Initial C library for libbinder.
This creates a simple wrapper around libbinder with a stable C ABI. It
also embeds the concept of an IBinder and IBinder transactions into the
ABI so that parts of their transactions can be changed and considered
implementation details of libbinder. With this basic class, you can
create a service, use it with primitive data types, but it does not yet
suppport the entire range of binder objects.
Follow-up items to handle/things still to consider
- b/112664205: make aidl-gen produce interfaces that use these (and
think about interoperation with existing interfaces).
- using onServiceConnected/onServiceDisconnected in the NDK
- if libbinder/libbinder_ndk classes use the same descriptor, there will
be problems in the same process (libbinder{_ndk} assumes binder class)
- sometimes getService takes 1s since there is a race for it getting
registered
- add generic class which allows for easy implementation of a class like
IFoo in this test.
- Parcel for additional types (and additional APIs, like data available)
- addition of APIs like AIBinder_ping/linkToDeath which all binders have
- embed Status into this API layer (so EX_HAS_REPLY_HEADER is handled)
- make remoteBinder/localBinder is const (and therefore isRemote)
- okay with associateClass or should just use interfaceDescriptor
- potentially changing out incStrong/decStrong
- adding @file/@addtogroup to comments
Bug: 111445392
Test: ndk/runtests.sh
Change-Id: Ifbca8f0fdf70a3213fe0d94320fc31eeb62408c4
diff --git a/libs/binder/ndk/AIBinder.cpp b/libs/binder/ndk/AIBinder.cpp
new file mode 100644
index 0000000..d0ce98d
--- /dev/null
+++ b/libs/binder/ndk/AIBinder.cpp
@@ -0,0 +1,345 @@
+/*
+ * 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 "AIBinder_internal.h"
+
+#include <android/binder_status.h>
+#include "AParcel_internal.h"
+
+#include <android-base/logging.h>
+
+using ::android::IBinder;
+using ::android::Parcel;
+using ::android::sp;
+using ::android::String16;
+using ::android::wp;
+
+AIBinder::AIBinder(const AIBinder_Class* clazz) : mClazz(clazz) {}
+AIBinder::~AIBinder() {}
+
+sp<AIBinder> AIBinder::associateClass(const AIBinder_Class* clazz) {
+ using ::android::String8;
+
+ if (clazz == nullptr) return nullptr;
+ if (mClazz == clazz) return this;
+
+ 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?";
+ return nullptr;
+ }
+
+ 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()
+ << "'.";
+ return nullptr;
+ }
+
+ 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 nullptr;
+ }
+
+ // The descriptor matches, so if it is local, this is guaranteed to be the libbinder_ndk class.
+ // An error here can occur if there is a conflict between descriptors (two unrelated classes
+ // define the same descriptor), but this should never happen.
+
+ // if this is a local ABBinder, mClazz should be non-null
+ CHECK(asABBinder() == nullptr);
+ CHECK(asABpBinder() != nullptr);
+
+ if (!isRemote()) {
+ // ABpBinder but proxy to a local object. Therefore that local object must be an ABBinder.
+ ABBinder* binder = static_cast<ABBinder*>(getBinder().get());
+ return binder;
+ }
+
+ // This is a remote object
+ mClazz = clazz;
+
+ return this;
+}
+
+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();
+}
+
+binder_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 EX_ILLEGAL_STATE;
+ }
+
+ const AParcel in = AParcel::readOnly(this, &data);
+ AParcel out = AParcel(this, reply, false /*owns*/);
+
+ return getClass()->onTransact(this, code, &in, &out);
+ } else {
+ return BBinder::onTransact(code, data, reply, flags);
+ }
+}
+
+ABpBinder::ABpBinder(::android::sp<::android::IBinder> binder)
+ : AIBinder(nullptr /*clazz*/), BpRefBase(binder) {
+ CHECK(binder != nullptr);
+}
+ABpBinder::~ABpBinder() {}
+
+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);
+}
+
+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);
+
+ AIBinder* ret = new ABBinder(clazz, userData);
+ AIBinder_incStrong(ret);
+ return ret;
+}
+
+bool AIBinder_isRemote(AIBinder* binder) {
+ if (binder == nullptr) {
+ return true;
+ }
+
+ return binder->isRemote();
+}
+
+void AIBinder_incStrong(AIBinder* binder) {
+ if (binder == nullptr) {
+ LOG(ERROR) << __func__ << ": on null binder";
+ 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();
+}
+
+void AIBinder_associateClass(AIBinder** binder, const AIBinder_Class* clazz) {
+ if (binder == nullptr || *binder == nullptr) {
+ return;
+ }
+
+ sp<AIBinder> result = (*binder)->associateClass(clazz);
+
+ // This function takes one refcount of 'binder' and delivers one refcount of 'result' to the
+ // callee. First we give the callee their refcount and then take it away from binder. This is
+ // done in this order in order to handle the case that the result and the binder are the same
+ // object.
