[weston] xkbcommon library is not optional.

[Joaquim Duran]

The database of keymaps are not included in xkbcommon library, you
should download from
http://www.freedesktop.org/wiki/Software/XKeyboardConfig and then just
install all keymaps that you need.

Joaquim Duran


2015-10-16 11:31 GMT+02:00 Arnaud Vrac <rawoul at gmail.com>:
> On Fri, Oct 16, 2015 at 11:10 AM, Pekka Paalanen <ppaalanen at gmail.com>
> wrote:
>>
>> On Fri, 16 Oct 2015 10:27:56 +0200
>> Hardening <rdp.effort at gmail.com> wrote:
>>
>> > Le 16/10/2015 03:28, Bryce Harrington a écrit :
>> > > On Tue, Oct 13, 2015 at 01:59:13PM +0200, Joaquim Duran wrote:
>> > >> Hello,
>> > >>
>> > >> When configuring the Weston project, it is possible to disable (don't
>> > >> include) the library libxkbcommon. To compile Weston successfully,
>> > >> even if the option --disable-xkbcommon is specified, the library must
>> > >> be installed because the file src/compositor.h requires it.
>> > >
>> > > Joaquim, good find.
>> > >
>> > > From the comments in configure.ac:
>> > >
>> > >           AS_HELP_STRING([--disable-xkbcommon], [Disable libxkbcommon
>> > >                   support: This is only useful in environments
>> > >                   where you do not have a hardware keyboard. If
>> > >                   libxkbcommon support is disabled clients will not
>> > >                   be sent a keymap and and must know how to
>> > >                   interpret the keycode sent for any key event.]),,
>> > >
>> > > So it sounds like this is a special case that is intended to work.
>> > >
>> > > The header include was from commit 855028fe three years ago, while the
>> > > --disable-xkbcommon was added by 382ff46f just two years ago.  That
>> > > makes me think that your situation was simply overlooked.
>> > >
>> > > If that's true, then presumably the fix would involve peppering
>> > > compositor.* and other files with tests like,
>> > >
>> > > #ifdef ENABLE_XKBCOMMON
>> > > ...
>> > > #endif
>> > >
>> > > For example it looks like the weston_xkb_info struct would need to
>> > > either be removed or stubbed out, and users of it be disabled.  There
>> > > are also some weston calls that use xkb_keymap, xkb_rule_names,
>> > > etc. structures for params that'd need addressed.
>> > >
>> > > On the face of it, seems like it could be a fair amount of work, and a
>> > > bit invasive, but maybe there's some tricks to make it simpler
>> > > (typedeffing the unsupported struct args and so on.)
>> > >
>> > > Alternatively, --disable-xkbcommon could be dropped.  However I get
>> > > the
>> > > sense it actually solves a real world need, and functional regression
>> > > is
>> > > rarely a good idea.
>> > >
>> >
>> > I'm to fix the bug. Anyway it's almost sure that there's no real usage
>> > of this flag as otherwise weston does not compile...
>>
>> I would be suprised if it didn't work at the time it was added. I
>> suspect we broke it later, and no-one noticed.
>>
>> I recall some discussions about some obscure embedded platform where
>> xkbcommon, even when it's tiny, was deemed as waste of space,
>> especially along with the xkeyboard-config database (even though you
>> don't even need the whole database). Or maybe it was about wasting
>> memory. Can't recall.
>
>
> If you know of a way to strip some parts of the database, I'm interested.
> I've tried only keep evdev mappings and a few layouts, but going at it it
> seemed like a very hard task so I just gave up.
>
>>
>>
>> Hrm, now that I actually test --disable-xkbcommon, Weston *does* build.
>> All I get during build is:
>>
>>   CC       src/weston-input.o
>> /home/pq/git/weston/src/input.c: In function ‘weston_seat_init_keyboard’:
>> /home/pq/git/weston/src/input.c:2226:1: warning: label ‘err’ defined but
>> not used [-Wunused-label]
>> /home/pq/git/weston/src/input.c: In function
>> ‘weston_keyboard_reset_state’:
>> /home/pq/git/weston/src/input.c:2238:20: warning: unused variable ‘state’
>> [-Wunused-variable]
>> /home/pq/git/weston/src/input.c: At top level:
>> /home/pq/git/weston/src/input.c:555:1: warning: ‘weston_xkb_info_destroy’
>> used but never defined [enabled by default]
>> /home/pq/git/weston/src/input.c:989:1: warning: ‘run_modifier_bindings’
>> defined but not used [-Wunused-function]
>>
>> And no other warning or error.
>>
>> I do not get a build failure, because libxkbcommon is installed in my
>> system, and so I don't need additional -I flags to find its headers.
>> When we build modules (backends, plugins, anything), missing symbols
>> are not fatal because the parent executable is providing some we must
>> not error on.
>>
>> At least x11-backend.so will fail to load doe to missing
>> xkbcommon symbols. Makes me wonder if there is some other backend that
>> doesn't fail so.
>>
>> So it's possible someone is or was actually getting away with this,
>> having xkbcommon installed for the build but not at runtime.
>>
>> We can remove --disable-xkbcommon, but be prepared having to revert and
>> fix that properly later.
>>
>>
>> Thanks,
>> pq
>
>
>
> --
> Arnaud
>
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