Leaking memory in Perl XS module

[Shaun]

Hi Everyone,
I've been staring at this for hours now and I can't work out where I'm 
leaking memory in a perl XS module I'm working on. Basically, I need to 
take a tree of C structures:

    typedef struct _SGraph {
        char *name;
        int size;
        Graph list[];
    } * Graph;
with a given head pointer and iterate through the graph and produce Perl 
hashes which look like { name => "__root__", parent => undef, list = [ { 
name => "child" }, parent => (ref to parent), list = ... } ]. I've got the 
algorithm working a number of different ways but each one leaks memory. 
I'm sending the current implementation along with this post, sorry for the 
long post, this is the shortest example that demonstrates the issue.

Thanks,
Shaun
SV *RvFromRv_noinc(SV *ptRv)
{
   return(newRV_noinc(SvRV(ptRv)));
}
HV *MakeHash(Graph ptGraph, SV *ptParent)
{
   static HV *ptGraphStash = NULL;
   HV *ptHash;
   SV *ptSubHash;
   AV *ptArray;
   int i;
   SV *ptResult;
   if (ptGraphStash == NULL)
   {
      ptGraphStash = gv_stashpv("OGDL::Graph", 0);
      if (!ptGraphStash)
         ptGraphStash = (HV *) -1;
   }
   ptHash = (HV *) newHV();
   if (!ptParent)
      /* Storing &PL_sv_undef does not work */
      hv_fetch(ptHash, "parent", 6, 1);
   else
      /* Store the reference to our parent */
      hv_store(ptHash, "parent", 6, RvFromRv(ptParent), 0);
   hv_store(ptHash, "name", 4, newSVpv(ptGraph->name, 0), 0);
   ptResult = newRV_noinc((SV *) ptHash);
   ptArray = newAV();
   av_extend(ptArray, ptGraph->size);
   for (i = 0; i < ptGraph->size; i++)
   {
      ptSubHash = MakeHash(ptGraph->nodes[i], ptResult);
      av_push(ptArray, RvFromRv_noinc((SV *) ptSubHash));
   }
   hv_store(ptHash, "list", 4, newRV_noinc((SV *) ptArray), 0);
   if (ptGraphStash && (ptGraphStash != (HV *) -1))
      sv_bless(ptResult, ptGraphStash);
   return(ptResult);
}
MODULE = OGDL::NativeParser      PACKAGE = OGDL::NativeParser
SV *GraphFile(char *sFile)
{
   SV *ptResult = NULL;
...
    ptResult = MakeHash(*ptParser->g, NULL);
    return(ptResult);
}
SV *
load(file)
      char *file
   PREINIT:
      Graph ptGraph = NULL;
   CODE:
      /* Create perl hashes to return */
      RETVAL = GraphFile(file);
   OUTPUT:
      RETVAL