jni/MediaProviderWrapper.cpp - SHIFTPHONES/android_packages_providers_MediaProvider - Gitiles

 /*
  * Copyright (C) 2019 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 specic language governing permissions and
  * limitations under the License.
  */

 #include "MediaProviderWrapper.h"
 #include "libfuse_jni/ReaddirHelper.h"

 #include <android-base/logging.h>
 #include <android-base/properties.h>
 #include <jni.h>
 #include <nativehelper/scoped_local_ref.h>
 #include <nativehelper/scoped_primitive_array.h>
 #include <nativehelper/scoped_utf_chars.h>

 #include <pthread.h>

 #include <mutex>
 #include <unordered_map>

 namespace mediaprovider {
 namespace fuse {
 using std::string;

 namespace {

 constexpr const char* kPropRedactionEnabled = "persist.sys.fuse.redaction-enabled";

 constexpr uid_t ROOT_UID = 0;
 constexpr uid_t SHELL_UID = 2000;

 // These need to stay in sync with MediaProvider.java's DIRECTORY_ACCESS_FOR_* constants.
 enum DirectoryAccessRequestType {
     kReadDirectoryRequest = 1,
     kWriteDirectoryRequest = 2,
     kCreateDirectoryRequest = 3,
     kDeleteDirectoryRequest = 4,
 };

 /** Private helper functions **/

 inline bool shouldBypassMediaProvider(uid_t uid) {
     return uid == SHELL_UID || uid == ROOT_UID;
 }

 static bool CheckForJniException(JNIEnv* env) {
     if (env->ExceptionCheck()) {
         env->ExceptionDescribe();
         env->ExceptionClear();
         return true;
     }
     return false;
 }

 /**
  * Auxiliary for caching class fields
  */
 static jfieldID CacheField(JNIEnv* env, jclass clazz, const char field_name[], const char type[]) {
     jfieldID fid;
     string actual_field_name(field_name);
     fid = env->GetFieldID(clazz, actual_field_name.c_str(), type);
     if (!fid) {
         LOG(FATAL) << "Error caching field: " << field_name << type;
     }
     return fid;
 }

 int insertFileInternal(JNIEnv* env, jobject media_provider_object, jmethodID mid_insert_file,
                        const string& path, uid_t uid) {
     ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));
     int res = env->CallIntMethod(media_provider_object, mid_insert_file, j_path.get(), uid);

     if (CheckForJniException(env)) {
         return EFAULT;
     }
     return res;
 }

 int deleteFileInternal(JNIEnv* env, jobject media_provider_object, jmethodID mid_delete_file,
                        const string& path, uid_t uid) {
     ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));
     int res = env->CallIntMethod(media_provider_object, mid_delete_file, j_path.get(), uid);

     if (CheckForJniException(env)) {
         return EFAULT;
     }
     return res;
 }

 int isDirAccessAllowedInternal(JNIEnv* env, jobject media_provider_object,
                                jmethodID mid_is_diraccess_allowed, const string& path, uid_t uid,
                                int accessType) {
     ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));
     int res = env->CallIntMethod(media_provider_object, mid_is_diraccess_allowed, j_path.get(), uid,
                                  accessType);

     if (CheckForJniException(env)) {
         return EFAULT;
     }
     return res;
 }

 bool isUidAllowedAccessToDataOrObbPathInternal(JNIEnv* env, jobject media_provider_object,
                                                jmethodID mid_is_uid_allowed_path_access_, uid_t uid,
                                                const string& path) {
     ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));
     bool res = env->CallBooleanMethod(media_provider_object, mid_is_uid_allowed_path_access_, uid,
                                       j_path.get());

     if (CheckForJniException(env)) {
         return false;
     }
     return res;
 }

 std::vector<std::shared_ptr<DirectoryEntry>> getFilesInDirectoryInternal(
         JNIEnv* env, jobject media_provider_object, jmethodID mid_get_files_in_dir, uid_t uid,
         const string& path) {
     std::vector<std::shared_ptr<DirectoryEntry>> directory_entries;
     ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));

     ScopedLocalRef<jobjectArray> files_list(
             env, static_cast<jobjectArray>(env->CallObjectMethod(
                          media_provider_object, mid_get_files_in_dir, j_path.get(), uid)));

     if (CheckForJniException(env)) {
         directory_entries.push_back(std::make_shared<DirectoryEntry>("", EFAULT));
         return directory_entries;
     }

     int de_count = env->GetArrayLength(files_list.get());
     if (de_count == 1) {
         ScopedLocalRef<jstring> j_d_name(env,
                                          (jstring)env->GetObjectArrayElement(files_list.get(), 0));
         ScopedUtfChars d_name(env, j_d_name.get());
         if (d_name.c_str() == nullptr) {
             LOG(ERROR) << "Error reading file name returned from MediaProvider at index " << 0;
             directory_entries.push_back(std::make_shared<DirectoryEntry>("", EFAULT));
             return directory_entries;
         } else if (d_name.c_str()[0] == '\0') {
             // Calling package has no storage permissions.
             directory_entries.push_back(std::make_shared<DirectoryEntry>("", EPERM));
             return directory_entries;
         }
     }

     for (int i = 0; i < de_count; i++) {
         ScopedLocalRef<jstring> j_d_name(env,
                                          (jstring)env->GetObjectArrayElement(files_list.get(), i));
         ScopedUtfChars d_name(env, j_d_name.get());

         if (d_name.c_str() == nullptr) {
             LOG(ERROR) << "Error reading file name returned from MediaProvider at index " << i;
             directory_entries.resize(0);
             directory_entries.push_back(std::make_shared<DirectoryEntry>("", EFAULT));
             break;
         }
         directory_entries.push_back(std::make_shared<DirectoryEntry>(d_name.c_str(), DT_REG));
     }
     return directory_entries;
 }

 int renameInternal(JNIEnv* env, jobject media_provider_object, jmethodID mid_rename,
                    const string& old_path, const string& new_path, uid_t uid) {
     ScopedLocalRef<jstring> j_old_path(env, env->NewStringUTF(old_path.c_str()));
     ScopedLocalRef<jstring> j_new_path(env, env->NewStringUTF(new_path.c_str()));
     int res = env->CallIntMethod(media_provider_object, mid_rename, j_old_path.get(),
                                  j_new_path.get(), uid);

     if (CheckForJniException(env)) {
         return EFAULT;
     }
     return res;
 }

 void onFileCreatedInternal(JNIEnv* env, jobject media_provider_object,
                            jmethodID mid_on_file_created, const string& path) {
     ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));

     env->CallVoidMethod(media_provider_object, mid_on_file_created, j_path.get());
     CheckForJniException(env);
     return;
 }

