libs/binder/LazyServiceRegistrar.cpp - android_frameworks_native - 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 specific language governing permissions and
  * limitations under the License.
  */

 #include "log/log_main.h"
 #define LOG_TAG "AidlLazyServiceRegistrar"

 #include <binder/LazyServiceRegistrar.h>
 #include <binder/IPCThreadState.h>
 #include <binder/IServiceManager.h>
 #include <android/os/BnClientCallback.h>
 #include <android/os/IServiceManager.h>
 #include <utils/Log.h>

 namespace android {
 namespace binder {
 namespace internal {

 using AidlServiceManager = android::os::IServiceManager;

 class ClientCounterCallbackImpl : public ::android::os::BnClientCallback {
 public:
     ClientCounterCallbackImpl() : mNumConnectedServices(0), mForcePersist(false) {}

     bool registerService(const sp<IBinder>& service, const std::string& name,
                          bool allowIsolated, int dumpFlags);
     void forcePersist(bool persist);

     void setActiveServicesCallback(const std::function<bool(bool)>& activeServicesCallback);

     bool tryUnregister();

     void reRegister();

 protected:
     Status onClients(const sp<IBinder>& service, bool clients) override;

 private:
     struct Service {
         sp<IBinder> service;
         bool allowIsolated;
         int dumpFlags;

         // whether, based on onClients calls, we know we have a client for this
         // service or not
         bool clients = false;
         bool registered = true;
     };

     /**
      * Looks up a service guaranteed to be registered (service from onClients).
      */
     std::map<std::string, Service>::iterator assertRegisteredService(const sp<IBinder>& service);

     /**
      * Unregisters all services that we can. If we can't unregister all, re-register other
      * services.
      */
     void tryShutdown();

     /**
      * Try to shutdown the process, unless:
      * - 'forcePersist' is 'true', or
      * - The active services count callback returns 'true', or
      * - Some services have clients.
      */
     void maybeTryShutdown();

     // count of services with clients
     size_t mNumConnectedServices;

     // previous value passed to the active services callback
     std::optional<bool> mPreviousHasClients;

     // map of registered names and services
     std::map<std::string, Service> mRegisteredServices;

     bool mForcePersist;

     // Callback used to report if there are services with clients
     std::function<bool(bool)> mActiveServicesCallback;
 };

 class ClientCounterCallback {
 public:
     ClientCounterCallback();

     bool registerService(const sp<IBinder>& service, const std::string& name,
                                             bool allowIsolated, int dumpFlags);

     /**
      * Set a flag to prevent services from automatically shutting down
      */
     void forcePersist(bool persist);

     void setActiveServicesCallback(const std::function<bool(bool)>& activeServicesCallback);

     bool tryUnregister();

     void reRegister();

 private:
     sp<ClientCounterCallbackImpl> mImpl;
 };

 bool ClientCounterCallbackImpl::registerService(const sp<IBinder>& service, const std::string& name,
                                             bool allowIsolated, int dumpFlags) {
     auto manager = interface_cast<AidlServiceManager>(asBinder(defaultServiceManager()));

     bool reRegister = mRegisteredServices.count(name) > 0;
     std::string regStr = (reRegister) ? "Re-registering" : "Registering";
     ALOGI("%s service %s", regStr.c_str(), name.c_str());

     if (Status status = manager->addService(name.c_str(), service, allowIsolated, dumpFlags);
         !status.isOk()) {
         ALOGE("Failed to register service %s (%s)", name.c_str(), status.toString8().c_str());
         return false;
     }

     if (!reRegister) {
         if (Status status =
                     manager->registerClientCallback(name, service,
                                                     sp<android::os::IClientCallback>::fromExisting(
                                                             this));
             !status.isOk()) {
             ALOGE("Failed to add client callback for service %s (%s)", name.c_str(),
                   status.toString8().c_str());
             return false;
         }

