src/ipcz/parcel.cc

// Copyright 2022 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 "ipcz/parcel.h"

#include <cctype>
#include <cstddef>
#include <cstdint>
#include <sstream>
#include <string>
#include <utility>

#include "third_party/abseil-cpp/absl/base/macros.h"
#include "third_party/abseil-cpp/absl/types/span.h"

namespace ipcz {

Parcel::Parcel() = default;

Parcel::Parcel(SequenceNumber sequence_number)
    : sequence_number_(sequence_number) {}

// Note: We do not use default move construction or assignment because we want
// to explicitly clear the data and object views of the moved-from Parcel.
Parcel::Parcel(Parcel&& other)
    : sequence_number_(other.sequence_number_),
      inlined_data_(std::move(other.inlined_data_)),
      objects_(std::move(other.objects_)),
      data_view_(std::exchange(other.data_view_, {})),
      objects_view_(std::exchange(other.objects_view_, {})) {}

Parcel& Parcel::operator=(Parcel&& other) {
  sequence_number_ = other.sequence_number_;
  inlined_data_ = std::move(other.inlined_data_);
  objects_ = std::move(other.objects_);
  data_view_ = std::exchange(other.data_view_, {});
  objects_view_ = std::exchange(other.objects_view_, {});
  return *this;
}

Parcel::~Parcel() {
  for (Ref<APIObject>& object : objects_) {
    if (object) {
      object->Close();
    }
  }
}

void Parcel::SetInlinedData(std::vector<uint8_t> data) {
  inlined_data_ = std::move(data);
  data_view_ = absl::MakeSpan(inlined_data_);
}

void Parcel::SetObjects(std::vector<Ref<APIObject>> objects) {
  objects_ = std::move(objects);
  objects_view_ = absl::MakeSpan(objects_);
}

void Parcel::Consume(size_t num_bytes, absl::Span<IpczHandle> out_handles) {
  auto data = data_view();
  auto objects = objects_view();
  ABSL_ASSERT(num_bytes <= data.size());
  ABSL_ASSERT(out_handles.size() <= objects.size());
  for (size_t i = 0; i < out_handles.size(); ++i) {
    out_handles[i] = APIObject::ReleaseAsHandle(std::move(objects[i]));
  }

  data_view_.remove_prefix(num_bytes);
  objects_view_.remove_prefix(out_handles.size());
}

std::string Parcel::Describe() const {
  std::stringstream ss;
  ss << "parcel " << sequence_number() << " (";
  if (!data_view().empty()) {
    // Cheesy heuristic: if the first character is an ASCII letter or number,
    // assume the parcel data is human-readable and print a few characters.
    if (std::isalnum(data_view()[0])) {
      const absl::Span<const uint8_t> preview = data_view().subspan(0, 8);
      ss << "\"" << std::string(preview.begin(), preview.end());
      if (preview.size() < data_size()) {
        ss << "...\", " << data_size() << " bytes";
      } else {
        ss << '"';
      }
    }
  } else {
    ss << "no data";
  }
  if (!objects_view().empty()) {
    ss << ", " << num_objects() << " handles";
  }
  ss << ")";
  return ss.str();
}

}  // namespace ipcz