runtime/openjdkjvmti/ti_search.cc

/* Copyright (C) 2017 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
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 */

#include "ti_search.h"

#include "jni.h"

#include "art_jvmti.h"
#include "base/enums.h"
#include "base/macros.h"
#include "class_linker.h"
#include "dex_file.h"
#include "jni_internal.h"
#include "mirror/class-inl.h"
#include "mirror/object.h"
#include "mirror/string.h"
#include "obj_ptr-inl.h"
#include "runtime.h"
#include "runtime_callbacks.h"
#include "scoped_thread_state_change-inl.h"
#include "ScopedLocalRef.h"
#include "ti_phase.h"
#include "thread-inl.h"
#include "thread_list.h"

namespace openjdkjvmti {

static std::vector<std::string> gSystemOnloadSegments;

static art::ObjPtr<art::mirror::Object> GetSystemProperties(art::Thread* self,
                                                            art::ClassLinker* class_linker)
    REQUIRES_SHARED(art::Locks::mutator_lock_) {
  art::ObjPtr<art::mirror::Class> system_class =
      class_linker->LookupClass(self, "Ljava/lang/System;", nullptr);
  DCHECK(system_class != nullptr);
  DCHECK(system_class->IsInitialized());

  art::ArtField* props_field =
      system_class->FindDeclaredStaticField("props", "Ljava/util/Properties;");
  DCHECK(props_field != nullptr);

  art::ObjPtr<art::mirror::Object> props_obj = props_field->GetObject(system_class);
  DCHECK(props_obj != nullptr);

  return props_obj;
}

static void Update() REQUIRES_SHARED(art::Locks::mutator_lock_) {
  if (gSystemOnloadSegments.empty()) {
    return;
  }

  // In the on-load phase we have to modify java.class.path to influence the system classloader.
  // As this is an unmodifiable system property, we have to access the "defaults" field.
  art::ClassLinker* class_linker = art::Runtime::Current()->GetClassLinker();
  DCHECK(class_linker != nullptr);
  art::Thread* self = art::Thread::Current();

  // Prepare: collect classes, fields and methods.
  art::ObjPtr<art::mirror::Class> properties_class =
      class_linker->LookupClass(self, "Ljava/util/Properties;", nullptr);
  DCHECK(properties_class != nullptr);

  ScopedLocalRef<jobject> defaults_jobj(self->GetJniEnv(), nullptr);
  {
    art::ObjPtr<art::mirror::Object> props_obj = GetSystemProperties(self, class_linker);

    art::ArtField* defaults_field =
        properties_class->FindDeclaredInstanceField("defaults", "Ljava/util/Properties;");
    DCHECK(defaults_field != nullptr);

    art::ObjPtr<art::mirror::Object> defaults_obj = defaults_field->GetObject(props_obj);
    DCHECK(defaults_obj != nullptr);
    defaults_jobj.reset(self->GetJniEnv()->AddLocalReference<jobject>(defaults_obj));
  }

  art::ArtMethod* get_property =
      properties_class->FindDeclaredVirtualMethod(
          "getProperty",
          "(Ljava/lang/String;)Ljava/lang/String;",
          art::kRuntimePointerSize);
  DCHECK(get_property != nullptr);
  art::ArtMethod* set_property =
      properties_class->FindDeclaredVirtualMethod(
          "setProperty",
          "(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/Object;",
          art::kRuntimePointerSize);
  DCHECK(set_property != nullptr);

  // This is an allocation. Do this late to avoid the need for handles.
  ScopedLocalRef<jobject> cp_jobj(self->GetJniEnv(), nullptr);
  {
    art::ObjPtr<art::mirror::Object> cp_key =
        art::mirror::String::AllocFromModifiedUtf8(self, "java.class.path");
    if (cp_key == nullptr) {
      self->AssertPendingOOMException();
      self->ClearException();
      return;
    }
    cp_jobj.reset(self->GetJniEnv()->AddLocalReference<jobject>(cp_key));
  }

  // OK, now get the current value.
  std::string str_value;
  {
    ScopedLocalRef<jobject> old_value(self->GetJniEnv(),
                                      self->GetJniEnv()->CallObjectMethod(
                                          defaults_jobj.get(),
                                          art::jni::EncodeArtMethod(get_property),
                                          cp_jobj.get()));
    DCHECK(old_value.get() != nullptr);

    str_value = self->DecodeJObject(old_value.get())->AsString()->ToModifiedUtf8();
    self->GetJniEnv()->DeleteLocalRef(old_value.release());
  }

  // Update the value by appending the new segments.
  for (const std::string& segment : gSystemOnloadSegments) {
    if (!str_value.empty()) {
      str_value += ":";
    }
    str_value += segment;
  }
  gSystemOnloadSegments.clear();

  // Create the new value object.
  ScopedLocalRef<jobject> new_val_jobj(self->GetJniEnv(), nullptr);
  {
    art::ObjPtr<art::mirror::Object> new_value =
        art::mirror::String::AllocFromModifiedUtf8(self, str_value.c_str());
    if (new_value == nullptr) {
      self->AssertPendingOOMException();
      self->ClearException();
      return;
    }

    new_val_jobj.reset(self->GetJniEnv()->AddLocalReference<jobject>(new_value));
  }

