[Libguestfs] minor Hivex.xs leaks

[Jim Meyering]

Hi Rich,

While I was looking at hivex today I ran coverity on it.
It spotted one problem but missed a similar one nearby.

The following are from Hivex.xs: (generated by generator.ml)

void
node_set_values (h, node, values)
      hive_h *h;
      int node;
      pl_set_values values = unpack_pl_set_values (ST(2));
PREINIT:
      int r;
 PPCODE:
      r = hivex_node_set_values (h, node, values.nr_values, values.values, 0);
      free (values.values);
      if (r == -1)
        croak ("%s: %s", "node_set_values", strerror (errno));

void
node_set_value (h, node, val)
      hive_h *h;
      int node;
      hive_set_value *val = unpack_set_value (ST(2));
PREINIT:
      int r;
 PPCODE:
      r = hivex_node_set_value (h, node, val, 0);
      free (val);
      if (r == -1)
        croak ("%s: %s", "node_set_value", strerror (errno));

--------------------------------------------
Here's the generated C.
Note how each function uses XSRETURN_UNDEF
without freeing the "values" or "val" data they
have just allocated:

XS(XS_Win__Hivex_node_set_values); /* prototype to pass -Wmissing-prototypes */
XS(XS_Win__Hivex_node_set_values)
{
#ifdef dVAR
    dVAR; dXSARGS;
#else
    dXSARGS;
#endif
    if (items != 3)
       croak_xs_usage(cv,  "h, node, values");
    PERL_UNUSED_VAR(ax); /* -Wall */
    SP -= items;
    {
	hive_h *	h;
	int	node = (int)SvIV(ST(1));
	pl_set_values	values = unpack_pl_set_values (ST(2));
#line 477 "Hivex.xs"
      int r;
#line 993 "Hivex.c"

    if (sv_isobject (ST(0)) && SvTYPE (SvRV (ST(0))) == SVt_PVMG)
        h = (hive_h *) SvIV ((SV *) SvRV (ST(0)));
    else {
        warn ("Win::Hivex::node_set_values(): h is not a blessed SV reference");
        XSRETURN_UNDEF;
    };
#line 479 "Hivex.xs"
      r = hivex_node_set_values (h, node, values.nr_values, values.values, 0);
      free (values.values);
      if (r == -1)
        croak ("%s: %s", "node_set_values", strerror (errno));
#line 1006 "Hivex.c"
	PUTBACK;
	return;
    }
}


XS(XS_Win__Hivex_node_set_value); /* prototype to pass -Wmissing-prototypes */
XS(XS_Win__Hivex_node_set_value)
{
#ifdef dVAR
    dVAR; dXSARGS;
#else
    dXSARGS;
#endif
    if (items != 3)
       croak_xs_usage(cv,  "h, node, val");
    PERL_UNUSED_VAR(ax); /* -Wall */
    SP -= items;
    {
	hive_h *	h;
	int	node = (int)SvIV(ST(1));
	hive_set_value *	val = unpack_set_value (ST(2));
#line 490 "Hivex.xs"
      int r;
#line 1031 "Hivex.c"

    if (sv_isobject (ST(0)) && SvTYPE (SvRV (ST(0))) == SVt_PVMG)
        h = (hive_h *) SvIV ((SV *) SvRV (ST(0)));
    else {
        warn ("Win::Hivex::node_set_value(): h is not a blessed SV reference");
        XSRETURN_UNDEF;
    };
#line 492 "Hivex.xs"
      r = hivex_node_set_value (h, node, val, 0);
      free (val);
      if (r == -1)
        croak ("%s: %s", "node_set_value", strerror (errno));
#line 1044 "Hivex.c"
	PUTBACK;
	return;
    }
}
--------------------------------------------

One way to fix it is to change generator.ml to induce this
change in Hivex.xs:

--- Hivex.xs.~1~	2011-06-28 21:01:28.374623171 +0200
+++ Hivex.xs	2011-06-28 21:01:43.351623367 +0200
@@ -472,10 +472,10 @@ void
 node_set_values (h, node, values)
       hive_h *h;
       int node;
-      pl_set_values values = unpack_pl_set_values (ST(2));
 PREINIT:
       int r;
  PPCODE:
+      pl_set_values values = unpack_pl_set_values (ST(2));
       r = hivex_node_set_values (h, node, values.nr_values, values.values, 0);
       free (values.values);
       if (r == -1)
@@ -485,10 +485,10 @@ void
 node_set_value (h, node, val)
       hive_h *h;
       int node;
-      hive_set_value *val = unpack_set_value (ST(2));
 PREINIT:
       int r;
  PPCODE:
+      hive_set_value *val = unpack_set_value (ST(2));
       r = hivex_node_set_value (h, node, val, 0);
       free (val);
       if (r == -1)