+
+ /* Some content files are very big, so we use a poor man's
+ digest here: a MD5 of the first and last 1e6 bytes with the
+ size of the first file tacked on the end as a string.
+ */
+ string const d = md5_digest_head_tail (p, 1000000) + raw_convert<string> (boost::filesystem::file_size (p.front ()));