Re: Keep compilable with --disable-string-variables

[Ethan A M. <merritt@u.washington.edu>]

On Thursday 13 July 2006 12:43 am, Juergen Wieferink wrote:
> 
> While in it, the snippet:
> 
>     v = add_udv_by_name("GPVAL_TERM");
>     if (v) {
> 	v->udv_undef = FALSE;
> 	Gstring(&v->udv_value,(char*)term->name); /* this can be pointer */
>     }
> 
> looks dangerous to me.  The string a variable points to may be freed
> if the variable is reset.

I take it that you are worried some other bit of code might call
gpfree_string(add_udv_by_name("GPVAL_TERM")), thus triggering
an error when it tries to free the static allocation of term->name?

The GPVAL_* variables cannot be over-written by the user,
and this one bit of code is the only place that gnuplot itself
sets this variable. So it is safe.  

> Would an additional function Gstring_copy() be useful, which could be called
> in places like this?

I don't think that is necessary. You can already do this easily:

  Gstring(&v->udv_value, gp_strdup(term->name));

Then you would have to modify the snippet of code above to deal with the
opposite problem, that unless the previous name is explicitly freed there
will be a memory leak.

-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742