 }  // namespace
 /*****************************************************************************************/
 /******************************* Public API Implementation *******************************/
 /*****************************************************************************************/

 JavaVM* MediaProviderWrapper::gJavaVm = nullptr;
 pthread_key_t MediaProviderWrapper::gJniEnvKey;

 void MediaProviderWrapper::OneTimeInit(JavaVM* vm) {
     gJavaVm = vm;
     CHECK(gJavaVm != nullptr);

     pthread_key_create(&MediaProviderWrapper::gJniEnvKey,
                        MediaProviderWrapper::DetachThreadFunction);
 }

 MediaProviderWrapper::MediaProviderWrapper(JNIEnv* env, jobject media_provider) {
     if (!media_provider) {
         LOG(FATAL) << "MediaProvider is null!";
     }

     media_provider_object_ = reinterpret_cast<jobject>(env->NewGlobalRef(media_provider));
     media_provider_class_ = env->FindClass("com/android/providers/media/MediaProvider");
     if (!media_provider_class_) {
         LOG(FATAL) << "Could not find class MediaProvider";
     }
     media_provider_class_ = reinterpret_cast<jclass>(env->NewGlobalRef(media_provider_class_));

     // Cache methods - Before calling a method, make sure you cache it here
     mid_insert_file_ = CacheMethod(env, "insertFileIfNecessary", "(Ljava/lang/String;I)I");
     mid_delete_file_ = CacheMethod(env, "deleteFile", "(Ljava/lang/String;I)I");
     mid_on_file_open_ = CacheMethod(env, "onFileOpen",
                                     "(Ljava/lang/String;Ljava/lang/String;IIIZZZ)Lcom/android/"
                                     "providers/media/FileOpenResult;");
     mid_is_diraccess_allowed_ = CacheMethod(env, "isDirAccessAllowed", "(Ljava/lang/String;II)I");
     mid_get_files_in_dir_ =
             CacheMethod(env, "getFilesInDirectory", "(Ljava/lang/String;I)[Ljava/lang/String;");
     mid_rename_ = CacheMethod(env, "rename", "(Ljava/lang/String;Ljava/lang/String;I)I");
     mid_is_uid_allowed_access_to_data_or_obb_path_ =
             CacheMethod(env, "isUidAllowedAccessToDataOrObbPath", "(ILjava/lang/String;)Z");
     mid_on_file_created_ = CacheMethod(env, "onFileCreated", "(Ljava/lang/String;)V");
     mid_should_allow_lookup_ = CacheMethod(env, "shouldAllowLookup", "(II)Z");
     mid_is_app_clone_user_ = CacheMethod(env, "isAppCloneUser", "(I)Z");
     mid_transform_ = CacheMethod(env, "transform", "(Ljava/lang/String;Ljava/lang/String;IIIII)Z");
     mid_file_lookup_ =
             CacheMethod(env, "onFileLookup",
                         "(Ljava/lang/String;II)Lcom/android/providers/media/FileLookupResult;");

     // FileLookupResult
     file_lookup_result_class_ = env->FindClass("com/android/providers/media/FileLookupResult");
     if (!file_lookup_result_class_) {
         LOG(FATAL) << "Could not find class FileLookupResult";
     }
     file_lookup_result_class_ =
             reinterpret_cast<jclass>(env->NewGlobalRef(file_lookup_result_class_));
     fid_file_lookup_transforms_ = CacheField(env, file_lookup_result_class_, "transforms", "I");
     fid_file_lookup_transforms_reason_ =
             CacheField(env, file_lookup_result_class_, "transformsReason", "I");
     fid_file_lookup_uid_ = CacheField(env, file_lookup_result_class_, "uid", "I");
     fid_file_lookup_transforms_complete_ =
             CacheField(env, file_lookup_result_class_, "transformsComplete", "Z");
     fid_file_lookup_transforms_supported_ =
             CacheField(env, file_lookup_result_class_, "transformsSupported", "Z");
     fid_file_lookup_io_path_ =
             CacheField(env, file_lookup_result_class_, "ioPath", "Ljava/lang/String;");

     // FileOpenResult
     file_open_result_class_ = env->FindClass("com/android/providers/media/FileOpenResult");
     if (!file_open_result_class_) {
         LOG(FATAL) << "Could not find class FileOpenResult";
     }
     file_open_result_class_ = reinterpret_cast<jclass>(env->NewGlobalRef(file_open_result_class_));
     fid_file_open_status_ = CacheField(env, file_open_result_class_, "status", "I");
     fid_file_open_uid_ = CacheField(env, file_open_result_class_, "uid", "I");
     fid_file_open_transforms_uid_ = CacheField(env, file_open_result_class_, "transformsUid", "I");
     fid_file_open_redaction_ranges_ =
             CacheField(env, file_open_result_class_, "redactionRanges", "[J");
     fid_file_open_fd_ = CacheField(env, file_open_result_class_, "nativeFd", "I");
 }

