[Xcb] xcb and protocol versions

Peter Hutterer mailinglists at who-t.net
Thu Feb 22 15:17:02 PST 2007

On 23/02/2007, at 05:48 , Jeremy A. Kolb wrote:
> I am unsure how to handle the case where the client uses a
> request from an older version of the extension that has now changed  
> its
> signature in a later version of xcb.

don't change it. If you decide to fill existing padding fields with  
data, that is fine because the client won't access them. if you start  
adding bytes, you will most likely get the client out of sync.  
there's probably some stuff you can do with fake padding. say you  
have a request with a length field and a count variable. count gives  
you the number of bytes after the 32 standard. you could change  
length but not count, resulting in fake padding bytes being added at  
the end. for newer versions, you can then stuff data in there. not  
sure it's wise to go there though.

If you want to extend a request, you have to have version negotiation  
and send back exactly what the client wants, depending on the version  
the client is running.


Multi-Pointer X Server

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