Craig A. Berry wrote:
On May 18, 2009, at 11:54 PM, John E. Malmberg wrote:
John E. Malmberg wrote:
The trail has taken me to the following lines just below the comment
with the tag AMS 20010810.
while(mg) {
const MGVTBL * const vtbl = mg->mg_virtual;
if (!(mg->mg_flags & MGf_GSKIP) && vtbl && vtbl->svt_get) {
CALL_FTPR(vtbl->sv_get)(aTHX_ sv, mg);
On the return from this call, the Ibody_roots[7] is corrupted.
*vtbl-sv_get at this point is loaded with the function Perl_magic_get,
and the value it is looking for is the '?'.
And looking there, I find VMS specific code where the
my_perl->Istatusvalue_vms is put into sv->sv_any->slv_targlen.
Istatusvalue_vms contains 44, the same bad pointer value.
The body size for type SVt_PVMG (7) appears to be 32, which means that
the LvTARGLEN(sv) writing at offset 32 is the culprit, corrupting the
linked list.
I am not sure how to fix this, but now that I have found out this
much, maybe someone else here can?
So you're saying that these lines in Perl_magic_get in mg.c:
case '?':
{
sv_setiv(sv, (IV)STATUS_CURRENT);
#ifdef COMPLEX_STATUS
LvTARGOFF(sv) = PL_statusvalue;
LvTARGLEN(sv) = PL_statusvalue_vms;
#endif
}
are where the damage occurs? So it looks like the SV in question does
not even have the relevant slots (xlv_targlen) we're trying to update
here.
Yes.
I wonder if it's because IPC::Cmd declares $? as local. Maybe we
are assuming $? is always lexical but it's not?
I do not know.
-John
wb8...@qsl.net
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