libs/binder/ndk/ibinder.cpp - platform/frameworks/native - Git at Google

 /*
  * Copyright (C) 2018 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 <android/binder_ibinder.h>
 #include "ibinder_internal.h"

 #include <android/binder_stability.h>
 #include <android/binder_status.h>
 #include "parcel_internal.h"
 #include "status_internal.h"

 #include <android-base/logging.h>
 #include <binder/IPCThreadState.h>
 #include <binder/IResultReceiver.h>
 #include <private/android_filesystem_config.h>

 using DeathRecipient = ::android::IBinder::DeathRecipient;

 using ::android::IBinder;
 using ::android::IResultReceiver;
 using ::android::Parcel;
 using ::android::sp;
 using ::android::status_t;
 using ::android::String16;
 using ::android::String8;
 using ::android::wp;

 namespace ABBinderTag {

 static const void* kId = "ABBinder";
 static void* kValue = static_cast<void*>(new bool{true});
 void clean(const void* /*id*/, void* /*obj*/, void* /*cookie*/){/* do nothing */};

 static void attach(const sp<IBinder>& binder) {
     binder->attachObject(kId, kValue, nullptr /*cookie*/, clean);
 }
 static bool has(const sp<IBinder>& binder) {
     return binder != nullptr && binder->findObject(kId) == kValue;
 }

 }  // namespace ABBinderTag

 namespace ABpBinderTag {

 static std::mutex gLock;
 static const void* kId = "ABpBinder";
 struct Value {
     wp<ABpBinder> binder;
 };
 void clean(const void* id, void* obj, void* cookie) {
     CHECK(id == kId) << id << " " << obj << " " << cookie;

     delete static_cast<Value*>(obj);
 };

 }  // namespace ABpBinderTag

 AIBinder::AIBinder(const AIBinder_Class* clazz) : mClazz(clazz) {}
 AIBinder::~AIBinder() {}

 bool AIBinder::associateClass(const AIBinder_Class* clazz) {
     if (clazz == nullptr) return false;
     if (mClazz == clazz) return true;

     String8 newDescriptor(clazz->getInterfaceDescriptor());

     if (mClazz != nullptr) {
         String8 currentDescriptor(mClazz->getInterfaceDescriptor());
         if (newDescriptor == currentDescriptor) {
             LOG(ERROR) << __func__ << ": Class descriptors '" << currentDescriptor
                        << "' match during associateClass, but they are different class objects. "
                           "Class descriptor collision?";
         } else {
             LOG(ERROR) << __func__
                        << ": Class cannot be associated on object which already has a class. "
                           "Trying to associate to '"
                        << newDescriptor.c_str() << "' but already set to '"
                        << currentDescriptor.c_str() << "'.";
         }

         // always a failure because we know mClazz != clazz
         return false;
     }

     CHECK(asABpBinder() != nullptr);  // ABBinder always has a descriptor

     String8 descriptor(getBinder()->getInterfaceDescriptor());
     if (descriptor != newDescriptor) {
         LOG(ERROR) << __func__ << ": Expecting binder to have class '" << newDescriptor.c_str()
                    << "' but descriptor is actually '" << descriptor.c_str() << "'.";
         return false;
     }

     // if this is a local object, it's not one known to libbinder_ndk
     mClazz = clazz;

     return true;
 }

 ABBinder::ABBinder(const AIBinder_Class* clazz, void* userData)
     : AIBinder(clazz), BBinder(), mUserData(userData) {
     CHECK(clazz != nullptr);
 }
 ABBinder::~ABBinder() {
     getClass()->onDestroy(mUserData);
 }

 const String16& ABBinder::getInterfaceDescriptor() const {
     return getClass()->getInterfaceDescriptor();
 }

 status_t ABBinder::dump(int fd, const ::android::Vector<String16>& args) {
     AIBinder_onDump onDump = getClass()->onDump;

     if (onDump == nullptr) {
         return STATUS_OK;
     }

     // technically UINT32_MAX would be okay here, but INT32_MAX is expected since this may be
     // null in Java
     if (args.size() > INT32_MAX) {
         LOG(ERROR) << "ABBinder::dump received too many arguments: " << args.size();
         return STATUS_BAD_VALUE;
     }

     std::vector<String8> utf8Args;  // owns memory of utf8s
     utf8Args.reserve(args.size());
     std::vector<const char*> utf8Pointers;  // what can be passed over NDK API
     utf8Pointers.reserve(args.size());

     for (size_t i = 0; i < args.size(); i++) {
         utf8Args.push_back(String8(args[i]));
         utf8Pointers.push_back(utf8Args[i].c_str());
     }

     return onDump(this, fd, utf8Pointers.data(), utf8Pointers.size());
 }

 status_t ABBinder::onTransact(transaction_code_t code, const Parcel& data, Parcel* reply,
                               binder_flags_t flags) {
     if (isUserCommand(code)) {
         if (!data.checkInterface(this)) {
             return STATUS_BAD_TYPE;
         }

         const AParcel in = AParcel::readOnly(this, &data);
         AParcel out = AParcel(this, reply, false /*owns*/);

         binder_status_t status = getClass()->onTransact(this, code, &in, &out);
         return PruneStatusT(status);
     } else if (code == SHELL_COMMAND_TRANSACTION && getClass()->handleShellCommand != nullptr) {
         int in = data.readFileDescriptor();
         int out = data.readFileDescriptor();
         int err = data.readFileDescriptor();

         int argc = data.readInt32();
         std::vector<String8> utf8Args;          // owns memory of utf8s
         std::vector<const char*> utf8Pointers;  // what can be passed over NDK API
         for (int i = 0; i < argc && data.dataAvail() > 0; i++) {
             utf8Args.push_back(String8(data.readString16()));
             utf8Pointers.push_back(utf8Args[i].c_str());
         }

         data.readStrongBinder();  // skip over the IShellCallback
         sp<IResultReceiver> resultReceiver = IResultReceiver::asInterface(data.readStrongBinder());

