Problem with mmap keyboard.

[Fred vS]

Ho, many thanks Emmanuel.

I will deeply study your mail.

By the way, I am busy to translate all the "steps" demos of the Wayland-book into Pascal:
https://github.com/fredvs/wayland-pascal

Now, Free Pascal compiler can create nice and working "Pure Wayland applications".
Note too that the C demos in Wayland-book have some ommisions in code ( I added the fixes in /src/c).
But for the "Keyboard events" step, I am blocked, the C "Keyboard events" demo in /src/c does not use the key-map, but it works to give the actions of the keys and the number of the keys. The same for the translated Pascal code.

But ok, I will try to make the map-keyboard working thanks to with your advices.

Many thanks.

Write you later.

Fre;D

________________________________
De : Emmanuel Gil Peyrot <linkmauve at linkmauve.fr>
Envoyé : mercredi 4 octobre 2023 20:28
À : Fred vS <fiens at hotmail.com>
Cc : wayland-devel at lists.freedesktop.org <wayland-devel at lists.freedesktop.org>
Objet : Re: Problem with mmap keyboard.

On Wed, Oct 04, 2023 at 06:19:30PM +0000, Fred vS wrote:
> Hello.

Hi,

>
>
> I try to make work the "Keyboard event" step from the Wayland-book but the C demo crash at loading.
>
> The problem comes from the mapping: with that error:
>
>
> Line 301: wl_keyboard_keymap: Assertion map_shm != MAP_FAILED' failed.
>
>
> Here is the function:
>
> static void
> wl_keyboard_keymap(void *data, struct wl_keyboard *wl_keyboard,
>              uint32_t format, int32_t fd, uint32_t size)
> {
>      struct client_state *client_state = data;
>      assert(format == WL_KEYBOARD_KEYMAP_FORMAT_XKB_V1);
>
>      // Line 301: Here problem with mapping
>      char *map_shm = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);

We can read in the documentation of this protocol:
https://wayland.app/protocols/wayland#wl_keyboard:event:keymap

“From version 7 onwards, the fd must be mapped with MAP_PRIVATE by the
recipient, as MAP_SHARED may fail.”

I don’t know which wl_shell version you are using, but check that maybe.

>      assert(map_shm != MAP_FAILED);
>
>      struct xkb_keymap *xkb_keymap = xkb_keymap_new_from_string(
>                      client_state->xkb_context, map_shm,
>                      XKB_KEYMAP_FORMAT_TEXT_V1, XKB_KEYMAP_COMPILE_NO_FLAGS);
>      munmap(map_shm, size);
>      close(fd);
>
>      struct xkb_state *xkb_state = xkb_state_new(xkb_keymap);
>      xkb_keymap_unref(client_state->xkb_keymap);
>      xkb_state_unref(client_state->xkb_state);
>      client_state->xkb_keymap = xkb_keymap;
>      client_state->xkb_state = xkb_state;
> }
>
>
>
> Why does the mapping fails, I did check fd and size and they are correctly assigned?
>
>
> Thanks.
>

--
Link Mauve
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