Re: [Libvir] [PATCH] XPath accessors cleanup
On Fri, Mar 30, 2007 at 11:01:25AM +0100, Mark McLoughlin wrote:
Hi Daniel,
Nice stuff !
On Fri, 2007-03-30 at 05:38 -0400, Daniel Veillard wrote:
> +char *
> +virXPathString(const char *xpath, xmlXPathContextPtr ctxt) {
...
> + ret = (char *) obj->stringval;
> + obj->stringval = NULL;
> +int
> +virXPathNodeSet(const char *xpath, xmlXPathContextPtr ctxt, xmlNodePtr **list) {
...
> + if (list != NULL) {
> + *list = obj->nodesetval->nodeTab;
> + obj->nodesetval->nodeTab = NULL;
> + }
This is all a little voodooish to me - e.g. you're assuming that
libxml2 allocated these with malloc() and you're also kind of breaking
the abstraction of xmlXPathObject by manipulating the structure like
this.
Right, sorry I just wanted to make the API and code as less dependant
from libxml2 idioms as possible, but you raise good point ;-)
i.e. you know this works, because you wrote libxml2, but you're
not
using the abstraction very cleanly.
I'd suggest either:
- copy the memory from the xmlXPathObject and return that
- make the functions return "libxml memory" and use xmlFree() in the
callers
I prefer to copy and limit the libxml2 expertise needed to understand the
normal parsing code, so I will implement #1, there is no harm is doing a few
extra malloc()/free() at that point there.
Daniel
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