SharedMemoryProxy.cpp revision 36967fb1a52f44cef9b5bdcca0f646aa136e285a 
1/*
2 * Copyright (C) 2017 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#define LOG_TAG "AAudioService"
18//#define LOG_NDEBUG 0
19#include <log/log.h>
20
21#include <errno.h>
22#include <string.h>
23
24#include <aaudio/AAudio.h>
25#include "SharedMemoryProxy.h"
26
27using namespace aaudio;
28
29SharedMemoryProxy::~SharedMemoryProxy()
30{
31    if (mOriginalSharedMemory != nullptr) {
32        munmap(mOriginalSharedMemory, mSharedMemorySizeInBytes);
33        mOriginalSharedMemory = nullptr;
34    }
35    if (mProxySharedMemory != nullptr) {
36        munmap(mProxySharedMemory, mSharedMemorySizeInBytes);
37        close(mProxyFileDescriptor);
38        mProxySharedMemory = nullptr;
39    }
40}
41
42aaudio_result_t SharedMemoryProxy::open(int originalFD, int32_t capacityInBytes) {
43    mOriginalFileDescriptor = originalFD;
44    mSharedMemorySizeInBytes = capacityInBytes;
45
46    mProxyFileDescriptor = ashmem_create_region("AAudioProxyDataBuffer", mSharedMemorySizeInBytes);
47    if (mProxyFileDescriptor < 0) {
48        ALOGE("SharedMemoryProxy::open() ashmem_create_region() failed %d", errno);
49        return AAUDIO_ERROR_INTERNAL;
50    }
51    int err = ashmem_set_prot_region(mProxyFileDescriptor, PROT_READ|PROT_WRITE);
52    if (err < 0) {
53        ALOGE("SharedMemoryProxy::open() ashmem_set_prot_region() failed %d", errno);
54        close(mProxyFileDescriptor);
55        mProxyFileDescriptor = -1;
56        return AAUDIO_ERROR_INTERNAL; // TODO convert errno to a better AAUDIO_ERROR;
57    }
58
59    // Get original memory address.
60    mOriginalSharedMemory = (uint8_t *) mmap(0, mSharedMemorySizeInBytes,
61                         PROT_READ|PROT_WRITE,
62                         MAP_SHARED,
63                         mOriginalFileDescriptor, 0);
64    if (mOriginalSharedMemory == MAP_FAILED) {
65        ALOGE("SharedMemoryProxy::open() original mmap(%d) failed %d (%s)",
66                mOriginalFileDescriptor, errno, strerror(errno));
67        return AAUDIO_ERROR_INTERNAL; // TODO convert errno to a better AAUDIO_ERROR;
68    }
69
70    // Map the fd to the same memory addresses.
71    mProxySharedMemory = (uint8_t *) mmap(mOriginalSharedMemory, mSharedMemorySizeInBytes,
72                         PROT_READ|PROT_WRITE,
73                         MAP_SHARED,
74                         mProxyFileDescriptor, 0);
75    if (mProxySharedMemory != mOriginalSharedMemory) {
76        ALOGE("SharedMemoryProxy::open() proxy mmap(%d) failed %d", mProxyFileDescriptor, errno);
77        munmap(mOriginalSharedMemory, mSharedMemorySizeInBytes);
78        mOriginalSharedMemory = nullptr;
79        close(mProxyFileDescriptor);
80        mProxyFileDescriptor = -1;
81        return AAUDIO_ERROR_INTERNAL; // TODO convert errno to a better AAUDIO_ERROR;
82    }
83
84    return AAUDIO_OK;
85}
86