[PATCH wayland 1/3 v2] shm: Deprecate wl_shm_buffer_create()

[Giulio Camuffo]

2015-10-16 16:46 GMT+03:00 Pekka Paalanen <ppaalanen at gmail.com>:
> On Sun, 4 Oct 2015 13:46:03 +0300
> Giulio Camuffo <giuliocamuffo at gmail.com> wrote:
>
>> 2015-06-26 19:34 GMT+03:00 Derek Foreman <derekf at osg.samsung.com>:
>> > From irc:
>> > <pq> it creates a wl_buffer object in a way that no client can ever
>> >      access the storage.
>> >
>> > So, let's replace it with abort(); and mark it with WL_DEPRECATED
>> > in the header.
>> >
>> > Signed-off-by: Derek Foreman <derekf at osg.samsung.com>
>> > ---
>> >
>> > This time using WL_DEPRECATED
>> >
>> >  src/wayland-server-core.h |  2 +-
>> >  src/wayland-shm.c         | 29 +----------------------------
>> >  2 files changed, 2 insertions(+), 29 deletions(-)
>> >
>> > diff --git a/src/wayland-server-core.h b/src/wayland-server-core.h
>> > index e605432..dc87168 100644
>> > --- a/src/wayland-server-core.h
>> > +++ b/src/wayland-server-core.h
>> > @@ -397,7 +397,7 @@ wl_display_add_shm_format(struct wl_display *display, uint32_t format);
>> >  struct wl_shm_buffer *
>> >  wl_shm_buffer_create(struct wl_client *client,
>> >                      uint32_t id, int32_t width, int32_t height,
>> > -                    int32_t stride, uint32_t format);
>> > +                    int32_t stride, uint32_t format) WL_DEPRECATED;
>> >
>> >  void wl_log_set_handler_server(wl_log_func_t handler);
>> >
>> > diff --git a/src/wayland-shm.c b/src/wayland-shm.c
>> > index 5c419fa..a9a0b76 100644
>> > --- a/src/wayland-shm.c
>> > +++ b/src/wayland-shm.c
>> > @@ -319,34 +319,7 @@ wl_shm_buffer_create(struct wl_client *client,
>> >                      uint32_t id, int32_t width, int32_t height,
>> >                      int32_t stride, uint32_t format)
>> >  {
>> > -       struct wl_shm_buffer *buffer;
>> > -
>> > -       if (!format_is_supported(client, format))
>> > -               return NULL;
>> > -
>> > -       buffer = malloc(sizeof *buffer + stride * height);
>> > -       if (buffer == NULL)
>> > -               return NULL;
>> > -
>> > -       buffer->width = width;
>> > -       buffer->height = height;
>> > -       buffer->format = format;
>> > -       buffer->stride = stride;
>> > -       buffer->offset = 0;
>> > -       buffer->pool = NULL;
>> > -
>> > -       buffer->resource =
>> > -               wl_resource_create(client, &wl_buffer_interface, 1, id);
>> > -       if (buffer->resource == NULL) {
>> > -               free(buffer);
>> > -               return NULL;
>> > -       }
>> > -
>> > -       wl_resource_set_implementation(buffer->resource,
>> > -                                      &shm_buffer_interface,
>> > -                                      buffer, destroy_buffer);
>> > -
>> > -       return buffer;
>> > +       abort();
>>
>>
>> If we abort() here we make the function unusable and fatal and i'd
>> argue that it may be better to just remove it instead, because no
>> function is better than a pretend function that will kill you without
>> arguing.
>
> We can't remove it, because that is a major ABI break. Not when it can
> be called without a crash at least. I suspect we'll have to keep the
> stub forever.

Imho making it abort() is an API break as well, in a sense, and a
worse one, because it's at runtime instead of at compile time. The
symbol is still there but any attempt at using it will punish you
hard, so in a way it's like if it wasn't there, but you don't have the
compiler complaining hard enough when you use it.


--
Giulio

>
>> Maybe it's better to make it return NULL instead?
>
> Yeah, that would be good enough.
>
> NULL or abort(),
> Reviewed-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
>
> Patch 2 needs a rewrite if you change anything here, but consider it
> Acked-by me.
>
> Patch 3 is Acked-by me too, I don't care too much if it's abort(),
> assert(), return NULL or all of them. If we hit a NULL pool, there is
> guaranteed a bug somewhere, so hopefully that would be caught ASAP
> somehow.
>
>
> Thanks,
> pq