Re: Destructors and magic [was: Re: Leaking memory with sv_usepvn()]

[Steve Hay]

Steve Hay wrote:

>Revised version (attached)
>
Damn.  Forgot to attach it.  Here it is.


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#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

#include "ppport.h"

typedef struct {
  I32 signature;
  char *buf;
} Foo;

static Foo *FooAlloc(pTHX);
static void FooFree(pTHX_ Foo *foo);
static int MagicFooFree(pTHX_ SV *sv, MAGIC *mg);

static MGVTBL Foo_vtbl = {
  NULL,
  NULL,
  NULL,
  NULL,
  MagicFooFree
};

static Foo *FooAlloc(pTHX) {
  Foo *foo;
  Newz(0, foo, 1, Foo);
  Newz(0, foo->buf, 1024, char);
  foo->signature = 42;
  strcpy(foo->buf, "Hello, world.");
  return foo;
}

static void FooFree(pTHX_ Foo *foo) {
  Safefree(foo->buf);
  Safefree(foo);
}

static int MagicFooFree(pTHX_ SV *sv, MAGIC *mg) {
  FooFree(aTHX_ (Foo *)mg->mg_ptr);
  return 1;
}

MODULE = Foo            PACKAGE = Foo           

void
magicfoo()
PPCODE:
{
  SV *sv;
  Foo *foo;
  MAGIC *mg;
  // Initialise
  foo = FooAlloc(aTHX);
  sv = NEWSV(0, 0);
  sv_magic(sv, sv, PERL_MAGIC_ext, (char *)foo, 0);
  SvRMAGICAL_off(sv);
  if (!(mg = mg_find(sv, PERL_MAGIC_ext)))
    croak("Can't find new magic");
  if (mg->mg_obj != sv)
    croak("Found wrong magic!");
  mg->mg_virtual = &Foo_vtbl;
  mg_magical(sv);
  SvREADONLY_on(sv);
  // Use it
  if (!(mg = mg_find(sv, PERL_MAGIC_ext)))
    croak("Can't find magic");
  if (!(foo = (Foo *)(mg->mg_ptr)))
    croak("Can't find magic pointer");
  if (foo->signature != 42)
    croak("Found wrong magic pointer");
  printf("%s\n", foo->buf);
  // Clean up
  SvREFCNT_dec(sv);
}

void
magicextfoo()
PPCODE:
{
  SV *sv;
  Foo *foo;
  MAGIC *mg;
  // Initialise
  foo = FooAlloc(aTHX);
  sv = NEWSV(0, 0);
  if (!sv_magicext(sv, NULL, PERL_MAGIC_ext, &Foo_vtbl, (char *)foo, 0))
    croak("Can't add magic");
  SvREADONLY_on(sv);
  // Use it
  if (!(mg = mg_find(sv, PERL_MAGIC_ext)))
    croak("Can't find magic");
  if (!(foo = (Foo *)(mg->mg_ptr)))
    croak("Can't find magic pointer");
  if (foo->signature != 42)
    croak("Found wrong magic pointer");
  printf("%s\n", foo->buf);
  // Clean up
  SvREFCNT_dec(sv);
}