[PATCH] shell: Check more thoroughly for undefined surface resource

[Bryce Harrington]

On Mon, Sep 14, 2015 at 12:31:10PM -0700, Bryce Harrington wrote:
> The surface can have an undefined resource in certain situations (such
> as with xwayland).  So, since NULL is a valid state for this parameter,
> and since the wl_resource_*, etc. calls require their parameters to be
> non-NULL, make a practice of always checking the surface resource before
> making wayland calls.
> 
> Signed-off-by: Bryce Harrington <bryce at osg.samsung.com>

Some of these checks I wasn't sure if maybe they should instead be
asserts().  E.g. the grab stuff may be predicated on there being a
defined resource, so asserts may be more appropriate there, but I wasn't
sure.  I can respin the patch with those if needed.

Bryce

> ---
>  desktop-shell/shell.c | 37 ++++++++++++++++++++++++++++++-------
>  1 file changed, 30 insertions(+), 7 deletions(-)
> 
> diff --git a/desktop-shell/shell.c b/desktop-shell/shell.c
> index ecc42c5..0b91ce6 100644
> --- a/desktop-shell/shell.c
> +++ b/desktop-shell/shell.c
> @@ -2148,7 +2148,7 @@ xdg_ping_timeout_handler(void *data)
>  			continue;
>  
>  		shsurf = get_shell_surface(pointer->focus->surface);
> -		if (shsurf &&
> +		if (shsurf && grab->shsurf->resource &&
>  		    wl_resource_get_client(shsurf->resource) == sc->client)
>  			set_busy_cursor(shsurf, pointer);
>  	}
> @@ -2183,7 +2183,8 @@ handle_xdg_ping(struct shell_surface *shsurf, uint32_t serial)
>  	if (shell_surface_is_xdg_surface(shsurf) ||
>  	    shell_surface_is_xdg_popup(shsurf))
>  		xdg_shell_send_ping(sc->resource, serial);
> -	else if (shell_surface_is_wl_shell_surface(shsurf))
> +	else if (shell_surface_is_wl_shell_surface(shsurf)
> +		 && grab->shsurf->resource)
>  		wl_shell_surface_send_ping(shsurf->resource, serial);
>  }
>  
> @@ -3372,7 +3373,9 @@ static const struct weston_touch_grab_interface touch_popup_grab_interface = {
>  static void
>  shell_surface_send_popup_done(struct shell_surface *shsurf)
>  {
> -	if (shell_surface_is_wl_shell_surface(shsurf))
> +	if (grab->shsurf->resource == NULL)
> +		return;
> +	else if (shell_surface_is_wl_shell_surface(shsurf))
>  		wl_shell_surface_send_popup_done(shsurf->resource);
>  	else if (shell_surface_is_xdg_popup(shsurf))
>  		xdg_popup_send_popup_done(shsurf->resource);
> @@ -3455,6 +3458,12 @@ add_popup_grab(struct shell_surface *shsurf,
>  	struct weston_pointer *pointer = weston_seat_get_pointer(seat);
>  	struct weston_touch *touch = weston_seat_get_touch(seat);
>  
> +	if (shsurf->resource == NULL) {
> +		wl_resource_post_error(shsurf->owner_resource,
> +				       WL_DISPLAY_ERROR_INVALID_OBJECT,
> +				       "undefined resource when grabbing");
> +		return -1;
> +	}
>  	parent = get_shell_surface(shsurf->parent);
>  	top_surface = get_top_popup(shseat);
>  	if (shell_surface_is_xdg_popup(shsurf) &&
> @@ -3619,7 +3628,8 @@ shell_destroy_shell_surface(struct wl_resource *resource)
>  
>  	if (!wl_list_empty(&shsurf->popup.grab_link))
>  		remove_popup_grab(shsurf);
> -	wl_list_remove(wl_resource_get_link(shsurf->resource));
> +	if (shsurf->resource)
> +		wl_list_remove(wl_resource_get_link(shsurf->resource));
>  	shsurf->resource = NULL;
>  }
>  
> @@ -3803,6 +3813,10 @@ shell_get_shell_surface(struct wl_client *client,
>  	shsurf->resource =
>  		wl_resource_create(client,
>  				   &wl_shell_surface_interface, 1, id);
> +	if (!shsurf->resource) {
> +		wl_resource_post_no_memory(surface_resource);
> +	        return;
> +	}
>  	wl_resource_set_implementation(shsurf->resource,
>  				       &shell_surface_implementation,
>  				       shsurf, shell_destroy_shell_surface);
> @@ -4150,6 +4164,10 @@ xdg_get_xdg_surface(struct wl_client *client,
>  	shsurf->resource =
>  		wl_resource_create(client,
>  				   &xdg_surface_interface, 1, id);
> +	if (!shsurf->resource) {
> +		wl_resource_post_no_memory(surface_resource);
> +		return;
> +	}
>  	wl_resource_set_implementation(shsurf->resource,
>  				       &xdg_surface_implementation,
>  				       shsurf, shell_destroy_shell_surface);
> @@ -4279,6 +4297,10 @@ xdg_get_xdg_popup(struct wl_client *client,
>  	shsurf->resource =
>  		wl_resource_create(client,
>  				   &xdg_popup_interface, 1, id);
> +	if (!shsurf->resource) {
> +		wl_resource_post_no_memory(surface_resource);
> +		return;
> +	}
>  	wl_resource_set_implementation(shsurf->resource,
>  				       &xdg_popup_implementation,
>  				       shsurf, shell_destroy_shell_surface);
> @@ -4299,9 +4321,10 @@ xdg_pong(struct wl_client *client,
>  static bool
>  shell_surface_is_xdg_popup(struct shell_surface *shsurf)
>  {
> -	return wl_resource_instance_of(shsurf->resource,
> -				       &xdg_popup_interface,
> -				       &xdg_popup_implementation);
> +	return (shsurf->resource &&
> +		wl_resource_instance_of(shsurf->resource,
> +					&xdg_popup_interface,
> +					&xdg_popup_implementation));
>  }
>  
>  static const struct xdg_shell_interface xdg_implementation = {
> -- 
> 1.9.1