Re: [Libvir] [PATCH] deep copy dom structure
On Mon, Mar 31, 2008 at 11:00:56AM +0100, Richard W.M. Jones wrote:
What problem are you trying to solve?
AFAICT, the problem is that the Domain/Network objects are being free'd
before the remote daemon has a chance to serialze the Error object into
XDR format. So it is accessing free'd memory when serializing the dom/net
field in the Error object & geting back garbage.
The 'conn', 'dom' and 'net' fields in a
virterror can't be accessed
safely, particularly from a garbage-collected language. The only safe
thing one could do with them is a physical equality test on the
pointer against an existing conn/dom/net pointer.
But the solution isn't to copy the dom object, since in a GC-d
language someone could grab a handle to the copied dom which would
have a different lifetime from the error object. If anything the
solution would be to remove those fields from the error object since
they are highly unlikely to be useful in any real world application.
We can't do this because of backwards compatibility promises but we
should instead deprecate them.
We should at the very least NULL-ify the dom/net fields in the Error
object associated with the Connection when we free the Domain/Network
object. We also probably need to re-arrange the remote daemon code a
little so that it serializes to XDR format before the Domain/Network object
are free'd.
I agree that deep copying isn't the answer here & messes up the reference
counting and will cause potential memory leaks.
Dan.
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