owncloud/core

Change: Copy the encryption keys first and then rename the files

Having encryption enabled, when a file was renamed, first the actual
file was renamed, and then the encryption keys were moved to the new
location. If something went wrong, it was possible that the keys weren't
moved. This caused the file to become inaccessible because we couldn't
decrypt the file due to the missing keys (which weren't in the right place)

Now, when a file is renamed, the encryption keys will be copied first, and
then the file will be renamed. If the encryption keys fail to be copied, the
rename will fail. After the encryption keys are copied, the file could
failed to be renamed. In this case, the copied keys will be removed, but
the file will still be accessible because we still keep the old keys.
The original keys (not the copy) will be removed if the file is renamed
successfully.

https://github.com/owncloud/core/pull/40433