Re: port initialization?

[Marius Vollmer]

Han-Wen <address@hidden> writes:

> what about
>   
>   z = scm_cell (scm_tc16_strport, 0);
>   SCM_DEFER_INTS;
>   pt = scm_add_to_port_table (z);
>   SCM_SET_CELL_TYPE (z, scm_tc16_strport | modes);
>   SCM_SETPTAB_ENTRY (z, pt);
>   SCM_SETSTREAM (z, SCM_UNPACK (str));
> 
> This looks like fishy code to me. When scm_add_to_port_table triggers
> GC then it will see the (scm_tc16_strport, 0) cell, which is (or
> should be) invalid.

Yes, but the GC will not notice since "z" still refers to it and
therefore the port cell wont be freed.  So we are safe.  It's a little
fishy, yes.  We could flag the port as closed until its ptab_entry is
set properly.  Closed ports do also have a NULL ptab_entry.

> Why not
> [...] 
>     {
>       scm_t_port *newport =  scm_add_to_port_table ();
>       SCM port = scm_cell (scm_tc16_port, newport);
>       newport->port = port;
>                     ..
>     }

This will leak newport when the call to scm_cell throws.