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