On Fri, 30 May 2014 12:08:15 +0200 Jonny Lamb <jonny.l...@collabora.co.uk> wrote:
> This already happens in weston. > --- > protocol/wayland.xml | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/protocol/wayland.xml b/protocol/wayland.xml > index 22eb6e7..3091d83 100644 > --- a/protocol/wayland.xml > +++ b/protocol/wayland.xml > @@ -222,6 +222,11 @@ > A buffer will keep a reference to the pool it was created from > so it is valid to destroy the pool immediately after creating > a buffer from it. > + > + If offset is negative, width or height are not greater than > + zero, or the stride is less than the width the invalid_stride > + protocol error is raised. If the format is not supported the > + invalid_format protocol error is raised. > </description> > > <arg name="id" type="new_id" interface="wl_buffer"/> Hi, yeah, this is the intention, but the existing protocol spec is strange. This error happens on wl_shm_pool.create_buffer request, it is sent against the wl_shm_pool object, but wl_shm_pool does not define this error! Instead, the error is defined on wl_shm interface, and technically those are not valid for wl_shm_pool. The namespace for the error codes is wrong. This problem is in both shm_pool_create_buffer() and shm_pool_resize() functions in libwayland-server. Furthermore, it seems wl_shm_buffer_end_access() is sending WL_SHM_ERROR_INVALID_FD on the wl_buffer, which is again a namespace violation. Because every interface defines (or does not define) their own error codes, and these codes are namespaced to the interface (so far all error enums start with 0 and overlap, I think), the namespacing is really needed to tell them apart in the receiving side. So far we haven't had problems, because no-one expects to get a specific error as part of normal flow. I still think this is a bad example, and should be fixed. Proposal: - Let's duplicate all wl_shm error codes in wl_shm_pool; this maintains the numeric values of the codes in a backward-compatible way, and makes the namespace valid. Could even add a comment there, that these error codes match wl_shm error codes, and wl_shm error codes can be used here. - wl_shm_buffer_end_access() should either use a generic wl_display error, or we need to add an error code to wl_buffer interface to have the proper namespace. Which? There is also a practical reason to get this fixed, rather than "oh it's just ugly": if someone writes a protocol analyzer, that could then decipher the error codes in addition to showing the error message. Thanks, pq _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/wayland-devel
