/* 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.h"

#include <mutex>
#include <unordered_set>

#include "art_jvmti.h"
#include "base/macros.h"
#include "class_table-inl.h"
#include "class_linker.h"
#include "events-inl.h"
#include "handle.h"
#include "jni_env_ext-inl.h"
#include "jni_internal.h"
#include "runtime.h"
#include "runtime_callbacks.h"
#include "ScopedLocalRef.h"
#include "scoped_thread_state_change-inl.h"
#include "thread-inl.h"
#include "thread_list.h"

namespace openjdkjvmti {

struct ClassCallback : public art::ClassLoadCallback {
  void ClassLoad(art::Handle<art::mirror::Class> klass) REQUIRES_SHARED(art::Locks::mutator_lock_) {
    if (event_handler->IsEventEnabledAnywhere(ArtJvmtiEvent::kClassLoad)) {
      art::Thread* thread = art::Thread::Current();
      ScopedLocalRef<jclass> jklass(thread->GetJniEnv(),
                                    thread->GetJniEnv()->AddLocalReference<jclass>(klass.Get()));
      ScopedLocalRef<jclass> jthread(
          thread->GetJniEnv(), thread->GetJniEnv()->AddLocalReference<jclass>(thread->GetPeer()));
      {
        art::ScopedThreadSuspension sts(thread, art::ThreadState::kNative);
        event_handler->DispatchEvent(thread,
                                     ArtJvmtiEvent::kClassLoad,
                                     reinterpret_cast<JNIEnv*>(thread->GetJniEnv()),
                                     jthread.get(),
                                     jklass.get());
      }
      AddTempClass(thread, jklass.get());
    }
  }

  void ClassPrepare(art::Handle<art::mirror::Class> temp_klass ATTRIBUTE_UNUSED,
                    art::Handle<art::mirror::Class> klass)
      REQUIRES_SHARED(art::Locks::mutator_lock_) {
    if (event_handler->IsEventEnabledAnywhere(ArtJvmtiEvent::kClassPrepare)) {
      art::Thread* thread = art::Thread::Current();
      ScopedLocalRef<jclass> jklass(thread->GetJniEnv(),
                                    thread->GetJniEnv()->AddLocalReference<jclass>(klass.Get()));
      ScopedLocalRef<jclass> jthread(
          thread->GetJniEnv(), thread->GetJniEnv()->AddLocalReference<jclass>(thread->GetPeer()));
      art::ScopedThreadSuspension sts(thread, art::ThreadState::kNative);
      event_handler->DispatchEvent(thread,
                                   ArtJvmtiEvent::kClassPrepare,
                                   reinterpret_cast<JNIEnv*>(thread->GetJniEnv()),
                                   jthread.get(),
                                   jklass.get());
    }
  }

  void AddTempClass(art::Thread* self, jclass klass) {
    std::unique_lock<std::mutex> mu(temp_classes_lock);
    temp_classes.push_back(reinterpret_cast<jclass>(self->GetJniEnv()->NewGlobalRef(klass)));
  }

  void HandleTempClass(art::Handle<art::mirror::Class> temp_klass,
                       art::Handle<art::mirror::Class> klass)
      REQUIRES_SHARED(art::Locks::mutator_lock_) {
    std::unique_lock<std::mutex> mu(temp_classes_lock);
    if (temp_classes.empty()) {
      return;
    }

    art::Thread* self = art::Thread::Current();
    for (auto it = temp_classes.begin(); it != temp_classes.end(); ++it) {
      if (temp_klass.Get() == art::ObjPtr<art::mirror::Class>::DownCast(self->DecodeJObject(*it))) {
        temp_classes.erase(it);
        FixupTempClass(temp_klass, klass);
      }
    }
  }

  void FixupTempClass(art::Handle<art::mirror::Class> temp_klass ATTRIBUTE_UNUSED,
                      art::Handle<art::mirror::Class> klass ATTRIBUTE_UNUSED)
     REQUIRES_SHARED(art::Locks::mutator_lock_) {
    // TODO: Implement.
  }

  // A set of all the temp classes we have handed out. We have to fix up references to these.
  // For simplicity, we store the temp classes as JNI global references in a vector. Normally a
  // Prepare event will closely follow, so the vector should be small.
  std::mutex temp_classes_lock;
  std::vector<jclass> temp_classes;

  EventHandler* event_handler = nullptr;
};

