HidlTransportSupport.h revision 00f4a391c6f9a698bbcbbd05bf3d80e213c82884 
1/*
2 * Copyright (C) 2016 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#ifndef ANDROID_HIDL_TRANSPORT_SUPPORT_H
18#define ANDROID_HIDL_TRANSPORT_SUPPORT_H
19
20#include <hidl/HidlSupport.h>
21#include <hidl/HidlBinderSupport.h>
22
23namespace android {
24namespace hardware {
25
26// cast the interface IParent to IChild.
27// Return nullptr if parent is null or any failure.
28template<typename IChild, typename IParent, typename BpChild, typename IHwParent>
29sp<IChild> castInterface(sp<IParent> parent, const char *childIndicator) {
30    if (parent.get() == nullptr) {
31        // casts always succeed with nullptrs.
32        return nullptr;
33    }
34    bool canCast = false;
35    parent->interfaceChain([&](const hidl_vec<hidl_string> &allowedCastTypes) {
36        for (size_t i = 0; i < allowedCastTypes.size(); i++) {
37            if (allowedCastTypes[i] == childIndicator) {
38                canCast = true;
39                break;
40            }
41        }
42    });
43
44    if (!canCast) {
45        return sp<IChild>(nullptr); // cast failed.
46    }
47    // TODO b/32001926 Needs to be fixed for socket mode.
48    if (parent->isRemote()) {
49        // binderized mode. Got BpChild. grab the remote and wrap it.
50        return sp<IChild>(new BpChild(toBinder<IParent, IHwParent>(parent)));
51    }
52    // Passthrough mode. Got BnChild and BsChild.
53    return sp<IChild>(static_cast<IChild *>(parent.get()));
54}
55
56}  // namespace hardware
57}  // namespace android
58
59
60#endif  // ANDROID_HIDL_TRANSPORT_SUPPORT_H
61