MQDescriptor.cpp

/*
 * Copyright (C) 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 "MQDescriptor"
#include <android-base/logging.h>

#include <hidl/MQDescriptor.h>

#include <cutils/native_handle.h>
#include <sys/mman.h>

namespace android {
namespace hardware {

MQDescriptor::MQDescriptor(
        const std::vector<GrantorDescriptor>& grantors,
        native_handle_t* nhandle,
        int32_t flags,
        size_t size)
    : mHandle(nhandle),
      mQuantum(size),
      mFlags(flags) {
    mGrantors.resize(grantors.size());
    for (size_t i = 0; i < grantors.size(); ++i) {
        mGrantors[i] = grantors[i];
    }
}

MQDescriptor::MQDescriptor(const MQDescriptor &other)
    : mGrantors(other.mGrantors),
      mHandle(nullptr),
      mQuantum(other.mQuantum),
      mFlags(other.mFlags) {
    if (other.mHandle != nullptr) {
        mHandle = native_handle_create(
                other.mHandle->numFds, other.mHandle->numInts);

        for (int i = 0; i < other.mHandle->numFds; ++i) {
            const_cast<native_handle_t *>(mHandle)->data[i] =
                dup(other.mHandle->data[i]);
        }

        memcpy(&const_cast<native_handle_t *>(mHandle)->data[other.mHandle->numFds],
               &other.mHandle->data[other.mHandle->numFds],
               other.mHandle->numInts * sizeof(int));
    }
}

MQDescriptor::~MQDescriptor() {
    if (mHandle != nullptr) {
        native_handle_close(const_cast<native_handle_t *>(mHandle));
        native_handle_delete(const_cast<native_handle_t *>(mHandle));
    }
}

/*
 * TODO: Modify design to send access flags over WireMQDescriptor
 * as well and use the same for the mmap call.
 */
void* MQDescriptor::mapGrantorDescr(uint32_t grantor_idx) {
  const native_handle_t* handle = mHandle;
  int fdIndex = mGrantors[grantor_idx].fdIndex;
  /*
   * Offset for mmap must be a multiple of PAGE_SIZE.
   */
  int mapOffset = (mGrantors[grantor_idx].offset / PAGE_SIZE) * PAGE_SIZE;
  int mapLength =
      mGrantors[grantor_idx].offset - mapOffset + mGrantors[grantor_idx].extent;

  void* address = mmap(0, mapLength, PROT_READ | PROT_WRITE, MAP_SHARED,
                       handle->data[fdIndex], mapOffset);
  return (address == MAP_FAILED)
             ? nullptr
             : (uint8_t*)address + (mGrantors[grantor_idx].offset - mapOffset);
}

void MQDescriptor::unmapGrantorDescr(void* address, uint32_t grantor_idx) {
  const native_handle_t* handle = mHandle;
  int mapOffset = (mGrantors[grantor_idx].offset / PAGE_SIZE) * PAGE_SIZE;
  int mapLength =
      mGrantors[grantor_idx].offset - mapOffset + mGrantors[grantor_idx].extent;
  void* baseAddress =
      (uint8_t*)address - (mGrantors[grantor_idx].offset - mapOffset);
  if (baseAddress) munmap(baseAddress, mapLength);
}

::android::status_t MQDescriptor::readEmbeddedFromParcel(
    const Parcel &parcel,
    size_t parentHandle,
    size_t parentOffset) {
    ::android::status_t _hidl_err = ::android::OK;

    size_t _hidl_grantors_child;

    _hidl_err = const_cast<hidl_vec<GrantorDescriptor> *>(
            &mGrantors)->readEmbeddedFromParcel(
                parcel,
                parentHandle,
                parentOffset + offsetof(MQDescriptor, mGrantors),
                &_hidl_grantors_child);

    if (_hidl_err != ::android::OK) { return _hidl_err; }

    const native_handle_t *_hidl_mq_handle_ptr = parcel.readEmbeddedNativeHandle(
            parentHandle,
            parentOffset + offsetof(MQDescriptor, mHandle));

    if (_hidl_mq_handle_ptr == nullptr) {
        _hidl_err = ::android::UNKNOWN_ERROR;
        return _hidl_err;
    }

_hidl_error:
    return _hidl_err;
}

::android::status_t MQDescriptor::writeEmbeddedToParcel(
    Parcel *parcel,
    size_t parentHandle,
    size_t parentOffset) const {
    ::android::status_t _hidl_err = ::android::OK;

    size_t _hidl_grantors_child;

    _hidl_err = mGrantors.writeEmbeddedToParcel(
            parcel,
            parentHandle,
            parentOffset + offsetof(MQDescriptor, mGrantors),
            &_hidl_grantors_child);

    if (_hidl_err != ::android::OK) { return _hidl_err; }

    _hidl_err = parcel->writeEmbeddedNativeHandle(
            mHandle,
            parentHandle,
            parentOffset + offsetof(MQDescriptor, mHandle));

    if (_hidl_err != ::android::OK) { return _hidl_err; }

_hidl_error:
    return _hidl_err;
}

}  // namespace hardware
}  // namespace android