openjdkjvmti/ti_class_definition.cc - platform/art - Gitiles

 /* Copyright (C) 2016 The Android Open Source Project
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This file implements interfaces from the file jvmti.h. This implementation
  * is licensed under the same terms as the file jvmti.h.  The
  * copyright and license information for the file jvmti.h follows.
  *
  * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */

 #include "ti_class_definition.h"

 #include "base/array_slice.h"
 #include "base/logging.h"
 #include "class_linker-inl.h"
 #include "class_root.h"
 #include "dex/dex_file.h"
 #include "fixed_up_dex_file.h"
 #include "handle.h"
 #include "handle_scope-inl.h"
 #include "mirror/class-inl.h"
 #include "mirror/class_ext.h"
 #include "mirror/object-inl.h"
 #include "reflection.h"
 #include "thread.h"

 namespace openjdkjvmti {

 void ArtClassDefinition::InitializeMemory() const {
   DCHECK(art::MemMap::kCanReplaceMapping);
   VLOG(signals) << "Initializing de-quickened memory for dex file of " << name_;
   CHECK(dex_data_mmap_.IsValid());
   CHECK(temp_mmap_.IsValid());
   CHECK_EQ(dex_data_mmap_.GetProtect(), PROT_NONE);
   CHECK_EQ(temp_mmap_.GetProtect(), PROT_READ | PROT_WRITE);

   std::string desc = std::string("L") + name_ + ";";
   std::unique_ptr<FixedUpDexFile>
       fixed_dex_file(FixedUpDexFile::Create(*initial_dex_file_unquickened_, desc.c_str()));
   CHECK(fixed_dex_file.get() != nullptr);
   CHECK_LE(fixed_dex_file->Size(), temp_mmap_.Size());
   CHECK_EQ(temp_mmap_.Size(), dex_data_mmap_.Size());
   // Copy the data to the temp mmap.
   memcpy(temp_mmap_.Begin(), fixed_dex_file->Begin(), fixed_dex_file->Size());

   // Move the mmap atomically.
   art::MemMap source;
   source.swap(temp_mmap_);
   std::string error;
   CHECK(dex_data_mmap_.ReplaceWith(&source, &error)) << "Failed to replace mmap for "
                                                      << name_ << " because " << error;
   CHECK(dex_data_mmap_.Protect(PROT_READ));
 }

 bool ArtClassDefinition::IsModified() const {
   // RedefineClasses calls always are 'modified' since they need to change the current_dex_file of
   // the class.
   if (redefined_) {
     return true;
   }

   // Check to see if any change has taken place.
   if (current_dex_file_.data() == dex_data_.data()) {
     // no change at all.
     return false;
   }

   // The dex_data_ was never touched by the agents.
   if (dex_data_mmap_.IsValid() && dex_data_mmap_.GetProtect() == PROT_NONE) {
     if (current_dex_file_.data() == dex_data_mmap_.Begin()) {
       // the dex_data_ looks like it changed (not equal to current_dex_file_) but we never
       // initialized the dex_data_mmap_. This means the new_dex_data was filled in without looking
       // at the initial dex_data_.
       return true;
     } else if (dex_data_.data() == dex_data_mmap_.Begin()) {
       // The dex file used to have modifications but they were not added again.
       return true;
     } else {
       // It's not clear what happened. It's possible that the agent got the current dex file data
       // from some other source so we need to initialize everything to see if it is the same.
       VLOG(signals) << "Lazy dex file for " << name_ << " was never touched but the dex_data_ is "
                     << "changed! Need to initialize the memory to see if anything changed";
       InitializeMemory();
     }
   }

   // We can definitely read current_dex_file_ and dex_file_ without causing page faults.

