1 /*
2 * Copyright (C) 2021 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 CPP_CAR_BINDER_LIB_LARGEPARCELABLE_INCLUDE_LARGEPARCELABLE_H_
18 #define CPP_CAR_BINDER_LIB_LARGEPARCELABLE_INCLUDE_LARGEPARCELABLE_H_
19
20 #include "LargeParcelableBase.h"
21 #include "SharedMemory.h"
22
23 #include <android/binder_parcel.h>
24 #include <android/binder_parcel_utils.h>
25 #include <android/binder_status.h>
26
27 #include <memory>
28 #include <optional>
29
30 namespace android {
31 namespace automotive {
32 namespace car_binder_lib {
33
34 // This class allows a stable AIDL parcelable to be marshalled to a shared memory file if its
35 // serialized parcel exceeds binder limitation.
36 template <class T>
37 class LargeParcelable : public LargeParcelableBase {
38 public:
LargeParcelable()39 LargeParcelable() {}
40
41 // Use an existing stable AIDL parcelable to initiate this large parcelable. The input
42 // parcelable's marshal/unmarshal method would be used to read/write from a shared memory
43 // file if needed.
44 //
45 // T must be a Parcelable.
LargeParcelable(std::unique_ptr<T> parcelable)46 explicit LargeParcelable(std::unique_ptr<T> parcelable) : mParcelable(std::move(parcelable)) {}
47
48 // Get the stable AIDL parcelable object. Caller is supposed to use 'LargeParcelable' class to
49 // parse data from 'AParcel' and then use 'getParcelable' to get the underlying parsed regular
50 // parcelable object.
getParcelable()51 inline const std::optional<const T*> getParcelable() const {
52 if (!hasDeserializedParcelable() || mParcelable == nullptr) {
53 return std::nullopt;
54 }
55 return mParcelable.get();
56 }
57
58 protected:
59 // Serialize this parcelable to 'dest'.
60 binder_status_t serialize(AParcel* dest) const override;
61
62 // Serialize a NULL parcelable for 'this' class to 'dest'.
63 binder_status_t serializeNullPayload(AParcel* dest) const override;
64
65 // Read a 'Parcelable' from the given AParcel. The src might be parsed to a NULL parcelable.
66 binder_status_t deserialize(const AParcel& src) override;
67
68 private:
69 std::unique_ptr<T> mParcelable;
70
71 // Serialize a nullable Parcelabel 'payload' to 'dest'.
72 static binder_status_t serializeNullablePayload(const T* payload, AParcel* dest);
73 };
74
75 template <class T>
serializeNullablePayload(const T * payload,AParcel * dest)76 binder_status_t LargeParcelable<T>::serializeNullablePayload(const T* payload, AParcel* dest) {
77 int32_t startPosition;
78 if (DBG_PAYLOAD) {
79 startPosition = AParcel_getDataPosition(dest);
80 }
81 if (payload == nullptr) {
82 // Write a null parcelable.
83 if (binder_status_t status =
84 ::ndk::AParcel_writeNullableParcelable(dest, std::optional<T>(std::nullopt));
85 status != STATUS_OK) {
86 ALOGE("failed to write null parcelable to parcel, status: %d", status);
87 return status;
88 }
89 } else {
90 if (binder_status_t status = ::ndk::AParcel_writeParcelable(dest, *payload);
91 status != STATUS_OK) {
92 ALOGE("failed to write parcelable to parcel, status: %d", status);
93 return status;
94 }
95 }
96
97 if (DBG_PAYLOAD) {
98 ALOGD("serialize-payload, start:%d size: %d", startPosition,
99 (AParcel_getDataPosition(dest) - startPosition));
100 }
101 return STATUS_OK;
102 }
103
104 template <class T>
serialize(AParcel * dest)105 binder_status_t LargeParcelable<T>::serialize(AParcel* dest) const {
106 return serializeNullablePayload(mParcelable.get(), dest);
107 }
108
109 template <class T>
serializeNullPayload(AParcel * dest)110 binder_status_t LargeParcelable<T>::serializeNullPayload(AParcel* dest) const {
111 return serializeNullablePayload(nullptr, dest);
112 }
113
114 template <class T>
deserialize(const AParcel & src)115 binder_status_t LargeParcelable<T>::deserialize(const AParcel& src) {
116 int32_t startPosition = AParcel_getDataPosition(&src);
117 if (DBG_PAYLOAD) {
118 ALOGD("start position: %d", startPosition);
119 }
120 std::optional<T> parcelable;
121 if (binder_status_t status = ::ndk::AParcel_readNullableParcelable(&src, &parcelable);
122 status != OK) {
123 ALOGE("failed to read parcelable from parcel, status: %d", status);
124 return status;
125 }
126 int32_t size = (AParcel_getDataPosition(&src) - startPosition);
127 if (!parcelable.has_value()) {
128 if (DBG_PAYLOAD) {
129 ALOGD("deserialize-payload: null parcelable, start: %d, size: %d", startPosition, size);
130 }
131 mParcelable = nullptr;
132 return STATUS_OK;
133 }
134 mParcelable = std::make_unique<T>(std::move(parcelable.value()));
135 if (DBG_PAYLOAD) {
136 ALOGD("deserialize-payload, start: %d, size: %d", startPosition, size);
137 }
138 return STATUS_OK;
139 }
140
141 } // namespace car_binder_lib
142 } // namespace automotive
143 } // namespace android
144
145 #endif // CPP_CAR_BINDER_LIB_LARGEPARCELABLE_INCLUDE_LARGEPARCELABLE_H_
146