Don't read past end of file

I'm dealing with an SFTP server that errors out if you send a `read()` for more bytes than the file has. Not sure if this is a common thing or my server is just not following specs (wouldn't surprise me).

I solved this by manually tracking the filesize and bytes read, but I'm wondering if there'd be any cons to just having this in the package?

Two options would be:

- Do what s3fs does and download into a temp file so that users won't encounter discrepancies between real filesystems and sftp
- Emulate reading beyond the last byte without actually sending requests