   // Check if the dex file we want to set is the same as the current one.
   // Unfortunately we need to do this check even if no modifications have been done since it could
   // be that agents were removed in the mean-time so we still have a different dex file. The dex
   // checksum means this is likely to be fairly fast.
   return current_dex_file_.size() != dex_data_.size() ||
       memcmp(current_dex_file_.data(), dex_data_.data(), current_dex_file_.size()) != 0;
 }

 jvmtiError ArtClassDefinition::InitCommon(art::Thread* self, jclass klass) {
   art::ScopedObjectAccess soa(self);
   art::ObjPtr<art::mirror::Class> m_klass(soa.Decode<art::mirror::Class>(klass));
   if (m_klass.IsNull()) {
     return ERR(INVALID_CLASS);
   }
   initialized_ = true;
   klass_ = klass;
   loader_ = soa.AddLocalReference<jobject>(m_klass->GetClassLoader());
   std::string descriptor_store;
   std::string descriptor(m_klass->GetDescriptor(&descriptor_store));
   name_ = descriptor.substr(1, descriptor.size() - 2);
   // Android doesn't really have protection domains.
   protection_domain_ = nullptr;
   return OK;
 }

 static void DequickenDexFile(const art::DexFile* dex_file,
                              const char* descriptor,
                              /*out*/std::vector<unsigned char>* dex_data)
     REQUIRES_SHARED(art::Locks::mutator_lock_) {
   std::unique_ptr<FixedUpDexFile> fixed_dex_file(FixedUpDexFile::Create(*dex_file, descriptor));
   dex_data->resize(fixed_dex_file->Size());
   memcpy(dex_data->data(), fixed_dex_file->Begin(), fixed_dex_file->Size());
 }

 // Gets the data surrounding the given class.
 static void GetDexDataForRetransformation(art::Handle<art::mirror::Class> klass,
                                           /*out*/std::vector<unsigned char>* dex_data)
     REQUIRES_SHARED(art::Locks::mutator_lock_) {
   art::StackHandleScope<3> hs(art::Thread::Current());
   art::Handle<art::mirror::ClassExt> ext(hs.NewHandle(klass->GetExtData()));
   const art::DexFile* dex_file = nullptr;
   if (!ext.IsNull()) {
     art::Handle<art::mirror::Object> orig_dex(hs.NewHandle(ext->GetOriginalDexFile()));
     if (!orig_dex.IsNull()) {
       if (orig_dex->IsArrayInstance()) {
         DCHECK(orig_dex->GetClass()->GetComponentType()->IsPrimitiveByte());
         art::Handle<art::mirror::ByteArray> orig_dex_bytes(
             hs.NewHandle(art::down_cast<art::mirror::ByteArray*>(orig_dex->AsArray())));
         dex_data->resize(orig_dex_bytes->GetLength());
         memcpy(dex_data->data(), orig_dex_bytes->GetData(), dex_data->size());
         return;
       } else if (orig_dex->IsDexCache()) {
         dex_file = orig_dex->AsDexCache()->GetDexFile();
       } else {
         DCHECK(orig_dex->GetClass()->DescriptorEquals("Ljava/lang/Long;"))
             << "Expected java/lang/Long but found object of type "
             << orig_dex->GetClass()->PrettyClass();
         art::ObjPtr<art::mirror::Class> prim_long_class(
             art::GetClassRoot(art::ClassRoot::kPrimitiveLong));
         art::JValue val;
         if (!art::UnboxPrimitiveForResult(orig_dex.Get(), prim_long_class, &val)) {
           // This should never happen.
           LOG(FATAL) << "Unable to unbox a primitive long value!";
         }
         dex_file = reinterpret_cast<const art::DexFile*>(static_cast<uintptr_t>(val.GetJ()));
       }
     }
   }
   if (dex_file == nullptr) {
     dex_file = &klass->GetDexFile();
   }
   std::string storage;
   DequickenDexFile(dex_file, klass->GetDescriptor(&storage), dex_data);
 }

 static bool DexNeedsDequickening(art::Handle<art::mirror::Class> klass,
                                  /*out*/ bool* from_class_ext)
     REQUIRES_SHARED(art::Locks::mutator_lock_) {
   art::ObjPtr<art::mirror::ClassExt> ext(klass->GetExtData());
   if (ext.IsNull()) {
     // We don't seem to have ever been redefined so be conservative and say we need de-quickening.
     *from_class_ext = false;
     return true;
   }
   art::ObjPtr<art::mirror::Object> orig_dex(ext->GetOriginalDexFile());
   if (orig_dex.IsNull()) {
     // We don't seem to have ever been redefined so be conservative and say we need de-quickening.
     *from_class_ext = false;
     return true;
   } else if (!orig_dex->IsArrayInstance()) {
     // We were redefined but the original is held in a dex-cache or dex file. This means that the
     // original dex file is the one from the disk, which might be quickened.
     DCHECK(orig_dex->IsDexCache() || orig_dex->GetClass()->DescriptorEquals("Ljava/lang/Long;"));
     *from_class_ext = true;
     return true;
   } else {
     // An array instance means the original-dex-file is from a redefineClasses which cannot have any
     // quickening, so it's fine to use directly.
     DCHECK(orig_dex->GetClass()->GetComponentType()->IsPrimitiveByte());
     *from_class_ext = true;
     return false;
   }
 }

