On Thu, 2006-07-13 at 18:49 -0500, Scott T. Hildreth wrote:
> I don't know how to see if it
> is in the RETVAL
I was not able to see RETVAL because the Makefile for my module had
OPTIMIZE set to -O2, which was overriding my -O0 set in the PASTHRU_INC
env. Once I took that out of the Makefile, RETVAL was not optimized
out. I tried to de-reference the var and saw that the memory address
was out of bounds (which I suspected all along). Now the important
lesson that I learned. :-) On 64 bit archs, the int is 4 bytes a
pointer is 8 bytes. I didn't have a function prototype declared for
this particular function. Gcc will default the type to be int if a
prototype doesn't declare it otherwise. So when the return value was
being treated as a char * the 8 bit pointer was actually an 4 byte int
and was pointing off into the abyss.
> >
> > (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 <[EMAIL PROTECTED]>
