transport/include/hidl/HidlPassthroughSupport.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_PASSTHROUGH_SUPPORT_H
#define ANDROID_HIDL_PASSTHROUGH_SUPPORT_H

#include <android/hidl/base/1.0/IBase.h>

namespace android {
namespace hardware {
namespace details {

/*
 * Wrap the given interface with the smallest BsChild possible. Will return the
 * argument directly if nullptr or isRemote().
 */
template <typename IType,
          typename = std::enable_if_t<std::is_same<i_tag, typename IType::_hidl_tag>::value>>
sp<IType> wrapPassthrough(sp<IType> iface) {
    using ::android::hidl::base::V1_0::IBase;

    if (iface.get() == nullptr || iface->isRemote()) {
        // doesn't know how to handle it.
        return iface;
    }
    std::string myDescriptor = getDescriptor(iface.get());
    if (myDescriptor.empty()) {
        // interfaceDescriptor fails
        return nullptr;
    }
    auto func = gBsConstructorMap.get(myDescriptor, nullptr);
    if (!func) {
        return nullptr;
    }

    sp<IBase> base = func(static_cast<void*>(iface.get()));

    // would normally call castFrom, but gBsConstructorMap guarantees
    // that its result is of the appropriate type (not necessaryly
    // BsType, but definitely a child of IType).
    return sp<IType>(static_cast<IType*>(base.get()));
}

}  // namespace details
}  // namespace hardware
}  // namespace android


#endif  // ANDROID_HIDL_PASSTHROUGH_SUPPORT_H