 MediaProviderWrapper::~MediaProviderWrapper() {
     JNIEnv* env = MaybeAttachCurrentThread();
     env->DeleteGlobalRef(media_provider_object_);
     env->DeleteGlobalRef(media_provider_class_);
 }

 int MediaProviderWrapper::InsertFile(const string& path, uid_t uid) {
     if (uid == ROOT_UID) {
         return 0;
     }

     JNIEnv* env = MaybeAttachCurrentThread();
     return insertFileInternal(env, media_provider_object_, mid_insert_file_, path, uid);
 }

 int MediaProviderWrapper::DeleteFile(const string& path, uid_t uid) {
     if (uid == ROOT_UID) {
         int res = unlink(path.c_str());
         return res;
     }

     JNIEnv* env = MaybeAttachCurrentThread();
     return deleteFileInternal(env, media_provider_object_, mid_delete_file_, path, uid);
 }

 std::unique_ptr<FileOpenResult> MediaProviderWrapper::OnFileOpen(const string& path,
                                                                  const string& io_path, uid_t uid,
                                                                  pid_t tid, int transforms_reason,
                                                                  bool for_write, bool redact,
                                                                  bool log_transforms_metrics) {
     JNIEnv* env = MaybeAttachCurrentThread();
     if (shouldBypassMediaProvider(uid)) {
         return std::make_unique<FileOpenResult>(0, uid, /* transforms_uid */ 0, /* nativeFd */ -1,
                                                 new RedactionInfo());
     }

     ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));
     ScopedLocalRef<jstring> j_io_path(env, env->NewStringUTF(io_path.c_str()));
     ScopedLocalRef<jobject> j_res_file_open_object(
             env, env->CallObjectMethod(media_provider_object_, mid_on_file_open_, j_path.get(),
                                        j_io_path.get(), uid, tid, transforms_reason, for_write,
                                        redact, log_transforms_metrics));

     if (CheckForJniException(env)) {
         return nullptr;
     }

     const int status = env->GetIntField(j_res_file_open_object.get(), fid_file_open_status_);
     const int original_uid = env->GetIntField(j_res_file_open_object.get(), fid_file_open_uid_);
     const int transforms_uid =
             env->GetIntField(j_res_file_open_object.get(), fid_file_open_transforms_uid_);
     const int fd = env->GetIntField(j_res_file_open_object.get(), fid_file_open_fd_);

     if (redact) {
         ScopedLocalRef<jlongArray> redaction_ranges_local_ref(
                 env, static_cast<jlongArray>(env->GetObjectField(j_res_file_open_object.get(),
                                                                  fid_file_open_redaction_ranges_)));
         ScopedLongArrayRO redaction_ranges(env, redaction_ranges_local_ref.get());

         std::unique_ptr<RedactionInfo> ri;
         if (redaction_ranges.size() % 2) {
             LOG(ERROR) << "Error while calculating redaction ranges: array length is uneven";
         } else if (redaction_ranges.size() > 0) {
             ri = std::make_unique<RedactionInfo>(redaction_ranges.size() / 2,
                                                  redaction_ranges.get());
         } else {
             // No ranges to redact
             ri = std::make_unique<RedactionInfo>();
         }
         return std::make_unique<FileOpenResult>(status, original_uid, transforms_uid, fd,
                                                 ri.release());
     } else {
         return std::make_unique<FileOpenResult>(status, original_uid, transforms_uid, fd,
                                                 new RedactionInfo());
     }
 }

 int MediaProviderWrapper::IsCreatingDirAllowed(const string& path, uid_t uid) {
     if (shouldBypassMediaProvider(uid)) {
         return 0;
     }

     JNIEnv* env = MaybeAttachCurrentThread();
     return isDirAccessAllowedInternal(env, media_provider_object_, mid_is_diraccess_allowed_, path,
                                       uid, kCreateDirectoryRequest);
 }

 int MediaProviderWrapper::IsDeletingDirAllowed(const string& path, uid_t uid) {
     if (shouldBypassMediaProvider(uid)) {
         return 0;
     }

     JNIEnv* env = MaybeAttachCurrentThread();
     return isDirAccessAllowedInternal(env, media_provider_object_, mid_is_diraccess_allowed_, path,
                                       uid, kDeleteDirectoryRequest);
 }

 std::vector<std::shared_ptr<DirectoryEntry>> MediaProviderWrapper::GetDirectoryEntries(
         uid_t uid, const string& path, DIR* dirp) {
     // Default value in case JNI thread was being terminated
     std::vector<std::shared_ptr<DirectoryEntry>> res;
     if (shouldBypassMediaProvider(uid)) {
         addDirectoryEntriesFromLowerFs(dirp, /* filter */ nullptr, &res);
         return res;
     }

     JNIEnv* env = MaybeAttachCurrentThread();
     res = getFilesInDirectoryInternal(env, media_provider_object_, mid_get_files_in_dir_, uid, path);

     const int res_size = res.size();
     if (res_size && res[0]->d_name[0] == '/') {
         // Path is unknown to MediaProvider, get files and directories from lower file system.
         res.resize(0);
         addDirectoryEntriesFromLowerFs(dirp, /* filter */ nullptr, &res);
     } else if (res_size == 0 || !res[0]->d_name.empty()) {
         // add directory names from lower file system.
         addDirectoryEntriesFromLowerFs(dirp, /* filter */ &isDirectory, &res);
     }
     return res;
 }

 int MediaProviderWrapper::IsOpendirAllowed(const string& path, uid_t uid, bool forWrite) {
     if (shouldBypassMediaProvider(uid)) {
         return 0;
     }

     JNIEnv* env = MaybeAttachCurrentThread();
     return isDirAccessAllowedInternal(env, media_provider_object_, mid_is_diraccess_allowed_, path,
                                       uid,
                                       forWrite ? kWriteDirectoryRequest : kReadDirectoryRequest);
 }

 bool MediaProviderWrapper::isUidAllowedAccessToDataOrObbPath(uid_t uid, const string& path) {
     if (shouldBypassMediaProvider(uid)) {
         return true;
     }