  // Write to the defaults.
  ScopedLocalRef<jobject> res_obj(self->GetJniEnv(),
                                  self->GetJniEnv()->CallObjectMethod(defaults_jobj.get(),
                                      art::jni::EncodeArtMethod(set_property),
                                      cp_jobj.get(),
                                      new_val_jobj.get()));
  if (self->IsExceptionPending()) {
    self->ClearException();
    return;
  }
}

struct SearchCallback : public art::RuntimePhaseCallback {
  void NextRuntimePhase(RuntimePhase phase) OVERRIDE REQUIRES_SHARED(art::Locks::mutator_lock_) {
    if (phase == RuntimePhase::kStart) {
      // It's time to update the system properties.
      Update();
    }
  }
};

static SearchCallback gSearchCallback;

void SearchUtil::Register() {
  art::Runtime* runtime = art::Runtime::Current();

  art::ScopedThreadStateChange stsc(art::Thread::Current(),
                                    art::ThreadState::kWaitingForDebuggerToAttach);
  art::ScopedSuspendAll ssa("Add search callback");
  runtime->GetRuntimeCallbacks()->AddRuntimePhaseCallback(&gSearchCallback);
}

void SearchUtil::Unregister() {
  art::ScopedThreadStateChange stsc(art::Thread::Current(),
                                    art::ThreadState::kWaitingForDebuggerToAttach);
  art::ScopedSuspendAll ssa("Remove search callback");
  art::Runtime* runtime = art::Runtime::Current();
  runtime->GetRuntimeCallbacks()->RemoveRuntimePhaseCallback(&gSearchCallback);
}

jvmtiError SearchUtil::AddToBootstrapClassLoaderSearch(jvmtiEnv* env ATTRIBUTE_UNUSED,
                                                       const char* segment) {
  art::Runtime* current = art::Runtime::Current();
  if (current == nullptr) {
    return ERR(WRONG_PHASE);
  }
  if (current->GetClassLinker() == nullptr) {
    // TODO: Support boot classpath change in OnLoad.
    return ERR(WRONG_PHASE);
  }
  if (segment == nullptr) {
    return ERR(NULL_POINTER);
  }

  std::string error_msg;
  std::vector<std::unique_ptr<const art::DexFile>> dex_files;
  if (!art::DexFile::Open(segment, segment, true, &error_msg, &dex_files)) {
    LOG(WARNING) << "Could not open " << segment << " for boot classpath extension: " << error_msg;
    return ERR(ILLEGAL_ARGUMENT);
  }

  art::ScopedObjectAccess soa(art::Thread::Current());
  for (std::unique_ptr<const art::DexFile>& dex_file : dex_files) {
    current->GetClassLinker()->AppendToBootClassPath(art::Thread::Current(), *dex_file.release());
  }

  return ERR(NONE);
}

jvmtiError SearchUtil::AddToSystemClassLoaderSearch(jvmtiEnv* jvmti_env ATTRIBUTE_UNUSED,
                                                    const char* segment) {
  if (segment == nullptr) {
    return ERR(NULL_POINTER);
  }

  jvmtiPhase phase = PhaseUtil::GetPhaseUnchecked();

  if (phase == jvmtiPhase::JVMTI_PHASE_ONLOAD) {
    // We could try and see whether it is a valid path. We could also try to allocate Java
    // objects to avoid later OOME.
    gSystemOnloadSegments.push_back(segment);
    return ERR(NONE);
  } else if (phase != jvmtiPhase::JVMTI_PHASE_LIVE) {
    return ERR(WRONG_PHASE);
  }

  jobject sys_class_loader = art::Runtime::Current()->GetSystemClassLoader();
  if (sys_class_loader == nullptr) {
    // This is unexpected.
    return ERR(INTERNAL);
  }

  // We'll use BaseDexClassLoader.addDexPath, as it takes care of array resizing etc. As a downside,
  // exceptions are swallowed.

  art::Thread* self = art::Thread::Current();
  JNIEnv* env = self->GetJniEnv();
  if (!env->IsInstanceOf(sys_class_loader,
                         art::WellKnownClasses::dalvik_system_BaseDexClassLoader)) {
    return ERR(INTERNAL);
  }

  jmethodID add_dex_path_id = env->GetMethodID(
      art::WellKnownClasses::dalvik_system_BaseDexClassLoader,
      "addDexPath",
      "(Ljava/lang/String;)V");
  if (add_dex_path_id == nullptr) {
    return ERR(INTERNAL);
  }

  ScopedLocalRef<jstring> dex_path(env, env->NewStringUTF(segment));
  if (dex_path.get() == nullptr) {
    return ERR(INTERNAL);
  }
  env->CallVoidMethod(sys_class_loader, add_dex_path_id, dex_path.get());

  if (env->ExceptionCheck()) {
    env->ExceptionClear();
    return ERR(ILLEGAL_ARGUMENT);
  }
  return ERR(NONE);
}

}  // namespace openjdkjvmti