 static const art::DexFile* GetQuickenedDexFile(art::Handle<art::mirror::Class> klass)
     REQUIRES_SHARED(art::Locks::mutator_lock_) {
   art::ObjPtr<art::mirror::ClassExt> ext(klass->GetExtData());
   if (ext.IsNull() || ext->GetOriginalDexFile() == nullptr) {
     return &klass->GetDexFile();
   }

   art::ObjPtr<art::mirror::Object> orig_dex(ext->GetOriginalDexFile());
   DCHECK(!orig_dex->IsArrayInstance());
   if (orig_dex->IsDexCache()) {
     return orig_dex->AsDexCache()->GetDexFile();
   }

   DCHECK(orig_dex->GetClass()->DescriptorEquals("Ljava/lang/Long;"))
       << "Expected java/lang/Long but found object of type "
       << orig_dex->GetClass()->PrettyClass();
   art::ObjPtr<art::mirror::Class> prim_long_class(
       art::GetClassRoot(art::ClassRoot::kPrimitiveLong));
   art::JValue val;
   if (!art::UnboxPrimitiveForResult(orig_dex.Ptr(), prim_long_class, &val)) {
     LOG(FATAL) << "Unable to unwrap a long value!";
   }
   return reinterpret_cast<const art::DexFile*>(static_cast<uintptr_t>(val.GetJ()));
 }

 template<typename GetOriginalDexFile>
 void ArtClassDefinition::InitWithDex(GetOriginalDexFile get_original,
                                      const art::DexFile* quick_dex) {
   art::Thread* self = art::Thread::Current();
   DCHECK(quick_dex != nullptr);
   if (art::MemMap::kCanReplaceMapping && kEnableOnDemandDexDequicken) {
     size_t dequick_size = quick_dex->GetDequickenedSize();
     std::string mmap_name("anon-mmap-for-redefine: ");
     mmap_name += name_;
     std::string error;
     dex_data_mmap_ = art::MemMap::MapAnonymous(mmap_name.c_str(),
                                                dequick_size,
                                                PROT_NONE,
                                                /*low_4gb=*/ false,
                                                &error);
     mmap_name += "-TEMP";
     temp_mmap_ = art::MemMap::MapAnonymous(mmap_name.c_str(),
                                            dequick_size,
                                            PROT_READ | PROT_WRITE,
                                            /*low_4gb=*/ false,
                                            &error);
     if (UNLIKELY(dex_data_mmap_.IsValid() && temp_mmap_.IsValid())) {
       // Need to save the initial dexfile so we don't need to search for it in the fault-handler.
       initial_dex_file_unquickened_ = quick_dex;
       dex_data_ = art::ArrayRef<const unsigned char>(dex_data_mmap_.Begin(),
                                                      dex_data_mmap_.Size());
       if (from_class_ext_) {
         // We got initial from class_ext so the current one must have undergone redefinition so no
         // cdex or quickening stuff.
         // We can only do this if it's not a first load.
         DCHECK(klass_ != nullptr);
         const art::DexFile& cur_dex = self->DecodeJObject(klass_)->AsClass()->GetDexFile();
         current_dex_file_ = art::ArrayRef<const unsigned char>(cur_dex.Begin(), cur_dex.Size());
       } else {
         // This class hasn't been redefined before. The dequickened current data is the same as the
         // dex_data_mmap_ when it's filled it. We don't need to copy anything because the mmap will
         // not be cleared until after everything is done.
         current_dex_file_ = art::ArrayRef<const unsigned char>(dex_data_mmap_.Begin(),
                                                                dequick_size);
       }
       return;
     }
   }
   dex_data_mmap_.Reset();
   temp_mmap_.Reset();
   // Failed to mmap a large enough area (or on-demand dequickening was disabled). This is
   // unfortunate. Since currently the size is just a guess though we might as well try to do it
   // manually.
   get_original(/*out*/&dex_data_memory_);
   dex_data_ = art::ArrayRef<const unsigned char>(dex_data_memory_);
   if (from_class_ext_) {
     // We got initial from class_ext so the current one must have undergone redefinition so no
     // cdex or quickening stuff.
     // We can only do this if it's not a first load.
     DCHECK(klass_ != nullptr);
     const art::DexFile& cur_dex = self->DecodeJObject(klass_)->AsClass()->GetDexFile();
     current_dex_file_ = art::ArrayRef<const unsigned char>(cur_dex.Begin(), cur_dex.Size());
   } else {
     // No redefinition must have ever happened so the (dequickened) cur_dex is the same as the
     // initial dex_data. We need to copy it into another buffer to keep it around if we have a
     // real redefinition.
     current_dex_memory_.resize(dex_data_.size());
     memcpy(current_dex_memory_.data(), dex_data_.data(), current_dex_memory_.size());
     current_dex_file_ = art::ArrayRef<const unsigned char>(current_dex_memory_);
   }
 }

