Native loader as a separate library

/*

 * Copyright (C) 2015 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#ifndef NATIVE_LOADER_H_

#define NATIVE_LOADER_H_

#include "jni.h"

#include <stdint.h>

namespace android {

__attribute__((visibility("default")))

void* OpenNativeLibrary(JNIEnv* env, int32_t target_sdk_version, const char* path,

                        jobject class_loader, jstring library_path);

};  // namespace android

#endif  // NATIVE_BRIDGE_H_

LOCAL_PATH:= $(call my-dir)

NATIVE_LOADER_COMMON_SRC_FILES := \

  native_loader.cpp

# Shared library for target

# ========================================================

include $(CLEAR_VARS)

LOCAL_MODULE:= libnativeloader

LOCAL_SRC_FILES:= $(NATIVE_LOADER_COMMON_SRC_FILES)

LOCAL_SHARED_LIBRARIES := libnativehelper liblog libcutils

LOCAL_STATIC_LIBRARIES := libbase

LOCAL_CLANG := true

LOCAL_CFLAGS += -Werror -Wall

LOCAL_CPPFLAGS := -std=gnu++14 -fvisibility=hidden

LOCAL_LDFLAGS := -ldl

LOCAL_MULTILIB := both

include $(BUILD_SHARED_LIBRARY)

# Shared library for host

# ========================================================

include $(CLEAR_VARS)

LOCAL_MODULE:= libnativeloader

LOCAL_SRC_FILES:= $(NATIVE_LOADER_COMMON_SRC_FILES)

LOCAL_SHARED_LIBRARIES := libnativehelper liblog libcutils

LOCAL_STATIC_LIBRARIES := libbase

LOCAL_CLANG := true

LOCAL_CFLAGS += -Werror -Wall

LOCAL_CPPFLAGS := -std=gnu++14 -fvisibility=hidden

LOCAL_LDFLAGS := -ldl

LOCAL_MULTILIB := both

include $(BUILD_HOST_SHARED_LIBRARY)

# Static library for host

# ========================================================

include $(CLEAR_VARS)

LOCAL_MODULE:= libnativeloader

LOCAL_SRC_FILES:= $(NATIVE_LOADER_COMMON_SRC_FILES)

LOCAL_STATIC_LIBRARIES := libnativehelper libcutils liblog libbase

LOCAL_CLANG := true

LOCAL_CFLAGS += -Werror -Wall

LOCAL_CPPFLAGS := -std=gnu++14 -fvisibility=hidden

LOCAL_LDFLAGS := -ldl

LOCAL_MULTILIB := both

include $(BUILD_HOST_STATIC_LIBRARY)

/*

 * Copyright (C) 2015 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include "nativeloader/native_loader.h"

#include "ScopedUtfChars.h"

#include <dlfcn.h>

#ifdef __ANDROID__

#include <android/dlext.h>

#include "cutils/properties.h"

#endif

#include <algorithm>

#include <vector>

#include <string>

#include <mutex>

#include "base/macros.h"

#include "base/strings.h"

namespace android {

#ifdef __ANDROID__

// TODO(dimitry): move this to system properties.

static const char* kPublicNativeLibraries = "libandroid.so:"

                                            "libc.so:"

                                            "libdl.so:"

                                            "libEGL.so:"

                                            "libGLESv1_CM.so:"

                                            "libGLESv2.so:"

                                            "libGLESv3.so:"

                                            "libjnigraphics.so:"

                                            "liblog.so:"

                                            "libmediandk.so:"

                                            "libm.so:"

                                            "libOpenMAXAL.so:"

                                            "libOpenSLES.so:"

                                            "libstdc++.so:"

                                            "libz.so";

class LibraryNamespaces {

 public:

  LibraryNamespaces() : initialized_(false) { }

  android_namespace_t* GetOrCreate(JNIEnv* env, jobject class_loader, jstring library_path) {

    ScopedUtfChars libraryPath(env, library_path);

    if (!initialized_ && !InitPublicNamespace(libraryPath.c_str())) {

      return nullptr;

    }

    std::lock_guard<std::mutex> guard(mutex_);

    auto it = FindNamespaceByClassLoader(env, class_loader);

    if (it != namespaces_.end()) {

      return it->second;

    }

    android_namespace_t* ns =

            android_create_namespace("classloader-namespace",

                                     nullptr,

                                     libraryPath.c_str(),

                                     true);

    namespaces_.push_back(std::make_pair(env->NewWeakGlobalRef(class_loader), ns));

    return ns;

  }

 private:

  bool InitPublicNamespace(const char* library_path) {

    // Make sure all the public libraries are loaded

    std::vector<std::string> sonames = android::base::Split(kPublicNativeLibraries, ":");

    for (const auto& soname : sonames) {

      if (dlopen(soname.c_str(), RTLD_NOW | RTLD_NODELETE) == nullptr) {

        return false;

      }

    }

    // Some apps call dlopen from generated code unknown to linker in which

    // case linker uses anonymous namespace. See b/25844435 for details.

    initialized_ = android_init_namespaces(kPublicNativeLibraries, library_path);

    return initialized_;

  }

  std::vector<std::pair<jweak, android_namespace_t*>>::const_iterator

  FindNamespaceByClassLoader(JNIEnv* env, jobject class_loader) {

    return std::find_if(namespaces_.begin(), namespaces_.end(),

            [&](const std::pair<jweak, android_namespace_t*>& value) {

              return env->IsSameObject(value.first, class_loader);

            });

  }

  bool initialized_;

  std::mutex mutex_;

  std::vector<std::pair<jweak, android_namespace_t*>> namespaces_;

  DISALLOW_COPY_AND_ASSIGN(LibraryNamespaces);

};

static LibraryNamespaces* g_namespaces = new LibraryNamespaces;

#endif

void* OpenNativeLibrary(JNIEnv* env, int32_t target_sdk_version, const char* path,

                        jobject class_loader, jstring library_path) {

#if defined(__ANDROID__)

  if (target_sdk_version == 0 || class_loader == nullptr) {

    return dlopen(path, RTLD_NOW);

  }

  android_namespace_t* ns = g_namespaces->GetOrCreate(env, class_loader, library_path);

  if (ns == nullptr) {

    return nullptr;

  }

  android_dlextinfo extinfo;

  extinfo.flags = ANDROID_DLEXT_USE_NAMESPACE;

  extinfo.library_namespace = ns;

  return android_dlopen_ext(path, RTLD_NOW, &extinfo);

#else

  UNUSED(env, target_sdk_version, class_loader, library_path);

  return dlopen(path, RTLD_NOW);

#endif

}

}; //  android namespace