root/mojo/public/cpp/bindings/lib/bindings_serialization.cc

DEFINITIONS

1. Align
2. EncodePointer
3. DecodePointerRaw
4. ValidatePointer
5. EncodeHandle
6. DecodeHandle

// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "mojo/public/cpp/bindings/lib/bindings_serialization.h"

#include <assert.h>

#include "mojo/public/cpp/bindings/lib/bindings_internal.h"

namespace mojo {
namespace internal {

size_t Align(size_t size) {
  const size_t kAlignment = 8;
  return size + (kAlignment - (size % kAlignment)) % kAlignment;
}

void EncodePointer(const void* ptr, uint64_t* offset) {
  if (!ptr) {
    *offset = 0;
    return;
  }

  const char* p_obj = reinterpret_cast<const char*>(ptr);
  const char* p_slot = reinterpret_cast<const char*>(offset);
  assert(p_obj > p_slot);

  *offset = static_cast<uint64_t>(p_obj - p_slot);
}

const void* DecodePointerRaw(const uint64_t* offset) {
  if (!*offset)
    return NULL;
  return reinterpret_cast<const char*>(offset) + *offset;
}

bool ValidatePointer(const void* ptr, const Message& message) {
  const uint8_t* data = static_cast<const uint8_t*>(ptr);
  if (reinterpret_cast<ptrdiff_t>(data) % 8 != 0)
    return false;

  const uint8_t* data_start = message.data();
  const uint8_t* data_end = data_start + message.data_num_bytes();

  return data >= data_start && data < data_end;
}

void EncodeHandle(Handle* handle, std::vector<Handle>* handles) {
  if (handle->is_valid()) {
    handles->push_back(*handle);
    handle->set_value(static_cast<MojoHandle>(handles->size() - 1));
  } else {
    // Encode -1 to mean the invalid handle.
    handle->set_value(static_cast<MojoHandle>(-1));
  }
}

bool DecodeHandle(Handle* handle, std::vector<Handle>* handles) {
  // Decode -1 to mean the invalid handle.
  if (handle->value() == static_cast<MojoHandle>(-1)) {
    *handle = Handle();
    return true;
  }
  if (handle->value() >= handles->size())
    return false;
  // Just leave holes in the vector so we don't screw up other indices.
  *handle = FetchAndReset(&handles->at(handle->value()));
  return true;
}

}  // namespace internal
}  // namespace mojo