         // Shell commands should only be callable by ADB.
         uid_t uid = AIBinder_getCallingUid();
         if (uid != AID_ROOT && uid != AID_SHELL) {
             if (resultReceiver != nullptr) {
                 resultReceiver->send(-1);
             }
             return STATUS_PERMISSION_DENIED;
         }

         // Check that the file descriptors are valid.
         if (in == STATUS_BAD_TYPE || out == STATUS_BAD_TYPE || err == STATUS_BAD_TYPE) {
             if (resultReceiver != nullptr) {
                 resultReceiver->send(-1);
             }
             return STATUS_BAD_VALUE;
         }

         binder_status_t status = getClass()->handleShellCommand(
                 this, in, out, err, utf8Pointers.data(), utf8Pointers.size());
         if (resultReceiver != nullptr) {
             resultReceiver->send(status);
         }
         return status;
     } else {
         return BBinder::onTransact(code, data, reply, flags);
     }
 }

 ABpBinder::ABpBinder(const ::android::sp<::android::IBinder>& binder)
     : AIBinder(nullptr /*clazz*/), BpRefBase(binder) {
     CHECK(binder != nullptr);
 }
 ABpBinder::~ABpBinder() {}

 void ABpBinder::onLastStrongRef(const void* id) {
     {
         std::lock_guard<std::mutex> lock(ABpBinderTag::gLock);
         // Since ABpBinder is OBJECT_LIFETIME_WEAK, we must remove this weak reference in order for
         // the ABpBinder to be deleted. Since a strong reference to this ABpBinder object should no
         // longer be able to exist at the time of this method call, there is no longer a need to
         // recover it.

         ABpBinderTag::Value* value =
                 static_cast<ABpBinderTag::Value*>(remote()->findObject(ABpBinderTag::kId));
         if (value != nullptr) {
             value->binder = nullptr;
         }
     }

     BpRefBase::onLastStrongRef(id);
 }

 sp<AIBinder> ABpBinder::lookupOrCreateFromBinder(const ::android::sp<::android::IBinder>& binder) {
     if (binder == nullptr) {
         return nullptr;
     }
     if (ABBinderTag::has(binder)) {
         return static_cast<ABBinder*>(binder.get());
     }

     // The following code ensures that for a given binder object (remote or local), if it is not an
     // ABBinder then at most one ABpBinder object exists in a given process representing it.
     std::lock_guard<std::mutex> lock(ABpBinderTag::gLock);

     ABpBinderTag::Value* value =
             static_cast<ABpBinderTag::Value*>(binder->findObject(ABpBinderTag::kId));
     if (value == nullptr) {
         value = new ABpBinderTag::Value;
         binder->attachObject(ABpBinderTag::kId, static_cast<void*>(value), nullptr /*cookie*/,
                              ABpBinderTag::clean);
     }

     sp<ABpBinder> ret = value->binder.promote();
     if (ret == nullptr) {
         ret = new ABpBinder(binder);
         value->binder = ret;
     }

     return ret;
 }

 struct AIBinder_Weak {
     wp<AIBinder> binder;
 };
 AIBinder_Weak* AIBinder_Weak_new(AIBinder* binder) {
     if (binder == nullptr) {
         return nullptr;
     }

     return new AIBinder_Weak{wp<AIBinder>(binder)};
 }
 void AIBinder_Weak_delete(AIBinder_Weak* weakBinder) {
     delete weakBinder;
 }
 AIBinder* AIBinder_Weak_promote(AIBinder_Weak* weakBinder) {
     if (weakBinder == nullptr) {
         return nullptr;
     }

     sp<AIBinder> binder = weakBinder->binder.promote();
     AIBinder_incStrong(binder.get());
     return binder.get();
 }

 AIBinder_Class::AIBinder_Class(const char* interfaceDescriptor, AIBinder_Class_onCreate onCreate,
                                AIBinder_Class_onDestroy onDestroy,
                                AIBinder_Class_onTransact onTransact)
     : onCreate(onCreate),
       onDestroy(onDestroy),
       onTransact(onTransact),
       mInterfaceDescriptor(interfaceDescriptor) {}

 AIBinder_Class* AIBinder_Class_define(const char* interfaceDescriptor,
                                       AIBinder_Class_onCreate onCreate,
                                       AIBinder_Class_onDestroy onDestroy,
                                       AIBinder_Class_onTransact onTransact) {
     if (interfaceDescriptor == nullptr || onCreate == nullptr || onDestroy == nullptr ||
         onTransact == nullptr) {
         return nullptr;
     }

     return new AIBinder_Class(interfaceDescriptor, onCreate, onDestroy, onTransact);
 }

 void AIBinder_Class_setOnDump(AIBinder_Class* clazz, AIBinder_onDump onDump) {
     CHECK(clazz != nullptr) << "setOnDump requires non-null clazz";

     // this is required to be called before instances are instantiated
     clazz->onDump = onDump;
 }

 void AIBinder_Class_setHandleShellCommand(AIBinder_Class* clazz,
                                           AIBinder_handleShellCommand handleShellCommand) {
     CHECK(clazz != nullptr) << "setHandleShellCommand requires non-null clazz";

     clazz->handleShellCommand = handleShellCommand;
 }

 void AIBinder_DeathRecipient::TransferDeathRecipient::binderDied(const wp<IBinder>& who) {
     CHECK(who == mWho);

     mOnDied(mCookie);

     sp<AIBinder_DeathRecipient> recipient = mParentRecipient.promote();
     sp<IBinder> strongWho = who.promote();