     JNIEnv* env = MaybeAttachCurrentThread();
     return isUidAllowedAccessToDataOrObbPathInternal(
             env, media_provider_object_, mid_is_uid_allowed_access_to_data_or_obb_path_, uid, path);
 }

 int MediaProviderWrapper::Rename(const string& old_path, const string& new_path, uid_t uid) {
     // Rename from SHELL_UID should go through MediaProvider to update database rows, so only bypass
     // MediaProvider for ROOT_UID.
     if (uid == ROOT_UID) {
         int res = rename(old_path.c_str(), new_path.c_str());
         if (res != 0) res = -errno;
         return res;
     }

     JNIEnv* env = MaybeAttachCurrentThread();
     return renameInternal(env, media_provider_object_, mid_rename_, old_path, new_path, uid);
 }

 void MediaProviderWrapper::OnFileCreated(const string& path) {
     JNIEnv* env = MaybeAttachCurrentThread();

     return onFileCreatedInternal(env, media_provider_object_, mid_on_file_created_, path);
 }

 bool MediaProviderWrapper::ShouldAllowLookup(uid_t uid, int path_user_id) {
     JNIEnv* env = MaybeAttachCurrentThread();

     bool res = env->CallBooleanMethod(media_provider_object_, mid_should_allow_lookup_, uid,
                                       path_user_id);

     if (CheckForJniException(env)) {
         return false;
     }
     return res;
 }

 bool MediaProviderWrapper::IsAppCloneUser(uid_t userId) {
     JNIEnv* env = MaybeAttachCurrentThread();

     bool res = env->CallBooleanMethod(media_provider_object_, mid_is_app_clone_user_, userId);

     if (CheckForJniException(env)) {
         return false;
     }
     return res;
 }

 std::unique_ptr<FileLookupResult> MediaProviderWrapper::FileLookup(const std::string& path,
                                                                    uid_t uid, pid_t tid) {
     JNIEnv* env = MaybeAttachCurrentThread();

     ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));

     ScopedLocalRef<jobject> j_res_file_lookup_object(
             env, env->CallObjectMethod(media_provider_object_, mid_file_lookup_, j_path.get(), uid,
                                        tid));

     if (CheckForJniException(env)) {
         return nullptr;
     }

     int transforms = env->GetIntField(j_res_file_lookup_object.get(), fid_file_lookup_transforms_);
     int transforms_reason =
             env->GetIntField(j_res_file_lookup_object.get(), fid_file_lookup_transforms_reason_);
     int original_uid = env->GetIntField(j_res_file_lookup_object.get(), fid_file_lookup_uid_);
     bool transforms_complete = env->GetBooleanField(j_res_file_lookup_object.get(),
                                                     fid_file_lookup_transforms_complete_);
     bool transforms_supported = env->GetBooleanField(j_res_file_lookup_object.get(),
                                                      fid_file_lookup_transforms_supported_);
     ScopedLocalRef<jstring> j_io_path(
             env,
             (jstring)env->GetObjectField(j_res_file_lookup_object.get(), fid_file_lookup_io_path_));
     ScopedUtfChars j_io_path_utf(env, j_io_path.get());

     std::unique_ptr<FileLookupResult> file_lookup_result = std::make_unique<FileLookupResult>(
             transforms, transforms_reason, original_uid, transforms_complete, transforms_supported,
             string(j_io_path_utf.c_str()));
     return file_lookup_result;
 }

 bool MediaProviderWrapper::Transform(const std::string& src, const std::string& dst, int transforms,
                                      int transforms_reason, uid_t read_uid, uid_t open_uid,
                                      uid_t transforms_uid) {
     JNIEnv* env = MaybeAttachCurrentThread();

     ScopedLocalRef<jstring> j_src(env, env->NewStringUTF(src.c_str()));
     ScopedLocalRef<jstring> j_dst(env, env->NewStringUTF(dst.c_str()));
     bool res = env->CallBooleanMethod(media_provider_object_, mid_transform_, j_src.get(),
                                       j_dst.get(), transforms, transforms_reason, read_uid,
                                       open_uid, transforms_uid);

     if (CheckForJniException(env)) {
         return false;
     }

     return res;
 }

 /*****************************************************************************************/
 /******************************** Private member functions *******************************/
 /*****************************************************************************************/

 /**
  * Finds MediaProvider method and adds it to methods map so it can be quickly called later.
  */
 jmethodID MediaProviderWrapper::CacheMethod(JNIEnv* env, const char method_name[],
                                             const char signature[]) {
     jmethodID mid;
     string actual_method_name(method_name);
     actual_method_name.append("ForFuse");
     mid = env->GetMethodID(media_provider_class_, actual_method_name.c_str(), signature);

     if (!mid) {
         LOG(FATAL) << "Error caching method: " << method_name << signature;
     }
     return mid;
 }

 void MediaProviderWrapper::DetachThreadFunction(void* unused) {
     int detach = gJavaVm->DetachCurrentThread();
     CHECK_EQ(detach, 0);
 }

 JNIEnv* MediaProviderWrapper::MaybeAttachCurrentThread() {
     // We could use pthread_getspecific here as that's likely quicker but
     // that would result in wrong behaviour for threads that don't need to
     // be attached (e.g, those that were created in managed code).
     JNIEnv* env = nullptr;
     if (gJavaVm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_4) == JNI_OK) {
         return env;
     }

     // This thread is currently unattached, so it must not have any TLS
     // value. Note that we don't really care about the actual value we store
     // in TLS -- we only care about the value destructor being called, which
     // will happen as long as the key is not null.
     CHECK(pthread_getspecific(gJniEnvKey) == nullptr);
     CHECK_EQ(gJavaVm->AttachCurrentThread(&env, nullptr), 0);
     CHECK(env != nullptr);

     pthread_setspecific(gJniEnvKey, env);
     return env;
 }

 }  // namespace fuse
 }  // namespace mediaprovider
	/*
	* Copyright (C) 2019 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 specic language governing permissions and
	* limitations under the License.
	*/