         // Only add this when a service is added for the first time, as it is not removed
         mRegisteredServices[name] = {
               .service = service,
               .allowIsolated = allowIsolated,
               .dumpFlags = dumpFlags
         };
     }

     return true;
 }

 std::map<std::string, ClientCounterCallbackImpl::Service>::iterator ClientCounterCallbackImpl::assertRegisteredService(const sp<IBinder>& service) {
     LOG_ALWAYS_FATAL_IF(service == nullptr, "Got onClients callback for null service");
     for (auto it = mRegisteredServices.begin(); it != mRegisteredServices.end(); ++it) {
         auto const& [name, registered] = *it;
         (void) name;
         if (registered.service != service) continue;
         return it;
     }
     LOG_ALWAYS_FATAL("Got callback on service which we did not register: %s", String8(service->getInterfaceDescriptor()).c_str());
     __builtin_unreachable();
 }

 void ClientCounterCallbackImpl::forcePersist(bool persist) {
     mForcePersist = persist;
     if (!mForcePersist) {
         // Attempt a shutdown in case the number of clients hit 0 while the flag was on
         maybeTryShutdown();
     }
 }

 bool ClientCounterCallbackImpl::tryUnregister() {
     auto manager = interface_cast<AidlServiceManager>(asBinder(defaultServiceManager()));

     for (auto& [name, entry] : mRegisteredServices) {
         Status status = manager->tryUnregisterService(name, entry.service);

         if (!status.isOk()) {
             ALOGI("Failed to unregister service %s (%s)", name.c_str(), status.toString8().c_str());
             return false;
         }
         entry.registered = false;
     }

     return true;
 }

 void ClientCounterCallbackImpl::reRegister() {
     for (auto& [name, entry] : mRegisteredServices) {
         // re-register entry if not already registered
         if (entry.registered) {
             continue;
         }

         if (!registerService(entry.service, name, entry.allowIsolated,
                              entry.dumpFlags)) {
             // Must restart. Otherwise, clients will never be able to get a hold of this service.
             LOG_ALWAYS_FATAL("Bad state: could not re-register services");
         }

         entry.registered = true;
     }
 }

 void ClientCounterCallbackImpl::maybeTryShutdown() {
     if (mForcePersist) {
         ALOGI("Shutdown prevented by forcePersist override flag.");
         return;
     }

     bool handledInCallback = false;
     if (mActiveServicesCallback != nullptr) {
         bool hasClients = mNumConnectedServices != 0;
         if (hasClients != mPreviousHasClients) {
             handledInCallback = mActiveServicesCallback(hasClients);
             mPreviousHasClients = hasClients;
         }
     }

     // If there is no callback defined or the callback did not handle this
     // client count change event, try to shutdown the process if its services
     // have no clients.
     if (!handledInCallback && mNumConnectedServices == 0) {
         tryShutdown();
     }
 }

 /**
  * onClients is oneway, so no need to worry about multi-threading. Note that this means multiple
  * invocations could occur on different threads however.
  */
 Status ClientCounterCallbackImpl::onClients(const sp<IBinder>& service, bool clients) {
     auto & [name, registered] = *assertRegisteredService(service);
     if (registered.clients == clients) {
         LOG_ALWAYS_FATAL("Process already thought %s had clients: %d but servicemanager has "
                          "notified has clients: %d", name.c_str(), registered.clients, clients);
     }
     registered.clients = clients;

     // update cache count of clients
     {
          size_t numWithClients = 0;
          for (const auto& [name, registered] : mRegisteredServices) {
              (void) name;
              if (registered.clients) numWithClients++;
          }
          mNumConnectedServices = numWithClients;
     }

     ALOGI("Process has %zu (of %zu available) client(s) in use after notification %s has clients: %d",
           mNumConnectedServices, mRegisteredServices.size(), name.c_str(), clients);

     maybeTryShutdown();
     return Status::ok();
 }

  void ClientCounterCallbackImpl::tryShutdown() {
      ALOGI("Trying to shut down the service. No clients in use for any service in process.");

     if (tryUnregister()) {
          ALOGI("Unregistered all clients and exiting");
          exit(EXIT_SUCCESS);
      }

     reRegister();
 }

 void ClientCounterCallbackImpl::setActiveServicesCallback(const std::function<bool(bool)>&
                                                           activeServicesCallback) {
     mActiveServicesCallback = activeServicesCallback;
 }