     // otherwise this will be cleaned up later with pruneDeadTransferEntriesLocked
     if (recipient != nullptr && strongWho != nullptr) {
         status_t result = recipient->unlinkToDeath(strongWho, mCookie);
         if (result != ::android::DEAD_OBJECT) {
             LOG(WARNING) << "Unlinking to dead binder resulted in: " << result;
         }
     }

     mWho = nullptr;
 }

 AIBinder_DeathRecipient::AIBinder_DeathRecipient(AIBinder_DeathRecipient_onBinderDied onDied)
     : mOnDied(onDied) {
     CHECK(onDied != nullptr);
 }

 void AIBinder_DeathRecipient::pruneDeadTransferEntriesLocked() {
     mDeathRecipients.erase(std::remove_if(mDeathRecipients.begin(), mDeathRecipients.end(),
                                           [](const sp<TransferDeathRecipient>& tdr) {
                                               return tdr->getWho() == nullptr;
                                           }),
                            mDeathRecipients.end());
 }

 binder_status_t AIBinder_DeathRecipient::linkToDeath(sp<IBinder> binder, void* cookie) {
     CHECK(binder != nullptr);

     std::lock_guard<std::mutex> l(mDeathRecipientsMutex);

     sp<TransferDeathRecipient> recipient =
             new TransferDeathRecipient(binder, cookie, this, mOnDied);

     status_t status = binder->linkToDeath(recipient, cookie, 0 /*flags*/);
     if (status != STATUS_OK) {
         return PruneStatusT(status);
     }

     mDeathRecipients.push_back(recipient);

     pruneDeadTransferEntriesLocked();
     return STATUS_OK;
 }

 binder_status_t AIBinder_DeathRecipient::unlinkToDeath(sp<IBinder> binder, void* cookie) {
     CHECK(binder != nullptr);

     std::lock_guard<std::mutex> l(mDeathRecipientsMutex);

     for (auto it = mDeathRecipients.rbegin(); it != mDeathRecipients.rend(); ++it) {
         sp<TransferDeathRecipient> recipient = *it;

         if (recipient->getCookie() == cookie && recipient->getWho() == binder) {
             mDeathRecipients.erase(it.base() - 1);

             status_t status = binder->unlinkToDeath(recipient, cookie, 0 /*flags*/);
             if (status != ::android::OK) {
                 LOG(ERROR) << __func__
                            << ": removed reference to death recipient but unlink failed.";
             }
             return PruneStatusT(status);
         }
     }

     return STATUS_NAME_NOT_FOUND;
 }

 // start of C-API methods

 AIBinder* AIBinder_new(const AIBinder_Class* clazz, void* args) {
     if (clazz == nullptr) {
         LOG(ERROR) << __func__ << ": Must provide class to construct local binder.";
         return nullptr;
     }

     void* userData = clazz->onCreate(args);

     sp<AIBinder> ret = new ABBinder(clazz, userData);
     ABBinderTag::attach(ret->getBinder());

     AIBinder_incStrong(ret.get());
     return ret.get();
 }

 bool AIBinder_isRemote(const AIBinder* binder) {
     if (binder == nullptr) {
         return false;
     }

     return binder->isRemote();
 }

 bool AIBinder_isAlive(const AIBinder* binder) {
     if (binder == nullptr) {
         return false;
     }

     return const_cast<AIBinder*>(binder)->getBinder()->isBinderAlive();
 }

 binder_status_t AIBinder_ping(AIBinder* binder) {
     if (binder == nullptr) {
         return STATUS_UNEXPECTED_NULL;
     }

     return PruneStatusT(binder->getBinder()->pingBinder());
 }

 binder_status_t AIBinder_dump(AIBinder* binder, int fd, const char** args, uint32_t numArgs) {
     if (binder == nullptr) {
         return STATUS_UNEXPECTED_NULL;
     }

     ABBinder* bBinder = binder->asABBinder();
     if (bBinder != nullptr) {
         AIBinder_onDump onDump = binder->getClass()->onDump;
         if (onDump == nullptr) {
             return STATUS_OK;
         }
         return PruneStatusT(onDump(bBinder, fd, args, numArgs));
     }

     ::android::Vector<String16> utf16Args;
     utf16Args.setCapacity(numArgs);
     for (uint32_t i = 0; i < numArgs; i++) {
         utf16Args.push(String16(String8(args[i])));
     }

     status_t status = binder->getBinder()->dump(fd, utf16Args);
     return PruneStatusT(status);
 }

 binder_status_t AIBinder_linkToDeath(AIBinder* binder, AIBinder_DeathRecipient* recipient,
                                      void* cookie) {
     if (binder == nullptr || recipient == nullptr) {
         LOG(ERROR) << __func__ << ": Must provide binder and recipient.";
         return STATUS_UNEXPECTED_NULL;
     }

     // returns binder_status_t
     return recipient->linkToDeath(binder->getBinder(), cookie);
 }

 binder_status_t AIBinder_unlinkToDeath(AIBinder* binder, AIBinder_DeathRecipient* recipient,
                                        void* cookie) {
     if (binder == nullptr || recipient == nullptr) {
         LOG(ERROR) << __func__ << ": Must provide binder and recipient.";
         return STATUS_UNEXPECTED_NULL;
     }