	#include "MediaProviderWrapper.h"
	#include "libfuse_jni/ReaddirHelper.h"

	#include <android-base/logging.h>
	#include <android-base/properties.h>
	#include <jni.h>
	#include <nativehelper/scoped_local_ref.h>
	#include <nativehelper/scoped_primitive_array.h>
	#include <nativehelper/scoped_utf_chars.h>

	#include <pthread.h>

	#include <mutex>
	#include <unordered_map>

	namespace mediaprovider {
	namespace fuse {
	using std::string;

	namespace {

	constexpr const char* kPropRedactionEnabled = "persist.sys.fuse.redaction-enabled";

	constexpr uid_t ROOT_UID = 0;
	constexpr uid_t SHELL_UID = 2000;

	// These need to stay in sync with MediaProvider.java's DIRECTORY_ACCESS_FOR_* constants.
	enum DirectoryAccessRequestType {
	kReadDirectoryRequest = 1,
	kWriteDirectoryRequest = 2,
	kCreateDirectoryRequest = 3,
	kDeleteDirectoryRequest = 4,
	};

	/ Private helper functions /

	inline bool shouldBypassMediaProvider(uid_t uid) {
	return uid == SHELL_UID \|\| uid == ROOT_UID;
	}

	static bool CheckForJniException(JNIEnv* env) {
	if (env->ExceptionCheck()) {
	env->ExceptionDescribe();
	env->ExceptionClear();
	return true;
	}
	return false;
	}

	/**
	* Auxiliary for caching class fields
	*/
	static jfieldID CacheField(JNIEnv* env, jclass clazz, const char field_name[], const char type[]) {
	jfieldID fid;
	string actual_field_name(field_name);
	fid = env->GetFieldID(clazz, actual_field_name.c_str(), type);
	if (!fid) {
	LOG(FATAL) << "Error caching field: " << field_name << type;
	}
	return fid;
	}

	int insertFileInternal(JNIEnv* env, jobject media_provider_object, jmethodID mid_insert_file,
	const string& path, uid_t uid) {
	ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));
	int res = env->CallIntMethod(media_provider_object, mid_insert_file, j_path.get(), uid);

	if (CheckForJniException(env)) {
	return EFAULT;
	}
	return res;
	}

	int deleteFileInternal(JNIEnv* env, jobject media_provider_object, jmethodID mid_delete_file,
	const string& path, uid_t uid) {
	ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));
	int res = env->CallIntMethod(media_provider_object, mid_delete_file, j_path.get(), uid);

	if (CheckForJniException(env)) {
	return EFAULT;
	}
	return res;
	}

	int isDirAccessAllowedInternal(JNIEnv* env, jobject media_provider_object,
	jmethodID mid_is_diraccess_allowed, const string& path, uid_t uid,
	int accessType) {
	ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));
	int res = env->CallIntMethod(media_provider_object, mid_is_diraccess_allowed, j_path.get(), uid,
	accessType);

	if (CheckForJniException(env)) {
	return EFAULT;
	}
	return res;
	}

	bool isUidAllowedAccessToDataOrObbPathInternal(JNIEnv* env, jobject media_provider_object,
	jmethodID mid_is_uid_allowed_path_access_, uid_t uid,
	const string& path) {
	ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));
	bool res = env->CallBooleanMethod(media_provider_object, mid_is_uid_allowed_path_access_, uid,
	j_path.get());

	if (CheckForJniException(env)) {
	return false;
	}
	return res;
	}

	std::vector<std::shared_ptr<DirectoryEntry>> getFilesInDirectoryInternal(
	JNIEnv* env, jobject media_provider_object, jmethodID mid_get_files_in_dir, uid_t uid,
	const string& path) {
	std::vector<std::shared_ptr<DirectoryEntry>> directory_entries;
	ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));

	ScopedLocalRef<jobjectArray> files_list(
	env, static_cast<jobjectArray>(env->CallObjectMethod(
	media_provider_object, mid_get_files_in_dir, j_path.get(), uid)));

	if (CheckForJniException(env)) {
	directory_entries.push_back(std::make_shared<DirectoryEntry>("", EFAULT));
	return directory_entries;
	}

	int de_count = env->GetArrayLength(files_list.get());
	if (de_count == 1) {
	ScopedLocalRef<jstring> j_d_name(env,
	(jstring)env->GetObjectArrayElement(files_list.get(), 0));
	ScopedUtfChars d_name(env, j_d_name.get());
	if (d_name.c_str() == nullptr) {
	LOG(ERROR) << "Error reading file name returned from MediaProvider at index " << 0;
	directory_entries.push_back(std::make_shared<DirectoryEntry>("", EFAULT));
	return directory_entries;
	} else if (d_name.c_str()[0] == '\0') {
	// Calling package has no storage permissions.
	directory_entries.push_back(std::make_shared<DirectoryEntry>("", EPERM));
	return directory_entries;
	}
	}

	for (int i = 0; i < de_count; i++) {
	ScopedLocalRef<jstring> j_d_name(env,
	(jstring)env->GetObjectArrayElement(files_list.get(), i));
	ScopedUtfChars d_name(env, j_d_name.get());

	if (d_name.c_str() == nullptr) {
	LOG(ERROR) << "Error reading file name returned from MediaProvider at index " << i;
	directory_entries.resize(0);
	directory_entries.push_back(std::make_shared<DirectoryEntry>("", EFAULT));
	break;
	}
	directory_entries.push_back(std::make_shared<DirectoryEntry>(d_name.c_str(), DT_REG));
	}
	return directory_entries;
	}

	int renameInternal(JNIEnv* env, jobject media_provider_object, jmethodID mid_rename,
	const string& old_path, const string& new_path, uid_t uid) {
	ScopedLocalRef<jstring> j_old_path(env, env->NewStringUTF(old_path.c_str()));
	ScopedLocalRef<jstring> j_new_path(env, env->NewStringUTF(new_path.c_str()));
	int res = env->CallIntMethod(media_provider_object, mid_rename, j_old_path.get(),
	j_new_path.get(), uid);

	if (CheckForJniException(env)) {
	return EFAULT;
	}
	return res;
	}

	void onFileCreatedInternal(JNIEnv* env, jobject media_provider_object,
	jmethodID mid_on_file_created, const string& path) {
	ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));

	env->CallVoidMethod(media_provider_object, mid_on_file_created, j_path.get());
	CheckForJniException(env);
	return;
	}

