cmds/idmap2/libidmap2/BinaryStreamVisitor.cpp

/*
 * Copyright (C) 2018 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.
 */

#include "idmap2/BinaryStreamVisitor.h"

#include <algorithm>
#include <cstring>
#include <string>

#include "android-base/macros.h"

namespace android::idmap2 {

void BinaryStreamVisitor::Write8(uint8_t value) {
  stream_.write(reinterpret_cast<char*>(&value), sizeof(uint8_t));
}

void BinaryStreamVisitor::Write16(uint16_t value) {
  uint16_t x = htodl(value);
  stream_.write(reinterpret_cast<char*>(&x), sizeof(uint16_t));
}

void BinaryStreamVisitor::Write32(uint32_t value) {
  uint32_t x = htodl(value);
  stream_.write(reinterpret_cast<char*>(&x), sizeof(uint32_t));
}

void BinaryStreamVisitor::WriteString(StringPiece value) {
  // pad with null to nearest word boundary;
  size_t padding_size = CalculatePadding(value.size());
  Write32(value.size());
  stream_.write(value.data(), value.size());
  stream_.write("\0\0\0\0", padding_size);
}

void BinaryStreamVisitor::visit(const Idmap& idmap ATTRIBUTE_UNUSED) {
  // nothing to do
}

void BinaryStreamVisitor::visit(const IdmapHeader& header) {
  Write32(header.GetMagic());
  Write32(header.GetVersion());
  Write32(header.GetTargetCrc());
  Write32(header.GetOverlayCrc());
  Write32(header.GetFulfilledPolicies());
  Write32(static_cast<uint8_t>(header.GetEnforceOverlayable()));
  WriteString(header.GetTargetPath());
  WriteString(header.GetOverlayPath());
  WriteString(header.GetOverlayName());
  WriteString(header.GetDebugInfo());
}

void BinaryStreamVisitor::visit(const IdmapData& data) {
  for (const auto& target_entry : data.GetTargetEntries()) {
    Write32(target_entry.target_id);
  }
  for (const auto& target_entry : data.GetTargetEntries()) {
    Write32(target_entry.overlay_id);
  }

  uint32_t current_inline_entry_values_count = 0;
  for (const auto& target_inline_entry : data.GetTargetInlineEntries()) {
    Write32(target_inline_entry.target_id);
  }
  for (const auto& target_inline_entry : data.GetTargetInlineEntries()) {
    Write32(current_inline_entry_values_count);
    Write32(target_inline_entry.values.size());
    current_inline_entry_values_count += target_inline_entry.values.size();
  }

  std::vector<ConfigDescription> configs;
  configs.reserve(data.GetHeader()->GetConfigCount());
  for (const auto& target_entry : data.GetTargetInlineEntries()) {
    for (const auto& target_entry_value : target_entry.values) {
      auto config_it = std::find(configs.begin(), configs.end(), target_entry_value.first);
      if (config_it != configs.end()) {
        Write32(config_it - configs.begin());
      } else {
        Write32(configs.size());
        configs.push_back(target_entry_value.first);
      }
      // We're writing a Res_value entry here, and the first 3 bytes of that are
      // sizeof() + a padding 0 byte
      static constexpr decltype(android::Res_value::size) kSize = sizeof(android::Res_value);
      Write16(kSize);
      Write8(0U);
      Write8(target_entry_value.second.data_type);
      Write32(target_entry_value.second.data_value);
    }
  }

  if (!configs.empty()) {
    stream_.write(reinterpret_cast<const char*>(&configs.front()),
                  sizeof(configs.front()) * configs.size());
    if (configs.size() >= 100) {
      // Let's write a message to future us so that they know when to replace the linear search
      // in `configs` vector with something more efficient.
      LOG(WARNING) << "Idmap got " << configs.size()
                   << " configurations, time to fix the bruteforce search";
    }
  }

  for (const auto& overlay_entry : data.GetOverlayEntries()) {
    Write32(overlay_entry.overlay_id);
  }
  for (const auto& overlay_entry : data.GetOverlayEntries()) {
    Write32(overlay_entry.target_id);
  }

  WriteString(data.GetStringPoolData());
}

void BinaryStreamVisitor::visit(const IdmapData::Header& header) {
  Write32(header.GetTargetEntryCount());
  Write32(header.GetTargetInlineEntryCount());
  Write32(header.GetTargetInlineEntryValueCount());
  Write32(header.GetConfigCount());
  Write32(header.GetOverlayEntryCount());
  Write32(header.GetStringPoolIndexOffset());
}

}  // namespace android::idmap2