On Thu, Feb 12, 2004 at 09:30:18AM +0000 Nick Ing-Simmons wrote:
> Tassilo Parseval <[EMAIL PROTECTED]> writes:
> >On Thu, Feb 12, 2004 at 12:45:29PM +1100 Sisyphus wrote:
> >
> >> Below is a very simple Inline::C script - and, in case it's useful,
> >> below my sig is the XS file that Inline autogenerates from that script.
> >>
> >> ----- start card.pl -----
> >> use Inline C => <<'EOC';
> >>
> >> typedef struct {
> >> SV * suit;
> >> int value;
> >> } Card;
> >>
> >>
> >> SV * create_structref(SV * s, int v) {
> >> Card * cptr;
> >> New(123, cptr, sizeof(Card), Card);
> >> if(cptr == NULL) croak("Failed to allocate memory");
> >> cptr->suit = s;
> >> cptr->value = v;
> >> return sv_setref_pv(newSViv(0), Nullch, cptr);
> >> }
> >>
> >> void clear_mem(SV * p) {
> >> Card* c = (Card *)SvIV(SvRV(p));
> >> printf("Clear_mem called\n");
> >> Safefree(c->suit);
>
> You don't Savefree() SVs - you do SvREFCNT_dec() on them
> and the memory gets linked to a pool for reuse.
> You should normally SvRECNT_inc an SV that you are going to save
> in a C struct so perl knows you are using it.
>
>
> >> /* c->value is an int, and not to be Safefreed */
> >> Safefree(c);
> >> }
> >>
> >> EOC
> >>
> >> $s_index = int(rand(4));
> >> $s = ('Hearts', 'Clubs', 'Diamonds', 'Spades')[$s_index];
> >> $v = int(rand(13)) + 1;
> >>
> >> $c = create_structref($s, $v);
> >>
> >> clear_mem($c);
> >>
> >> __END__
> >> ----- end card.pl ------
> >>
> >> On win32, there's no problem with that (perl 5.6.1, 5.8.0, and 5.8.2).
> >>
> >> On linux, where I have only perl 5.8.0, it prints:
> >>
> >> Clear_mem called
> >> Segmentation fault
> >>
> >> I can get rid of the Segmentation fault by commenting out
> >> 'Safefree(c->suit);' in the 'clear_mem()' function.
> >
> >That is what I would expect. You pass $v to create_structref and store a
> >pointer to it in c->suit. You should only manually free it when you
> >copied the SV. Something like that:
> >
> > SV * create_structref(SV * s, int v) {
> > Card * cptr;
> > New(123, cptr, sizeof(Card), Card);
> > cptr->suite = sv_mortalcopy(s);
>
> A 'mortal' will be freed by perl on scope (statement) exit.
You are right, a mortal isn't a terribly good idea here. But a
non-mortal copy should do. Or simply incrementing s' refcount.
Tassilo
--
$_=q#",}])!JAPH!qq(tsuJ[{@"tnirp}3..0}_$;//::niam/s~=)]3[))_$-3(rellac(=_$({
pam{rekcahbus})(rekcah{lrePbus})(lreP{rehtonabus})!JAPH!qq(rehtona{tsuJbus#;
$_=reverse,s+(?<=sub).+q#q!'"qq.\t$&."'!#+sexisexiixesixeseg;y~\n~~dddd;eval
