config: modularize; add config watcher and move error variants

Cargo.lock

@@ -38,7 +38,7 @@ version = "1.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "79947af37f4177cfead1110013d678905c37501914fba0efea834c3fe9a8d60c"
 dependencies = [
- "windows-sys",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -49,9 +49,15 @@ checksum = "ca3534e77181a9cc07539ad51f2141fe32f6c3ffd4df76db8ad92346b003ae4e"
 dependencies = [
  "anstyle",
  "once_cell",
- "windows-sys",
+ "windows-sys 0.59.0",
 ]
 
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
 [[package]]
 name = "bitflags"
 version = "2.9.0"
@@ -123,7 +129,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "46f93780a459b7d656ef7f071fe699c4d3d2cb201c4b24d085b6ddc505276e73"
 dependencies = [
  "nix",
- "windows-sys",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -144,7 +150,7 @@ dependencies = [
  "libc",
  "option-ext",
  "redox_users",
- "windows-sys",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -153,6 +159,27 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "877a4ace8713b0bcf2a4e7eec82529c029f1d0619886d18145fea96c3ffe5c0f"
 
+[[package]]
+name = "filetime"
+version = "0.2.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "35c0522e981e68cbfa8c3f978441a5f34b30b96e146b33cd3359176b50fe8586"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "libredox",
+ "windows-sys 0.59.0",
+]
+
+[[package]]
+name = "fsevent-sys"
+version = "4.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "76ee7a02da4d231650c7cea31349b889be2f45ddb3ef3032d2ec8185f6313fd2"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "getrandom"
 version = "0.2.16"
@@ -192,12 +219,52 @@ dependencies = [
  "hashbrown",
 ]
 
+[[package]]
+name = "inotify"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f37dccff2791ab604f9babef0ba14fbe0be30bd368dc541e2b08d07c8aa908f3"
+dependencies = [
+ "bitflags 2.9.0",
+ "inotify-sys",
+ "libc",
+]
+
+[[package]]
+name = "inotify-sys"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e05c02b5e89bff3b946cedeca278abc628fe811e604f027c45a8aa3cf793d0eb"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "is_terminal_polyfill"
 version = "1.70.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7943c866cc5cd64cbc25b2e01621d07fa8eb2a1a23160ee81ce38704e97b8ecf"
 
+[[package]]
+name = "kqueue"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eac30106d7dce88daf4a3fcb4879ea939476d5074a9b7ddd0fb97fa4bed5596a"
+dependencies = [
+ "kqueue-sys",
+ "libc",
+]
+
+[[package]]
+name = "kqueue-sys"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ed9625ffda8729b85e45cf04090035ac368927b8cebc34898e7c120f52e4838b"
+dependencies = [
+ "bitflags 1.3.2",
+ "libc",
+]
+
 [[package]]
 name = "libc"
 version = "0.2.172"
@@ -210,28 +277,75 @@ version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c0ff37bd590ca25063e35af745c343cb7a0271906fb7b37e4813e8f79f00268d"
 dependencies = [
- "bitflags",
+ "bitflags 2.9.0",
  "libc",
+ "redox_syscall",
 ]
 
+[[package]]
+name = "log"
+version = "0.4.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13dc2df351e3202783a1fe0d44375f7295ffb4049267b0f3018346dc122a1d94"
+
 [[package]]
 name = "memchr"
 version = "2.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
 
+[[package]]
+name = "mio"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2886843bf800fba2e3377cff24abf6379b4c4d5c6681eaf9ea5b0d15090450bd"
+dependencies = [
+ "libc",
+ "log",
+ "wasi",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "nix"
 version = "0.30.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "74523f3a35e05aba87a1d978330aef40f67b0304ac79c1c00b294c9830543db6"
 dependencies = [
- "bitflags",
+ "bitflags 2.9.0",
  "cfg-if",
  "cfg_aliases",
  "libc",
 ]
 
