Re: [patch] serious problem in pango_layout_set_text()

[Owen Taylor <otaylor redhat com>]

Sven Neumann <sven gimp org> writes:

> Hi,
> 
> Owen Taylor <otaylor redhat com> writes:
> 
> > void
> > pango_layout_set_text (PangoLayout *layout,
> > 		       const char  *text,
> > 		       int          length)
> > {
> >   const gchar *end;
> >   
> >   g_return_if_fail (layout != NULL);
> >   g_return_if_fail (length == 0 || text != NULL);
> 
> you allow text == NULL && length == 0 here and this used to work before
> and cleared the layout. 
> 
> >   if (!g_utf8_validate (text, length, &end))
> >     g_warning ("Invalid UTF8 string passed to pango_layout_set_text()");
> 
> g_utf8_validate() does not like text == NULL however and will return FALSE
> with a warning. 
> 
> >   length = end - text;
> 
> here you use the undefined value of end which has never been touched by
> g_utf8_validate() ...

This is irrelevant. Remember, you got a *Gtk-Criticial*, all future
bets are off. -)

> >   layout->text = g_malloc (length + 1);
> 
> ... which leads to a fatal crash here unless you are unlucky or have lots
> of RAM.
> 
> Not sure how this would be fixed best...

 if (length != 0)
   {
     if (!g_utf8_validate (text, length, &end))
       g_warning ("Invalid UTF8 string passed to pango_layout_set_text()");
     length = end - text;
   }

Or we could make g_utf8_validate accept length == 0 && text == NULL, but that
doesn't seem all that useful.

Regards,
                                        Owen