 ClientCounterCallback::ClientCounterCallback() {
       mImpl = sp<ClientCounterCallbackImpl>::make();
 }

 bool ClientCounterCallback::registerService(const sp<IBinder>& service, const std::string& name,
                                             bool allowIsolated, int dumpFlags) {
     return mImpl->registerService(service, name, allowIsolated, dumpFlags);
 }

 void ClientCounterCallback::forcePersist(bool persist) {
     mImpl->forcePersist(persist);
 }

 void ClientCounterCallback::setActiveServicesCallback(const std::function<bool(bool)>&
                                                       activeServicesCallback) {
     mImpl->setActiveServicesCallback(activeServicesCallback);
 }

 bool ClientCounterCallback::tryUnregister() {
     return mImpl->tryUnregister();
 }

 void ClientCounterCallback::reRegister() {
     mImpl->reRegister();
 }

 }  // namespace internal

 LazyServiceRegistrar::LazyServiceRegistrar() {
     mClientCC = std::make_shared<internal::ClientCounterCallback>();
 }

 LazyServiceRegistrar& LazyServiceRegistrar::getInstance() {
     static auto registrarInstance = new LazyServiceRegistrar();
     return *registrarInstance;
 }

 status_t LazyServiceRegistrar::registerService(const sp<IBinder>& service, const std::string& name,
                                                bool allowIsolated, int dumpFlags) {
     if (!mClientCC->registerService(service, name, allowIsolated, dumpFlags)) {
         return UNKNOWN_ERROR;
     }
     return OK;
 }

 void LazyServiceRegistrar::forcePersist(bool persist) {
     mClientCC->forcePersist(persist);
 }

 void LazyServiceRegistrar::setActiveServicesCallback(const std::function<bool(bool)>&
                                                      activeServicesCallback) {
     mClientCC->setActiveServicesCallback(activeServicesCallback);
 }

 bool LazyServiceRegistrar::tryUnregister() {
     return mClientCC->tryUnregister();
 }

 void LazyServiceRegistrar::reRegister() {
     mClientCC->reRegister();
 }

 }  // namespace hardware
 }  // namespace android
	/*
	* 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 specific language governing permissions and
	* limitations under the License.
	*/

	#include "log/log_main.h"
	#define LOG_TAG "AidlLazyServiceRegistrar"

	#include <binder/LazyServiceRegistrar.h>
	#include <binder/IPCThreadState.h>
	#include <binder/IServiceManager.h>
	#include <android/os/BnClientCallback.h>
	#include <android/os/IServiceManager.h>
	#include <utils/Log.h>

	namespace android {
	namespace binder {
	namespace internal {

	using AidlServiceManager = android::os::IServiceManager;

	class ClientCounterCallbackImpl : public ::android::os::BnClientCallback {
	public:
	ClientCounterCallbackImpl() : mNumConnectedServices(0), mForcePersist(false) {}

	bool registerService(const sp<IBinder>& service, const std::string& name,
	bool allowIsolated, int dumpFlags);
	void forcePersist(bool persist);

	void setActiveServicesCallback(const std::function<bool(bool)>& activeServicesCallback);

	bool tryUnregister();

	void reRegister();

	protected:
	Status onClients(const sp<IBinder>& service, bool clients) override;

	private:
	struct Service {
	sp<IBinder> service;
	bool allowIsolated;
	int dumpFlags;

	// whether, based on onClients calls, we know we have a client for this
	// service or not
	bool clients = false;
	bool registered = true;
	};

	/**
	* Looks up a service guaranteed to be registered (service from onClients).
	*/
	std::map<std::string, Service>::iterator assertRegisteredService(const sp<IBinder>& service);

	/**
	* Unregisters all services that we can. If we can't unregister all, re-register other
	* services.
	*/
	void tryShutdown();

	/**
	* Try to shutdown the process, unless:
	* - 'forcePersist' is 'true', or
	* - The active services count callback returns 'true', or
	* - Some services have clients.
	*/
	void maybeTryShutdown();

	// count of services with clients
	size_t mNumConnectedServices;

	// previous value passed to the active services callback
	std::optional<bool> mPreviousHasClients;

