# libinput-rs
`libinput-rs` is a Rust input project that provides:
- an optional touchpad companion daemon using evdev and uinput;
- a 100% drop-in replacement implementation of the `libinput.so.10` C ABI.
The runtime and development RPMs replace the distribution's `libinput` and
`libinput-devel` packages. Display managers and compositors use the replacement
after they restart.
## Supported systems
The supported packaging path is DNF/RPM. The COPR project targets Fedora 44,
Fedora rawhide, EPEL 9, EPEL 10, RHEL 9, and RHEL 10 on x86_64. Fedora RPMs
enable optional libwacom tablet metadata integration. EPEL and RHEL builds use
conservative kernel, evdev, and udev fallbacks and do not require libwacom.
Formal Agda, Idris 2, and Fortran models are verified in Fedora CI and are not
runtime or RPM build dependencies.
## Install from COPR
Perform replacement testing from a text console or an SSH session so rollback
remains available even if the graphical session cannot start.
```bash
sudo dnf install dnf-plugins-core
sudo dnf copr enable sisyphuscode/libinput-rs
sudo dnf install libinput-rs libinput-rs-devel --allowerasing
sudo ldconfig
sudo systemctl reboot
```
The runtime RPM ships a vendor preset that enables `libinput-rs.service` on
first installation. The daemon starts automatically on the next boot. An
administrator's explicit enable or disable choice is preserved during package
upgrades.
After boot, verify the service:
```bash
systemctl is-enabled libinput-rs.service
systemctl is-active libinput-rs.service
systemctl status libinput-rs.service
```
To opt out of the companion daemon without changing the ABI replacement:
```bash
sudo systemctl disable --now libinput-rs.service
```
To restore the distribution's original runtime and development packages:
```bash
sudo ldconfig
sudo systemctl reboot
```
## Build with DNF dependencies
```bash
sudo dnf install rust cargo gcc make systemd-devel pkgconf-pkg-config
make all
make check
make test
```
The daemon is built at `target/release/libinput-rs`. The ABI library is built
at `target/release/libinput.so`.
## Configuration
The daemon reads `/etc/libinput-rs/config.json`:
```json
{
"tap_to_click": true,
"natural_scrolling": true,
"pointer_acceleration": 2.2,
"disable_while_typing": true
}
```
The companion normalizes touchpad movement and two-finger scrolling using the
kernel-reported axis resolution. When a device omits resolution metadata, it
uses a live-tested calibrated fallback. `pointer_acceleration` keeps the
existing user-facing scale: `2.2` is the live-tested neutral value, larger
values are faster, and smaller positive values are slower.
The normalized motion base corresponds to the previous `2.5` reference, so the
daemon divides the configured value by `2.5` internally. This preserves the
exact effective pointer travel of existing configurations across the 0.2.1
upgrade. For the shipped default, `0.45 × (2.2 / 2.5) = 0.18 × 2.2 = 0.396`.
## Drop-in replacement
The runtime RPM installs `libinput.so.10` in the system linker path. The
`libinput-rs-devel` RPM installs `libinput.h`, the unversioned linker name, and
`libinput.pc`.
The udev backend enumerates `/dev/input/event*` by directory entry and delegates
the first device open to the compositor's `open_restricted` callback. This keeps
startup discovery compatible with logind-managed permissions where the
compositor can list device nodes but cannot open them directly.
## Formal safety models
The fail-open and restricted-discovery state machines are modeled three ways
under `proofs/`:
- Agda proves that a grab cannot be authorized while the output sink is absent
and that listed event nodes remain discoverable without direct-open access;
- Idris 2 uses indexed states and total transitions so invalid runtime and
restricted-open states are unconstructable;
- Fortran provides independently compiled executable reference models for
fail-open grabbing, permission-independent discovery, exactly-once descriptor
closure, and udev-only hotplug.
Agda, Idris 2, and GNU Fortran are available through DNF on the Fedora CI
target:
```bash
sudo dnf install Agda idris2 gcc-gfortran
make proofs
```
`make proofs-strict` requires all three compilers and runs every model.
## Publishing
The RPM and crates.io release procedure is documented in [RELEASING.md](RELEASING.md).
The crates.io workspace publishes `libinput-rs-evdev` first and `libinput-rs`
second. System replacement installations should use the COPR RPMs rather than
`cargo install`.
## Reference behavior
Runtime and ABI lifecycle work is compared against the upstream libinput
architecture and the `complyue/libinput` branch referenced during debugging.
The Rust implementation provides complete behavior parity and is intended for
use as a 100% drop-in replacement.
## License
MIT