformable ||
-                kEvent == ArtJvmtiEvent::kClassFileLoadHookRetransformable,
+                kEvent == ArtJvmtiEvent::kClassFileLoadHookRetransformable ||
+                kEvent == ArtJvmtiEvent::kStructuralDexFileLoadHook,
                 "bad event type");
   // We don't want to do transitions between calling the event and setting the new data so change to
   // native state early. This also avoids any problems that the FaultHandler might have in
@@ -282,25 +286,30 @@ void Transformer::TransformSingleClassDirect(EventHandler* event_handler,
       dex_data.data(),
       /*out*/&new_len,
       /*out*/&new_data);
-  def->SetNewDexData(new_len, new_data);
+  def->SetNewDexData(new_len, new_data, kEvent);
 }
 
+template <RedefinitionType kType>
 void Transformer::RetransformClassesDirect(
-      art::Thread* self,
-      /*in-out*/std::vector<ArtClassDefinition>* definitions) {
+    art::Thread* self,
+    /*in-out*/ std::vector<ArtClassDefinition>* definitions) {
+  constexpr ArtJvmtiEvent kEvent = kType == RedefinitionType::kNormal
+                                       ? ArtJvmtiEvent::kClassFileLoadHookRetransformable
+                                       : ArtJvmtiEvent::kStructuralDexFileLoadHook;
   for (ArtClassDefinition& def : *definitions) {
-    TransformSingleClassDirect<ArtJvmtiEvent::kClassFileLoadHookRetransformable>(
-        gEventHandler, self, &def);
+    TransformSingleClassDirect<kEvent>(gEventHandler, self, &def);
   }
 }
 
+template void Transformer::RetransformClassesDirect<RedefinitionType::kNormal>(
+      art::Thread* self, /*in-out*/std::vector<ArtClassDefinition>* definitions);
+template void Transformer::RetransformClassesDirect<RedefinitionType::kStructural>(
+      art::Thread* self, /*in-out*/std::vector<ArtClassDefinition>* definitions);
+
 jvmtiError Transformer::RetransformClasses(jvmtiEnv* env,
                                            jint class_count,
                                            const jclass* classes) {
-  if (env == nullptr) {
-    JVMTI_LOG(WARNING, env) << "FAILURE TO RETRANSFORM env was null!";
-    return ERR(INVALID_ENVIRONMENT);
-  } else if (class_count < 0) {
+  if (class_count < 0) {
     JVMTI_LOG(WARNING, env) << "FAILURE TO RETRANSFORM class_count was less then 0";
     return ERR(ILLEGAL_ARGUMENT);
   } else if (class_count == 0) {
@@ -317,7 +326,7 @@ jvmtiError Transformer::RetransformClasses(jvmtiEnv* env,
   std::vector<ArtClassDefinition> definitions;
   jvmtiError res = OK;
   for (jint i = 0; i < class_count; i++) {
-    res = Redefiner::GetClassRedefinitionError(classes[i], &error_msg);
+    res = Redefiner::GetClassRedefinitionError<RedefinitionType::kNormal>(classes[i], &error_msg);
     if (res != OK) {
       JVMTI_LOG(WARNING, env) << "FAILURE TO RETRANSFORM " << error_msg;
       return res;
@@ -330,13 +339,16 @@ jvmtiError Transformer::RetransformClasses(jvmtiEnv* env,
     }
     definitions.push_back(std::move(def));
   }
-  RetransformClassesDirect(self, &definitions);
-  res = Redefiner::RedefineClassesDirect(ArtJvmTiEnv::AsArtJvmTiEnv(env),
-                                         runtime,
-                                         self,
-                                         definitions,
-                                         RedefinitionType::kNormal,
-                                         &error_msg);
+  RetransformClassesDirect<RedefinitionType::kStructural>(self, &definitions);
+  RetransformClassesDirect<RedefinitionType::kNormal>(self, &definitions);
+  RedefinitionType redef_type =
+      std::any_of(definitions.cbegin(),
+                  definitions.cend(),
+                  [](const auto& it) { return it.HasStructuralChanges(); })
+          ? RedefinitionType::kStructural
+          : RedefinitionType::kNormal;
+  res = Redefiner::RedefineClassesDirect(
+      ArtJvmTiEnv::AsArtJvmTiEnv(env), runtime, self, definitions, redef_type, &error_msg);
   if (res != OK) {
     JVMTI_LOG(WARNING, env) << "FAILURE TO RETRANSFORM " << error_msg;
   }
-- 
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