     // returns binder_status_t
     return recipient->unlinkToDeath(binder->getBinder(), cookie);
 }

 uid_t AIBinder_getCallingUid() {
     return ::android::IPCThreadState::self()->getCallingUid();
 }

 pid_t AIBinder_getCallingPid() {
     return ::android::IPCThreadState::self()->getCallingPid();
 }

 void AIBinder_incStrong(AIBinder* binder) {
     if (binder == nullptr) {
         return;
     }

     binder->incStrong(nullptr);
 }
 void AIBinder_decStrong(AIBinder* binder) {
     if (binder == nullptr) {
         LOG(ERROR) << __func__ << ": on null binder";
         return;
     }

     binder->decStrong(nullptr);
 }
 int32_t AIBinder_debugGetRefCount(AIBinder* binder) {
     if (binder == nullptr) {
         LOG(ERROR) << __func__ << ": on null binder";
         return -1;
     }

     return binder->getStrongCount();
 }

 bool AIBinder_associateClass(AIBinder* binder, const AIBinder_Class* clazz) {
     if (binder == nullptr) {
         return false;
     }

     return binder->associateClass(clazz);
 }

 const AIBinder_Class* AIBinder_getClass(AIBinder* binder) {
     if (binder == nullptr) {
         return nullptr;
     }

     return binder->getClass();
 }

 void* AIBinder_getUserData(AIBinder* binder) {
     if (binder == nullptr) {
         return nullptr;
     }

     ABBinder* bBinder = binder->asABBinder();
     if (bBinder == nullptr) {
         return nullptr;
     }

     return bBinder->getUserData();
 }

 binder_status_t AIBinder_prepareTransaction(AIBinder* binder, AParcel** in) {
     if (binder == nullptr || in == nullptr) {
         LOG(ERROR) << __func__ << ": requires non-null parameters.";
         return STATUS_UNEXPECTED_NULL;
     }
     const AIBinder_Class* clazz = binder->getClass();
     if (clazz == nullptr) {
         LOG(ERROR) << __func__
                    << ": Class must be defined for a remote binder transaction. See "
                       "AIBinder_associateClass.";
         return STATUS_INVALID_OPERATION;
     }

     if (!binder->isRemote()) {
         LOG(WARNING) << "A binder object at " << binder
                      << " is being transacted on, however, this object is in the same process as "
                         "its proxy. Transacting with this binder is expensive compared to just "
                         "calling the corresponding functionality in the same process.";
     }

     *in = new AParcel(binder);
     status_t status = (*in)->get()->writeInterfaceToken(clazz->getInterfaceDescriptor());
     binder_status_t ret = PruneStatusT(status);

     if (ret != STATUS_OK) {
         delete *in;
         *in = nullptr;
     }

     return ret;
 }

 static void DestroyParcel(AParcel** parcel) {
     delete *parcel;
     *parcel = nullptr;
 }

 binder_status_t AIBinder_transact(AIBinder* binder, transaction_code_t code, AParcel** in,
                                   AParcel** out, binder_flags_t flags) {
     if (in == nullptr) {
         LOG(ERROR) << __func__ << ": requires non-null in parameter";
         return STATUS_UNEXPECTED_NULL;
     }

     using AutoParcelDestroyer = std::unique_ptr<AParcel*, void (*)(AParcel**)>;
     // This object is the input to the transaction. This function takes ownership of it and deletes
     // it.
     AutoParcelDestroyer forIn(in, DestroyParcel);

     if (!isUserCommand(code)) {
         LOG(ERROR) << __func__ << ": Only user-defined transactions can be made from the NDK.";
         return STATUS_UNKNOWN_TRANSACTION;
     }

     constexpr binder_flags_t kAllFlags = FLAG_PRIVATE_VENDOR | FLAG_ONEWAY;
     if ((flags & ~kAllFlags) != 0) {
         LOG(ERROR) << __func__ << ": Unrecognized flags sent: " << flags;
         return STATUS_BAD_VALUE;
     }

     if (binder == nullptr || *in == nullptr || out == nullptr) {
         LOG(ERROR) << __func__ << ": requires non-null parameters.";
         return STATUS_UNEXPECTED_NULL;
     }

     if ((*in)->getBinder() != binder) {
         LOG(ERROR) << __func__ << ": parcel is associated with binder object " << binder
                    << " but called with " << (*in)->getBinder();
         return STATUS_BAD_VALUE;
     }

     *out = new AParcel(binder);

     status_t status = binder->getBinder()->transact(code, *(*in)->get(), (*out)->get(), flags);
     binder_status_t ret = PruneStatusT(status);

     if (ret != STATUS_OK) {
         delete *out;
         *out = nullptr;
     }

     return ret;
 }

 AIBinder_DeathRecipient* AIBinder_DeathRecipient_new(
         AIBinder_DeathRecipient_onBinderDied onBinderDied) {
     if (onBinderDied == nullptr) {
         LOG(ERROR) << __func__ << ": requires non-null onBinderDied parameter.";
         return nullptr;
     }
     auto ret = new AIBinder_DeathRecipient(onBinderDied);
     ret->incStrong(nullptr);
     return ret;
 }

 void AIBinder_DeathRecipient_delete(AIBinder_DeathRecipient* recipient) {
     if (recipient == nullptr) {
         return;
     }

     recipient->decStrong(nullptr);
 }

 binder_status_t AIBinder_getExtension(AIBinder* binder, AIBinder** outExt) {
     if (binder == nullptr || outExt == nullptr) {
         if (outExt != nullptr) {
             *outExt = nullptr;
         }
         return STATUS_UNEXPECTED_NULL;
     }

     sp<IBinder> ext;
     status_t res = binder->getBinder()->getExtension(&ext);

     if (res != android::OK) {
         *outExt = nullptr;
         return PruneStatusT(res);
     }

     sp<AIBinder> ret = ABpBinder::lookupOrCreateFromBinder(ext);
     if (ret != nullptr) ret->incStrong(binder);

     *outExt = ret.get();
     return STATUS_OK;
 }

 binder_status_t AIBinder_setExtension(AIBinder* binder, AIBinder* ext) {
     if (binder == nullptr || ext == nullptr) {
         return STATUS_UNEXPECTED_NULL;
     }

