Re: Perl XS: garbage-collecting my malloc'd buffer

Well, I'm wrapping wxSocket* for wxPerl. Take a look in this function. Is the wxSocketBase::Read, that write directly to a buffer point of a Perl Scalar (SV):

long
wxSocketBase::Read( buf , size , leng = 0 )
    SV* buf
    long size
    long leng
  CODE:
    // Tell that the scalar is string only (not integer, double, utf8.
+..)
    SvPOK_only(buf) ;
    // Get the original size:
    int org_size = SvCUR(buf) ;

    // Grow the scalar to receive the data and return a char* point:
    char* buffer = SvGROW( buf , size + 1 ) ;
    // Get the char* point of the end if you want to append data (len 
+> 0):
    if ( leng > 0 ) { buffer = SvEND(buf) ;}
    else { org_size = 0 ;}

    THIS->Read( buffer , size ) ;
    // Get the amount of data read in the socket:
    int nread = THIS->LastCount() ;
    
    if ( nread > 0 ) {
      // null-terminate the buffer, not necessary, but does not hurt
      buffer[nread] = 0 ;
      // tell Perl how long the string is
      SvCUR_set( buf , org_size + nread ) ;
    }
    // Return the amount of data read, like Perl read().
    RETVAL = nread ;
  OUTPUT: RETVAL

The good of this is that you can see how to write or append to a buffer. And is more Perl based.

Note that "SvPOK_only(buf)" is important! Since if your variable is set for integer, like this:

my $var = 123 ;

.. you can't use SvGROW, SvCUR and SvCUR_set!

Take a look in the POD perlapi and perlguts too.

Graciliano M. P.
"The creativity is the expression of the liberty".