Root dir checks

[stuartmcalpine]

Add some checks on the root_dir before registering data

Changes

• Add check during dataset registration to raise an exception if the root_dir does not exist
• Add check before copying any data (i.e., old_location != None) that the user has write permission to the root_dir folder.

Thoughts

• Is this the behavior we want? Are there any other scenarios/checks to cover?

Todo

• Add CI test

[JoanneBogart]

Is this the behavior we want?

That's the question all right. It is consistent with the way register currently works, creating directories directly under root_dir when necessary. But it isn't always necessary. Most of the time the owner_type directory at least will already be there, often owner_type/owner as well. If they exist, the caller only needs write permission there. On the other hand, we currently have no reason (or automated ability) to make permissions different for different levels of the file hierarchy.

[JoanneBogart]

This is fine the way it is for now.