Function from_error_code

src/common/error_code.cc:158–194

This is more complicated. For the case of categories defined elsewhere, we have to convert everything here.

// This is more complicated. For the case of categories defined
// elsewhere, we have to convert everything here.
[[nodiscard]] int from_error_code(boost::system::error_code e) noexcept
{
  if (!e)
    return 0;

  auto c = dynamic_cast<const converting_category*>(&e.category());
  // For categories we define
  if (c)
    return c->from_code(e.value());

  // For categories matching values of errno
  if (e.category() == boost::system::system_category() ||
      e.category() == boost::system::generic_category() ||
      // ASIO uses the system category for these and matches system
      // error values.
      e.category() == boost::asio::error::get_netdb_category() ||
      e.category() == boost::asio::error::get_addrinfo_category())
    return -e.value();

  if (e.category() == boost::asio::error::get_misc_category()) {
    // These values are specific to asio
    switch (e.value()) {
    case boost::asio::error::already_open:
      return -EIO;
    case boost::asio::error::eof:
      return -EIO;
    case boost::asio::error::not_found:
      return -ENOENT;
    case boost::asio::error::fd_set_failure:
      return -EINVAL;
    }
  }
  // Add any other categories we use here.

  // So many things defautl to EIO this is probably the safest
  return -EIO;
}
}
#pragma GCC diagnostic pop
#pragma clang diagnostic pop