 jvmtiError ArtClassDefinition::Init(art::Thread* self, jclass klass) {
   jvmtiError res = InitCommon(self, klass);
   if (res != OK) {
     return res;
   }
   art::ScopedObjectAccess soa(self);
   art::StackHandleScope<1> hs(self);
   art::Handle<art::mirror::Class> m_klass(hs.NewHandle(self->DecodeJObject(klass)->AsClass()));
   if (!DexNeedsDequickening(m_klass, &from_class_ext_)) {
     // We don't need to do any dequickening. We want to copy the data just so we don't need to deal
     // with the GC moving it around.
     art::ObjPtr<art::mirror::ByteArray> orig_dex(
         m_klass->GetExtData()->GetOriginalDexFile()->AsByteArray());
     dex_data_memory_.resize(orig_dex->GetLength());
     memcpy(dex_data_memory_.data(), orig_dex->GetData(), dex_data_memory_.size());
     dex_data_ = art::ArrayRef<const unsigned char>(dex_data_memory_);

     // Since we are here we must not have any quickened instructions since we were redefined.
     const art::DexFile& cur_dex = m_klass->GetDexFile();
     DCHECK(from_class_ext_);
     current_dex_file_ = art::ArrayRef<const unsigned char>(cur_dex.Begin(), cur_dex.Size());
     return OK;
   }

   // We need to dequicken stuff. This is often super slow (10's of ms). Instead we will do it
   // dynamically.
   const art::DexFile* quick_dex = GetQuickenedDexFile(m_klass);
   auto get_original = [&](/*out*/std::vector<unsigned char>* dex_data)
       REQUIRES_SHARED(art::Locks::mutator_lock_) {
     GetDexDataForRetransformation(m_klass, dex_data);
   };
   InitWithDex(get_original, quick_dex);
   return OK;
 }

 jvmtiError ArtClassDefinition::Init(art::Thread* self, const jvmtiClassDefinition& def) {
   jvmtiError res = InitCommon(self, def.klass);
   if (res != OK) {
     return res;
   }
   // We are being directly redefined.
   redefined_ = true;
   current_dex_file_ = art::ArrayRef<const unsigned char>(def.class_bytes, def.class_byte_count);
   dex_data_ = art::ArrayRef<const unsigned char>(def.class_bytes, def.class_byte_count);
   return OK;
 }

 void ArtClassDefinition::InitFirstLoad(const char* descriptor,
                                        art::Handle<art::mirror::ClassLoader> klass_loader,
                                        const art::DexFile& dex_file) {
   art::Thread* self = art::Thread::Current();
   art::ScopedObjectAccess soa(self);
   initialized_ = true;
   // No Class
   klass_ = nullptr;
   loader_ = soa.AddLocalReference<jobject>(klass_loader.Get());
   std::string descriptor_str(descriptor);
   name_ = descriptor_str.substr(1, descriptor_str.size() - 2);
   // Android doesn't really have protection domains.
   protection_domain_ = nullptr;
   auto get_original = [&](/*out*/std::vector<unsigned char>* dex_data)
       REQUIRES_SHARED(art::Locks::mutator_lock_) {
     DequickenDexFile(&dex_file, descriptor, dex_data);
   };
   InitWithDex(get_original, &dex_file);
 }

