Re: [PATCH] fopencookie: Mangle function pointers stored on the heap [BZ #20222]

[Florian Weimer <fweimer at redhat dot com>]

On 06/10/2016 05:55 PM, Carlos O'Donell wrote:

> > +/* Copy the callbacks from SOURCE to *TARGET, with pointer
> > +   mangling.  */
> > +static void
> > +set_callbacks (_IO_cookie_io_functions_t *target,
> > +	       _IO_cookie_io_functions_t source)
> > +{
> > +  PTR_MANGLE (source.read);
> > +  PTR_MANGLE (source.write);
> > +  PTR_MANGLE (source.seek);
> > +  PTR_MANGLE (source.close);
>
> Isn't this modifying the user's copy of the callbacks
> passed in during the call to fopencookie?

No, C function arguments are pass-by-value.  It's not a 
pointer-to-struct, it's the struct object itself.

Thanks,
Florian