Comment 2 for bug 332500

I'm sure this is an implementation detail, but could we write some metadata for each backup, such as the backup date and time, the size required and maybe a file list. This would allow Deja Dup to know almost immediately that it does not have enough available space in either the cache dir or the destination dir. It also allows Deja Dup to come back much more quickly with the date and time of the backup you want to restore (rather that eating my cpu to get this information). The file list (which should probably be encrypted) might allow future functionality of either warning the user when they request to restore a non-existent directory or allowing the user to pick from a list of directories they wish to (or to not) restore.