ClassCallback gClassCallback;

void ClassUtil::Register(EventHandler* handler) {
  gClassCallback.event_handler = handler;
  art::ScopedThreadStateChange stsc(art::Thread::Current(),
                                    art::ThreadState::kWaitingForDebuggerToAttach);
  art::ScopedSuspendAll ssa("Add load callback");
  art::Runtime::Current()->GetRuntimeCallbacks()->AddClassLoadCallback(&gClassCallback);
}

void ClassUtil::Unregister() {
  art::ScopedThreadStateChange stsc(art::Thread::Current(),
                                    art::ThreadState::kWaitingForDebuggerToAttach);
  art::ScopedSuspendAll ssa("Remove thread callback");
  art::Runtime* runtime = art::Runtime::Current();
  runtime->GetRuntimeCallbacks()->RemoveClassLoadCallback(&gClassCallback);
}

jvmtiError ClassUtil::GetClassFields(jvmtiEnv* env,
                                     jclass jklass,
                                     jint* field_count_ptr,
                                     jfieldID** fields_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 (field_count_ptr == nullptr || fields_ptr == nullptr) {
    return ERR(NULL_POINTER);
  }

  art::IterationRange<art::StrideIterator<art::ArtField>> ifields = klass->GetIFields();
  art::IterationRange<art::StrideIterator<art::ArtField>> sfields = klass->GetSFields();
  size_t array_size = klass->NumInstanceFields() + klass->NumStaticFields();

  unsigned char* out_ptr;
  jvmtiError allocError = env->Allocate(array_size * sizeof(jfieldID), &out_ptr);
  if (allocError != ERR(NONE)) {
    return allocError;
  }
  jfieldID* field_array = reinterpret_cast<jfieldID*>(out_ptr);

  size_t array_idx = 0;
  for (art::ArtField& field : sfields) {
    field_array[array_idx] = art::jni::EncodeArtField(&field);
    ++array_idx;
  }
  for (art::ArtField& field : ifields) {
    field_array[array_idx] = art::jni::EncodeArtField(&field);
    ++array_idx;
  }

  *field_count_ptr = static_cast<jint>(array_size);
  *fields_ptr = field_array;

  return ERR(NONE);
}

jvmtiError ClassUtil::GetClassMethods(jvmtiEnv* env,
                                      jclass jklass,
                                      jint* method_count_ptr,
                                      jmethodID** methods_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 (method_count_ptr == nullptr || methods_ptr == nullptr) {
    return ERR(NULL_POINTER);
  }

  size_t array_size = klass->NumDeclaredVirtualMethods() + klass->NumDirectMethods();
  unsigned char* out_ptr;
  jvmtiError allocError = env->Allocate(array_size * sizeof(jmethodID), &out_ptr);
  if (allocError != ERR(NONE)) {
    return allocError;
  }
  jmethodID* method_array = reinterpret_cast<jmethodID*>(out_ptr);

  if (art::kIsDebugBuild) {
    size_t count = 0;
    for (auto& m ATTRIBUTE_UNUSED : klass->GetDeclaredMethods(art::kRuntimePointerSize)) {
      count++;
    }
    CHECK_EQ(count, klass->NumDirectMethods() + klass->NumDeclaredVirtualMethods());
  }

  size_t array_idx = 0;
  for (auto& m : klass->GetDeclaredMethods(art::kRuntimePointerSize)) {
    method_array[array_idx] = art::jni::EncodeArtMethod(&m);
    ++array_idx;
  }

  *method_count_ptr = static_cast<jint>(array_size);
  *methods_ptr = method_array;

  return ERR(NONE);
}

jvmtiError ClassUtil::GetImplementedInterfaces(jvmtiEnv* env,
                                               jclass jklass,
                                               jint* interface_count_ptr,
                                               jclass** interfaces_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 (interface_count_ptr == nullptr || interfaces_ptr == nullptr) {
    return ERR(NULL_POINTER);
  }