     ABBinder* rawBinder = binder->asABBinder();
     if (rawBinder == nullptr) {
         return STATUS_INVALID_OPERATION;
     }

     rawBinder->setExtension(ext->getBinder());
     return STATUS_OK;
 }
	/*
	* Copyright (C) 2018 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 <android/binder_ibinder.h>
	#include "ibinder_internal.h"

	#include <android/binder_stability.h>
	#include <android/binder_status.h>
	#include "parcel_internal.h"
	#include "status_internal.h"

	#include <android-base/logging.h>
	#include <binder/IPCThreadState.h>
	#include <binder/IResultReceiver.h>
	#include <private/android_filesystem_config.h>

	using DeathRecipient = ::android::IBinder::DeathRecipient;

	using ::android::IBinder;
	using ::android::IResultReceiver;
	using ::android::Parcel;
	using ::android::sp;
	using ::android::status_t;
	using ::android::String16;
	using ::android::String8;
	using ::android::wp;

	namespace ABBinderTag {

	static const void* kId = "ABBinder";
	static void* kValue = static_cast<void*>(new bool{true});
	void clean(const void* /id/, void* /obj/, void* /cookie/){/* do nothing */};

	static void attach(const sp<IBinder>& binder) {
	binder->attachObject(kId, kValue, nullptr /cookie/, clean);
	}
	static bool has(const sp<IBinder>& binder) {
	return binder != nullptr && binder->findObject(kId) == kValue;
	}

	} // namespace ABBinderTag

	namespace ABpBinderTag {

	static std::mutex gLock;
	static const void* kId = "ABpBinder";
	struct Value {
	wp<ABpBinder> binder;
	};
	void clean(const void* id, void* obj, void* cookie) {
	CHECK(id == kId) << id << " " << obj << " " << cookie;

	delete static_cast<Value*>(obj);
	};

	} // namespace ABpBinderTag

	AIBinder::AIBinder(const AIBinder_Class* clazz) : mClazz(clazz) {}
	AIBinder::~AIBinder() {}

	bool AIBinder::associateClass(const AIBinder_Class* clazz) {
	if (clazz == nullptr) return false;
	if (mClazz == clazz) return true;

	String8 newDescriptor(clazz->getInterfaceDescriptor());

	if (mClazz != nullptr) {
	String8 currentDescriptor(mClazz->getInterfaceDescriptor());
	if (newDescriptor == currentDescriptor) {
	LOG(ERROR) << __func__ << ": Class descriptors '" << currentDescriptor
	<< "' match during associateClass, but they are different class objects. "
	"Class descriptor collision?";
	} else {
	LOG(ERROR) << __func__
	<< ": Class cannot be associated on object which already has a class. "
	"Trying to associate to '"
	<< newDescriptor.c_str() << "' but already set to '"
	<< currentDescriptor.c_str() << "'.";
	}

	// always a failure because we know mClazz != clazz
	return false;
	}

	CHECK(asABpBinder() != nullptr); // ABBinder always has a descriptor

	String8 descriptor(getBinder()->getInterfaceDescriptor());
	if (descriptor != newDescriptor) {
	LOG(ERROR) << __func__ << ": Expecting binder to have class '" << newDescriptor.c_str()
	<< "' but descriptor is actually '" << descriptor.c_str() << "'.";
	return false;
	}

	// if this is a local object, it's not one known to libbinder_ndk
	mClazz = clazz;

	return true;
	}

	ABBinder::ABBinder(const AIBinder_Class* clazz, void* userData)
	: AIBinder(clazz), BBinder(), mUserData(userData) {
	CHECK(clazz != nullptr);
	}
	ABBinder::~ABBinder() {
	getClass()->onDestroy(mUserData);
	}

	const String16& ABBinder::getInterfaceDescriptor() const {
	return getClass()->getInterfaceDescriptor();
	}

	status_t ABBinder::dump(int fd, const ::android::Vector<String16>& args) {
	AIBinder_onDump onDump = getClass()->onDump;

	if (onDump == nullptr) {
	return STATUS_OK;
	}

	// technically UINT32_MAX would be okay here, but INT32_MAX is expected since this may be
	// null in Java
	if (args.size() > INT32_MAX) {
	LOG(ERROR) << "ABBinder::dump received too many arguments: " << args.size();
	return STATUS_BAD_VALUE;
	}

	std::vector<String8> utf8Args; // owns memory of utf8s
	utf8Args.reserve(args.size());
	std::vector<const char*> utf8Pointers; // what can be passed over NDK API
	utf8Pointers.reserve(args.size());

	for (size_t i = 0; i < args.size(); i++) {
	utf8Args.push_back(String8(args[i]));
	utf8Pointers.push_back(utf8Args[i].c_str());
	}

	return onDump(this, fd, utf8Pointers.data(), utf8Pointers.size());
	}

	status_t ABBinder::onTransact(transaction_code_t code, const Parcel& data, Parcel* reply,
	binder_flags_t flags) {
	if (isUserCommand(code)) {
	if (!data.checkInterface(this)) {
	return STATUS_BAD_TYPE;
	}

	const AParcel in = AParcel::readOnly(this, &data);
	AParcel out = AParcel(this, reply, false /owns/);

	binder_status_t status = getClass()->onTransact(this, code, &in, &out);
	return PruneStatusT(status);
	} else if (code == SHELL_COMMAND_TRANSACTION && getClass()->handleShellCommand != nullptr) {
	int in = data.readFileDescriptor();
	int out = data.readFileDescriptor();
	int err = data.readFileDescriptor();

	int argc = data.readInt32();
	std::vector<String8> utf8Args; // owns memory of utf8s
	std::vector<const char*> utf8Pointers; // what can be passed over NDK API
	for (int i = 0; i < argc && data.dataAvail() > 0; i++) {
	utf8Args.push_back(String8(data.readString16()));
	utf8Pointers.push_back(utf8Args[i].c_str());
	}

	data.readStrongBinder(); // skip over the IShellCallback
	sp<IResultReceiver> resultReceiver = IResultReceiver::asInterface(data.readStrongBinder());

