Hmm. Sounds like that remote storage system is horribly broken. You still shouldn't necessarily need a metadata file storing how many bytes you've received -- just look at the file you've got. Count how many bytes it has, and skip that many. This is probably error-prone, but hopefully better than nothing. In any case, I assume you are able to tell the remote store to skip some amount of bytes before starting the transfer back up, right? If not... I'm not sure how you would accomplish this.

just look at the file you've got. Count how many bytes it has, I want to support multiple passes, to make sure it was read the first time. That is, "verify" won't see a short file, but the whole file size.

Also, I want to be able to allocate the entire file size ahead of time, to make sure it fits in the destination.

I assume you are able to tell the remote store to skip some amount of bytes before starting the transfer back up, right? Right, just seek.

—John