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);
> /* 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);
cptr->value = v;
...
}
void clear_mem(SV *p) {
Card *c = (Card*)SvIV(SvRV(p));
sv_free(c->suit);
Safefree(c);
}
Copying the SV is a good idea anyways because otherwise c->suit is
destroyed when perl garbage-collects $v. If you don't want to create a
copy, you should increment the refcount of 's' in create_structref. In
this case you should also be able to store a pointer to s in your
structure.
Tassilo
--
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$_=reverse,s+(?<=sub).+q#q!'"qq.\t$&."'!#+sexisexiixesixeseg;y~\n~~dddd;eval
