[ccan] help with gracefully dealing with alloc failure in a recursive function

[Rusty Russell]

On Tue, 11 Oct 2011 19:24:27 -0400, Joey Adams <joeyadams3.14159 at gmail.com> wrote:
> On Tue, Oct 11, 2011 at 6:23 PM, Sam Watkins <sam at nipl.net> wrote:
> > As for freeing the XML data structures, aren't they linked together?
> > Why not long-jump out of the parser however you'd like to, then call
> > free_whole_xml_tree() or whatever?  Or it could just return 'the tree so far'
> > with an error code, and let the user free it or keep it.
> 
> This is a good idea.  However, you have to ensure that, for every
> function call that does a long jump:
> 
>  * All objects are attached to the tree.  Those that aren't can be
> attached, or they can be freed manually.
> 
>  * The tree is in a valid state, at least as far as your tree freeing
> code is concerned.  An example of an invalid node would be a tagged
> union where the tag hasn't been initialized yet.

  * That you test it.  See ccan/failtest for one way.

Cheers,
Rusty.