[PATCH wayland] shm: Log a warning if a shm buffer address is requested when it may be invalid

[Bryce Harrington]

On Tue, Feb 09, 2016 at 04:29:49PM -0600, Derek Foreman wrote:
> If wl_shm_buffer_get_data() is called on a shm pool that has an external
> reference and a pending resize, then the buffer may be outside the pool's
> current mapping.
> 
> Log a warning if this happens.
> 
> Signed-off-by: Derek Foreman <derekf at osg.samsung.com>

Part of me wonders if this should be treated as an error situation, but
adding a log message doesn't prevent that and may help in diagnosing
issues, so:

Reviewed-by: Bryce Harrington <bryce at osg.samsung.com>

> ---
>  src/wayland-shm.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/src/wayland-shm.c b/src/wayland-shm.c
> index 6351259..7c67575 100644
> --- a/src/wayland-shm.c
> +++ b/src/wayland-shm.c
> @@ -387,6 +387,11 @@ wl_shm_buffer_get_data(struct wl_shm_buffer *buffer)
>  	if (!buffer->pool)
>  		return NULL;
>  
> +	if (buffer->pool->external_refcount &&
> +	    (buffer->pool->size != buffer->pool->new_size))
> +		wl_log("Buffer address requested when its parent pool "
> +		       "has an external reference and a deferred resize "
> +		       "pending.\n");
>  	return buffer->pool->data + buffer->offset;
>  }
>  
> -- 
> 2.7.0
> 
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