Function GetPlatformTemporaryDirs

cpp/src/arrow/util/io_util.cc:1886–1934

Return a list of preferred locations for temporary files

// Return a list of preferred locations for temporary files
std::vector<NativePathString> GetPlatformTemporaryDirs() {
  struct TempDirSelector {
    std::string env_var;
    NativePathString path_append;
  };

  std::vector<TempDirSelector> selectors;
  NativePathString fallback_tmp;

#if _WIN32
  selectors = {
      {"TMP", L""}, {"TEMP", L""}, {"LOCALAPPDATA", L"Temp"}, {"USERPROFILE", L"Temp"}};
  fallback_tmp = GetWindowsDirectoryPath();

#else
  selectors = {{"TMPDIR", ""}, {"TMP", ""}, {"TEMP", ""}, {"TEMPDIR", ""}};
#  ifdef __ANDROID__
  fallback_tmp = "/data/local/tmp";
#  else
  fallback_tmp = "/tmp";
#  endif
#endif

  std::vector<NativePathString> temp_dirs;
  for (const auto& sel : selectors) {
    auto result = GetEnvVarNative(sel.env_var);
    if (result.status().IsKeyError()) {
      // Environment variable absent, skip
      continue;
    }
    if (!result.ok()) {
      ARROW_LOG(WARNING) << "Failed getting env var '" << sel.env_var
                         << "': " << result.status().ToString();
      continue;
    }
    NativePathString p = *std::move(result);
    if (p.empty()) {
      // Environment variable set to empty string, skip
      continue;
    }
    if (sel.path_append.empty()) {
      temp_dirs.push_back(p);
    } else {
      temp_dirs.push_back(p + kNativeSep + sel.path_append);
    }
  }
  temp_dirs.push_back(fallback_tmp);
  return temp_dirs;
}

std::string MakeRandomName(int num_chars) {
  constexpr std::string_view chars = "0123456789abcdefghijklmnopqrstuvwxyz";