util/ios/scoped_vm_read.cc

// Copyright 2021 The Crashpad Authors. All rights reserved.
//
// 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.

#include "util/ios/scoped_vm_read.h"

#include "util/ios/raw_logging.h"

namespace crashpad {
namespace internal {

ScopedVMReadInternal::ScopedVMReadInternal()
    : data_(0), vm_read_data_(0), vm_read_data_count_(0) {}

ScopedVMReadInternal::~ScopedVMReadInternal() {
  if (data_) {
    kern_return_t kr =
        vm_deallocate(mach_task_self(), vm_read_data_, vm_read_data_count_);
    if (kr != KERN_SUCCESS)
      RAW_LOG_ERROR(kr, "vm_deallocate");
  }
}

bool ScopedVMReadInternal::Read(const void* data, const size_t data_length) {
  if (data_) {
    kern_return_t kr =
        vm_deallocate(mach_task_self(), vm_read_data_, vm_read_data_count_);
    if (kr != KERN_SUCCESS)
      RAW_LOG_ERROR(kr, "vm_deallocate");
    data_ = 0;
  }
  vm_address_t data_address = reinterpret_cast<vm_address_t>(data);
  vm_address_t page_region_address = trunc_page(data_address);
  vm_size_t page_region_size =
      round_page(data_address - page_region_address + data_length);
  kern_return_t kr = vm_read(mach_task_self(),
                             page_region_address,
                             page_region_size,
                             &vm_read_data_,
                             &vm_read_data_count_);

  if (kr == KERN_SUCCESS) {
    data_ = vm_read_data_ + (data_address - page_region_address);
    return true;
  } else {
    RAW_LOG_ERROR(kr, "vm_read");
    return false;
  }
}

}  // namespace internal
}  // namespace crashpad