+[[package]]
+name = "notify"
+version = "8.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2fee8403b3d66ac7b26aee6e40a897d85dc5ce26f44da36b8b73e987cc52e943"
+dependencies = [
+ "bitflags 2.9.0",
+ "filetime",
+ "fsevent-sys",
+ "inotify",
+ "kqueue",
+ "libc",
+ "log",
+ "mio",
+ "notify-types",
+ "walkdir",
+ "windows-sys 0.59.0",
+]
+
+[[package]]
+name = "notify-types"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5e0826a989adedc2a244799e823aece04662b66609d96af8dff7ac6df9a8925d"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "num_cpus"
 version = "1.16.0"
@@ -272,6 +386,15 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.5.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "928fca9cf2aa042393a8325b9ead81d2f0df4cb12e1e24cef072922ccd99c5af"
+dependencies = [
+ "bitflags 2.9.0",
+]
+
 [[package]]
 name = "redox_users"
 version = "0.5.0"
@@ -283,6 +406,15 @@ dependencies = [
  "thiserror",
 ]
 
+[[package]]
+name = "same-file"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93fc1dc3aaa9bfed95e02e6eadabb4baf7e3078b0bd1b4d7b6b0b68378900502"
+dependencies = [
+ "winapi-util",
+]
+
 [[package]]
 name = "serde"
 version = "1.0.219"
@@ -325,6 +457,7 @@ dependencies = [
  "clap",
  "ctrlc",
  "dirs",
+ "notify",
  "num_cpus",
  "serde",
  "toml",
@@ -414,12 +547,40 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
 
+[[package]]
+name = "walkdir"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "29790946404f91d9c5d06f9874efddea1dc06c5efe94541a7d6863108e3a5e4b"
+dependencies = [
+ "same-file",
+ "winapi-util",
+]
+
 [[package]]
 name = "wasi"
 version = "0.11.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
+[[package]]
+name = "winapi-util"
+version = "0.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
+dependencies = [
+ "windows-sys 0.59.0",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.52.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
+dependencies = [
+ "windows-targets",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.59.0"

Cargo.toml

@@ -10,3 +10,4 @@ dirs = "6.0"
 clap = { version = "4.0", features = ["derive"] }
 num_cpus = "1.16"
 ctrlc = "3.4"
+notify = { version = "8.0.0", features = ["serde"] }

src/config/load.rs

@@ -0,0 +1,76 @@
+// Configuration loading functionality
+use std::fs;
+use std::path::PathBuf;
+
+use crate::config::types::{AppConfig, AppConfigToml, ConfigError, DaemonConfig, ProfileConfig};
+
+// The primary function to load application configuration.
+// It tries user-specific and then system-wide TOML files.
+// Falls back to default settings if no file is found or if parsing fails.
+pub fn load_config() -> Result<AppConfig, ConfigError> {
+    let mut config_paths: Vec<PathBuf> = Vec::new();
+
+    // User-specific path
+    if let Some(home_dir) = dirs::home_dir() {
+        let user_config_path = home_dir.join(".config/auto_cpufreq_rs/config.toml");
+        config_paths.push(user_config_path);
+    } else {
+        eprintln!(
+            "Warning: Could not determine home directory. User-specific config will not be loaded."
+        );
+    }
+
+    // System-wide path
+    let system_config_path = PathBuf::from("/etc/auto_cpufreq_rs/config.toml");
+    config_paths.push(system_config_path);
+
+    for path in config_paths {
+        if path.exists() {
+            println!("Attempting to load config from: {}", path.display());
+            match fs::read_to_string(&path) {
+                Ok(contents) => {
+                    match toml::from_str::<AppConfigToml>(&contents) {
+                        Ok(toml_app_config) => {
+                            // Convert AppConfigToml to AppConfig
+                            let app_config = AppConfig {
+                                charger: ProfileConfig::from(toml_app_config.charger),
+                                battery: ProfileConfig::from(toml_app_config.battery),
+                                battery_charge_thresholds: toml_app_config.battery_charge_thresholds,
+                                ignored_power_supplies: toml_app_config.ignored_power_supplies,
+                                poll_interval_sec: toml_app_config.poll_interval_sec,
+                                daemon: DaemonConfig {
+                                    poll_interval_sec: toml_app_config.daemon.poll_interval_sec,
+                                    adaptive_interval: toml_app_config.daemon.adaptive_interval,
+                                    min_poll_interval_sec: toml_app_config.daemon.min_poll_interval_sec,
+                                    max_poll_interval_sec: toml_app_config.daemon.max_poll_interval_sec,
+                                    throttle_on_battery: toml_app_config.daemon.throttle_on_battery,
+                                    log_level: toml_app_config.daemon.log_level,
+                                    stats_file_path: toml_app_config.daemon.stats_file_path,
+                                },
+                            };
+                            return Ok(app_config);
+                        }
+                        Err(e) => {
+                            eprintln!("Error parsing config file {}: {}", path.display(), e);
+                        }
+                    }
+                }
+                Err(e) => {
+                    eprintln!("Error reading config file {}: {}", path.display(), e);
+                }
+            }
+        }
+    }
+
+    println!("No configuration file found or all failed to parse. Using default configuration.");
+    // Construct default AppConfig by converting default AppConfigToml
+    let default_toml_config = AppConfigToml::default();
+    Ok(AppConfig {
+        charger: ProfileConfig::from(default_toml_config.charger),
+        battery: ProfileConfig::from(default_toml_config.battery),
+        battery_charge_thresholds: default_toml_config.battery_charge_thresholds,
+        ignored_power_supplies: default_toml_config.ignored_power_supplies,
+        poll_interval_sec: default_toml_config.poll_interval_sec,
+        daemon: DaemonConfig::default(),
+    })
+}

