libs/binder/ndk/AIBinder.cpp

/*
 * 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;

namespace ABBinderTag {

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

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

} // namespace ABBinderTag

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

bool AIBinder::associateClass(const AIBinder_Class* clazz) {
    using ::android::String8;

    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();
}

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

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

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) {
    if (weakBinder == nullptr) {
        return;
    }

    delete *weakBinder;
    *weakBinder = nullptr;
}
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);

    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 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();
}

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 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;
    }

    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);
    binder_status_t status = (**in)->writeInterfaceToken(clazz->getInterfaceDescriptor());
    if (status != EX_NONE) {
        delete *in;
        *in = nullptr;
    }

    return status;
}

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;
    }

    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, AParcel_delete);

    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;
}