[Xcb] XCB parsing and valueparam

Julien Danjou julien at danjou.info
Fri Aug 29 01:35:55 PDT 2008

At 1219993454 time_t, Barton C Massey wrote:
> The specific problem here is that there is not supposed to
> be any padding on the end of the ConfigureWindow request
> (see the protocol spec p. 125).  The LISTofVALUE on the end
> should have a 2-byte pad between the bitmask and the (zero
> or more) values, but that's presumably taken care of by
> valueparam.  The current code generator is doing the right
> thing here. :-)

I don't think so. The C struct generated by the code is:

typedef struct xcb_configure_window_request_t {
    uint8_t      major_opcode; /**<  */
    uint8_t      pad0; /**<  */
    uint16_t     length; /**<  */
    xcb_window_t window; /**<  */
    uint16_t     value_mask; /**<  */
} xcb_configure_window_request_t;

and does not include the value_param (which is ok since it's only used
in the function xcb_configure_window() later:

xcb_configure_window (xcb_connection_t *c  /**< */,
                      xcb_window_t      window  /**< */,
                      uint16_t          value_mask  /**< */,
                      const uint32_t   *value_list  /**< */);

which fill a xcb_configure_window_request_t automagically and then send

But here, I think again the XML is bad since it does not include the
2 bytes padding which are between the value_mask and the value_padding
as you saw on specs.

So currently the struct generated as above is anyway mis-aligned (its
size is 10) and the compiler add… 2 bytes to align it and set its size
to 12.

Sorry if I'm wrong, I just try to really understand this stuff. :)

Julien Danjou
// ᐰ <julien at danjou.info>   http://julien.danjou.info
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