Using off_t, at least, in DiskAdaptor layer is problematic because
torrent can contain under 2GiB files but total sum of those files may
exceed 2GiB limit, which makes off_t overflow in 32 bit system without
large file support. So we use int64_t in API. We'll check the file
length before download so that it does not exceed max off_t.
If relative URI is found in Metalink file, aria2 resolves its full URI
contatenating the URI from which Metalink file is retrieved and
relative URI in Metalink file. This feature is not available if
Metalink file in local disk is specified in command line.
Tatsuhiro Tsujikawa