Method GetFileInfo

cpp/src/arrow/filesystem/s3fs.cc:3146–3211

std::string S3FileSystem::region() const { return impl_->region(); }

Result<FileInfo> S3FileSystem::GetFileInfo(const std::string& s) {
  ARROW_ASSIGN_OR_RAISE(auto client_lock, impl_->holder_->Lock());

  ARROW_ASSIGN_OR_RAISE(auto path, S3Path::FromString(s));
  FileInfo info;
  info.set_path(s);

  if (path.empty()) {
    // It's the root path ""
    info.set_type(FileType::Directory);
    return info;
  } else if (path.key.empty()) {
    // It's a bucket
    S3Model::HeadBucketRequest req;
    req.SetBucket(ToAwsString(path.bucket));

    auto outcome = client_lock.Move()->HeadBucket(req);
    if (!outcome.IsSuccess()) {
      impl_->GetOrSetBackend(outcome.GetError());
      if (!IsNotFound(outcome.GetError())) {
        const auto msg = "When getting information for bucket '" + path.bucket + "': ";
        return ErrorToStatus(msg, "HeadBucket", outcome.GetError(),
                             impl_->options().region);
      }
      info.set_type(FileType::NotFound);
      return info;
    }
    // NOTE: S3 doesn't have a bucket modification time.  Only a creation
    // time is available, and you have to list all buckets to get it.
    info.set_type(FileType::Directory);
    return info;
  } else {
    // It's an object
    S3Model::HeadObjectRequest req;
    req.SetBucket(ToAwsString(path.bucket));
    req.SetKey(ToAwsString(path.key));

    auto outcome = client_lock.Move()->HeadObject(req);
    if (outcome.IsSuccess()) {
      // "File" object found
      FileObjectToInfo(path.key, outcome.GetResult(), &info);
      return info;
    }
    impl_->GetOrSetBackend(outcome.GetError());
    if (!IsNotFound(outcome.GetError())) {
      const auto msg = "When getting information for key '" + path.key + "' in bucket '" +
                       path.bucket + "': ";
      return ErrorToStatus(msg, "HeadObject", outcome.GetError(),
                           impl_->options().region);
    }
    // Not found => perhaps it's an empty "directory"
    ARROW_ASSIGN_OR_RAISE(bool is_dir, impl_->IsEmptyDirectory(path, &outcome));
    if (is_dir) {
      info.set_type(FileType::Directory);
      return info;
    }
    // Not found => perhaps it's a non-empty "directory"
    ARROW_ASSIGN_OR_RAISE(is_dir, impl_->IsNonEmptyDirectory(path));