media/libaaudio/src/binding/SharedMemoryParcelable.cpp

/*
 * Copyright 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define LOG_TAG "SharedMemoryParcelable"
//#define LOG_NDEBUG 0
#include <utils/Log.h>

#include <stdint.h>
#include <stdio.h>

#include <sys/mman.h>
#include <aaudio/AAudio.h>

#include <android-base/unique_fd.h>
#include <binder/Parcelable.h>
#include <utility/AAudioUtilities.h>

#include "binding/SharedMemoryParcelable.h"

using android::base::unique_fd;
using android::NO_ERROR;
using android::status_t;
using android::Parcel;
using android::Parcelable;

using namespace aaudio;

SharedMemoryParcelable::SharedMemoryParcelable() {}
SharedMemoryParcelable::~SharedMemoryParcelable() {};

void SharedMemoryParcelable::setup(const unique_fd& fd, int32_t sizeInBytes) {
    mFd.reset(dup(fd.get())); // store a duplicate fd
    ALOGV("setup(fd = %d -> %d, size = %d) this = %p\n", fd.get(), mFd.get(), sizeInBytes, this);
    mSizeInBytes = sizeInBytes;
}

status_t SharedMemoryParcelable::writeToParcel(Parcel* parcel) const {
    status_t status = AAudioConvert_aaudioToAndroidStatus(validate());
    if (status != NO_ERROR) return status;

    status = parcel->writeInt32(mSizeInBytes);
    if (status != NO_ERROR) return status;
    if (mSizeInBytes > 0) {
        ALOGV("writeToParcel() mFd = %d, this = %p\n", mFd.get(), this);
        status = parcel->writeUniqueFileDescriptor(mFd);
        ALOGE_IF(status != NO_ERROR, "SharedMemoryParcelable writeDupFileDescriptor failed : %d",
                 status);
    }
    return status;
}

status_t SharedMemoryParcelable::readFromParcel(const Parcel* parcel) {
    status_t status = parcel->readInt32(&mSizeInBytes);
    if (status != NO_ERROR) goto error;

    if (mSizeInBytes > 0) {
        // The Parcel owns the file descriptor and will close it later.
        unique_fd mmapFd;
        status = parcel->readUniqueFileDescriptor(&mmapFd);
        if (status != NO_ERROR) {
            ALOGE("readFromParcel() readUniqueFileDescriptor() failed : %d", status);
            goto error;
        }

        // Resolve the memory now while we still have the FD from the Parcel.
        // Closing the FD will not affect the shared memory once mmap() has been called.
        aaudio_result_t result = resolveSharedMemory(mmapFd);
        status = AAudioConvert_aaudioToAndroidStatus(result);
        if (status != NO_ERROR) goto error;
    }

    return AAudioConvert_aaudioToAndroidStatus(validate());

error:
    return status;
}

aaudio_result_t SharedMemoryParcelable::close() {
    if (mResolvedAddress != MMAP_UNRESOLVED_ADDRESS) {
        int err = munmap(mResolvedAddress, mSizeInBytes);
        if (err < 0) {
            ALOGE("close() munmap() failed %d", err);
            return AAudioConvert_androidToAAudioResult(err);
        }
        mResolvedAddress = MMAP_UNRESOLVED_ADDRESS;
    }
    return AAUDIO_OK;
}

aaudio_result_t SharedMemoryParcelable::resolveSharedMemory(const unique_fd& fd) {
    mResolvedAddress = (uint8_t *) mmap(0, mSizeInBytes, PROT_READ | PROT_WRITE,
                                        MAP_SHARED, fd.get(), 0);
    if (mResolvedAddress == MMAP_UNRESOLVED_ADDRESS) {
        ALOGE("mmap() failed for fd = %d, nBytes = %d, errno = %s",
              fd.get(), mSizeInBytes, strerror(errno));
        return AAUDIO_ERROR_INTERNAL;
    }
    return AAUDIO_OK;
}

aaudio_result_t SharedMemoryParcelable::resolve(int32_t offsetInBytes, int32_t sizeInBytes,
                                              void **regionAddressPtr) {
    if (offsetInBytes < 0) {
        ALOGE("illegal offsetInBytes = %d", offsetInBytes);
        return AAUDIO_ERROR_OUT_OF_RANGE;
    } else if ((offsetInBytes + sizeInBytes) > mSizeInBytes) {
        ALOGE("out of range, offsetInBytes = %d, "
                      "sizeInBytes = %d, mSizeInBytes = %d",
              offsetInBytes, sizeInBytes, mSizeInBytes);
        return AAUDIO_ERROR_OUT_OF_RANGE;
    }

    aaudio_result_t result = AAUDIO_OK;

    if (mResolvedAddress == MMAP_UNRESOLVED_ADDRESS) {
        if (mFd.get() != -1) {
            result = resolveSharedMemory(mFd);
        } else {
            ALOGE("has no file descriptor for shared memory.");
            result = AAUDIO_ERROR_INTERNAL;
        }
    }

    if (result == AAUDIO_OK && mResolvedAddress != MMAP_UNRESOLVED_ADDRESS) {
        *regionAddressPtr = mResolvedAddress + offsetInBytes;
        ALOGV("mResolvedAddress = %p", mResolvedAddress);
        ALOGV("offset by %d, *regionAddressPtr = %p", offsetInBytes, *regionAddressPtr);
    }
    return result;
}

int32_t SharedMemoryParcelable::getSizeInBytes() {
    return mSizeInBytes;
}

aaudio_result_t SharedMemoryParcelable::validate() const {
    if (mSizeInBytes < 0 || mSizeInBytes >= MAX_MMAP_SIZE_BYTES) {
        ALOGE("invalid mSizeInBytes = %d", mSizeInBytes);
        return AAUDIO_ERROR_OUT_OF_RANGE;
    }
    return AAUDIO_OK;
}

void SharedMemoryParcelable::dump() {
    ALOGD("mFd = %d", mFd.get());
    ALOGD("mSizeInBytes = %d", mSizeInBytes);
}