BitTube.cpp revision 90ed3e8d7883d9c80fb8bf11b1c593bd8b2b39d0 
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#include <stdint.h>
18#include <sys/types.h>
19#include <sys/socket.h>
20
21#include <fcntl.h>
22#include <unistd.h>
23
24#include <utils/Errors.h>
25
26#include <binder/Parcel.h>
27
28#include <gui/BitTube.h>
29
30namespace android {
31// ----------------------------------------------------------------------------
32
33// Socket buffer size.  The default is typically about 128KB, which is much larger than
34// we really need.  So we make it smaller.
35static const size_t DEFAULT_SOCKET_BUFFER_SIZE = 4 * 1024;
36
37
38BitTube::BitTube()
39    : mSendFd(-1), mReceiveFd(-1)
40{
41    init(DEFAULT_SOCKET_BUFFER_SIZE, DEFAULT_SOCKET_BUFFER_SIZE);
42}
43
44BitTube::BitTube(size_t bufsize)
45    : mSendFd(-1), mReceiveFd(-1)
46{
47    init(bufsize, bufsize);
48}
49
50BitTube::BitTube(const Parcel& data)
51    : mSendFd(-1), mReceiveFd(-1)
52{
53    mReceiveFd = dup(data.readFileDescriptor());
54    if (mReceiveFd < 0) {
55        mReceiveFd = -errno;
56        ALOGE("BitTube(Parcel): can't dup filedescriptor (%s)",
57                strerror(-mReceiveFd));
58    }
59}
60
61BitTube::~BitTube()
62{
63    if (mSendFd >= 0)
64        close(mSendFd);
65
66    if (mReceiveFd >= 0)
67        close(mReceiveFd);
68}
69
70void BitTube::init(size_t rcvbuf, size_t sndbuf) {
71    int sockets[2];
72    if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, sockets) == 0) {
73        size_t size = DEFAULT_SOCKET_BUFFER_SIZE;
74        setsockopt(sockets[0], SOL_SOCKET, SO_RCVBUF, &rcvbuf, sizeof(rcvbuf));
75        setsockopt(sockets[1], SOL_SOCKET, SO_SNDBUF, &sndbuf, sizeof(sndbuf));
76        // sine we don't use the "return channel", we keep it small...
77        setsockopt(sockets[0], SOL_SOCKET, SO_SNDBUF, &size, sizeof(size));
78        setsockopt(sockets[1], SOL_SOCKET, SO_RCVBUF, &size, sizeof(size));
79        fcntl(sockets[0], F_SETFL, O_NONBLOCK);
80        fcntl(sockets[1], F_SETFL, O_NONBLOCK);
81        mReceiveFd = sockets[0];
82        mSendFd = sockets[1];
83    } else {
84        mReceiveFd = -errno;
85        ALOGE("BitTube: pipe creation failed (%s)", strerror(-mReceiveFd));
86    }
87}
88
89status_t BitTube::initCheck() const
90{
91    if (mReceiveFd < 0) {
92        return status_t(mReceiveFd);
93    }
94    return NO_ERROR;
95}
96
97int BitTube::getFd() const
98{
99    return mReceiveFd;
100}
101
102ssize_t BitTube::write(void const* vaddr, size_t size)
103{
104    ssize_t err, len;
105    do {
106        len = ::send(mSendFd, vaddr, size, MSG_DONTWAIT | MSG_NOSIGNAL);
107        // cannot return less than size, since we're using SOCK_SEQPACKET
108        err = len < 0 ? errno : 0;
109    } while (err == EINTR);
110    return err == 0 ? len : -err;
111}
112
113ssize_t BitTube::read(void* vaddr, size_t size)
114{
115    ssize_t err, len;
116    do {
117        len = ::recv(mReceiveFd, vaddr, size, MSG_DONTWAIT);
118        err = len < 0 ? errno : 0;
119    } while (err == EINTR);
120    if (err == EAGAIN || err == EWOULDBLOCK) {
121        // EAGAIN means that we have non-blocking I/O but there was
122        // no data to be read. Nothing the client should care about.
123        return 0;
124    }
125    return err == 0 ? len : -err;
126}
127
128status_t BitTube::writeToParcel(Parcel* reply) const
129{
130    if (mReceiveFd < 0)
131        return -EINVAL;
132
133    status_t result = reply->writeDupFileDescriptor(mReceiveFd);
134    close(mReceiveFd);
135    mReceiveFd = -1;
136    return result;
137}
138
139
140ssize_t BitTube::sendObjects(const sp<BitTube>& tube,
141        void const* events, size_t count, size_t objSize)
142{
143    const char* vaddr = reinterpret_cast<const char*>(events);
144    ssize_t size = tube->write(vaddr, count*objSize);
145
146    // should never happen because of SOCK_SEQPACKET
147    LOG_ALWAYS_FATAL_IF((size >= 0) && (size % objSize),
148            "BitTube::sendObjects(count=%d, size=%d), res=%d (partial events were sent!)",
149            count, objSize, size);
150
151    //ALOGE_IF(size<0, "error %d sending %d events", size, count);
152    return size < 0 ? size : size / objSize;
153}
154
155ssize_t BitTube::recvObjects(const sp<BitTube>& tube,
156        void* events, size_t count, size_t objSize)
157{
158    char* vaddr = reinterpret_cast<char*>(events);
159    ssize_t size = tube->read(vaddr, count*objSize);
160
161    // should never happen because of SOCK_SEQPACKET
162    LOG_ALWAYS_FATAL_IF((size >= 0) && (size % objSize),
163            "BitTube::recvObjects(count=%d, size=%d), res=%d (partial events were received!)",
164            count, objSize, size);
165
166    //ALOGE_IF(size<0, "error %d receiving %d events", size, count);
167    return size < 0 ? size : size / objSize;
168}
169
170// ----------------------------------------------------------------------------
171}; // namespace android
172