Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ffdaf7b0 authored by Devin Moore's avatar Devin Moore
Browse files

Add a delegate helper for AIDL Delegators 

This will check if the binder already has/is a delegator by looking in the
attached objects and attempting to promote the object with the right
objectID.
If the object is already a delegator, it will be unwrapped.
If the object already has a delegator, the delegator will be returned
instead.
If neither of those is true, it will create new delegator that wraps the
binder and return the new delegator.

Test: atest binderUnitTest aidl_integration_test
Bug: 220141324
Change-Id: Ide61342ae5eb30525196384b40c460934146621f
parent 3faaa000

libs/binder/include/binder/Delegate.h

0 → 100644
+93 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2022 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.

 */



#pragma once



#include <binder/IBinder.h>



#ifndef __BIONIC__

#ifndef __assert



// defined differently by liblog

#pragma push_macro("LOG_PRI")

#ifdef LOG_PRI

#undef LOG_PRI

#endif

#include <syslog.h>

#pragma pop_macro("LOG_PRI")



#define __assert(a, b, c)          \

    do {                           \

        syslog(LOG_ERR, a ": " c); \

        abort();                   \

    } while (false)

#endif // __assert

#endif // __BIONIC__



namespace android {



/*

 * Used to manage AIDL's *Delegator types.

 * This is used to:

 * - create a new *Delegator object that delegates to the binder argument.

 * - or return an existing *Delegator object that already delegates to the

 * binder argument.

 * - or return the underlying delegate binder if the binder argument is a

 * *Delegator itself.

 *

 * @param binder - the binder to delegate to or unwrap

 *

 * @return pointer to the *Delegator object or the unwrapped binder object

 */

template <typename T>

sp<T> delegate(const sp<T>& binder) {

    const void* isDelegatorId = &T::descriptor;

    const void* hasDelegatorId = &T::descriptor + 1;

    // is binder itself a delegator?

    if (T::asBinder(binder)->findObject(isDelegatorId)) {

        if (T::asBinder(binder)->findObject(hasDelegatorId)) {

            __assert(__FILE__, __LINE__,

                     "This binder has a delegator and is also delegator itself! This is "

                     "likely an unintended mixing of binders.");

            return nullptr;

        }

        // unwrap the delegator

        return static_cast<typename T::DefaultDelegator*>(binder.get())->getImpl();

    }



    struct MakeArgs {

        const sp<T>* binder;

        const void* id;

    } makeArgs;

    makeArgs.binder = &binder;

    makeArgs.id = isDelegatorId;



    // the binder is not a delegator, so construct one

    sp<IBinder> newDelegator = T::asBinder(binder)->lookupOrCreateWeak(

            hasDelegatorId,

            [](const void* args) -> sp<IBinder> {

                auto delegator = sp<typename T::DefaultDelegator>::make(

                        *static_cast<const MakeArgs*>(args)->binder);

                // make sure we know this binder is a delegator by attaching a unique ID

                (void)delegator->attachObject(static_cast<const MakeArgs*>(args)->id,

                                              reinterpret_cast<void*>(0x1), nullptr, nullptr);

                return delegator;

            },

            static_cast<const void*>(&makeArgs));

    return sp<typename T::DefaultDelegator>::cast(newDelegator);

}



} // namespace android