Re: X server bug?

[Michael Richardson <mcr%sandelman.ca@localhost>]

--------

Mouse <mouse%Rodents-Montreal.ORG@localhost> wrote:
    > I might as well mention it now; it's been sleeper-public for a year or
    > two and it'll go a bit more public in a couple of months anyway.

    > I've been building an X interface library - something that sits in the
    > same place in the software stack as Xlib or xcb - based heavily around
    > callbacks.  One of the things it does is to eliminate the way Xlib uses
    > protocol values for all the API defines.  To quote a comment:

So you want type checking between things that devolve into an int, so are
indistinguishable.   Linux kernel has this problem too.
*rust* :-)

I think it's: https://www.kernel.org/doc/html/v6.1/dev-tools/sparse.html
That they use.

    > * We can pick values which are known to be disjoint from X IDs because
    > *  X IDs never have any of the 0xe0000000 bits set.

    > 0x2000001a is LX_PIXMAP_None, which is the API value representing None
    > as a pixmap (as opposed to None as a window or None as a graphics
    > context or etc).  I obviously neglected to add code to map
    > LX_PIXMAP_None in the clip-mask setting to 0 on the wire (the protocol
    > spec says that None there is represented as 0), but the returned error
    > confused me because it was saying 0 was invalid, which it isn't; 0 is a
    > valid value for that field in the wire protocol.  It wasn't until I
    > snooped the wire protocol and saw it putting 2000001a on the wire that
    > I realized what I'd done wrong, then saw the 0 coming back in the error
    > event and realized what the server was doing wrong.

Oh, I see!

    >> I had to add #include <stdlib.h>,

    > Hm, yeah, I should write return(0) instead of exit(0) at the end.

    >> and I had to build with -lX11:

    > Well, sure; it's an X program.  (Admittedly, I probably should have
    > remarked on the need for -lX11.)

It was an obvious duh, but often more than -lX11 is needed, and I am glad I
didn't have to guess further.

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