	// Shell commands should only be callable by ADB.
	uid_t uid = AIBinder_getCallingUid();
	if (uid != AID_ROOT && uid != AID_SHELL) {
	if (resultReceiver != nullptr) {
	resultReceiver->send(-1);
	}
	return STATUS_PERMISSION_DENIED;
	}

	// Check that the file descriptors are valid.
	if (in == STATUS_BAD_TYPE \|\| out == STATUS_BAD_TYPE \|\| err == STATUS_BAD_TYPE) {
	if (resultReceiver != nullptr) {
	resultReceiver->send(-1);
	}
	return STATUS_BAD_VALUE;
	}

	binder_status_t status = getClass()->handleShellCommand(
	this, in, out, err, utf8Pointers.data(), utf8Pointers.size());
	if (resultReceiver != nullptr) {
	resultReceiver->send(status);
	}
	return status;
	} else {
	return BBinder::onTransact(code, data, reply, flags);
	}
	}

	ABpBinder::ABpBinder(const ::android::sp<::android::IBinder>& binder)
	: AIBinder(nullptr /clazz/), BpRefBase(binder) {
	CHECK(binder != nullptr);
	}
	ABpBinder::~ABpBinder() {}

	void ABpBinder::onLastStrongRef(const void* id) {
	{
	std::lock_guard<std::mutex> lock(ABpBinderTag::gLock);
	// Since ABpBinder is OBJECT_LIFETIME_WEAK, we must remove this weak reference in order for
	// the ABpBinder to be deleted. Since a strong reference to this ABpBinder object should no
	// longer be able to exist at the time of this method call, there is no longer a need to
	// recover it.

	ABpBinderTag::Value* value =
	static_cast<ABpBinderTag::Value*>(remote()->findObject(ABpBinderTag::kId));
	if (value != nullptr) {
	value->binder = nullptr;
	}
	}

	BpRefBase::onLastStrongRef(id);
	}

	sp<AIBinder> ABpBinder::lookupOrCreateFromBinder(const ::android::sp<::android::IBinder>& binder) {
	if (binder == nullptr) {
	return nullptr;
	}
	if (ABBinderTag::has(binder)) {
	return static_cast<ABBinder*>(binder.get());
	}

	// The following code ensures that for a given binder object (remote or local), if it is not an
	// ABBinder then at most one ABpBinder object exists in a given process representing it.
	std::lock_guard<std::mutex> lock(ABpBinderTag::gLock);

	ABpBinderTag::Value* value =
	static_cast<ABpBinderTag::Value*>(binder->findObject(ABpBinderTag::kId));
	if (value == nullptr) {
	value = new ABpBinderTag::Value;
	binder->attachObject(ABpBinderTag::kId, static_cast<void>(value), nullptr /cookie*/,
	ABpBinderTag::clean);
	}

	sp<ABpBinder> ret = value->binder.promote();
	if (ret == nullptr) {
	ret = new ABpBinder(binder);
	value->binder = ret;
	}

	return ret;
	}

	struct AIBinder_Weak {
	wp<AIBinder> binder;
	};
	AIBinder_Weak* AIBinder_Weak_new(AIBinder* binder) {
	if (binder == nullptr) {
	return nullptr;
	}

	return new AIBinder_Weak{wp<AIBinder>(binder)};
	}
	void AIBinder_Weak_delete(AIBinder_Weak* weakBinder) {
	delete weakBinder;
	}
	AIBinder* AIBinder_Weak_promote(AIBinder_Weak* weakBinder) {
	if (weakBinder == nullptr) {
	return nullptr;
	}

	sp<AIBinder> binder = weakBinder->binder.promote();
	AIBinder_incStrong(binder.get());
	return binder.get();
	}

	AIBinder_Class::AIBinder_Class(const char* interfaceDescriptor, AIBinder_Class_onCreate onCreate,
	AIBinder_Class_onDestroy onDestroy,
	AIBinder_Class_onTransact onTransact)
	: onCreate(onCreate),
	onDestroy(onDestroy),
	onTransact(onTransact),
	mInterfaceDescriptor(interfaceDescriptor) {}

	AIBinder_Class* AIBinder_Class_define(const char* interfaceDescriptor,
	AIBinder_Class_onCreate onCreate,
	AIBinder_Class_onDestroy onDestroy,
	AIBinder_Class_onTransact onTransact) {
	if (interfaceDescriptor == nullptr \|\| onCreate == nullptr \|\| onDestroy == nullptr \|\|
	onTransact == nullptr) {
	return nullptr;
	}

	return new AIBinder_Class(interfaceDescriptor, onCreate, onDestroy, onTransact);
	}

	void AIBinder_Class_setOnDump(AIBinder_Class* clazz, AIBinder_onDump onDump) {
	CHECK(clazz != nullptr) << "setOnDump requires non-null clazz";

	// this is required to be called before instances are instantiated
	clazz->onDump = onDump;
	}

	void AIBinder_Class_setHandleShellCommand(AIBinder_Class* clazz,
	AIBinder_handleShellCommand handleShellCommand) {
	CHECK(clazz != nullptr) << "setHandleShellCommand requires non-null clazz";

	clazz->handleShellCommand = handleShellCommand;
	}

	void AIBinder_DeathRecipient::TransferDeathRecipient::binderDied(const wp<IBinder>& who) {
	CHECK(who == mWho);

	mOnDied(mCookie);

	sp<AIBinder_DeathRecipient> recipient = mParentRecipient.promote();
	sp<IBinder> strongWho = who.promote();