src/config/mod.rs

@@ -0,0 +1,9 @@
+pub mod watcher;
+
+// Re-export all configuration types and functions
+pub use self::types::*;
+pub use self::load::*;
+
+// Internal organization of config submodules
+mod types;
+mod load;

src/config/types.rs

@@ -1,7 +1,6 @@
+// Configuration types and structures for superfreq
 use crate::core::TurboSetting;
 use serde::Deserialize;
-use std::fs;
-use std::path::PathBuf;
 
 // Structs for configuration using serde::Deserialize
 #[derive(Deserialize, Debug, Clone)]
@@ -83,82 +82,6 @@ impl std::fmt::Display for ConfigError {
 
 impl std::error::Error for ConfigError {}
 
-// The primary function to load application configuration.
-// It tries user-specific and then system-wide TOML files.
-// Falls back to default settings if no file is found or if parsing fails.
-pub fn load_config() -> Result<AppConfig, ConfigError> {
-    let mut config_paths: Vec<PathBuf> = Vec::new();
-
-    // User-specific path
-    if let Some(home_dir) = dirs::home_dir() {
-        let user_config_path = home_dir.join(".config/auto_cpufreq_rs/config.toml");
-        config_paths.push(user_config_path);
-    } else {
-        eprintln!(
-            "Warning: Could not determine home directory. User-specific config will not be loaded."
-        );
-    }
-
-    // System-wide path
-    let system_config_path = PathBuf::from("/etc/auto_cpufreq_rs/config.toml");
-    config_paths.push(system_config_path);
-
-    for path in config_paths {
-        if path.exists() {
-            println!("Attempting to load config from: {}", path.display());
-            match fs::read_to_string(&path) {
-                Ok(contents) => {
-                    match toml::from_str::<AppConfigToml>(&contents) {
-                        Ok(toml_app_config) => {
-                            // Convert AppConfigToml to AppConfig
-                            let app_config = AppConfig {
-                                charger: ProfileConfig::from(toml_app_config.charger),
-                                battery: ProfileConfig::from(toml_app_config.battery),
-                                battery_charge_thresholds: toml_app_config
-                                    .battery_charge_thresholds,
-                                ignored_power_supplies: toml_app_config.ignored_power_supplies,
-                                poll_interval_sec: toml_app_config.poll_interval_sec,
-                                daemon: DaemonConfig {
-                                    poll_interval_sec: toml_app_config.daemon.poll_interval_sec,
-                                    adaptive_interval: toml_app_config.daemon.adaptive_interval,
-                                    min_poll_interval_sec: toml_app_config
-                                        .daemon
-                                        .min_poll_interval_sec,
-                                    max_poll_interval_sec: toml_app_config
-                                        .daemon
-                                        .max_poll_interval_sec,
-                                    throttle_on_battery: toml_app_config.daemon.throttle_on_battery,
-                                    log_level: toml_app_config.daemon.log_level,
-                                    stats_file_path: toml_app_config.daemon.stats_file_path,
-                                },
-                            };
-                            return Ok(app_config);
-                        }
-                        Err(e) => {
-                            eprintln!("Error parsing config file {}: {}", path.display(), e);
-                        }
-                    }
-                }
-                Err(e) => {
-                    eprintln!("Error reading config file {}: {}", path.display(), e);
-                }
-            }
-        }
-    }
-
-    println!("No configuration file found or all failed to parse. Using default configuration.");
-    // Construct default AppConfig by converting default AppConfigToml
-    let default_toml_config = AppConfigToml::default();
-    Ok(AppConfig {
-        charger: ProfileConfig::from(default_toml_config.charger),
-        battery: ProfileConfig::from(default_toml_config.battery),
-        battery_charge_thresholds: default_toml_config.battery_charge_thresholds,
-        ignored_power_supplies: default_toml_config.ignored_power_supplies,
-        poll_interval_sec: default_toml_config.poll_interval_sec,
-        daemon: DaemonConfig::default(),
-    })
-}
-
 // Intermediate structs for TOML parsing
 #[derive(Deserialize, Debug, Clone)]
 pub struct ProfileConfigToml {
@@ -350,4 +273,4 @@ impl Default for DaemonConfigToml {
             stats_file_path: default_stats_file_path(),
         }
     }
-}
+}