+ if (result != nullptr) {
+ AIBinder_incStrong(result.get());
+ }
+ AIBinder_decStrong(*binder);
+
+ *binder = result.get(); // Maybe no-op
+}
+
+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 EX_NULL_POINTER;
+ }
+ 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 EX_ILLEGAL_STATE;
+ }
+
+ *in = new AParcel(binder);
+ binder_status_t status = (**in)->writeInterfaceToken(clazz->getInterfaceDescriptor());
+ if (status != EX_NONE) {
+ delete *in;
+ *in = nullptr;
+ }
+
+ return status;
+}
+
+using AutoParcelDestroyer = std::unique_ptr<AParcel*, void (*)(AParcel**)>;
+static void destroy_parcel(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 EX_NULL_POINTER;
+ }
+
+ // This object is the input to the transaction. This function takes ownership of it and deletes
+ // it.
+ AutoParcelDestroyer forIn(in, destroy_parcel);
+
+ if (!isUserCommand(code)) {
+ LOG(ERROR) << __func__ << ": Only user-defined transactions can be made from the NDK.";
+ return EX_UNSUPPORTED_OPERATION;
+ }
+
+ if ((flags & ~FLAG_ONEWAY) != 0) {
+ LOG(ERROR) << __func__ << ": Unrecognized flags sent: " << flags;
+ return EX_ILLEGAL_ARGUMENT;
+ }
+
+ if (binder == nullptr || *in == nullptr || out == nullptr) {
+ LOG(ERROR) << __func__ << ": requires non-null parameters.";
+ return EX_NULL_POINTER;
+ }
+
+ if ((*in)->getBinder() != binder) {
+ LOG(ERROR) << __func__ << ": parcel is associated with binder object " << binder
+ << " but called with " << (*in)->getBinder();
+ return EX_ILLEGAL_STATE;
+ }
+
+ *out = new AParcel(binder);
+
+ binder_status_t parcelStatus =
+ binder->getBinder()->transact(code, *(*in)->operator->(), (*out)->operator->(), flags);
+
+ if (parcelStatus != EX_NONE) {
+ delete *out;
+ *out = nullptr;
+ }
+
+ return parcelStatus;
+}
+
+binder_status_t AIBinder_finalizeTransaction(AIBinder* binder, AParcel** out) {
+ if (out == nullptr) {
+ LOG(ERROR) << __func__ << ": requires non-null out parameter";
+ return EX_NULL_POINTER;
+ }
+
+ // This object is the input to the transaction. This function takes ownership of it and deletes
+ // it.
+ AutoParcelDestroyer forOut(out, destroy_parcel);
+
+ if (binder == nullptr || *out == nullptr) {
+ LOG(ERROR) << __func__ << ": requires non-null parameters.";
+ return EX_NULL_POINTER;
+ }
+
+ if ((*out)->getBinder() != binder) {
+ LOG(ERROR) << __func__ << ": parcel is associated with binder object " << binder
+ << " but called with " << (*out)->getBinder();
+ return EX_ILLEGAL_STATE;
+ }
+
+ if ((**out)->dataAvail() != 0) {
+ LOG(ERROR) << __func__
+ << ": Only part of this transaction was read. There is remaining data left.";
+ return EX_ILLEGAL_STATE;
+ }
+
+ return EX_NONE;
+}