feat(uci): add generalized UCI configuration source

Introduce the UciSource abstraction as a config-rs Source that reads
UCI packages and maps them into the configuration tree. Supports
package selection, required/optional behavior, and custom config/save
directories. Move rust-uci dependency to cfg(unix) to enable UCI
support on all Unix systems for development and testing, while
Linux/OpenWrt remains the production-supported platform.

Cargo.lock

@@ -540,9 +540,9 @@ dependencies = [
 
 [[package]]
 name = "toml"
-version = "1.1.4+spec-1.1.0"
+version = "1.1.3+spec-1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3aace63f4bbcdfc2c965b059de67119c89c4017a70d633be6c104910f67056f5"
+checksum = "53c96ecdfa941c8fc4fcaed14f99ada8ebed502eef533015095a07e3301d4c3c"
 dependencies = [
  "serde_core",
  "serde_spanned",
@@ -562,9 +562,9 @@ dependencies = [
 
 [[package]]
 name = "toml_parser"
-version = "1.1.3+spec-1.1.0"
+version = "1.1.2+spec-1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1d38ac1cf9b95face32296c0a3ede1fdc270627c9d9c02a7274dd6d960dc4d56"
+checksum = "a2abe9b86193656635d2411dc43050282ca48aa31c2451210f4202550afb7526"
 dependencies = [
  "winnow",
 ]

Cargo.toml

@@ -36,6 +36,8 @@ version = "0.4"
 [target.'cfg(target_os = "linux")'.dependencies]
 netlink-bindings = { version = "0.3.3", features = ["rt-link", "tc"] }
 netlink-socket2 = { version = "0.3.3" }
+
+[target.'cfg(unix)'.dependencies]
 rust-uci = { git = "https://github.com/namib-project/rust-uci.git", rev = "3e7b6153b6df92b45428c32bb6461756563deecb", optional = true }
 
 [features]

build.rs

@@ -7,8 +7,8 @@ fn main() {
 
     if uci_enabled && target_os != "linux" {
         println!(
-            "cargo::warning=feature `uci` is unsupported for target `{target}`; \
+            "cargo:warning=UCI support on {target} is intended for development \
-             UCI integration will not be compiled"
+             and testing; Linux/OpenWrt remains the production-supported platform"
         );
     }
 

src/platform.rs

@@ -42,6 +42,9 @@ mod linux;
 #[cfg(target_os = "macos")]
 mod macos;
 
+#[cfg(unix)]
+pub mod unix;
+
 #[cfg(not(any(target_os = "freebsd", target_os = "linux", target_os = "macos")))]
 mod unsupported;
 

src/platform/unix/mod.rs

@@ -0,0 +1,2 @@
+#[cfg(feature = "uci")]
+pub mod uci;