src/cpu.rs

@@ -3,8 +3,6 @@ use crate::util::error::ControlError;
 use core::str;
 use std::{fs, io, path::Path, string::ToString};
 
-impl std::error::Error for ControlError {}
-
 pub type Result<T, E = ControlError> = std::result::Result<T, E>;
 
 // Write a value to a sysfs file

src/daemon.rs

@@ -1,4 +1,5 @@
 use crate::config::{AppConfig, LogLevel};
+use crate::config::watcher::ConfigWatcher;
 use crate::conflict;
 use crate::core::SystemReport;
 use crate::engine;
@@ -10,7 +11,7 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::time::{Duration, Instant};
 
 /// Run the daemon
-pub fn run_daemon(config: AppConfig, verbose: bool) -> Result<(), Box<dyn std::error::Error>> {
+pub fn run_daemon(mut config: AppConfig, verbose: bool) -> Result<(), Box<dyn std::error::Error>> {
     // Set effective log level based on config and verbose flag
     let effective_log_level = if verbose {
         LogLevel::Debug
@@ -63,6 +64,34 @@ pub fn run_daemon(config: AppConfig, verbose: bool) -> Result<(), Box<dyn std::e
         );
     }
 
+    // Initialize config file watcher if a path is available
+    let config_file_path = if let Ok(path) = std::env::var("SUPERFREQ_CONFIG") { Some(path) } else {
+        let default_paths = [
+            "/etc/superfreq/config.toml",
+            "/etc/superfreq.toml",
+        ];
+        
+        default_paths.iter()
+            .find(|&path| std::path::Path::new(path).exists())
+            .map(|path| (*path).to_string())
+    };
+    
+    let config_watcher: Option<ConfigWatcher> = match config_file_path {
+        Some(path) => {
+            match ConfigWatcher::new(&path) {
+                Ok(watcher) => {
+                    println!("Watching config file: {path}");
+                    Some(watcher)
+                },
+                Err(e) => {
+                    eprintln!("Failed to initialize config file watcher: {e}");
+                    None
+                }
+            }
+        },
+        None => None,
+    };
+
     // Variables for adaptive polling
     let mut current_poll_interval = config.daemon.poll_interval_sec;
     let mut last_settings_change = Instant::now();
@@ -72,6 +101,24 @@ pub fn run_daemon(config: AppConfig, verbose: bool) -> Result<(), Box<dyn std::e
     while running.load(Ordering::SeqCst) {
         let start_time = Instant::now();
 
+        // Check for configuration changes
+        if let Some(watcher) = &config_watcher {
+            if let Some(config_result) = watcher.check_for_changes() {
+                match config_result {
+                    Ok(new_config) => {
+                        if verbose {
+                            println!("Config file changed, updating configuration");
+                        }
+                        config = new_config;
+                    },
+                    Err(e) => {
+                        eprintln!("Error loading new configuration: {e}");
+                        // Continue with existing config
+                    }
+                }
+            }
+        }
+
         match monitor::collect_system_report(&config) {
             Ok(report) => {
                 log_message(

