clawmates/crates/cm-files/src/lib.rs

//! Blob storage behind the three file drives (spec §7.4). The local
//! filesystem implementation serves dev and the air-gapped target; an
//! S3-compatible implementation slots in behind the same trait for cloud.

mod s3;

pub use s3::S3BlobStore;

use std::path::{Component, Path, PathBuf};

#[derive(Debug, thiserror::Error)]
pub enum BlobError {
    #[error("blob not found")]
    NotFound,
    #[error("invalid blob key: {0}")]
    InvalidKey(String),
    #[error("storage io: {0}")]
    Io(String),
}

#[async_trait::async_trait]
pub trait BlobStore: Send + Sync {
    async fn put(&self, key: &str, bytes: &[u8]) -> Result<(), BlobError>;
    async fn get(&self, key: &str) -> Result<Vec<u8>, BlobError>;
    async fn delete(&self, key: &str) -> Result<(), BlobError>;
}

/// Filesystem-backed store rooted at a data directory.
pub struct LocalBlobStore {
    root: PathBuf,
}

impl LocalBlobStore {
    pub fn new(root: PathBuf) -> LocalBlobStore {
        LocalBlobStore { root }
    }

    /// Resolves a key strictly below the root: rejects absolute paths and
    /// any `..`/`.` components so keys can never escape the data dir.
    fn resolve(&self, key: &str) -> Result<PathBuf, BlobError> {
        let path = Path::new(key);
        if path.is_absolute() || key.is_empty() {
            return Err(BlobError::InvalidKey(key.to_owned()));
        }
        for component in path.components() {
            match component {
                Component::Normal(_) => {}
                _ => return Err(BlobError::InvalidKey(key.to_owned())),
            }
        }
        Ok(self.root.join(path))
    }
}

#[async_trait::async_trait]
impl BlobStore for LocalBlobStore {
    async fn put(&self, key: &str, bytes: &[u8]) -> Result<(), BlobError> {
        let path = self.resolve(key)?;
        if let Some(parent) = path.parent() {
            tokio::fs::create_dir_all(parent)
                .await
                .map_err(|e| BlobError::Io(e.to_string()))?;
        }
        tokio::fs::write(&path, bytes)
            .await
            .map_err(|e| BlobError::Io(e.to_string()))
    }

    async fn get(&self, key: &str) -> Result<Vec<u8>, BlobError> {
        let path = self.resolve(key)?;
        match tokio::fs::read(&path).await {
            Ok(bytes) => Ok(bytes),
            Err(e) if e.kind() == std::io::ErrorKind::NotFound => Err(BlobError::NotFound),
            Err(e) => Err(BlobError::Io(e.to_string())),
        }
    }

    async fn delete(&self, key: &str) -> Result<(), BlobError> {
        let path = self.resolve(key)?;
        match tokio::fs::remove_file(&path).await {
            Ok(()) => Ok(()),
            Err(e) if e.kind() == std::io::ErrorKind::NotFound => Err(BlobError::NotFound),
            Err(e) => Err(BlobError::Io(e.to_string())),
        }
    }
}