Callers of streamCopy() expect an array to be returned containing count and result.

otherwise the returned internalPath will not match followup calls to e.g. Cache::getID()

due to internal implementations touch will always be successful - $mtime will be stored in the cache
from desktop client perspective it is necessary to set the mtime under every condition

PHP Fatal error: Can't inherit abstract function OCP\ISession::set() (previously declared abstract in OC\Session\Session)

The user id has to be returned.

updating a existing large file creates new file chunks. Therefore createFile() needs to check not only if we can write to the parent folder but also if we can update the existing file"

If a existing file in Shared/ with update permissions gets updated we need to write the .part file to a different place because we can't create new files in the Shared folder