	} // namespace
	/*****************************************************************************************/
	/***************************** Public API Implementation *****************************/
	/*****************************************************************************************/

	JavaVM* MediaProviderWrapper::gJavaVm = nullptr;
	pthread_key_t MediaProviderWrapper::gJniEnvKey;

	void MediaProviderWrapper::OneTimeInit(JavaVM* vm) {
	gJavaVm = vm;
	CHECK(gJavaVm != nullptr);

	pthread_key_create(&MediaProviderWrapper::gJniEnvKey,
	MediaProviderWrapper::DetachThreadFunction);
	}

	MediaProviderWrapper::MediaProviderWrapper(JNIEnv* env, jobject media_provider) {
	if (!media_provider) {
	LOG(FATAL) << "MediaProvider is null!";
	}

	media_provider_object_ = reinterpret_cast<jobject>(env->NewGlobalRef(media_provider));
	media_provider_class_ = env->FindClass("com/android/providers/media/MediaProvider");
	if (!media_provider_class_) {
	LOG(FATAL) << "Could not find class MediaProvider";
	}
	media_provider_class_ = reinterpret_cast<jclass>(env->NewGlobalRef(media_provider_class_));

	// Cache methods - Before calling a method, make sure you cache it here
	mid_insert_file_ = CacheMethod(env, "insertFileIfNecessary", "(Ljava/lang/String;I)I");
	mid_delete_file_ = CacheMethod(env, "deleteFile", "(Ljava/lang/String;I)I");
	mid_on_file_open_ = CacheMethod(env, "onFileOpen",
	"(Ljava/lang/String;Ljava/lang/String;IIIZZZ)Lcom/android/"
	"providers/media/FileOpenResult;");
	mid_is_diraccess_allowed_ = CacheMethod(env, "isDirAccessAllowed", "(Ljava/lang/String;II)I");
	mid_get_files_in_dir_ =
	CacheMethod(env, "getFilesInDirectory", "(Ljava/lang/String;I)[Ljava/lang/String;");
	mid_rename_ = CacheMethod(env, "rename", "(Ljava/lang/String;Ljava/lang/String;I)I");
	mid_is_uid_allowed_access_to_data_or_obb_path_ =
	CacheMethod(env, "isUidAllowedAccessToDataOrObbPath", "(ILjava/lang/String;)Z");
	mid_on_file_created_ = CacheMethod(env, "onFileCreated", "(Ljava/lang/String;)V");
	mid_should_allow_lookup_ = CacheMethod(env, "shouldAllowLookup", "(II)Z");
	mid_is_app_clone_user_ = CacheMethod(env, "isAppCloneUser", "(I)Z");
	mid_transform_ = CacheMethod(env, "transform", "(Ljava/lang/String;Ljava/lang/String;IIIII)Z");
	mid_file_lookup_ =
	CacheMethod(env, "onFileLookup",
	"(Ljava/lang/String;II)Lcom/android/providers/media/FileLookupResult;");

	// FileLookupResult
	file_lookup_result_class_ = env->FindClass("com/android/providers/media/FileLookupResult");
	if (!file_lookup_result_class_) {
	LOG(FATAL) << "Could not find class FileLookupResult";
	}
	file_lookup_result_class_ =
	reinterpret_cast<jclass>(env->NewGlobalRef(file_lookup_result_class_));
	fid_file_lookup_transforms_ = CacheField(env, file_lookup_result_class_, "transforms", "I");
	fid_file_lookup_transforms_reason_ =
	CacheField(env, file_lookup_result_class_, "transformsReason", "I");
	fid_file_lookup_uid_ = CacheField(env, file_lookup_result_class_, "uid", "I");
	fid_file_lookup_transforms_complete_ =
	CacheField(env, file_lookup_result_class_, "transformsComplete", "Z");
	fid_file_lookup_transforms_supported_ =
	CacheField(env, file_lookup_result_class_, "transformsSupported", "Z");
	fid_file_lookup_io_path_ =
	CacheField(env, file_lookup_result_class_, "ioPath", "Ljava/lang/String;");

	// FileOpenResult
	file_open_result_class_ = env->FindClass("com/android/providers/media/FileOpenResult");
	if (!file_open_result_class_) {
	LOG(FATAL) << "Could not find class FileOpenResult";
	}
	file_open_result_class_ = reinterpret_cast<jclass>(env->NewGlobalRef(file_open_result_class_));
	fid_file_open_status_ = CacheField(env, file_open_result_class_, "status", "I");
	fid_file_open_uid_ = CacheField(env, file_open_result_class_, "uid", "I");
	fid_file_open_transforms_uid_ = CacheField(env, file_open_result_class_, "transformsUid", "I");
	fid_file_open_redaction_ranges_ =
	CacheField(env, file_open_result_class_, "redactionRanges", "[J");
	fid_file_open_fd_ = CacheField(env, file_open_result_class_, "nativeFd", "I");
	}

