logging added, permission checks added, basic error handling

Cargo.toml

@@ -1,11 +1,17 @@
 [package]
-name = "swhkd"
+name = "Simple-Wayland-HotKey-Daemon"
 version = "0.1.0"
 edition = "2021"
 
 [dependencies]
 evdev = "0.11.3"
 glob = "0.3.0"
+log = "0.4.0"
+env_logger = "0.8.4"
+nix = "0.23.1"
+
+
+clap = "3.0.4"
 tokio = { version = "1.15.0", features = ["full"] }
 
 [[bin]]

src/main.rs

@@ -1,28 +1,69 @@
 use evdev::Device;
 use evdev::Key;
 use glob::glob;
+use nix::unistd;
+use std::process::exit;
 
 pub fn main() {
+    std::env::set_var("RUST_LOG", "trace");
+    env_logger::init();
+    log::trace!("Logger initialized.");
+
+    if unistd::Uid::current().is_root() {
+        log::error!("Refusing to run swhkd as root.");
+        exit(1);
+    }
+
+    log::trace!("Checking if invoking user is in input group or not.");
+    let groups = unistd::getgroups();
+    let mut is_in_input_group: bool = false;
+    'init_loop: for (_, groups) in groups.iter().enumerate() {
+        for group in groups {
+            let group = unistd::Group::from_gid(*group);
+            if group.unwrap().unwrap().name == "input" {
+                log::debug!("Invoking user is in input group.");
+                is_in_input_group = true;
+                break 'init_loop;
+            }
+        }
+    }
+
+    if is_in_input_group == false {
+        log::error!("Invoking user is NOT in input group.");
+        exit(1);
+    }
+
+    log::trace!("Attempting to find all keyboard file descriptors.");
     for entry in glob("/dev/input/event*").expect("Failed to read /dev/input/event*.") {
         match entry {
             Ok(path) => {
                 check_keyboard(path.into_os_string().into_string().unwrap());
             }
-            Err(_) => continue,
+            Err(error) => log::error!("Unexpected error occured: {}", error),
         }
     }
 }
 
-fn check_keyboard(input_path: String) -> bool {
-    let device = Device::open(&input_path).expect("Failed to open device.");
+pub fn check_keyboard(input_path: String) -> bool {
+    /* Try to open the device fd. */
+    let device = Device::open(&input_path);
+    match &device {
+        Ok(_) => (),
+        Err(error) => {
+            log::error!("Failed to open device {}: {}", input_path, error);
+        }
+    }
+
+    /* Check for the presence of enter key. */
     if device
+        .unwrap()
         .supported_keys()
         .map_or(false, |keys| keys.contains(Key::KEY_ENTER))
     {
-        println!("{} is a keyboard.", input_path);
+        log::debug!("{} is a keyboard.", input_path);
         return true;
     } else {
-        println!("{} is not a keyboard.", input_path);
+        log::debug!("{} is not a keyboard.", input_path);
         return false;
     }
 }