  // Need to handle array specifically. Arrays implement Serializable and Cloneable, but the
  // spec says these should not be reported.
  if (klass->IsArrayClass()) {
    *interface_count_ptr = 0;
    *interfaces_ptr = nullptr;  // TODO: Should we allocate a dummy here?
    return ERR(NONE);
  }

  size_t array_size = klass->NumDirectInterfaces();
  unsigned char* out_ptr;
  jvmtiError allocError = env->Allocate(array_size * sizeof(jclass), &out_ptr);
  if (allocError != ERR(NONE)) {
    return allocError;
  }
  jclass* interface_array = reinterpret_cast<jclass*>(out_ptr);

  art::StackHandleScope<1> hs(soa.Self());
  art::Handle<art::mirror::Class> h_klass(hs.NewHandle(klass));

  for (uint32_t idx = 0; idx != array_size; ++idx) {
    art::ObjPtr<art::mirror::Class> inf_klass =
        art::mirror::Class::ResolveDirectInterface(soa.Self(), h_klass, idx);
    if (inf_klass == nullptr) {
      soa.Self()->ClearException();
      env->Deallocate(out_ptr);
      // TODO: What is the right error code here?
      return ERR(INTERNAL);
    }
    interface_array[idx] = soa.AddLocalReference<jclass>(inf_klass);
  }

  *interface_count_ptr = static_cast<jint>(array_size);
  *interfaces_ptr = interface_array;

  return ERR(NONE);
}

jvmtiError ClassUtil::GetClassSignature(jvmtiEnv* env,
                                         jclass jklass,
                                         char** signature_ptr,
                                         char** generic_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);
  }

  JvmtiUniquePtr sig_copy;
  if (signature_ptr != nullptr) {
    std::string storage;
    const char* descriptor = klass->GetDescriptor(&storage);

    unsigned char* tmp;
    jvmtiError ret = CopyString(env, descriptor, &tmp);
    if (ret != ERR(NONE)) {
      return ret;
    }
    sig_copy = MakeJvmtiUniquePtr(env, tmp);
    *signature_ptr = reinterpret_cast<char*>(tmp);
  }

  // TODO: Support generic signature.
  if (generic_ptr != nullptr) {
    *generic_ptr = nullptr;
  }

  // Everything is fine, release the buffers.
  sig_copy.release();

  return ERR(NONE);
}

jvmtiError ClassUtil::GetClassStatus(jvmtiEnv* env ATTRIBUTE_UNUSED,
                                     jclass jklass,
                                     jint* status_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 (status_ptr == nullptr) {
    return ERR(NULL_POINTER);
  }

  if (klass->IsArrayClass()) {
    *status_ptr = JVMTI_CLASS_STATUS_ARRAY;
  } else if (klass->IsPrimitive()) {
    *status_ptr = JVMTI_CLASS_STATUS_PRIMITIVE;
  } else {
    *status_ptr = JVMTI_CLASS_STATUS_VERIFIED;  // All loaded classes are structurally verified.
    // This is finicky. If there's an error, we'll say it wasn't prepared.
    if (klass->IsResolved()) {
      *status_ptr |= JVMTI_CLASS_STATUS_PREPARED;
    }
    if (klass->IsInitialized()) {
      *status_ptr |= JVMTI_CLASS_STATUS_INITIALIZED;
    }
    // Technically the class may be erroneous for other reasons, but we do not have enough info.
    if (klass->IsErroneous()) {
      *status_ptr |= JVMTI_CLASS_STATUS_ERROR;
    }
  }

  return ERR(NONE);
}

template <typename T>
static jvmtiError ClassIsT(jclass jklass, T test, jboolean* is_t_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 (is_t_ptr == nullptr) {
    return ERR(NULL_POINTER);
  }

  *is_t_ptr = test(klass) ? JNI_TRUE : JNI_FALSE;
  return ERR(NONE);
}

jvmtiError ClassUtil::IsInterface(jvmtiEnv* env ATTRIBUTE_UNUSED,
                                  jclass jklass,
                                  jboolean* is_interface_ptr) {
  auto test = [](art::ObjPtr<art::mirror::Class> klass) REQUIRES_SHARED(art::Locks::mutator_lock_) {
    return klass->IsInterface();
  };
  return ClassIsT(jklass, test, is_interface_ptr);
}

jvmtiError ClassUtil::IsArrayClass(jvmtiEnv* env ATTRIBUTE_UNUSED,
                                   jclass jklass,
                                   jboolean* is_array_class_ptr) {
  auto test = [](art::ObjPtr<art::mirror::Class> klass) REQUIRES_SHARED(art::Locks::mutator_lock_) {
    return klass->IsArrayClass();
  };
  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);
}

jvmtiError ClassUtil::GetClassLoader(jvmtiEnv* env ATTRIBUTE_UNUSED,
                                     jclass jklass,
                                     jobject* classloader_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 (classloader_ptr == nullptr) {
    return ERR(NULL_POINTER);
  }