	// otherwise this will be cleaned up later with pruneDeadTransferEntriesLocked
	if (recipient != nullptr && strongWho != nullptr) {
	status_t result = recipient->unlinkToDeath(strongWho, mCookie);
	if (result != ::android::DEAD_OBJECT) {
	LOG(WARNING) << "Unlinking to dead binder resulted in: " << result;
	}
	}

	mWho = nullptr;
	}

	AIBinder_DeathRecipient::AIBinder_DeathRecipient(AIBinder_DeathRecipient_onBinderDied onDied)
	: mOnDied(onDied) {
	CHECK(onDied != nullptr);
	}

	void AIBinder_DeathRecipient::pruneDeadTransferEntriesLocked() {
	mDeathRecipients.erase(std::remove_if(mDeathRecipients.begin(), mDeathRecipients.end(),
	[](const sp<TransferDeathRecipient>& tdr) {
	return tdr->getWho() == nullptr;
	}),
	mDeathRecipients.end());
	}

	binder_status_t AIBinder_DeathRecipient::linkToDeath(sp<IBinder> binder, void* cookie) {
	CHECK(binder != nullptr);

	std::lock_guard<std::mutex> l(mDeathRecipientsMutex);

	sp<TransferDeathRecipient> recipient =
	new TransferDeathRecipient(binder, cookie, this, mOnDied);

	status_t status = binder->linkToDeath(recipient, cookie, 0 /flags/);
	if (status != STATUS_OK) {
	return PruneStatusT(status);
	}

	mDeathRecipients.push_back(recipient);

	pruneDeadTransferEntriesLocked();
	return STATUS_OK;
	}

	binder_status_t AIBinder_DeathRecipient::unlinkToDeath(sp<IBinder> binder, void* cookie) {
	CHECK(binder != nullptr);

	std::lock_guard<std::mutex> l(mDeathRecipientsMutex);

	for (auto it = mDeathRecipients.rbegin(); it != mDeathRecipients.rend(); ++it) {
	sp<TransferDeathRecipient> recipient = *it;

	if (recipient->getCookie() == cookie && recipient->getWho() == binder) {
	mDeathRecipients.erase(it.base() - 1);

	status_t status = binder->unlinkToDeath(recipient, cookie, 0 /flags/);
	if (status != ::android::OK) {
	LOG(ERROR) << __func__
	<< ": removed reference to death recipient but unlink failed.";
	}
	return PruneStatusT(status);
	}
	}

	return STATUS_NAME_NOT_FOUND;
	}

	// start of C-API methods

	AIBinder* AIBinder_new(const AIBinder_Class* clazz, void* args) {
	if (clazz == nullptr) {
	LOG(ERROR) << __func__ << ": Must provide class to construct local binder.";
	return nullptr;
	}

	void* userData = clazz->onCreate(args);

	sp<AIBinder> ret = new ABBinder(clazz, userData);
	ABBinderTag::attach(ret->getBinder());

	AIBinder_incStrong(ret.get());
	return ret.get();
	}

	bool AIBinder_isRemote(const AIBinder* binder) {
	if (binder == nullptr) {
	return false;
	}

	return binder->isRemote();
	}

	bool AIBinder_isAlive(const AIBinder* binder) {
	if (binder == nullptr) {
	return false;
	}

	return const_cast<AIBinder*>(binder)->getBinder()->isBinderAlive();
	}

	binder_status_t AIBinder_ping(AIBinder* binder) {
	if (binder == nullptr) {
	return STATUS_UNEXPECTED_NULL;
	}

	return PruneStatusT(binder->getBinder()->pingBinder());
	}

	binder_status_t AIBinder_dump(AIBinder* binder, int fd, const char** args, uint32_t numArgs) {
	if (binder == nullptr) {
	return STATUS_UNEXPECTED_NULL;
	}

	ABBinder* bBinder = binder->asABBinder();
	if (bBinder != nullptr) {
	AIBinder_onDump onDump = binder->getClass()->onDump;
	if (onDump == nullptr) {
	return STATUS_OK;
	}
	return PruneStatusT(onDump(bBinder, fd, args, numArgs));
	}

	::android::Vector<String16> utf16Args;
	utf16Args.setCapacity(numArgs);
	for (uint32_t i = 0; i < numArgs; i++) {
	utf16Args.push(String16(String8(args[i])));
	}

	status_t status = binder->getBinder()->dump(fd, utf16Args);
	return PruneStatusT(status);
	}

	binder_status_t AIBinder_linkToDeath(AIBinder* binder, AIBinder_DeathRecipient* recipient,
	void* cookie) {
	if (binder == nullptr \|\| recipient == nullptr) {
	LOG(ERROR) << __func__ << ": Must provide binder and recipient.";
	return STATUS_UNEXPECTED_NULL;
	}

	// returns binder_status_t
	return recipient->linkToDeath(binder->getBinder(), cookie);
	}

	binder_status_t AIBinder_unlinkToDeath(AIBinder* binder, AIBinder_DeathRecipient* recipient,
	void* cookie) {
	if (binder == nullptr \|\| recipient == nullptr) {
	LOG(ERROR) << __func__ << ": Must provide binder and recipient.";
	return STATUS_UNEXPECTED_NULL;
	}

