Wayland specification doesn't match code generation

Boyan Ding stu_dby at 126.com
Wed Sep 3 20:59:26 PDT 2014


It is actually not a fault in wayland, instead it is designed to be so.
new_id's without interface specified in the protocol (such as the one in
wl_registry::bind) must come with 3 arguments (s: interface name, u:
version, n: the actual new_id). That's why 'n' turns into 'sun'. If a
language binding generates the wrong code, please contact the author of
the language binding and let him correct it. If you are changing how
wayland-scanner (the official C code generator) works, the whole world
will break before you.

Refer to "How protocol objects are created" section in [1] to see the

Boyan Ding


On Wed, 2014-09-03 at 22:32 -0500, Paul Sbarra wrote:
> I tried to start some discussion on this topic previously, but it
> apparently didn't make it through the moderator, so I'm trying again
> having now joined the list.
> I've recently taken an interest in the gowl implementation of the
> wayland protocol and noticed that the specification doesn't match the
> interface that gets generated by the wayland scanner.
> If I attempt to code-gen gowl using the wayland.xml file the
> wl_registry bind interface is missing a couple arguments that weston
> expects, resulting in the following runtime error:
> libwayland: message too short, object (2), message bind(usun)
> However, the spec indicates a bind request signature of "un".
> I tracked this down into some curious logic in the scanner and have
> been working on a patch to try and allow the corrected signature to be
> specified in the protocol.  Unfortunately this has become more
> interesting then I'd anticipated.
> Attached is my naive attempt at resolving this issue.  I'm horrified
> by the string->interface lookup and the wl_registry_bind api change
> but I'm not sure what else one can do.  Any feedback or additional
> help would be appreciated.
> Note that this patch applies to the 1.5.91 tagged commit and compiles
> cleanly (for wayland).  Weston didn't like having the lookup function
> defined in multiple files, so maybe there would be a better place to
> put such functionality.
> Thanks,
> Paul
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