 }  // namespace openjdkjvmti
	/* Copyright (C) 2016 The Android Open Source Project
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This file implements interfaces from the file jvmti.h. This implementation
	* is licensed under the same terms as the file jvmti.h. The
	* copyright and license information for the file jvmti.h follows.
	*
	* Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	#include "ti_class_definition.h"

	#include "base/array_slice.h"
	#include "base/logging.h"
	#include "class_linker-inl.h"
	#include "class_root.h"
	#include "dex/dex_file.h"
	#include "fixed_up_dex_file.h"
	#include "handle.h"
	#include "handle_scope-inl.h"
	#include "mirror/class-inl.h"
	#include "mirror/class_ext.h"
	#include "mirror/object-inl.h"
	#include "reflection.h"
	#include "thread.h"

	namespace openjdkjvmti {

	void ArtClassDefinition::InitializeMemory() const {
	DCHECK(art::MemMap::kCanReplaceMapping);
	VLOG(signals) << "Initializing de-quickened memory for dex file of " << name_;
	CHECK(dex_data_mmap_.IsValid());
	CHECK(temp_mmap_.IsValid());
	CHECK_EQ(dex_data_mmap_.GetProtect(), PROT_NONE);
	CHECK_EQ(temp_mmap_.GetProtect(), PROT_READ \| PROT_WRITE);

	std::string desc = std::string("L") + name_ + ";";
	std::unique_ptr<FixedUpDexFile>
	fixed_dex_file(FixedUpDexFile::Create(*initial_dex_file_unquickened_, desc.c_str()));
	CHECK(fixed_dex_file.get() != nullptr);
	CHECK_LE(fixed_dex_file->Size(), temp_mmap_.Size());
	CHECK_EQ(temp_mmap_.Size(), dex_data_mmap_.Size());
	// Copy the data to the temp mmap.
	memcpy(temp_mmap_.Begin(), fixed_dex_file->Begin(), fixed_dex_file->Size());

	// Move the mmap atomically.
	art::MemMap source;
	source.swap(temp_mmap_);
	std::string error;
	CHECK(dex_data_mmap_.ReplaceWith(&source, &error)) << "Failed to replace mmap for "
	<< name_ << " because " << error;
	CHECK(dex_data_mmap_.Protect(PROT_READ));
	}

	bool ArtClassDefinition::IsModified() const {
	// RedefineClasses calls always are 'modified' since they need to change the current_dex_file of
	// the class.
	if (redefined_) {
	return true;
	}

	// Check to see if any change has taken place.
	if (current_dex_file_.data() == dex_data_.data()) {
	// no change at all.
	return false;
	}

	// The dex_data_ was never touched by the agents.
	if (dex_data_mmap_.IsValid() && dex_data_mmap_.GetProtect() == PROT_NONE) {
	if (current_dex_file_.data() == dex_data_mmap_.Begin()) {
	// the dex_data_ looks like it changed (not equal to current_dex_file_) but we never
	// initialized the dex_data_mmap_. This means the new_dex_data was filled in without looking
	// at the initial dex_data_.
	return true;
	} else if (dex_data_.data() == dex_data_mmap_.Begin()) {
	// The dex file used to have modifications but they were not added again.
	return true;
	} else {
	// It's not clear what happened. It's possible that the agent got the current dex file data
	// from some other source so we need to initialize everything to see if it is the same.
	VLOG(signals) << "Lazy dex file for " << name_ << " was never touched but the dex_data_ is "
	<< "changed! Need to initialize the memory to see if anything changed";
	InitializeMemory();
	}
	}

	// We can definitely read current_dex_file_ and dex_file_ without causing page faults.

