kc3-lang/libxkbcommon

Diff

  • Show log

    Commit

  • Hash : cb3565b1
    Author : Julian Orth
    Date : 2025-03-07T17:59:33 

    keymap: Fix segfault due to invalid group wrapping

The modular arithmetic is incorrect for negative values, e.g. for
num_groups = 1. It triggers a segfault for the following settings:

- layouts count (per key or total) N: `N > 0`, and
- layout index n: `n = - k * N` (`k > 0`)

% returns the *remainder* of the division, not the modulus (see C11
standard 6.5.5 “Multiplicative operators”: a % b = a - (a/b)*b. While
both operators return the same result for positive operands, they do
not for e.g. a negative dividend: remainder may be negative (in the
open interval ]-num_groups, num_groups[) while the modulus is always
positive. So if the remainder is negative, we must add `num_groups` to
get the modulus.

Fixes: 67b03cea ("state: correctly wrap state->locked_group and ->group")
Signed-off-by: Julian Orth <ju.orth@gmail.com>
Co-authored-by: Julian Orth <ju.orth@gmail.com>
Co-authored-by: Pierre Le Marre <dev@wismill.eu>

  • Properties

  • Git HTTP https://git.kmx.io/kc3-lang/libxkbcommon.git
    Git SSH git@git.kmx.io:kc3-lang/libxkbcommon.git
    Public access ? public
    Description

    keymap handling library for toolkits and window systems
    Users
    		 thodg_m kc3_lang_org thodg_w www_kmx_io thodg thodg_l
    Tags

  • README.md

  • libxkbcommon

    libxkbcommon is a keyboard keymap compiler and support library which processes a reduced subset of keymaps as defined by the XKB (X Keyboard Extension) specification. It also contains a module for handling Compose and dead keys and a separate registry library for listing available keyboard layouts.

    Quick Guide

    Building

    libxkbcommon is built with Meson:

    meson setup build
meson compile -C build
meson test -C build # Run the tests.

    To build for use with Wayland, you can disable X11 support while still using the X11 keyboard configuration resource files thusly:

    meson setup build \
    -Denable-x11=false \
    -Dxkb-config-root=/usr/share/X11/xkb \
    -Dx-locale-root=/usr/share/X11/locale
meson compile -C build
    Complete list of user options @include meson_options.txt

    API

    While libxkbcommon’s API is somewhat derived from the classic XKB API as found in X11/extensions/XKB.h and friends, it has been substantially reworked to expose fewer internal details to clients.

    See the API Documentation.

    Dataset

    libxkbcommon does not distribute a keyboard layout dataset itself, other than for testing purposes. The most common dataset is xkeyboard-config, which is used by all current distributions for their X11 XKB data. Further information on xkeyboard-config is available at its homepage and at its repository.

    The dataset for Compose is distributed in libX11, as part of the X locale data.

    Relation to X11

    See Compatibility notes.

    Development

    An extremely rudimentary homepage can be found at

    https://xkbcommon.org

    xkbcommon is maintained in git at

    https://github.com/xkbcommon/libxkbcommon

    Patches are always welcome, and may be sent to either xorg-devel@lists.x.org or wayland-devel@lists.freedesktop.org or in a GitHub pull request.

    Bug reports (and usage questions) are also welcome, and may be filed at GitHub.

    The maintainers are:

    Credits

    Many thanks are due to Dan Nicholson for his heroic work in getting xkbcommon off the ground initially.

kmx.io     mail     discord kmxgit v0.4.0