	// map of registered names and services
	std::map<std::string, Service> mRegisteredServices;

	bool mForcePersist;

	// Callback used to report if there are services with clients
	std::function<bool(bool)> mActiveServicesCallback;
	};

	class ClientCounterCallback {
	public:
	ClientCounterCallback();

	bool registerService(const sp<IBinder>& service, const std::string& name,
	bool allowIsolated, int dumpFlags);

	/**
	* Set a flag to prevent services from automatically shutting down
	*/
	void forcePersist(bool persist);

	void setActiveServicesCallback(const std::function<bool(bool)>& activeServicesCallback);

	bool tryUnregister();

	void reRegister();

	private:
	sp<ClientCounterCallbackImpl> mImpl;
	};

	bool ClientCounterCallbackImpl::registerService(const sp<IBinder>& service, const std::string& name,
	bool allowIsolated, int dumpFlags) {
	auto manager = interface_cast<AidlServiceManager>(asBinder(defaultServiceManager()));

	bool reRegister = mRegisteredServices.count(name) > 0;
	std::string regStr = (reRegister) ? "Re-registering" : "Registering";
	ALOGI("%s service %s", regStr.c_str(), name.c_str());

	if (Status status = manager->addService(name.c_str(), service, allowIsolated, dumpFlags);
	!status.isOk()) {
	ALOGE("Failed to register service %s (%s)", name.c_str(), status.toString8().c_str());
	return false;
	}

	if (!reRegister) {
	if (Status status =
	manager->registerClientCallback(name, service,
	sp<android::os::IClientCallback>::fromExisting(
	this));
	!status.isOk()) {
	ALOGE("Failed to add client callback for service %s (%s)", name.c_str(),
	status.toString8().c_str());
	return false;
	}

	// Only add this when a service is added for the first time, as it is not removed
	mRegisteredServices[name] = {
	.service = service,
	.allowIsolated = allowIsolated,
	.dumpFlags = dumpFlags
	};
	}

	return true;
	}

	std::map<std::string, ClientCounterCallbackImpl::Service>::iterator ClientCounterCallbackImpl::assertRegisteredService(const sp<IBinder>& service) {
	LOG_ALWAYS_FATAL_IF(service == nullptr, "Got onClients callback for null service");
	for (auto it = mRegisteredServices.begin(); it != mRegisteredServices.end(); ++it) {
	auto const& [name, registered] = *it;
	(void) name;
	if (registered.service != service) continue;
	return it;
	}
	LOG_ALWAYS_FATAL("Got callback on service which we did not register: %s", String8(service->getInterfaceDescriptor()).c_str());
	__builtin_unreachable();
	}

	void ClientCounterCallbackImpl::forcePersist(bool persist) {
	mForcePersist = persist;
	if (!mForcePersist) {
	// Attempt a shutdown in case the number of clients hit 0 while the flag was on
	maybeTryShutdown();
	}
	}

	bool ClientCounterCallbackImpl::tryUnregister() {
	auto manager = interface_cast<AidlServiceManager>(asBinder(defaultServiceManager()));

	for (auto& [name, entry] : mRegisteredServices) {
	Status status = manager->tryUnregisterService(name, entry.service);

	if (!status.isOk()) {
	ALOGI("Failed to unregister service %s (%s)", name.c_str(), status.toString8().c_str());
	return false;
	}
	entry.registered = false;
	}

	return true;
	}

	void ClientCounterCallbackImpl::reRegister() {
	for (auto& [name, entry] : mRegisteredServices) {
	// re-register entry if not already registered
	if (entry.registered) {
	continue;
	}

	if (!registerService(entry.service, name, entry.allowIsolated,
	entry.dumpFlags)) {
	// Must restart. Otherwise, clients will never be able to get a hold of this service.
	LOG_ALWAYS_FATAL("Bad state: could not re-register services");
	}

	entry.registered = true;
	}
	}

	void ClientCounterCallbackImpl::maybeTryShutdown() {
	if (mForcePersist) {
	ALOGI("Shutdown prevented by forcePersist override flag.");
	return;
	}

	bool handledInCallback = false;
	if (mActiveServicesCallback != nullptr) {
	bool hasClients = mNumConnectedServices != 0;
	if (hasClients != mPreviousHasClients) {
	handledInCallback = mActiveServicesCallback(hasClients);
	mPreviousHasClients = hasClients;
	}
	}