	MediaProviderWrapper::~MediaProviderWrapper() {
	JNIEnv* env = MaybeAttachCurrentThread();
	env->DeleteGlobalRef(media_provider_object_);
	env->DeleteGlobalRef(media_provider_class_);
	}

	int MediaProviderWrapper::InsertFile(const string& path, uid_t uid) {
	if (uid == ROOT_UID) {
	return 0;
	}

	JNIEnv* env = MaybeAttachCurrentThread();
	return insertFileInternal(env, media_provider_object_, mid_insert_file_, path, uid);
	}

	int MediaProviderWrapper::DeleteFile(const string& path, uid_t uid) {
	if (uid == ROOT_UID) {
	int res = unlink(path.c_str());
	return res;
	}

	JNIEnv* env = MaybeAttachCurrentThread();
	return deleteFileInternal(env, media_provider_object_, mid_delete_file_, path, uid);
	}

	std::unique_ptr<FileOpenResult> MediaProviderWrapper::OnFileOpen(const string& path,
	const string& io_path, uid_t uid,
	pid_t tid, int transforms_reason,
	bool for_write, bool redact,
	bool log_transforms_metrics) {
	JNIEnv* env = MaybeAttachCurrentThread();
	if (shouldBypassMediaProvider(uid)) {
	return std::make_unique<FileOpenResult>(0, uid, /* transforms_uid / 0, / nativeFd */ -1,
	new RedactionInfo());
	}

	ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));
	ScopedLocalRef<jstring> j_io_path(env, env->NewStringUTF(io_path.c_str()));
	ScopedLocalRef<jobject> j_res_file_open_object(
	env, env->CallObjectMethod(media_provider_object_, mid_on_file_open_, j_path.get(),
	j_io_path.get(), uid, tid, transforms_reason, for_write,
	redact, log_transforms_metrics));

	if (CheckForJniException(env)) {
	return nullptr;
	}

	const int status = env->GetIntField(j_res_file_open_object.get(), fid_file_open_status_);
	const int original_uid = env->GetIntField(j_res_file_open_object.get(), fid_file_open_uid_);
	const int transforms_uid =
	env->GetIntField(j_res_file_open_object.get(), fid_file_open_transforms_uid_);
	const int fd = env->GetIntField(j_res_file_open_object.get(), fid_file_open_fd_);

	if (redact) {
	ScopedLocalRef<jlongArray> redaction_ranges_local_ref(
	env, static_cast<jlongArray>(env->GetObjectField(j_res_file_open_object.get(),
	fid_file_open_redaction_ranges_)));
	ScopedLongArrayRO redaction_ranges(env, redaction_ranges_local_ref.get());

	std::unique_ptr<RedactionInfo> ri;
	if (redaction_ranges.size() % 2) {
	LOG(ERROR) << "Error while calculating redaction ranges: array length is uneven";
	} else if (redaction_ranges.size() > 0) {
	ri = std::make_unique<RedactionInfo>(redaction_ranges.size() / 2,
	redaction_ranges.get());
	} else {
	// No ranges to redact
	ri = std::make_unique<RedactionInfo>();
	}
	return std::make_unique<FileOpenResult>(status, original_uid, transforms_uid, fd,
	ri.release());
	} else {
	return std::make_unique<FileOpenResult>(status, original_uid, transforms_uid, fd,
	new RedactionInfo());
	}
	}

	int MediaProviderWrapper::IsCreatingDirAllowed(const string& path, uid_t uid) {
	if (shouldBypassMediaProvider(uid)) {
	return 0;
	}

	JNIEnv* env = MaybeAttachCurrentThread();
	return isDirAccessAllowedInternal(env, media_provider_object_, mid_is_diraccess_allowed_, path,
	uid, kCreateDirectoryRequest);
	}

	int MediaProviderWrapper::IsDeletingDirAllowed(const string& path, uid_t uid) {
	if (shouldBypassMediaProvider(uid)) {
	return 0;
	}

	JNIEnv* env = MaybeAttachCurrentThread();
	return isDirAccessAllowedInternal(env, media_provider_object_, mid_is_diraccess_allowed_, path,
	uid, kDeleteDirectoryRequest);
	}

	std::vector<std::shared_ptr<DirectoryEntry>> MediaProviderWrapper::GetDirectoryEntries(
	uid_t uid, const string& path, DIR* dirp) {
	// Default value in case JNI thread was being terminated
	std::vector<std::shared_ptr<DirectoryEntry>> res;
	if (shouldBypassMediaProvider(uid)) {
	addDirectoryEntriesFromLowerFs(dirp, /* filter */ nullptr, &res);
	return res;
	}

	JNIEnv* env = MaybeAttachCurrentThread();
	res = getFilesInDirectoryInternal(env, media_provider_object_, mid_get_files_in_dir_, uid, path);

	const int res_size = res.size();
	if (res_size && res[0]->d_name[0] == '/') {
	// Path is unknown to MediaProvider, get files and directories from lower file system.
	res.resize(0);
	addDirectoryEntriesFromLowerFs(dirp, /* filter */ nullptr, &res);
	} else if (res_size == 0 \|\| !res[0]->d_name.empty()) {
	// add directory names from lower file system.
	addDirectoryEntriesFromLowerFs(dirp, /* filter */ &isDirectory, &res);
	}
	return res;
	}

	int MediaProviderWrapper::IsOpendirAllowed(const string& path, uid_t uid, bool forWrite) {
	if (shouldBypassMediaProvider(uid)) {
	return 0;
	}

	JNIEnv* env = MaybeAttachCurrentThread();
	return isDirAccessAllowedInternal(env, media_provider_object_, mid_is_diraccess_allowed_, path,
	uid,
	forWrite ? kWriteDirectoryRequest : kReadDirectoryRequest);
	}

	bool MediaProviderWrapper::isUidAllowedAccessToDataOrObbPath(uid_t uid, const string& path) {
	if (shouldBypassMediaProvider(uid)) {
	return true;
	}