	// returns binder_status_t
	return recipient->unlinkToDeath(binder->getBinder(), cookie);
	}

	uid_t AIBinder_getCallingUid() {
	return ::android::IPCThreadState::self()->getCallingUid();
	}

	pid_t AIBinder_getCallingPid() {
	return ::android::IPCThreadState::self()->getCallingPid();
	}

	void AIBinder_incStrong(AIBinder* binder) {
	if (binder == nullptr) {
	return;
	}

	binder->incStrong(nullptr);
	}
	void AIBinder_decStrong(AIBinder* binder) {
	if (binder == nullptr) {
	LOG(ERROR) << __func__ << ": on null binder";
	return;
	}

	binder->decStrong(nullptr);
	}
	int32_t AIBinder_debugGetRefCount(AIBinder* binder) {
	if (binder == nullptr) {
	LOG(ERROR) << __func__ << ": on null binder";
	return -1;
	}

	return binder->getStrongCount();
	}

	bool AIBinder_associateClass(AIBinder* binder, const AIBinder_Class* clazz) {
	if (binder == nullptr) {
	return false;
	}

	return binder->associateClass(clazz);
	}

	const AIBinder_Class* AIBinder_getClass(AIBinder* binder) {
	if (binder == nullptr) {
	return nullptr;
	}

	return binder->getClass();
	}

	void* AIBinder_getUserData(AIBinder* binder) {
	if (binder == nullptr) {
	return nullptr;
	}

	ABBinder* bBinder = binder->asABBinder();
	if (bBinder == nullptr) {
	return nullptr;
	}

	return bBinder->getUserData();
	}

	binder_status_t AIBinder_prepareTransaction(AIBinder* binder, AParcel** in) {
	if (binder == nullptr \|\| in == nullptr) {
	LOG(ERROR) << __func__ << ": requires non-null parameters.";
	return STATUS_UNEXPECTED_NULL;
	}
	const AIBinder_Class* clazz = binder->getClass();
	if (clazz == nullptr) {
	LOG(ERROR) << __func__
	<< ": Class must be defined for a remote binder transaction. See "
	"AIBinder_associateClass.";
	return STATUS_INVALID_OPERATION;
	}

	if (!binder->isRemote()) {
	LOG(WARNING) << "A binder object at " << binder
	<< " is being transacted on, however, this object is in the same process as "
	"its proxy. Transacting with this binder is expensive compared to just "
	"calling the corresponding functionality in the same process.";
	}

	*in = new AParcel(binder);
	status_t status = (*in)->get()->writeInterfaceToken(clazz->getInterfaceDescriptor());
	binder_status_t ret = PruneStatusT(status);

	if (ret != STATUS_OK) {
	delete *in;
	*in = nullptr;
	}

	return ret;
	}

	static void DestroyParcel(AParcel** parcel) {
	delete *parcel;
	*parcel = nullptr;
	}

	binder_status_t AIBinder_transact(AIBinder* binder, transaction_code_t code, AParcel** in,
	AParcel** out, binder_flags_t flags) {
	if (in == nullptr) {
	LOG(ERROR) << __func__ << ": requires non-null in parameter";
	return STATUS_UNEXPECTED_NULL;
	}

	using AutoParcelDestroyer = std::unique_ptr<AParcel, void ()(AParcel**)>;
	// This object is the input to the transaction. This function takes ownership of it and deletes
	// it.
	AutoParcelDestroyer forIn(in, DestroyParcel);

	if (!isUserCommand(code)) {
	LOG(ERROR) << __func__ << ": Only user-defined transactions can be made from the NDK.";
	return STATUS_UNKNOWN_TRANSACTION;
	}

	constexpr binder_flags_t kAllFlags = FLAG_PRIVATE_VENDOR \| FLAG_ONEWAY;
	if ((flags & ~kAllFlags) != 0) {
	LOG(ERROR) << __func__ << ": Unrecognized flags sent: " << flags;
	return STATUS_BAD_VALUE;
	}

	if (binder == nullptr \|\| *in == nullptr \|\| out == nullptr) {
	LOG(ERROR) << __func__ << ": requires non-null parameters.";
	return STATUS_UNEXPECTED_NULL;
	}

	if ((*in)->getBinder() != binder) {
	LOG(ERROR) << __func__ << ": parcel is associated with binder object " << binder
	<< " but called with " << (*in)->getBinder();
	return STATUS_BAD_VALUE;
	}

	*out = new AParcel(binder);

	status_t status = binder->getBinder()->transact(code, (in)->get(), (*out)->get(), flags);
	binder_status_t ret = PruneStatusT(status);

	if (ret != STATUS_OK) {
	delete *out;
	*out = nullptr;
	}

	return ret;
	}

	AIBinder_DeathRecipient* AIBinder_DeathRecipient_new(
	AIBinder_DeathRecipient_onBinderDied onBinderDied) {
	if (onBinderDied == nullptr) {
	LOG(ERROR) << __func__ << ": requires non-null onBinderDied parameter.";
	return nullptr;
	}
	auto ret = new AIBinder_DeathRecipient(onBinderDied);
	ret->incStrong(nullptr);
	return ret;
	}

	void AIBinder_DeathRecipient_delete(AIBinder_DeathRecipient* recipient) {
	if (recipient == nullptr) {
	return;
	}

	recipient->decStrong(nullptr);
	}

	binder_status_t AIBinder_getExtension(AIBinder* binder, AIBinder** outExt) {
	if (binder == nullptr \|\| outExt == nullptr) {
	if (outExt != nullptr) {
	*outExt = nullptr;
	}
	return STATUS_UNEXPECTED_NULL;
	}

	sp<IBinder> ext;
	status_t res = binder->getBinder()->getExtension(&ext);

	if (res != android::OK) {
	*outExt = nullptr;
	return PruneStatusT(res);
	}

	sp<AIBinder> ret = ABpBinder::lookupOrCreateFromBinder(ext);
	if (ret != nullptr) ret->incStrong(binder);

	*outExt = ret.get();
	return STATUS_OK;
	}

	binder_status_t AIBinder_setExtension(AIBinder* binder, AIBinder* ext) {
	if (binder == nullptr \|\| ext == nullptr) {
	return STATUS_UNEXPECTED_NULL;
	}

	ABBinder* rawBinder = binder->asABBinder();
	if (rawBinder == nullptr) {
	return STATUS_INVALID_OPERATION;
	}

	rawBinder->setExtension(ext->getBinder());
	return STATUS_OK;
	}