transport/include/hidl/HidlBinderSupport.h

/*
 * Copyright (C) 2016 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.
 */

#ifndef ANDROID_HIDL_BINDER_SUPPORT_H
#define ANDROID_HIDL_BINDER_SUPPORT_H

#include <hidl/HidlSupport.h>
#include <hidl/HidlTransportUtils.h>
#include <hidl/MQDescriptor.h>
#include <hidl/Static.h>
#include <hwbinder/IBinder.h>
#include <hwbinder/Parcel.h>
#include <android/hidl/base/1.0/BnBase.h>
// Defines functions for hidl_string, hidl_version, Status, hidl_vec, MQDescriptor,
// etc. to interact with Parcel.

namespace android {
namespace hardware {

// ---------------------- hidl_memory

status_t readEmbeddedFromParcel(hidl_memory *memory,
        const Parcel &parcel, size_t parentHandle, size_t parentOffset);

status_t writeEmbeddedToParcel(const hidl_memory &memory,
        Parcel *parcel, size_t parentHandle, size_t parentOffset);

// ---------------------- hidl_string

status_t readEmbeddedFromParcel(hidl_string *string,
        const Parcel &parcel, size_t parentHandle, size_t parentOffset);

status_t writeEmbeddedToParcel(const hidl_string &string,
        Parcel *parcel, size_t parentHandle, size_t parentOffset);

// ---------------------- hidl_version

status_t writeToParcel(const hidl_version &version, android::hardware::Parcel& parcel);

// Caller is responsible for freeing the returned object.
hidl_version* readFromParcel(const android::hardware::Parcel& parcel);

// ---------------------- Status

// Bear in mind that if the client or service is a Java endpoint, this
// is not the logic which will provide/interpret the data here.
status_t readFromParcel(Status *status, const Parcel& parcel);
status_t writeToParcel(const Status &status, Parcel* parcel);

// ---------------------- hidl_vec

template<typename T>
status_t readEmbeddedFromParcel(
        hidl_vec<T> * /*vec*/,
        const Parcel &parcel,
        size_t parentHandle,
        size_t parentOffset,
        size_t *handle) {
    const void *ptr = parcel.readEmbeddedBuffer(
            handle,
            parentHandle,
            parentOffset + hidl_vec<T>::kOffsetOfBuffer);

    return ptr != NULL ? OK : UNKNOWN_ERROR;
}

template<typename T>
status_t writeEmbeddedToParcel(
        const hidl_vec<T> &vec,
        Parcel *parcel,
        size_t parentHandle,
        size_t parentOffset,
        size_t *handle) {
    return parcel->writeEmbeddedBuffer(
            vec.data(),
            sizeof(T) * vec.size(),
            handle,
            parentHandle,
            parentOffset + hidl_vec<T>::kOffsetOfBuffer);
}

template<typename T>
status_t findInParcel(const hidl_vec<T> &vec, const Parcel &parcel, size_t *handle) {
    return parcel.quickFindBuffer(vec.data(), handle);
}

// ---------------------- MQDescriptor

template<MQFlavor flavor>
::android::status_t readEmbeddedFromParcel(
        MQDescriptor<flavor> *obj,
        const ::android::hardware::Parcel &parcel,
        size_t parentHandle,
        size_t parentOffset) {
    ::android::status_t _hidl_err = ::android::OK;

    size_t _hidl_grantors_child;

    _hidl_err = ::android::hardware::readEmbeddedFromParcel(
                &obj->grantors(),
                parcel,
                parentHandle,
                parentOffset + MQDescriptor<flavor>::kOffsetOfGrantors,
                &_hidl_grantors_child);

    if (_hidl_err != ::android::OK) { return _hidl_err; }

    const native_handle_t *_hidl_mq_handle_ptr = parcel.readEmbeddedNativeHandle(
            parentHandle,
            parentOffset + MQDescriptor<flavor>::kOffsetOfHandle);

    if (_hidl_mq_handle_ptr == nullptr) {
        _hidl_err = ::android::UNKNOWN_ERROR;
        return _hidl_err;
    }

    return _hidl_err;
}

template<MQFlavor flavor>
::android::status_t writeEmbeddedToParcel(
        const MQDescriptor<flavor> &obj,
        ::android::hardware::Parcel *parcel,
        size_t parentHandle,
        size_t parentOffset) {
    ::android::status_t _hidl_err = ::android::OK;

    size_t _hidl_grantors_child;

    _hidl_err = ::android::hardware::writeEmbeddedToParcel(
            obj.grantors(),
            parcel,
            parentHandle,
            parentOffset + MQDescriptor<flavor>::kOffsetOfGrantors,
            &_hidl_grantors_child);

    if (_hidl_err != ::android::OK) { return _hidl_err; }

    _hidl_err = parcel->writeEmbeddedNativeHandle(
            obj.handle(),
            parentHandle,
            parentOffset + MQDescriptor<flavor>::kOffsetOfHandle);