src/platform/unix/uci.rs

@@ -0,0 +1,237 @@
+use std::path::{Path, PathBuf};
+
+use config::{ConfigError as SourceError, Map, Source, Value, ValueKind};
+
+use rust_uci::config::{
+    Config as UciConfig, Package as UciPackage, SectionSelector, Value as UciValue,
+};
+
+#[derive(Clone, Debug)]
+enum PackageSelection {
+    Selected(Vec<String>),
+    All,
+}
+
+#[derive(Clone, Debug)]
+pub(crate) struct UciSource {
+    packages: PackageSelection,
+    required: bool,
+    config_dir: Option<PathBuf>,
+    save_dir: Option<PathBuf>,
+}
+
+impl UciSource {
+    fn with_selection(packages: PackageSelection) -> Self {
+        Self {
+            packages,
+            required: true,
+            config_dir: None,
+            save_dir: None,
+        }
+    }
+
+    pub(crate) fn new<I, S>(packages: I) -> Self
+    where
+        I: IntoIterator<Item = S>,
+        S: Into<String>,
+    {
+        Self::with_selection(PackageSelection::Selected(
+            packages.into_iter().map(Into::into).collect(),
+        ))
+    }
+
+    #[allow(dead_code)]
+    pub(crate) fn all() -> Self {
+        Self::with_selection(PackageSelection::All)
+    }
+
+    pub(crate) fn required(mut self, required: bool) -> Self {
+        self.required = required;
+        self
+    }
+
+    #[allow(dead_code)]
+    pub(crate) fn with_directories(
+        mut self,
+        config_dir: impl AsRef<Path>,
+        save_dir: impl AsRef<Path>,
+    ) -> Self {
+        self.config_dir = Some(config_dir.as_ref().to_owned());
+        self.save_dir = Some(save_dir.as_ref().to_owned());
+        self
+    }
+
+    fn open(&self) -> Result<UciConfig, SourceError> {
+        let mut uci = rust_uci::Uci::new()
+            .map_err(|e| SourceError::Message(format!("failed to open UCI: {e}")))?;
+
+        if let Some(config_dir) = &self.config_dir {
+            uci.set_config_dir(config_dir).map_err(|e| {
+                SourceError::Message(format!(
+                    "failed to set UCI config directory {config_dir:?}: {e}"
+                ))
+            })?;
+        }
+
+        if let Some(save_dir) = &self.save_dir {
+            uci.set_save_dir(save_dir).map_err(|e| {
+                SourceError::Message(format!(
+                    "failed to set UCI save directory {save_dir:?}: {e}"
+                ))
+            })?;
+        }
+
+        Ok(uci.into())
+    }
+
+    fn config_selector(selector: &SectionSelector<'_>) -> String {
+        match selector {
+            SectionSelector::Named(name) => (*name).to_owned(),
+
+            SectionSelector::Anonymous {
+                section_type,
+                index,
+            } => format!("{section_type}[{index}]"),
+        }
+    }
+
+    fn collect_package(
+        &self,
+        package_name: &str,
+        package: &UciPackage,
+        values: &mut Map<String, Value>,
+    ) -> Result<(), SourceError> {
+        let sections = package.sections().map_err(|e| {
+            SourceError::Message(format!(
+                "failed to retrieve sections from UCI package \
+                 {package_name:?}: {e}"
+            ))
+        })?;
+
+        for section in sections {
+            let selector = section.selector().ok_or_else(|| {
+                SourceError::Message(format!(
+                    "loaded UCI section of type {:?} in package \
+                     {package_name:?} has no selector",
+                    section.type_()
+                ))
+            })?;
+
+            let options = section.options().map_err(|e| {
+                SourceError::Message(format!(
+                    "failed to retrieve options from UCI section \
+                     {package_name}.{selector}: {e}"
+                ))
+            })?;
+
+            for option in options {
+                let option_name = option.name();
+
+                let config_relative_key =
+                    format!("{}.{option_name}", Self::config_selector(&selector),);
+
+                let destination_key = format!("{package_name}.{config_relative_key}");
+
+                let uci_relative_key = format!("{selector}.{option_name}");
+                let uci_key = format!("{package_name}.{uci_relative_key}");
+
+                let Some(value) = option.get().map_err(|e| {
+                    SourceError::Message(format!(
+                        "failed to retrieve UCI option \
+                         {uci_key}: {e}"
+                    ))
+                })?
+                else {
+                    continue;
+                };
+
+                let origin = format!("UCI option {uci_key}");
+
+                let value = match value {
+                    UciValue::String(value) => Value::new(Some(&origin), ValueKind::String(value)),
+
+                    UciValue::List(items) => {
+                        let items = items
+                            .into_iter()
+                            .map(|item| Value::new(Some(&origin), ValueKind::String(item)))
+                            .collect();
+
+                        Value::new(Some(&origin), ValueKind::Array(items))
+                    }
+                };
+
+                if values.insert(destination_key.clone(), value).is_some() {
+                    return Err(SourceError::Message(format!(
+                        "duplicate UCI destination key \
+                         {destination_key:?} while mapping {uci_key:?}"
+                    )));
+                }
+            }
+        }
+
+        Ok(())
+    }
+}
+
+impl Source for UciSource {
+    fn clone_into_box(&self) -> Box<dyn Source + Send + Sync> {
+        Box::new(self.clone())
+    }
+
+    fn collect(&self) -> Result<Map<String, Value>, SourceError> {
+        let resolved = (|| {
+            let uci = self.open()?;
+
+            let packages: Vec<UciPackage> = match &self.packages {
+                PackageSelection::Selected(package_names) => package_names
+                    .iter()
+                    .map(|package_name| {
+                        uci.package(package_name)
+                            .map_err(|e| {
+                                SourceError::Message(format!(
+                                    "failed to open UCI package {package_name:?}: {e}"
+                                ))
+                            })?
+                            .ok_or_else(|| {
+                                SourceError::NotFound(format!("UCI package {package_name:?}"))
+                            })
+                    })
+                    .collect::<Result<_, SourceError>>()?,
+
+                PackageSelection::All => uci
+                    .packages()
+                    .map_err(|e| {
+                        SourceError::Message(format!("failed to enumerate UCI packages: {e}"))
+                    })?
+                    .collect(),
+            };
+
+            Ok::<_, SourceError>((uci, packages))
+        })();
+
+        let (_uci, packages) = match resolved {
+            Ok(resolved) => resolved,
+
+            Err(_) if !self.required => {
+                return Ok(Map::new());
+            }
+
+            Err(error) => {
+                return Err(error);
+            }
+        };
+
+        let mut values = Map::new();
+
+        for package in packages {
+            let package_name = package
+                .name()
+                .map_err(|e| SourceError::Message(format!("failed to read UCI package name: {e}")))?
+                .to_owned();
+
+            self.collect_package(&package_name, &package, &mut values)?;
+        }
+
+        Ok(values)
+    }
+}

src/settings/mod.rs

@@ -9,6 +9,9 @@ use serde::{Deserialize, Deserializer, de};
 use std::fmt::{self, Display};
 use std::str::FromStr;
 
+#[cfg(all(feature = "uci", unix))]
+use crate::platform::unix::uci::UciSource;
+
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub enum MeasurementType {
     Icmp = 1,
@@ -76,6 +79,9 @@ impl Settings {
     pub(crate) fn load() -> Result<Self, ConfigError> {
         let builder = Config::builder();
 
+        #[cfg(all(feature = "uci", unix))]
+        let builder = builder.add_source(UciSource::new(["sqm-autorate-rust"]).required(false));
+
         #[cfg(feature = "toml")]
         let builder = builder.add_source(
             config::File::with_name("/etc/sqm-autorate-rust/config.toml").required(false),