You could configure a loopback device on the file with an offset, then access the loopback device's block device as a file. If you need to append to the file, then you will need to pad it first and know at what offset to begin writing--or just append to the original file, but it won't be accessible to the lo device (and you shouldn't write to the portion of the original file mapped by the lo device).
Depending on your end goal this may or may not help. /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
