1/*
2 * Copyright (C) 2010 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#include <android-base/unique_fd.h>
20#include <binder/Parcelable.h>
21#include <utils/Errors.h>
22
23namespace android {
24
25class Parcel;
26
27namespace gui {
28
29class BitTube : public Parcelable {
30public:
31    // creates an uninitialized BitTube (to unparcel into)
32    BitTube() = default;
33
34    // creates a BitTube with a a specified send and receive buffer size
35    explicit BitTube(size_t bufsize);
36
37    // creates a BitTube with a default (4KB) send buffer
38    struct DefaultSizeType {};
39    static constexpr DefaultSizeType DefaultSize{};
40    explicit BitTube(DefaultSizeType);
41
42    explicit BitTube(const Parcel& data);
43
44    virtual ~BitTube() = default;
45
46    // check state after construction
47    status_t initCheck() const;
48
49    // get receive file-descriptor
50    int getFd() const;
51
52    // get the send file-descriptor.
53    int getSendFd() const;
54
55    // moves the receive file descriptor out of this BitTube
56    base::unique_fd moveReceiveFd();
57
58    // resets this BitTube's receive file descriptor to receiveFd
59    void setReceiveFd(base::unique_fd&& receiveFd);
60
61    // send objects (sized blobs). All objects are guaranteed to be written or the call fails.
62    template <typename T>
63    static ssize_t sendObjects(BitTube* tube, T const* events, size_t count) {
64        return sendObjects(tube, events, count, sizeof(T));
65    }
66
67    // receive objects (sized blobs). If the receiving buffer isn't large enough, excess messages
68    // are silently discarded.
69    template <typename T>
70    static ssize_t recvObjects(BitTube* tube, T* events, size_t count) {
71        return recvObjects(tube, events, count, sizeof(T));
72    }
73
74    // implement the Parcelable protocol. Only parcels the receive file descriptor
75    status_t writeToParcel(Parcel* reply) const;
76    status_t readFromParcel(const Parcel* parcel);
77
78private:
79    void init(size_t rcvbuf, size_t sndbuf);
80
81    // send a message. The write is guaranteed to send the whole message or fail.
82    ssize_t write(void const* vaddr, size_t size);
83
84    // receive a message. the passed buffer must be at least as large as the write call used to send
85    // the message, excess data is silently discarded.
86    ssize_t read(void* vaddr, size_t size);
87
88    base::unique_fd mSendFd;
89    mutable base::unique_fd mReceiveFd;
90
91    static ssize_t sendObjects(BitTube* tube, void const* events, size_t count, size_t objSize);
92
93    static ssize_t recvObjects(BitTube* tube, void* events, size_t count, size_t objSize);
94};
95
96} // namespace gui
97} // namespace android
98