  *classloader_ptr = soa.AddLocalReference<jobject>(klass->GetClassLoader());

  return ERR(NONE);
}

jvmtiError ClassUtil::GetClassLoaderClasses(jvmtiEnv* env,
                                            jobject initiating_loader,
                                            jint* class_count_ptr,
                                            jclass** classes_ptr) {
  UNUSED(env, initiating_loader, class_count_ptr, classes_ptr);

  if (class_count_ptr == nullptr || classes_ptr == nullptr) {
    return ERR(NULL_POINTER);
  }
  art::Thread* self = art::Thread::Current();
  if (!self->GetJniEnv()->IsInstanceOf(initiating_loader,
                                       art::WellKnownClasses::java_lang_ClassLoader)) {
    return ERR(ILLEGAL_ARGUMENT);
  }
  if (self->GetJniEnv()->IsInstanceOf(initiating_loader,
                                      art::WellKnownClasses::java_lang_BootClassLoader)) {
    // Need to use null for the BootClassLoader.
    initiating_loader = nullptr;
  }

  art::ScopedObjectAccess soa(self);
  art::ObjPtr<art::mirror::ClassLoader> class_loader =
      soa.Decode<art::mirror::ClassLoader>(initiating_loader);

  art::ClassLinker* class_linker = art::Runtime::Current()->GetClassLinker();

  art::ReaderMutexLock mu(self, *art::Locks::classlinker_classes_lock_);

  art::ClassTable* class_table = class_linker->ClassTableForClassLoader(class_loader);
  if (class_table == nullptr) {
    // Nothing loaded.
    *class_count_ptr = 0;
    *classes_ptr = nullptr;
    return ERR(NONE);
  }

  struct ClassTableCount {
    bool operator()(art::ObjPtr<art::mirror::Class> klass) {
      DCHECK(klass != nullptr);
      ++count;
      return true;
    }

    size_t count = 0;
  };
  ClassTableCount ctc;
  class_table->Visit(ctc);

  if (ctc.count == 0) {
    // Nothing loaded.
    *class_count_ptr = 0;
    *classes_ptr = nullptr;
    return ERR(NONE);
  }

  unsigned char* data;
  jvmtiError data_result = env->Allocate(ctc.count * sizeof(jclass), &data);
  if (data_result != ERR(NONE)) {
    return data_result;
  }
  jclass* class_array = reinterpret_cast<jclass*>(data);

  struct ClassTableFill {
    bool operator()(art::ObjPtr<art::mirror::Class> klass)
        REQUIRES_SHARED(art::Locks::mutator_lock_) {
      DCHECK(klass != nullptr);
      DCHECK_LT(count, ctc_ref.count);
      local_class_array[count++] = soa_ptr->AddLocalReference<jclass>(klass);
      return true;
    }

    jclass* local_class_array;
    const ClassTableCount& ctc_ref;
    art::ScopedObjectAccess* soa_ptr;
    size_t count;
  };
  ClassTableFill ctf = { class_array, ctc, &soa, 0 };
  class_table->Visit(ctf);
  DCHECK_EQ(ctc.count, ctf.count);

  *class_count_ptr = ctc.count;
  *classes_ptr = class_array;

  return ERR(NONE);
}

jvmtiError ClassUtil::GetClassVersionNumbers(jvmtiEnv* env ATTRIBUTE_UNUSED,
                                             jclass jklass,
                                             jint* minor_version_ptr,
                                             jint* major_version_ptr) {
  art::ScopedObjectAccess soa(art::Thread::Current());
  if (jklass == nullptr) {
    return ERR(INVALID_CLASS);
  }
  art::ObjPtr<art::mirror::Object> jklass_obj = soa.Decode<art::mirror::Object>(jklass);
  if (!jklass_obj->IsClass()) {
    return ERR(INVALID_CLASS);
  }
  art::ObjPtr<art::mirror::Class> klass = jklass_obj->AsClass();
  if (klass->IsPrimitive() || klass->IsArrayClass()) {
    return ERR(INVALID_CLASS);
  }

  if (minor_version_ptr == nullptr || major_version_ptr == nullptr) {
    return ERR(NULL_POINTER);
  }

  // Note: proxies will show the dex file version of java.lang.reflect.Proxy, as that is
  //       what their dex cache copies from.
  uint32_t version = klass->GetDexFile().GetHeader().GetVersion();

  *major_version_ptr = static_cast<jint>(version);
  *minor_version_ptr = 0;

  return ERR(NONE);
}

}  // namespace openjdkjvmti