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      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 "SharedMemoryProxy"
     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 
     27 using namespace aaudio;
     28 
     29 SharedMemoryProxy::~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 
     42 aaudio_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("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("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("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("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