On Wed, 15 Oct 2014 22:44:25 +0400
Dmitry Cherkassov <dcherkas...@gmail.com> wrote:
> Hi list!
>
> The definition of wl_display_interface symbol can come from
> libwayland-server.so or libwayland-client.so.
>
> There is a code in closed source EGL implementation that does
> interfaces comparison via pointers, yielding negative results when
> addresses are different (one address is saved by QtWayland, the other
> one is from &wl_display_interface in EGL source code).
>
> Is there a smarter way to compare wl_display_interface's?
>
> There is this function:
>
> wl_interface_equal(const struct wl_interface *a, const struct wl_interface *b)
> {
> return a == b || strcmp(a->name, b->name) == 0;
> }
>
> But as you can see it's not safe to use it alone because in case of
> bad pointer we will get undefined results.
>
> Currently struct wl_interface is the following:
> struct wl_interface {
> const char *name;
> int version;
> int method_count;
> const struct wl_message *methods;
> int event_count;
> const struct wl_message *events;
> };
>
> Since there is no magic field at the beginning it is not possible to
> see whether a pointer points to the valid wl_interface structure.
>
> So my question is: how can we compare wl_interfaces in more clever and
> safer way?
Hmm, why would you ever have a bad pointer?
Bad pointers in general tend to cause crashes and stuff, so you
shouldn't be having a bad one in the first place.
What is the background for your question/problem?
Thanks,
pq
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