A problem with this patch is that the user may have an IXMLDOMNode * reference to the attribute node being removed. The xmlFreeProp will free the xmlnode so accessing the IXMLDOMNode could result in memory corruption. Under MSXML it's possible to access such node and even reconnect it e.g. to a different documents (at least I seem to remember such a thing for element nodes). I don't think supporting it is possible with our current reference counting only for the whole document. I was thinking about also keeping reference counts for each connected component and each node. The connected component count could be used to determine if the node can be freed in such a situation and the node count could be used to update the connected component counts if the tree gets split. But so far I haven't written any code (Another possibility is to keep in each node the refcount of the whole subtree starting in this node. This is more elegant but it would take a linear time with respect to the tree height to update the refcount).
Mikołaj Zalewski
Mikołaj Zalewski wrote:
A problem with this patch is that the user may have an IXMLDOMNode * reference to the attribute node being removed. The xmlFreeProp will free the xmlnode so accessing the IXMLDOMNode could result in memory corruption. Under MSXML it's possible to access such node and even reconnect it e.g. to a different documents (at least I seem to remember such a thing for element nodes). I don't think supporting it is possible with our current reference counting only for the whole document. I was thinking about also keeping reference counts for each connected component and each node. The connected component count could be used to determine if the node can be freed in such a situation and the node count could be used to update the connected component counts if the tree gets split. But so far I haven't written any code (Another possibility is to keep in each node the refcount of the whole subtree starting in this node. This is more elegant but it would take a linear time with respect to the tree height to update the refcount).
Mikołaj Zalewski
Thanks for pointing this out. Ill write some tests, and retry again shortly.
Alistair Leslie-Hughes
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Alistair Leslie-Hughes -
Mikołaj Zalewski