[Chicago-talk] [Fwd: Re: 64 bit problems - XS wrappers]

[Scott T. Hildreth]

Anybody on the list run into this problem?

-------- Forwarded Message --------
From: Scott T. Hildreth <shildret at scotth.emsphone.com>
Reply-To: shildreth at allantgroup.com
To: Perl-Xs <perl-xs at perl.org>
Subject: Re: 64 bit problems - XS wrappers
Date: Thu, 13 Jul 2006 18:49:14 -0500


On Thu, 2006-07-13 at 18:32 -0500, Scott T. Hildreth wrote:
> I changed the XS declaration to a SV * and changed,
> 
>    RETVAL = (char *)fmt_get_fld_location(fmt, fld);
> 
>    to  RETVAL = (SV *)fmt_get_fld_location(fmt, fld)
> 
> ...and in gdb I could see more, 
> 
> (gdb) n
> 1197                IV tmp = SvIV((SV*)SvRV(ST(1)));
> (gdb) n
> 419             RETVAL = (SV *)fmt_get_fld_location(fmt, fld);
> (gdb) n
> 1205            ST(0) = RETVAL;
> (gdb) p RETVAL
> No symbol "RETVAL" in current context.
> (gdb) n
> 1206            sv_2mortal(ST(0));
> (gdb) p ST(0)
> $6 = (SV *) 0x600ea0
> (gdb) p *ST(0)

       ...okay this doesn't tell me anything.  I got the same result on
for another function call, which does not seg fault.  It also returns a 
(char *) and works.  I'm stumped.  If I step into the function I see the
null string is created and the returned.  I don't know how to see if it 
is in the RETVAL

> $7 = {sv_any = 0x0, sv_refcnt = 2147482504, sv_flags = 8388608}
> 
> 
>       ...shouldn't sv_any not be null?
> 
> (gdb) n
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x0000000000473459 in Perl_sv_2mortal ()
> 
> 
> On Thu, 2006-07-13 at 17:15 -0500, Scott T. Hildreth wrote:
> > Posting again, didn't see it show up on the list.
> > 
> > ..I've seen the strlen() seg fault problem by searching, 
> > just no solutions.  The string returned in RETVAL is null terminated, 
> > so I don't understand.  
> > 
> > 
> > On Thu, 2006-07-13 at 14:56 -0500, Scott T. Hildreth wrote:
> > > ...we are installing 64bit Suse boxes.  I normally compile our own Perl,
> > > leaving the vendor Perl alone.  I don't think this will help with this 
> > > problem though (unless I compile as 32 bit).  The following XS code
> > > fails in libc - strlen(),
> > > 
> > > =============================================================================
> > > 
> > > 1180    {
> > > (gdb) n
> > > 1181        dXSARGS;
> > > (gdb) n
> > > 1182        if (items != 2)
> > > (gdb) n
> > > 1188            dXSTARG;
> > > (gdb) n
> > > 1190            if (sv_derived_from(ST(0), "FMTPtr")) {
> > > (gdb) n
> > > 1191                IV tmp = SvIV((SV*)SvRV(ST(0)));
> > > (gdb) n
> > > 1197            if (sv_derived_from(ST(1), "FMT_FLDPtr")) {
> > > (gdb) n
> > > 1198                IV tmp = SvIV((SV*)SvRV(ST(1)));
> > > (gdb) n
> > > 419             RETVAL = (char *)fmt_get_fld_location(fmt, fld);
> > > (gdb) p tmp
> > > $4 = 11516288
> > > (gdb) n 
> > > 1206            sv_setpv(TARG, RETVAL); XSprePUSH; PUSHTARG;
> > > (gdb) p RETVAL
> > > No symbol "RETVAL" in current context.
> > > (gdb) s
> > > 419             RETVAL = (char *)fmt_get_fld_location(fmt, fld);
> > > (gdb) s
> > > 1206            sv_setpv(TARG, RETVAL); XSprePUSH; PUSHTARG;
> > > (gdb) s
> > > 
> > > Program received signal SIGSEGV, Segmentation fault.
> > > 0x00002ad1795286d0 in strlen () from /lib64/libc.so.6
> > > 
> > > =================================================================================
> > > 
> > > ...at first I thought it was the threaded-64 bit Perls, but it seg
> > > faults  on a non-threaded version as well.  It runs fine on a 32 bit 
> > > server.  
> > > 
> > > I am really hopping someone has run into this, any help would be much
> > > appreciated.
> > > 
> > > 
> > >                                       STH
> > > 
> > > 
> > > 
> > >  

-- 
Scott T. Hildreth <shild at sbcglobal.net>
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