[Xcb] [PATCH libxcb 9/7] c_client.py: don't start xcb_parts at offset 2 for no reason

[Ran Benita]

On Tue, Feb 25, 2014 at 05:34:27AM -0800, Josh Triplett wrote:
> On Tue, Feb 25, 2014 at 02:11:36PM +0200, Ran Benita wrote:
> > Currently the generated code looks like this:
> > 
> >     struct iovec xcb_parts[4];
> >     xcb_big_requests_enable_cookie_t xcb_ret;
> >     xcb_big_requests_enable_request_t xcb_out;
> > 
> >     xcb_parts[2].iov_base = (char *) &xcb_out;
> >     xcb_parts[2].iov_len = sizeof(xcb_out);
> >     xcb_parts[3].iov_base = 0;
> >     xcb_parts[3].iov_len = -xcb_parts[2].iov_len & 3;
> > 
> >     xcb_ret.sequence = xcb_send_request(c, XCB_REQUEST_CHECKED, xcb_parts + 2, &xcb_req);
> > 
> > But there is no reason to allocate e.g. 4 parts and then skip the first
> > 2. Start at 0 instead.
> 
> Take a look at the implementation of xcb_send_request: if it needs to
> send extra data before the request, it will use the iovec entries before
> the passed-in pointer.  Yes, that's part of the API.  It really ought to
> be more clearly documented.

Oh, that's easy to miss. I need to add big requests to my testings.
Thanks for catching this, and thanks Uli for documenting it.

Ran

> - Josh Triplett