minio-go: Object.Read doesn't return error on truncated response

Thanos and Cortex are using the Minio client as S3 client. From time to time we’ve some reports of bugs that looks like if we get a partial/truncated response from the server which is not treated as an error from our application.

I’ve tried to simulate a scenario (which I don’t know how much realistic could be) where the server returns a body response smaller than the Content-Length. The Minio Object.Read() returns no error once all response has been consumed while, as comparison, the Google GCS client does return io.ErrUnexpectedEOF.

I’ve added a test in Thanos to show it: https://github.com/thanos-io/thanos/pull/3795

Questions:

• Why the Minio client doesn’t check if the received response size matches the Content-Length?
• The scenario described shouldn’t be reported as an error by the Minio client?