1 /*
2  * Copyright (C) 2020 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #pragma once
18 
19 // WARNING: DO NOT USE THIS
20 // You should:
21 // - have code know how it is handling things. Pass in caller information rather
22 //   than assuming that code is running in a specific global context
23 // - use AIDL exclusively in your stack (HIDL is no longer required anywhere)
24 
25 #include <binder/IPCThreadState.h>
26 #include <hwbinder/IPCThreadState.h>
27 
28 namespace android {
29 
30 enum class BinderCallType {
31     NONE,
32     BINDER,
33     HWBINDER,
34 };
35 
36 // Based on where we are in recursion of nested binder/hwbinder calls, determine
37 // which one we are closer to.
getCurrentServingCall()38 inline static BinderCallType getCurrentServingCall() {
39     const void* hwbinderSp = android::hardware::IPCThreadState::self()->getServingStackPointer();
40     const void* binderSp = android::IPCThreadState::self()->getServingStackPointer();
41 
42     if (hwbinderSp == nullptr && binderSp == nullptr) return BinderCallType::NONE;
43     if (hwbinderSp == nullptr) return BinderCallType::BINDER;
44     if (binderSp == nullptr) return BinderCallType::HWBINDER;
45 
46     if (hwbinderSp < binderSp) return BinderCallType::HWBINDER;
47     return BinderCallType::BINDER;
48 }
49 
50 } // namespace android
51