Re: tied handle in xs

[plobsing]

I have no experience working with tied objects in XS, but I imagine it would be similar to whatever the perl core does.

First lookup what op does the same thing you want to do. In this case, read (called pp_read in C and located in mathoms.c). It delegates to pp_sysread in pp_sys.c.

The definition of this op is in the section following PP(pp_sysread)

The section that handles tied handles is:

    if ((PL_op->op_type == OP_READ || PL_op->op_type == OP_SYSREAD)
        && gv && (io = GvIO(gv)) )
    {
        const MAGIC * mg = SvTIED_mg((SV*)io, PERL_MAGIC_tiedscalar);
        if (mg) {
            SV *sv;
            PUSHMARK(MARK-1);
            *MARK = SvTIED_obj((SV*)io, mg);
            ENTER;
            call_method("READ", G_SCALAR);
            LEAVE;
            SPAGAIN;
            sv = POPs;
            SP = ORIGMARK;
            PUSHs(sv);
            RETURN;
        }
    }

[Anonymous Monk]

I have no experience working with tied objects in XS, but I imagine it would be similar to whatever the perl core does.
There's better ways, perlXStut: EXAMPLE 9 Passing open files to XSes.

[plobsing]

I've read that. It suggests using typemaps for PerlIO objects (my first resort).

However, looking at the T_IN and T_INOUT typemaps, they both do $var = IoIFP(sv_2io($arg)).

That apparently isn't working for spacepille. So I looked for other options.

[Anonymous Monk]

It should work, so spacepille must be omitting something.

[spacepille]

big thank you, it works...

IO *io = sv_2io( sv );
PerlIO *perlio = IoIFP( io );
if( perlio != NULL ) {
    PerlIO_read( perlio, ... );
}
else {
    const MAGIC *mg = SvTIED_mg( (SV *) io, 'q' );
    if( mg != NULL ) {
        sv = SvTIED_obj( (SV *) io, mg );
        // call the READ method with sv as object...
    }
    else {
        Perl_croak( aTHX_ "invalid IO handle" );
    }
}