	// Check if the dex file we want to set is the same as the current one.
	// Unfortunately we need to do this check even if no modifications have been done since it could
	// be that agents were removed in the mean-time so we still have a different dex file. The dex
	// checksum means this is likely to be fairly fast.
	return current_dex_file_.size() != dex_data_.size() \|\|
	memcmp(current_dex_file_.data(), dex_data_.data(), current_dex_file_.size()) != 0;
	}

	jvmtiError ArtClassDefinition::InitCommon(art::Thread* self, jclass klass) {
	art::ScopedObjectAccess soa(self);
	art::ObjPtr<art::mirror::Class> m_klass(soa.Decode<art::mirror::Class>(klass));
	if (m_klass.IsNull()) {
	return ERR(INVALID_CLASS);
	}
	initialized_ = true;
	klass_ = klass;
	loader_ = soa.AddLocalReference<jobject>(m_klass->GetClassLoader());
	std::string descriptor_store;
	std::string descriptor(m_klass->GetDescriptor(&descriptor_store));
	name_ = descriptor.substr(1, descriptor.size() - 2);
	// Android doesn't really have protection domains.
	protection_domain_ = nullptr;
	return OK;
	}

	static void DequickenDexFile(const art::DexFile* dex_file,
	const char* descriptor,
	/out/std::vector<unsigned char>* dex_data)
	REQUIRES_SHARED(art::Locks::mutator_lock_) {
	std::unique_ptr<FixedUpDexFile> fixed_dex_file(FixedUpDexFile::Create(*dex_file, descriptor));
	dex_data->resize(fixed_dex_file->Size());
	memcpy(dex_data->data(), fixed_dex_file->Begin(), fixed_dex_file->Size());
	}

	// Gets the data surrounding the given class.
	static void GetDexDataForRetransformation(art::Handle<art::mirror::Class> klass,
	/out/std::vector<unsigned char>* dex_data)
	REQUIRES_SHARED(art::Locks::mutator_lock_) {
	art::StackHandleScope<3> hs(art::Thread::Current());
	art::Handle<art::mirror::ClassExt> ext(hs.NewHandle(klass->GetExtData()));
	const art::DexFile* dex_file = nullptr;
	if (!ext.IsNull()) {
	art::Handle<art::mirror::Object> orig_dex(hs.NewHandle(ext->GetOriginalDexFile()));
	if (!orig_dex.IsNull()) {
	if (orig_dex->IsArrayInstance()) {
	DCHECK(orig_dex->GetClass()->GetComponentType()->IsPrimitiveByte());
	art::Handle<art::mirror::ByteArray> orig_dex_bytes(
	hs.NewHandle(art::down_cast<art::mirror::ByteArray*>(orig_dex->AsArray())));
	dex_data->resize(orig_dex_bytes->GetLength());
	memcpy(dex_data->data(), orig_dex_bytes->GetData(), dex_data->size());
	return;
	} else if (orig_dex->IsDexCache()) {
	dex_file = orig_dex->AsDexCache()->GetDexFile();
	} else {
	DCHECK(orig_dex->GetClass()->DescriptorEquals("Ljava/lang/Long;"))
	<< "Expected java/lang/Long but found object of type "
	<< orig_dex->GetClass()->PrettyClass();
	art::ObjPtr<art::mirror::Class> prim_long_class(
	art::GetClassRoot(art::ClassRoot::kPrimitiveLong));
	art::JValue val;
	if (!art::UnboxPrimitiveForResult(orig_dex.Get(), prim_long_class, &val)) {
	// This should never happen.
	LOG(FATAL) << "Unable to unbox a primitive long value!";
	}
	dex_file = reinterpret_cast<const art::DexFile*>(static_cast<uintptr_t>(val.GetJ()));
	}
	}
	}
	if (dex_file == nullptr) {
	dex_file = &klass->GetDexFile();
	}
	std::string storage;
	DequickenDexFile(dex_file, klass->GetDescriptor(&storage), dex_data);
	}

	static bool DexNeedsDequickening(art::Handle<art::mirror::Class> klass,
	/out/ bool* from_class_ext)
	REQUIRES_SHARED(art::Locks::mutator_lock_) {
	art::ObjPtr<art::mirror::ClassExt> ext(klass->GetExtData());
	if (ext.IsNull()) {
	// We don't seem to have ever been redefined so be conservative and say we need de-quickening.
	*from_class_ext = false;
	return true;
	}
	art::ObjPtr<art::mirror::Object> orig_dex(ext->GetOriginalDexFile());
	if (orig_dex.IsNull()) {
	// We don't seem to have ever been redefined so be conservative and say we need de-quickening.
	*from_class_ext = false;
	return true;
	} else if (!orig_dex->IsArrayInstance()) {
	// We were redefined but the original is held in a dex-cache or dex file. This means that the
	// original dex file is the one from the disk, which might be quickened.
	DCHECK(orig_dex->IsDexCache() \|\| orig_dex->GetClass()->DescriptorEquals("Ljava/lang/Long;"));
	*from_class_ext = true;
	return true;
	} else {
	// An array instance means the original-dex-file is from a redefineClasses which cannot have any
	// quickening, so it's fine to use directly.
	DCHECK(orig_dex->GetClass()->GetComponentType()->IsPrimitiveByte());
	*from_class_ext = true;
	return false;
	}
	}

