Method WriteJsonFile

Source/cmFileAPI.cxx:213–271

}

std::string cmFileAPI::WriteJsonFile(
  Json::Value const& value, std::string const& prefix,
  std::string (*computeSuffix)(std::string const&))
{
  std::string fileName;

  // Write the json file with a temporary name.
  std::string const& tmpFile = this->APIv1 + "/tmp.json";
  cmsys::ofstream ftmp(tmpFile.c_str());
  this->JsonWriter->write(value, &ftmp);
  ftmp << "\n";
  ftmp.close();
  if (!ftmp) {
    cmSystemTools::RemoveFile(tmpFile);
    return fileName;
  }

  // Compute the final name for the file.
  std::string suffix = computeSuffix(tmpFile);
  std::string suffixWithExtension = cmStrCat('-', suffix, ".json");
  fileName = cmStrCat(prefix, suffixWithExtension);

  // Truncate the file name length
  // eCryptFS has a maximal file name length recommendation of 140
  size_t const maxFileNameLength = 140;
  size_t const fileNameLength = fileName.size();
  if (fileNameLength > maxFileNameLength) {
    size_t const newHashLength = 20;
    size_t const newSuffixLength =
      suffixWithExtension.size() - suffix.size() + newHashLength;
    size_t const overLength =
      fileNameLength - maxFileNameLength + newSuffixLength;
    size_t const startPos = fileNameLength - overLength;
    std::string const toBeRemoved = fileName.substr(startPos, overLength);
    suffix = cmCryptoHash(cmCryptoHash::AlgoSHA256)
               .HashString(toBeRemoved)
               .substr(0, newHashLength);
    suffixWithExtension = cmStrCat('-', suffix, ".json");
    fileName.replace(startPos, overLength, suffixWithExtension);
  }

  // Create the destination.
  std::string file = this->APIv1 + "/reply";
  cmSystemTools::MakeDirectory(file);
  file += "/";
  file += fileName;

  // If the final name already exists then assume it has proper content.
  // Otherwise, atomically place the reply file at its final name
  if (cmSystemTools::FileExists(file, true) ||
      !cmSystemTools::RenameFile(tmpFile, file)) {
    cmSystemTools::RemoveFile(tmpFile);
  }

  // Record this among files we have just written.
  this->ReplyFiles.insert(fileName);

  return fileName;