ConfigFS: Everything Should Be A File

ConfigFS is a library for creating filesystem's that allow users to view and modify structured data and settings. It is inspired by another filesystem of the same name, ConfigFS, a ram based filesystem on linux that allows users to configure kernel objects.

ConfigFS relies on fuse3. It can be installed via your favorite package manager.

You can view the docs here

How Does It Work?

struct FavNumberConfig {
    fav_number: i64,
    output: String,
    modified: bool,
}

impl FavNumberConfig {
    pub fn new(fav_number: i64, output: String) -> Configuration {
        Configuration::Basic(Arc::new(RwLock::new(FavNumberConfig{fav_number, output, modified: false})))
    }
}

#[async_trait]
impl BasicConfigHook for FavNumberConfig {
    async fn fetch(&mut self) -> Result<Vec<u8>> {
        Ok(format!("{}", self.fav_number).as_bytes().to_vec())
    }

    async fn size(&mut self) -> Result<u64> {
        Ok(format!("{}", self.fav_number).as_bytes().len() as u64)
    }

    async fn update(&mut self, data: Vec<u8>) -> Result<()> {
        let input = String::from_utf8(data).map_err(|_| Errno::from(libc::EIO))?;
        let number = i64::from_str_radix(&input, 10).map_err(|_| Errno::from(libc::EIO))?;

        self.fav_number = number;
        println!("My new favourite number is {}", number);
        self.modified = true;
        Ok(())
    }
    
    async fn tick(&mut self) {
        if !self.modified {
            return
        }

        self.modified = false;
        let mut Ok(file) = fs::File::create(&self.output).await else {
            return
        };
        file.write_all(format!("{}", self.fav_number).as_bytes()).await.ok();
    }

    fn tick_interval(&self) -> Duration {
        Duration::from_secs(1)
    }
}

First you create your config interface by implementing the config type's respective trait. Basic configs function as files. Complex configs function as directories.

let mount = Mount::new();
{
    let mut mnt = mount.write().await;
    mnt.mount("/", FavNumberConfig::new(42));
}

Then you define how your configs should be mounted into the config filesystem. This allows you to mount multiple config interfaces into a single filesystem.

FS::mount("Fav Number FS", "/mnt/fav_number", mount)
    .await
    .unwrap()
    .await
    .unwrap()
    .unwrap()

Finally you mount your config filesystem.

License

This software is provided under the MIT license. Click here to view.