	static const art::DexFile* GetQuickenedDexFile(art::Handle<art::mirror::Class> klass)
	REQUIRES_SHARED(art::Locks::mutator_lock_) {
	art::ObjPtr<art::mirror::ClassExt> ext(klass->GetExtData());
	if (ext.IsNull() \|\| ext->GetOriginalDexFile() == nullptr) {
	return &klass->GetDexFile();
	}

	art::ObjPtr<art::mirror::Object> orig_dex(ext->GetOriginalDexFile());
	DCHECK(!orig_dex->IsArrayInstance());
	if (orig_dex->IsDexCache()) {
	return orig_dex->AsDexCache()->GetDexFile();
	}

	DCHECK(orig_dex->GetClass()->DescriptorEquals("Ljava/lang/Long;"))
	<< "Expected java/lang/Long but found object of type "
	<< orig_dex->GetClass()->PrettyClass();
	art::ObjPtr<art::mirror::Class> prim_long_class(
	art::GetClassRoot(art::ClassRoot::kPrimitiveLong));
	art::JValue val;
	if (!art::UnboxPrimitiveForResult(orig_dex.Ptr(), prim_long_class, &val)) {
	LOG(FATAL) << "Unable to unwrap a long value!";
	}
	return reinterpret_cast<const art::DexFile*>(static_cast<uintptr_t>(val.GetJ()));
	}

	template<typename GetOriginalDexFile>
	void ArtClassDefinition::InitWithDex(GetOriginalDexFile get_original,
	const art::DexFile* quick_dex) {
	art::Thread* self = art::Thread::Current();
	DCHECK(quick_dex != nullptr);
	if (art::MemMap::kCanReplaceMapping && kEnableOnDemandDexDequicken) {
	size_t dequick_size = quick_dex->GetDequickenedSize();
	std::string mmap_name("anon-mmap-for-redefine: ");
	mmap_name += name_;
	std::string error;
	dex_data_mmap_ = art::MemMap::MapAnonymous(mmap_name.c_str(),
	dequick_size,
	PROT_NONE,
	/low_4gb=/ false,
	&error);
	mmap_name += "-TEMP";
	temp_mmap_ = art::MemMap::MapAnonymous(mmap_name.c_str(),
	dequick_size,
	PROT_READ \| PROT_WRITE,
	/low_4gb=/ false,
	&error);
	if (UNLIKELY(dex_data_mmap_.IsValid() && temp_mmap_.IsValid())) {
	// Need to save the initial dexfile so we don't need to search for it in the fault-handler.
	initial_dex_file_unquickened_ = quick_dex;
	dex_data_ = art::ArrayRef<const unsigned char>(dex_data_mmap_.Begin(),
	dex_data_mmap_.Size());
	if (from_class_ext_) {
	// We got initial from class_ext so the current one must have undergone redefinition so no
	// cdex or quickening stuff.
	// We can only do this if it's not a first load.
	DCHECK(klass_ != nullptr);
	const art::DexFile& cur_dex = self->DecodeJObject(klass_)->AsClass()->GetDexFile();
	current_dex_file_ = art::ArrayRef<const unsigned char>(cur_dex.Begin(), cur_dex.Size());
	} else {
	// This class hasn't been redefined before. The dequickened current data is the same as the
	// dex_data_mmap_ when it's filled it. We don't need to copy anything because the mmap will
	// not be cleared until after everything is done.
	current_dex_file_ = art::ArrayRef<const unsigned char>(dex_data_mmap_.Begin(),
	dequick_size);
	}
	return;
	}
	}
	dex_data_mmap_.Reset();
	temp_mmap_.Reset();
	// Failed to mmap a large enough area (or on-demand dequickening was disabled). This is
	// unfortunate. Since currently the size is just a guess though we might as well try to do it
	// manually.
	get_original(/out/&dex_data_memory_);
	dex_data_ = art::ArrayRef<const unsigned char>(dex_data_memory_);
	if (from_class_ext_) {
	// We got initial from class_ext so the current one must have undergone redefinition so no
	// cdex or quickening stuff.
	// We can only do this if it's not a first load.
	DCHECK(klass_ != nullptr);
	const art::DexFile& cur_dex = self->DecodeJObject(klass_)->AsClass()->GetDexFile();
	current_dex_file_ = art::ArrayRef<const unsigned char>(cur_dex.Begin(), cur_dex.Size());
	} else {
	// No redefinition must have ever happened so the (dequickened) cur_dex is the same as the
	// initial dex_data. We need to copy it into another buffer to keep it around if we have a
	// real redefinition.
	current_dex_memory_.resize(dex_data_.size());
	memcpy(current_dex_memory_.data(), dex_data_.data(), current_dex_memory_.size());
	current_dex_file_ = art::ArrayRef<const unsigned char>(current_dex_memory_);
	}
	}

