This is very similar to a hypothetical virus scanner so many of the
techniques should apply. I've read TN2127 and the list archives about
implementing a virus scanner and one question that's never been
definitively answered is how the kernel can block and then call out to
a user level application. In fact TN2127 says in the Listener Gotchas
section that the only foolproof method is the implement the scanner
completely in the kernel. Is this still the recommended approach? If
it is will I be able to implement my version of Time Machine?
It is legitimate to block in the VNODE scope handlers; the kernel
will do this in some cases.
What you're describing (a lazy file backup mechanism) is quite
practical, but note that it may have a very poor user experience (due
to high latency introduced by blocking file opens while making backups).
You may find it wiser to perform deferred last-close backups; wait
for a few seconds after a FILEOP_CLOSE notification (so you don't
backup something that's going to be opened or deleted shortly
afterwards) and then make the backup in the background.
Yes, I know that you're envisaging an "undo" semantic, but trust me,
users like to have backups that protect them from more than just
their own mistakes...
= Mike
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Darwin-kernel mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/darwin-kernel/email@hidden
