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.
> 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
