John E. Malmberg wrote:
John E. Malmberg wrote:
Nicholas Clark wrote:
On Mon, Apr 27, 2009 at 12:27:02AM -0500, John E. Malmberg wrote:
I just started looking into a failure of 19_CPANPLUS-Dist. I have
not determined what exactly is wrong, and am out of time for the
moment.
I will try to get some more information later.
It is failing from an access violation in SV.C.
ok 57 - Perl version not high enough
%SYSTEM-F-ACCVIO, access violation, reason mask=00, virtual
address=000000000000002C, PC=00000000000F9AB8, PS=0000001B
%TRACE-F-TRACEBACK, symbolic stack dump follows
image module routine line rel PC
abs PC
DBGPERLSHR SV Perl_sv_upgrade 73671 0000000000001F58
#define new_body_inline(xpv, sv_type) \
STMT_START { \
void ** const r3wt = &PL_body_roots[sv_type]; \
xpv = (PTR_TBL_ENT_t*) (*((void **)(r3wt)) \
? *((void **)(r3wt)) : more_bodies(sv_type)); \
*(r3wt) = *(void**)(xpv); \
} STMT_END
I'm curious what the value of sv_type is. It's the second (real)
parameter:
void
Perl_sv_upgrade(pTHX_ register SV *const sv, svtype new_type)
case SVt_PVMG:
...
new_body_inline(new_body, new_type);
new_type = SVt_PVMG,
SVt_PVMG has a value of 7.
new_body = 44.
PL_Body_roots[sv_type] = 44.
From the code, it looks like this was expected to contain a valid
pointer.
From looking at the source code, it appears that the linked list of
bodies is corrupted. my_perl->Ibodyroots[7] has 44.
I have been looking at the S_more_bodies routine. Would it be practical
to put an assert on for a pointer being added to the linked list with a
value above 512? On VMS, the first page of memory is protected no access.
I put a modified test script at
http://eisner.encompasserve.org/~malmberg/perl/19_CPANPLUS-DIST.TXT
I commented out as much as I could and still reproduce the access violation.
-John
wb8...@qsl.net
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