Ignore special files for live config reload

When using `--config-file /dev/null` with `live_config_reload`, each
write to `/dev/null` was forcing alacritty to reload its configuration.

This commit makes alacritty ignore special files for live config reload.

Co-authored-by: Christian Duerr <contact@christianduerr.com>

CHANGELOG.md

@@ -40,6 +40,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Incorrect built-in glyphs for `U+2567` and `U+2568`
 - Character mappings in the DEC special graphics character set (line drawing)
 - Window flickering on resize on Wayland
+- Unnecessary config reload when using `/dev/null` as a config file
 
 ## 0.10.1
 

alacritty/src/config/mod.rs

@@ -2,7 +2,7 @@ use std::fmt::{self, Display, Formatter};
 use std::path::{Path, PathBuf};
 use std::{env, fs, io};
 
-use log::{error, info};
+use log::{debug, error, info};
 use serde::Deserialize;
 use serde_yaml::mapping::Mapping;
 use serde_yaml::Value;
@@ -125,6 +125,8 @@ pub fn load(options: &Options) -> UiConfig {
 
 /// Attempt to reload the configuration file.
 pub fn reload(config_path: &Path, options: &Options) -> Result<UiConfig> {
+    debug!("Reloading configuration file: {:?}", config_path);
+
     // Load config, propagating errors.
     let config_options = options.config_options.clone();
     let mut config = load_from(config_path, config_options)?;

alacritty/src/config/monitor.rs

@@ -21,6 +21,13 @@ pub fn watch(mut paths: Vec<PathBuf>, event_proxy: EventLoopProxy<Event>) {
         return;
     }
 
+    // Exclude char devices like `/dev/null`, sockets, and so on, by checking that file type is a
+    // regular file.
+    paths.retain(|path| {
+        // Call `metadata` to resolve symbolink links.
+        path.metadata().map_or(false, |metadata| metadata.file_type().is_file())
+    });
+
     // Canonicalize paths, keeping the base paths for symlinks.
     for i in 0..paths.len() {
         if let Ok(canonical_path) = paths[i].canonicalize() {