	JNIEnv* env = MaybeAttachCurrentThread();
	return isUidAllowedAccessToDataOrObbPathInternal(
	env, media_provider_object_, mid_is_uid_allowed_access_to_data_or_obb_path_, uid, path);
	}

	int MediaProviderWrapper::Rename(const string& old_path, const string& new_path, uid_t uid) {
	// Rename from SHELL_UID should go through MediaProvider to update database rows, so only bypass
	// MediaProvider for ROOT_UID.
	if (uid == ROOT_UID) {
	int res = rename(old_path.c_str(), new_path.c_str());
	if (res != 0) res = -errno;
	return res;
	}

	JNIEnv* env = MaybeAttachCurrentThread();
	return renameInternal(env, media_provider_object_, mid_rename_, old_path, new_path, uid);
	}

	void MediaProviderWrapper::OnFileCreated(const string& path) {
	JNIEnv* env = MaybeAttachCurrentThread();

	return onFileCreatedInternal(env, media_provider_object_, mid_on_file_created_, path);
	}

	bool MediaProviderWrapper::ShouldAllowLookup(uid_t uid, int path_user_id) {
	JNIEnv* env = MaybeAttachCurrentThread();

	bool res = env->CallBooleanMethod(media_provider_object_, mid_should_allow_lookup_, uid,
	path_user_id);

	if (CheckForJniException(env)) {
	return false;
	}
	return res;
	}

	bool MediaProviderWrapper::IsAppCloneUser(uid_t userId) {
	JNIEnv* env = MaybeAttachCurrentThread();

	bool res = env->CallBooleanMethod(media_provider_object_, mid_is_app_clone_user_, userId);

	if (CheckForJniException(env)) {
	return false;
	}
	return res;
	}

	std::unique_ptr<FileLookupResult> MediaProviderWrapper::FileLookup(const std::string& path,
	uid_t uid, pid_t tid) {
	JNIEnv* env = MaybeAttachCurrentThread();

	ScopedLocalRef<jstring> j_path(env, env->NewStringUTF(path.c_str()));

	ScopedLocalRef<jobject> j_res_file_lookup_object(
	env, env->CallObjectMethod(media_provider_object_, mid_file_lookup_, j_path.get(), uid,
	tid));

	if (CheckForJniException(env)) {
	return nullptr;
	}

	int transforms = env->GetIntField(j_res_file_lookup_object.get(), fid_file_lookup_transforms_);
	int transforms_reason =
	env->GetIntField(j_res_file_lookup_object.get(), fid_file_lookup_transforms_reason_);
	int original_uid = env->GetIntField(j_res_file_lookup_object.get(), fid_file_lookup_uid_);
	bool transforms_complete = env->GetBooleanField(j_res_file_lookup_object.get(),
	fid_file_lookup_transforms_complete_);
	bool transforms_supported = env->GetBooleanField(j_res_file_lookup_object.get(),
	fid_file_lookup_transforms_supported_);
	ScopedLocalRef<jstring> j_io_path(
	env,
	(jstring)env->GetObjectField(j_res_file_lookup_object.get(), fid_file_lookup_io_path_));
	ScopedUtfChars j_io_path_utf(env, j_io_path.get());

	std::unique_ptr<FileLookupResult> file_lookup_result = std::make_unique<FileLookupResult>(
	transforms, transforms_reason, original_uid, transforms_complete, transforms_supported,
	string(j_io_path_utf.c_str()));
	return file_lookup_result;
	}

	bool MediaProviderWrapper::Transform(const std::string& src, const std::string& dst, int transforms,
	int transforms_reason, uid_t read_uid, uid_t open_uid,
	uid_t transforms_uid) {
	JNIEnv* env = MaybeAttachCurrentThread();

	ScopedLocalRef<jstring> j_src(env, env->NewStringUTF(src.c_str()));
	ScopedLocalRef<jstring> j_dst(env, env->NewStringUTF(dst.c_str()));
	bool res = env->CallBooleanMethod(media_provider_object_, mid_transform_, j_src.get(),
	j_dst.get(), transforms, transforms_reason, read_uid,
	open_uid, transforms_uid);

	if (CheckForJniException(env)) {
	return false;
	}

	return res;
	}

	/*****************************************************************************************/
	/****************************** Private member functions *****************************/
	/*****************************************************************************************/

	/**
	* Finds MediaProvider method and adds it to methods map so it can be quickly called later.
	*/
	jmethodID MediaProviderWrapper::CacheMethod(JNIEnv* env, const char method_name[],
	const char signature[]) {
	jmethodID mid;
	string actual_method_name(method_name);
	actual_method_name.append("ForFuse");
	mid = env->GetMethodID(media_provider_class_, actual_method_name.c_str(), signature);

	if (!mid) {
	LOG(FATAL) << "Error caching method: " << method_name << signature;
	}
	return mid;
	}

	void MediaProviderWrapper::DetachThreadFunction(void* unused) {
	int detach = gJavaVm->DetachCurrentThread();
	CHECK_EQ(detach, 0);
	}

	JNIEnv* MediaProviderWrapper::MaybeAttachCurrentThread() {
	// We could use pthread_getspecific here as that's likely quicker but
	// that would result in wrong behaviour for threads that don't need to
	// be attached (e.g, those that were created in managed code).
	JNIEnv* env = nullptr;
	if (gJavaVm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_4) == JNI_OK) {
	return env;
	}

	// This thread is currently unattached, so it must not have any TLS
	// value. Note that we don't really care about the actual value we store
	// in TLS -- we only care about the value destructor being called, which
	// will happen as long as the key is not null.
	CHECK(pthread_getspecific(gJniEnvKey) == nullptr);
	CHECK_EQ(gJavaVm->AttachCurrentThread(&env, nullptr), 0);
	CHECK(env != nullptr);

	pthread_setspecific(gJniEnvKey, env);
	return env;
	}

	} // namespace fuse
	} // namespace mediaprovider