	jvmtiError ArtClassDefinition::Init(art::Thread* self, jclass klass) {
	jvmtiError res = InitCommon(self, klass);
	if (res != OK) {
	return res;
	}
	art::ScopedObjectAccess soa(self);
	art::StackHandleScope<1> hs(self);
	art::Handle<art::mirror::Class> m_klass(hs.NewHandle(self->DecodeJObject(klass)->AsClass()));
	if (!DexNeedsDequickening(m_klass, &from_class_ext_)) {
	// We don't need to do any dequickening. We want to copy the data just so we don't need to deal
	// with the GC moving it around.
	art::ObjPtr<art::mirror::ByteArray> orig_dex(
	m_klass->GetExtData()->GetOriginalDexFile()->AsByteArray());
	dex_data_memory_.resize(orig_dex->GetLength());
	memcpy(dex_data_memory_.data(), orig_dex->GetData(), dex_data_memory_.size());
	dex_data_ = art::ArrayRef<const unsigned char>(dex_data_memory_);

	// Since we are here we must not have any quickened instructions since we were redefined.
	const art::DexFile& cur_dex = m_klass->GetDexFile();
	DCHECK(from_class_ext_);
	current_dex_file_ = art::ArrayRef<const unsigned char>(cur_dex.Begin(), cur_dex.Size());
	return OK;
	}

	// We need to dequicken stuff. This is often super slow (10's of ms). Instead we will do it
	// dynamically.
	const art::DexFile* quick_dex = GetQuickenedDexFile(m_klass);
	auto get_original = [&](/out/std::vector<unsigned char>* dex_data)
	REQUIRES_SHARED(art::Locks::mutator_lock_) {
	GetDexDataForRetransformation(m_klass, dex_data);
	};
	InitWithDex(get_original, quick_dex);
	return OK;
	}

	jvmtiError ArtClassDefinition::Init(art::Thread* self, const jvmtiClassDefinition& def) {
	jvmtiError res = InitCommon(self, def.klass);
	if (res != OK) {
	return res;
	}
	// We are being directly redefined.
	redefined_ = true;
	current_dex_file_ = art::ArrayRef<const unsigned char>(def.class_bytes, def.class_byte_count);
	dex_data_ = art::ArrayRef<const unsigned char>(def.class_bytes, def.class_byte_count);
	return OK;
	}

	void ArtClassDefinition::InitFirstLoad(const char* descriptor,
	art::Handle<art::mirror::ClassLoader> klass_loader,
	const art::DexFile& dex_file) {
	art::Thread* self = art::Thread::Current();
	art::ScopedObjectAccess soa(self);
	initialized_ = true;
	// No Class
	klass_ = nullptr;
	loader_ = soa.AddLocalReference<jobject>(klass_loader.Get());
	std::string descriptor_str(descriptor);
	name_ = descriptor_str.substr(1, descriptor_str.size() - 2);
	// Android doesn't really have protection domains.
	protection_domain_ = nullptr;
	auto get_original = [&](/out/std::vector<unsigned char>* dex_data)
	REQUIRES_SHARED(art::Locks::mutator_lock_) {
	DequickenDexFile(&dex_file, descriptor, dex_data);
	};
	InitWithDex(get_original, &dex_file);
	}

	} // namespace openjdkjvmti