src/engine.rs

@@ -1,37 +1,7 @@
 use crate::config::{AppConfig, ProfileConfig};
 use crate::core::{OperationalMode, SystemReport, TurboSetting};
 use crate::cpu::{self};
-use crate::util::error::ControlError;
+use crate::util::error::EngineError;
-
-#[derive(Debug)]
-pub enum EngineError {
-    ControlError(ControlError),
-    ConfigurationError(String),
-}
-
-impl From<ControlError> for EngineError {
-    fn from(err: ControlError) -> Self {
-        Self::ControlError(err)
-    }
-}
-
-impl std::fmt::Display for EngineError {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            Self::ControlError(e) => write!(f, "CPU control error: {e}"),
-            Self::ConfigurationError(s) => write!(f, "Configuration error: {s}"),
-        }
-    }
-}
-
-impl std::error::Error for EngineError {
-    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
-        match self {
-            Self::ControlError(e) => Some(e),
-            Self::ConfigurationError(_) => None,
-        }
-    }
-}
 
 /// Determines the appropriate CPU profile based on power status or forced mode,
 /// and applies the settings using functions from the `cpu` module.
@@ -158,6 +128,13 @@ fn manage_auto_turbo(report: &SystemReport, config: &ProfileConfig) -> Result<()
         }
     };
 
+    // Validate the configuration to ensure it's usable
+    if turbo_settings.load_threshold_high <= turbo_settings.load_threshold_low {
+        return Err(EngineError::ConfigurationError(
+            "Invalid turbo auto settings: high threshold must be greater than low threshold".to_string()
+        ));
+    }
+
     // Decision logic for enabling/disabling turbo
     let enable_turbo = match (cpu_temp, avg_cpu_usage) {
         // If temperature is too high, disable turbo regardless of load

src/monitor.rs

@@ -1,11 +1,10 @@
 use crate::config::AppConfig;
 use crate::core::{BatteryInfo, CpuCoreInfo, CpuGlobalInfo, SystemInfo, SystemLoad, SystemReport};
-use crate::cpu::{get_logical_core_count, get_platform_profiles};
+use crate::cpu::get_logical_core_count;
-use crate::util::error::ControlError;
 use crate::util::error::SysMonitorError;
 use std::{
     collections::HashMap,
-    fs, io,
+    fs,
     path::{Path, PathBuf},
     str::FromStr,
     thread,
@@ -13,8 +12,6 @@ use std::{
     time::SystemTime,
 };
 
-impl std::error::Error for SysMonitorError {}
-
 pub type Result<T, E = SysMonitorError> = std::result::Result<T, E>;
 
 // Read a sysfs file to a string, trimming whitespace
@@ -417,8 +414,8 @@ pub fn get_cpu_global_info(cpu_cores: &[CpuCoreInfo]) -> CpuGlobalInfo {
         None
     };
 
-    let available_governors = if cpufreq_base.join("scaling_available_governors").exists() {
+    let available_governors = if cpufreq_base_path.join("scaling_available_governors").exists() {
-        read_sysfs_file_trimmed(cpufreq_base.join("scaling_available_governors")).map_or_else(
+        read_sysfs_file_trimmed(cpufreq_base_path.join("scaling_available_governors")).map_or_else(
             |_| vec![],
             |s| s.split_whitespace().map(String::from).collect(),
         )

src/util/error.rs

@@ -39,6 +39,8 @@ impl std::fmt::Display for ControlError {
     }
 }
 
+impl std::error::Error for ControlError {}
+
 #[derive(Debug)]
 pub enum SysMonitorError {
     Io(io::Error),
@@ -67,3 +69,35 @@ impl std::fmt::Display for SysMonitorError {
         }
     }
 }
+
+impl std::error::Error for SysMonitorError {}
+
+#[derive(Debug)]
+pub enum EngineError {
+    ControlError(ControlError),
+    ConfigurationError(String),
+}
+
+impl From<ControlError> for EngineError {
+    fn from(err: ControlError) -> Self {
+        Self::ControlError(err)
+    }
+}
+
+impl std::fmt::Display for EngineError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::ControlError(e) => write!(f, "CPU control error: {e}"),
+            Self::ConfigurationError(s) => write!(f, "Configuration error: {s}"),
+        }
+    }
+}
+
+impl std::error::Error for EngineError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::ControlError(e) => Some(e),
+            Self::ConfigurationError(_) => None,
+        }
+    }
+}