	// If there is no callback defined or the callback did not handle this
	// client count change event, try to shutdown the process if its services
	// have no clients.
	if (!handledInCallback && mNumConnectedServices == 0) {
	tryShutdown();
	}
	}

	/**
	* onClients is oneway, so no need to worry about multi-threading. Note that this means multiple
	* invocations could occur on different threads however.
	*/
	Status ClientCounterCallbackImpl::onClients(const sp<IBinder>& service, bool clients) {
	auto & [name, registered] = *assertRegisteredService(service);
	if (registered.clients == clients) {
	LOG_ALWAYS_FATAL("Process already thought %s had clients: %d but servicemanager has "
	"notified has clients: %d", name.c_str(), registered.clients, clients);
	}
	registered.clients = clients;

	// update cache count of clients
	{
	size_t numWithClients = 0;
	for (const auto& [name, registered] : mRegisteredServices) {
	(void) name;
	if (registered.clients) numWithClients++;
	}
	mNumConnectedServices = numWithClients;
	}

	ALOGI("Process has %zu (of %zu available) client(s) in use after notification %s has clients: %d",
	mNumConnectedServices, mRegisteredServices.size(), name.c_str(), clients);

	maybeTryShutdown();
	return Status::ok();
	}

	void ClientCounterCallbackImpl::tryShutdown() {
	ALOGI("Trying to shut down the service. No clients in use for any service in process.");

	if (tryUnregister()) {
	ALOGI("Unregistered all clients and exiting");
	exit(EXIT_SUCCESS);
	}

	reRegister();
	}

	void ClientCounterCallbackImpl::setActiveServicesCallback(const std::function<bool(bool)>&
	activeServicesCallback) {
	mActiveServicesCallback = activeServicesCallback;
	}

	ClientCounterCallback::ClientCounterCallback() {
	mImpl = sp<ClientCounterCallbackImpl>::make();
	}

	bool ClientCounterCallback::registerService(const sp<IBinder>& service, const std::string& name,
	bool allowIsolated, int dumpFlags) {
	return mImpl->registerService(service, name, allowIsolated, dumpFlags);
	}

	void ClientCounterCallback::forcePersist(bool persist) {
	mImpl->forcePersist(persist);
	}

	void ClientCounterCallback::setActiveServicesCallback(const std::function<bool(bool)>&
	activeServicesCallback) {
	mImpl->setActiveServicesCallback(activeServicesCallback);
	}

	bool ClientCounterCallback::tryUnregister() {
	return mImpl->tryUnregister();
	}

	void ClientCounterCallback::reRegister() {
	mImpl->reRegister();
	}

	} // namespace internal

	LazyServiceRegistrar::LazyServiceRegistrar() {
	mClientCC = std::make_shared<internal::ClientCounterCallback>();
	}

	LazyServiceRegistrar& LazyServiceRegistrar::getInstance() {
	static auto registrarInstance = new LazyServiceRegistrar();
	return *registrarInstance;
	}

	status_t LazyServiceRegistrar::registerService(const sp<IBinder>& service, const std::string& name,
	bool allowIsolated, int dumpFlags) {
	if (!mClientCC->registerService(service, name, allowIsolated, dumpFlags)) {
	return UNKNOWN_ERROR;
	}
	return OK;
	}

	void LazyServiceRegistrar::forcePersist(bool persist) {
	mClientCC->forcePersist(persist);
	}

	void LazyServiceRegistrar::setActiveServicesCallback(const std::function<bool(bool)>&
	activeServicesCallback) {
	mClientCC->setActiveServicesCallback(activeServicesCallback);
	}

	bool LazyServiceRegistrar::tryUnregister() {
	return mClientCC->tryUnregister();
	}

	void LazyServiceRegistrar::reRegister() {
	mClientCC->reRegister();
	}

	} // namespace hardware
	} // namespace android