Add raw evdev input emulation backend

Adds an evdev/uinput-based input emulation backend for Linux that creates
a virtual mouse/keyboard, bypassing Wayland restrictions. Useful as a
fallback on systems without a working remote desktop portal (e.g. COSMIC).

Rebased onto the build.rs cfg-alias mechanism (evdev / evdev_emulation)
introduced after the original PR. The backend is preferred in the
auto-fallback order when /dev/uinput is accessible and falls back cleanly
to the other backends otherwise. Documents the udev-rule permissions setup
in the README.

Original work by Sam Vervaeck (feschber#297).

Co-authored-by: Sam Vervaeck <samvv@pm.me>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: 3 people

Cargo.lock

@@ -81,6 +81,7 @@ default = [
     "libei_emulation",
     "rdp_emulation",
     "x11_emulation",
+    "evdev_emulation",
 ]
 gtk = ["dep:lan-mouse-gtk"]
 layer_shell_capture = ["input-capture/layer_shell"]
@@ -90,6 +91,7 @@ libei_emulation = ["input-event/libei", "input-emulation/libei"]
 wlroots_emulation = ["input-emulation/wlroots"]
 x11_emulation = ["input-emulation/x11"]
 rdp_emulation = ["input-emulation/remote_desktop_portal"]
+evdev_emulation = ["input-emulation/evdev"]
 
 [package.metadata.bundle]
 name = "Lan Mouse"

Cargo.toml

@@ -55,6 +55,27 @@ Most current desktop environments and operating systems are fully supported, thi
 
 For more detailed information about os support see [Detailed OS Support](#detailed-os-support)
 
+### evdev emulation backend (Linux)
+
+On Linux, Lan Mouse can emulate input through a virtual `evdev`/`uinput` device.
+This backend works independently of the compositor and is useful as a fallback on
+systems without a working remote desktop portal (for example COSMIC).
+
+It requires access to `/dev/uinput`. Rather than running as root, grant your user
+access with a dedicated group and a udev rule:
+
+```sh
+sudo groupadd --system lan-mouse
+sudo usermod -aG lan-mouse <username>
+echo 'KERNEL=="uinput", GROUP="lan-mouse"' | sudo tee /lib/udev/rules.d/05-lan-mouse.rules
+```
+
+Log out and back in (or reboot) for the group change to take effect. When
+`/dev/uinput` is accessible, the `evdev` backend is preferred automatically; if it
+is not accessible, Lan Mouse falls back to the other emulation backends. It can
+also be selected explicitly with `--emulation-backend evdev` or via
+`emulation_backend = "evdev"` in the config.
+
 ### Android & IOS
 
 A proof of concept for an Android / IOS Application by [rohitsangwan01](https://github.com/rohitsangwan01) can be found [here](https://github.com/rohitsangwan01/lan-mouse-mobile).

README.md

@@ -17,6 +17,8 @@ fn main() {
     let x11_emulation = cfg!(feature = "x11_emulation");
     let wlroots_emulation = cfg!(feature = "wlroots_emulation");
     let rdp_emulation = cfg!(feature = "rdp_emulation");
+    let evdev_emulation = cfg!(feature = "evdev_emulation");
+    let linux = cfg!(target_os = "linux");
 
     let layer_shell_capture = unix && !macos && layer_shell_capture;
     let libei_capture = unix && !macos && libei_capture;
@@ -26,6 +28,7 @@ fn main() {
     let rdp_emulation = unix && !macos && rdp_emulation;
     let wlroots_emulation = unix && !macos && wlroots_emulation;
     let x11_emulation = unix && !macos && x11_emulation;
+    let evdev_emulation = linux && evdev_emulation;
 
