You should try passing in a \$buf instead of $buf (using both implementations).

The "char * buf" formal argument is misleading and is only ever used as an ordinary lexcial "char *" variable.

The PREINIT: line, SV * const bufsv = SvROK(ST(2­)) ? SvRV(ST(2)­) : ST(2); means that you can either pass in $buf to have it populated or pass in \$buf. It looks to me like the line you asked about is just wasteful in the case of passing in $buf. I think it actually breaks things if you pass in \$buf.

It smells like historical baggage. I'd rewrite the code like so: 

pg_lo_read( dbh, fd, bufsv, len )
    SV *    dbh
    int     fd
    SV *    bufsv
    size_t  len
CODE:
    int     ret;
    char *  buf;
    if(  SvROK(bufsv)  ) {
        bufsv= SvRV(bufsv);
    }
    sv_setpvn(bufsv,"",0); /* Make sure we can grow it safely */
    buf= SvGROW( bufsv, len + 1 );
    ret= pg_db_lo_read( dbh, fd, buf, len );
    if(  0 < ret  ) {
        SvCUR_set( bufsv, ret );
        *SvEND(bufsv)= '\0';
        SvSETMAGIC( bufsv );
    }
    ST(0)= 0 <= ret
        ? sv_2mortal(newSViv(ret))
        : &PL_sv_undef;

[download]

- tye        

In reply to Re: Perl XS - is this code required in DBD::Pg? (cruft) by tye
in thread Perl XS - is this code required in DBD::Pg? by mje

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