    if (_hidl_err != ::android::OK) { return _hidl_err; }

    return _hidl_err;
}

// ---------------------- pointers for HIDL

template <typename T>
static status_t readEmbeddedReferenceFromParcel(
        T const* * /* bufptr */,
        const Parcel & parcel,
        size_t parentHandle,
        size_t parentOffset,
        size_t *handle,
        bool *shouldResolveRefInBuffer
    ) {
    // *bufptr is ignored because, if I am embedded in some
    // other buffer, the kernel should have fixed me up already.
    bool isPreviouslyWritten;
    status_t result = parcel.readEmbeddedReference(
        nullptr, // ignored, not written to bufptr.
        handle,
        parentHandle,
        parentOffset,
        &isPreviouslyWritten);
    // tell caller to run T::readEmbeddedToParcel and
    // T::readEmbeddedReferenceToParcel if necessary.
    // It is not called here because we don't know if these two are valid methods.
    *shouldResolveRefInBuffer = !isPreviouslyWritten;
    return result;
}

template <typename T>
static status_t writeEmbeddedReferenceToParcel(
        T const* buf,
        Parcel *parcel, size_t parentHandle, size_t parentOffset,
        size_t *handle,
        bool *shouldResolveRefInBuffer
        ) {

    if(buf == nullptr) {
        *shouldResolveRefInBuffer = false;
        return parcel->writeEmbeddedNullReference(handle, parentHandle, parentOffset);
    }

    // find whether the buffer exists
    size_t childHandle, childOffset;
    status_t result;
    bool found;

    result = parcel->findBuffer(buf, sizeof(T), &found, &childHandle, &childOffset);

    // tell caller to run T::writeEmbeddedToParcel and
    // T::writeEmbeddedReferenceToParcel if necessary.
    // It is not called here because we don't know if these two are valid methods.
    *shouldResolveRefInBuffer = !found;

    if(result != OK) {
        return result; // bad pointers and length given
    }
    if(!found) { // did not find it.
        return parcel->writeEmbeddedBuffer(buf, sizeof(T), handle,
                parentHandle, parentOffset);
    }
    // found the buffer. easy case.
    return parcel->writeEmbeddedReference(
            handle,
            childHandle,
            childOffset,
            parentHandle,
            parentOffset);
}

template <typename T>
static status_t readReferenceFromParcel(
        T const* *bufptr,
        const Parcel & parcel,
        size_t *handle,
        bool *shouldResolveRefInBuffer
    ) {
    bool isPreviouslyWritten;
    status_t result = parcel.readReference(reinterpret_cast<void const* *>(bufptr),
            handle, &isPreviouslyWritten);
    // tell caller to run T::readEmbeddedToParcel and
    // T::readEmbeddedReferenceToParcel if necessary.
    // It is not called here because we don't know if these two are valid methods.
    *shouldResolveRefInBuffer = !isPreviouslyWritten;
    return result;
}

template <typename T>
static status_t writeReferenceToParcel(
        T const *buf,
        Parcel * parcel,
        size_t *handle,
        bool *shouldResolveRefInBuffer
    ) {

    if(buf == nullptr) {
        *shouldResolveRefInBuffer = false;
        return parcel->writeNullReference(handle);
    }

    // find whether the buffer exists
    size_t childHandle, childOffset;
    status_t result;
    bool found;

    result = parcel->findBuffer(buf, sizeof(T), &found, &childHandle, &childOffset);

    // tell caller to run T::writeEmbeddedToParcel and
    // T::writeEmbeddedReferenceToParcel if necessary.
    // It is not called here because we don't know if these two are valid methods.
    *shouldResolveRefInBuffer = !found;

    if(result != OK) {
        return result; // bad pointers and length given
    }
    if(!found) { // did not find it.
        return parcel->writeBuffer(buf, sizeof(T), handle);
    }
    // found the buffer. easy case.
    return parcel->writeReference(handle,
        childHandle, childOffset);
}

// ---------------------- support for casting interfaces

// Construct a smallest possible binder from the given interface.
// If it is remote, then its remote() will be retrieved.
// Otherwise, the smallest possible BnChild is found where IChild is a subclass of IType
// and iface is of class IChild. BnChild will be used to wrapped the given iface.
// Return nullptr if iface is null or any failure.
template <typename IType, typename ProxyType>
sp<IBinder> toBinder(sp<IType> iface) {
    IType *ifacePtr = iface.get();
    if (ifacePtr == nullptr) {
        return nullptr;
    }
    if (ifacePtr->isRemote()) {
        return ::android::hardware::IInterface::asBinder(static_cast<ProxyType *>(ifacePtr));
    } else {
        std::string myDescriptor = getDescriptor(ifacePtr);
        if (myDescriptor.empty()) {
            // interfaceChain fails
            return nullptr;
        }
        auto iter = gBnConstructorMap.find(myDescriptor);
        if (iter == gBnConstructorMap.end()) {
            return nullptr;
        }
        return sp<IBinder>((iter->second)(reinterpret_cast<void *>(ifacePtr)));
    }
}

template <typename IType, typename ProxyType, typename StubType>
sp<IType> fromBinder(const sp<IBinder>& binderIface) {
    using ::android::hidl::base::V1_0::IBase;
    using ::android::hidl::base::V1_0::BnBase;

    if (binderIface.get() == nullptr) {
        return nullptr;
    }
    if (binderIface->localBinder() == nullptr) {
        return new ProxyType(binderIface);
    }
    sp<IBase> base = static_cast<BnBase*>(binderIface.get())->getImpl();
    if (canCastInterface(base.get(), IType::descriptor)) {
        StubType* stub = static_cast<StubType*>(binderIface.get());
        return stub->getImpl();
    } else {
        return nullptr;
    }
}

}  // namespace hardware
}  // namespace android


#endif  // ANDROID_HIDL_BINDER_SUPPORT_H