BitTube.cpp revision 99fe3c6d3dcb6fb26bf283343f946d031b052dff 
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
20#include <fcntl.h>
21#include <signal.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
33BitTube::BitTube()
34    : mSendFd(-1), mReceiveFd(-1)
35{
36    int fds[2];
37    if (pipe(fds) == 0) {
38        mReceiveFd = fds[0];
39        mSendFd = fds[1];
40        fcntl(mReceiveFd, F_SETFL, O_NONBLOCK);
41        fcntl(mSendFd, F_SETFL, O_NONBLOCK);
42        // ignore SIGPIPE, we handle write errors through EPIPE instead
43        signal(SIGPIPE, SIG_IGN);
44    } else {
45        mReceiveFd = -errno;
46        ALOGE("BitTube: pipe creation failed (%s)", strerror(-mReceiveFd));
47    }
48}
49
50BitTube::BitTube(const Parcel& data)
51    : mSendFd(-1), mReceiveFd(-1)
52{
53    mReceiveFd = dup(data.readFileDescriptor());
54    if (mReceiveFd >= 0) {
55        fcntl(mReceiveFd, F_SETFL, O_NONBLOCK);
56    } else {
57        mReceiveFd = -errno;
58        ALOGE("BitTube(Parcel): can't dup filedescriptor (%s)",
59                strerror(-mReceiveFd));
60    }
61}
62
63BitTube::~BitTube()
64{
65    if (mSendFd >= 0)
66        close(mSendFd);
67
68    if (mReceiveFd >= 0)
69        close(mReceiveFd);
70}
71
72status_t BitTube::initCheck() const
73{
74    if (mReceiveFd < 0) {
75        return status_t(mReceiveFd);
76    }
77    return NO_ERROR;
78}
79
80int BitTube::getFd() const
81{
82    return mReceiveFd;
83}
84
85ssize_t BitTube::write(void const* vaddr, size_t size)
86{
87    ssize_t err, len;
88    do {
89        len = ::write(mSendFd, vaddr, size);
90        err = len < 0 ? errno : 0;
91    } while (err == EINTR);
92    return err == 0 ? len : -err;
93
94}
95
96ssize_t BitTube::read(void* vaddr, size_t size)
97{
98    ssize_t err, len;
99    do {
100        len = ::read(mReceiveFd, vaddr, size);
101        err = len < 0 ? errno : 0;
102    } while (err == EINTR);
103    if (err == EAGAIN || err == EWOULDBLOCK) {
104        // EAGAIN means that we have non-blocking I/O but there was
105        // no data to be read. Nothing the client should care about.
106        return 0;
107    }
108    return err == 0 ? len : -err;
109}
110
111status_t BitTube::writeToParcel(Parcel* reply) const
112{
113    if (mReceiveFd < 0)
114        return -EINVAL;
115
116    status_t result = reply->writeDupFileDescriptor(mReceiveFd);
117    close(mReceiveFd);
118    mReceiveFd = -1;
119    return result;
120}
121
122// ----------------------------------------------------------------------------
123}; // namespace android
124