Steve Hay <[EMAIL PROTECTED]> writes:
>Nick Ing-Simmons wrote:
>>If you use the MAGIC * as the "signature" it can't fail ;-)
>>
>An excellent idea.
>
>So attached is hopefully my final take.
Which looks fine - I see there is another mail though so will
study that.
>
>Using sv_magic(), I've dropped the re-use of the SV in the 2nd arg since
>(a) I couldn't pull that trick if I actually wanted to use mg_obj for
>something else and (b) the subsequent mg_find() call is always
>_immediately_ after sv_magic() anyway so no other magic could have been
>added. the MAGIC * is then stored within the struct itself. Later on
>(and possibly in another part of the code, when mg_find() wouldn't be
>"safe"), the pointer stored with the struct is used to verify that the
>correct MAGIC * was found.
>
>Using sv_magicext() is even easier since it returns the MAGIC * for us.
>
>Thanks (once again!) for your help.
>
>- Steve
>
>
>------------------------------------------------
>Radan Computational Ltd.
>
>The information contained in this message and any files transmitted with it are
>confidential and intended for the addressee(s) only. If you have received this
>message in error or there are any problems, please notify the sender immediately.
>The unauthorized use, disclosure, copying or alteration of this message is strictly
>forbidden. Note that any views or opinions presented in this email are solely those
>of the author and do not necessarily represent those of Radan Computational Ltd. The
>recipient(s) of this message should check it and any attached files for viruses:
>Radan Computational will accept no liability for any damage caused by any virus
>transmitted by this email.
>#include "EXTERN.h"
>#include "perl.h"
>#include "XSUB.h"
>
>#include "ppport.h"
>
>typedef struct {
> MAGIC *mg;
> 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);
> 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, NULL, PERL_MAGIC_ext, (char *)foo, 0);
> // This mg_find() can't fail since we're doing it straight away.
> if (!(mg = mg_find(sv, PERL_MAGIC_ext)))
> croak("Can't find new magic");
> foo->mg = mg;
> mg->mg_virtual = &Foo_vtbl;
> SvREADONLY_on(sv);
> // Use it. This could be much later in another function, so we
> // need to check that mg_find() found the right magic.
> 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->mg != mg)
> 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 (!(mg = sv_magicext(sv, NULL, PERL_MAGIC_ext, &Foo_vtbl, (char *)foo, 0)))
> croak("Can't add magic");
> foo->mg = mg;
> SvREADONLY_on(sv);
> // Use it. This could be much later in another function, so we
> // need to check that mg_find() found the right magic.
> 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->mg != mg)
> croak("Found wrong magic pointer");
> //printf("%s\n", foo->buf);
> // Clean up
> SvREFCNT_dec(sv);
>}
