composefs-storage 0.4.0

Read-only access to containers-storage (overlay driver)
Documentation 
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//! Configuration parsing for container storage.
//!
//! This module provides structures for parsing storage.conf files used by
//! containers-storage. Configuration files define storage locations, drivers,
//! and additional read-only image stores.
//!
//! # Overview
//!
//! Container storage configuration is typically found in:
//! - System-wide: `/etc/containers/storage.conf`
//! - User-specific: `~/.config/containers/storage.conf`
//!
//! The configuration uses TOML format and specifies the storage driver
//! (overlay, btrfs, etc.), root paths, and additional layer/image stores.
//!
//! # Configuration Structure
//!
//! A typical storage.conf file looks like:
//! ```toml
//! [storage]
//! driver = "overlay"
//! root = "/var/lib/containers/storage"
//! run_root = "/run/containers/storage"
//!
//! # Additional read-only image stores
//! image_stores = [
//!     "/usr/share/containers/storage"
//! ]
//!
//! # Additional layer stores configuration
//! [[storage.layer_stores]]
//! path = "/mnt/layers"
//! with_reference = true
//! ```

use serde::Deserialize;
use std::path::PathBuf;

/// Storage configuration, typically parsed from storage.conf files.
///
/// Configuration files are searched in:
/// - `/etc/containers/storage.conf`
/// - `$HOME/.config/containers/storage.conf`
#[derive(Debug, Clone, Deserialize)]
pub struct StorageConfig {
    /// Storage driver name (should be "overlay" for this library).
    #[serde(default)]
    pub driver: String,

    /// Primary storage root path.
    #[serde(default)]
    pub root: PathBuf,

    /// Runtime root for transient data.
    #[serde(default)]
    pub run_root: PathBuf,

    /// Additional read-only image stores.
    #[serde(default)]
    pub image_stores: Vec<PathBuf>,

    /// Additional layer stores configuration.
    #[serde(default)]
    pub layer_stores: Vec<AdditionalLayerStore>,
}

/// Configuration for an additional layer store.
#[derive(Debug, Clone, Deserialize)]
pub struct AdditionalLayerStore {
    /// Path to the additional layer store.
    pub path: PathBuf,

    /// Whether to use base64-encoded references in paths.
    #[serde(default)]
    pub with_reference: bool,
}

impl StorageConfig {
    /// Parse storage configuration from TOML content.
    ///
    /// # Errors
    ///
    /// Returns an error if the TOML content is invalid.
    pub fn from_toml(content: &str) -> Result<Self, toml::de::Error> {
        toml::from_str(content)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_parse_basic_config() {
        let config_str = r#"
driver = "overlay"
root = "/var/lib/containers/storage"
"#;
        let config = StorageConfig::from_toml(config_str).unwrap();
        assert_eq!(config.driver, "overlay");
        assert_eq!(config.root, PathBuf::from("/var/lib/containers/storage"));
    }

    #[test]
    fn test_parse_with_layer_stores() {
        let config_str = r#"
driver = "overlay"
root = "/var/lib/containers/storage"

[[layer_stores]]
path = "/mnt/layers"
with_reference = true
"#;
        let config = StorageConfig::from_toml(config_str).unwrap();
        assert_eq!(config.layer_stores.len(), 1);
        assert_eq!(config.layer_stores[0].path, PathBuf::from("/mnt/layers"));
        assert!(config.layer_stores[0].with_reference);
    }
}