     println!("cargo::rustc-check-cfg=cfg(layer_shell_capture)");
     println!("cargo::rustc-check-cfg=cfg(libei_capture)");
@@ -35,6 +38,7 @@ fn main() {
     println!("cargo::rustc-check-cfg=cfg(rdp_emulation)");
     println!("cargo::rustc-check-cfg=cfg(wlroots_emulation)");
     println!("cargo::rustc-check-cfg=cfg(x11_emulation)");
+    println!("cargo::rustc-check-cfg=cfg(evdev_emulation)");
 
     if layer_shell_capture {
         println!("cargo::rustc-cfg=layer_shell_capture");
@@ -58,4 +62,7 @@ fn main() {
     if x11_emulation {
         println!("cargo::rustc-cfg=x11_emulation");
     }
+    if evdev_emulation {
+        println!("cargo::rustc-cfg=evdev_emulation");
+    }
 }

build.rs

@@ -46,6 +46,10 @@ ashpd = { version = "0.13.9", default-features = false, features = [
     "tokio",
 ], optional = true }
 reis = { version = "0.7.0", features = ["tokio"], optional = true }
+evdev = { version = "0.13.1", features = [
+    "stream-trait",
+    "tokio",
+], optional = true }
 
 [target.'cfg(target_os="macos")'.dependencies]
 bitflags = "2.6.0"
@@ -66,13 +70,14 @@ windows = { version = "0.61.2", features = [
 ] }
 
 [features]
-default = ["wlroots", "x11", "remote_desktop_portal", "libei"]
+default = ["wlroots", "x11", "remote_desktop_portal", "libei", "evdev"]
 wlroots = [
     "dep:wayland-client",
     "dep:wayland-protocols",
     "dep:wayland-protocols-wlr",
     "dep:wayland-protocols-misc",
 ]
+evdev = ["dep:evdev"]
 x11 = ["dep:x11"]
 remote_desktop_portal = ["dep:ashpd"]
 libei = ["dep:reis", "dep:ashpd"]

input-emulation/Cargo.toml

@@ -5,20 +5,27 @@ fn main() {
     let macos = cfg!(target_os = "macos");
     let wlroots = cfg!(feature = "wlroots");
     let rdp = cfg!(feature = "remote_desktop_portal");
+    let evdev = cfg!(feature = "evdev");
+    let linux = cfg!(target_os = "linux");
 
     let libei = unix && !macos && libei;
     let wlroots = unix && !macos && wlroots;
     let x11 = unix && !macos && x11;
     let rdp = unix && !macos && rdp;
+    let evdev = linux && evdev;
 
     println!("cargo::rustc-check-cfg=cfg(wlroots)");
     println!("cargo::rustc-check-cfg=cfg(libei)");
     println!("cargo::rustc-check-cfg=cfg(x11)");
     println!("cargo::rustc-check-cfg=cfg(rdp)");
+    println!("cargo::rustc-check-cfg=cfg(evdev)");
 
     if libei {
         println!("cargo::rustc-cfg=libei");
     }
+    if evdev {
+        println!("cargo::rustc-cfg=evdev");
+    }
     if x11 {
         println!("cargo::rustc-cfg=x11");
     }

input-emulation/build.rs

@@ -43,6 +43,9 @@ pub enum EmulationCreationError {
     #[cfg(libei)]
     #[error("libei backend: `{0}`")]
     Libei(#[from] LibeiEmulationCreationError),
+    #[cfg(evdev)]
+    #[error("evdev backend: `{0}`")]
+    Evdev(#[from] EvdevEmulationCreationError),
     #[cfg(rdp)]
     #[error("xdg-desktop-portal: `{0}`")]
     Xdp(#[from] XdpEmulationCreationError),
@@ -127,6 +130,13 @@ pub enum LibeiEmulationCreationError {
     Reis(#[from] reis::Error),
 }
 
+#[cfg(evdev)]
+#[derive(Debug, Error)]
+pub enum EvdevEmulationCreationError {
+    #[error(transparent)]
+    Io(#[from] std::io::Error),
+}
+
 #[cfg(rdp)]
 #[derive(Debug, Error)]
 pub enum XdpEmulationCreationError {