ax-net 0.13.4

//! Filesystem-backed Unix socket namespace hook.
//!
//! Abstract Unix socket names are managed inside ax-net. Path-based Unix socket
//! names are delegated to an optional filesystem provider through this trait.
//!
//! # Integration Boundary
//!
//! The network crate only needs to resolve, create, and remove bind slots for a
//! path. It does not own dentries, permissions, mount namespaces, or lifecycle
//! rules beyond unbinding the slot when the Unix socket transport is dropped.
//! Kernels that do not enable filesystem support can leave this provider
//! unregistered and still use unnamed or abstract Unix sockets.

use alloc::{boxed::Box, sync::Arc};

use ax_lazyinit::OnceLock;

use super::BindSlot;
use crate::{NetError, NetResult};

/// Path-based Unix socket namespace provider.
///
/// Provides filesystem backing for Unix domain socket path bindings.
/// Abstract namespace sockets are handled separately within ax-net.
/// Callbacks run in sleepable task context: path lookup, creation, and removal
/// can perform filesystem I/O and wait for filesystem locks.
pub trait UnixNamespace: Send + Sync {
    /// Resolve an existing socket path binding.
    fn resolve(&self, path: &str) -> NetResult<Arc<BindSlot>>;

    /// Create or get a socket path binding.
    fn bind(&self, path: &str) -> NetResult<Arc<BindSlot>>;

    /// Remove a socket path binding.
    fn unbind(&self, path: &str) -> NetResult<()>;
}

static UNIX_NS: OnceLock<Box<dyn UnixNamespace>> = OnceLock::new();

/// Register Unix namespace provider.
///
/// Must be called before using path-based Unix sockets.
pub fn register_unix_namespace(ns: impl UnixNamespace + 'static) {
    UNIX_NS.call_once(|| Box::new(ns));
}

/// Access the registered Unix namespace.
///
/// Returns `NetError::Unsupported` if no filesystem-backed namespace is available.
pub(crate) fn with_namespace<R>(
    f: impl FnOnce(&dyn UnixNamespace) -> NetResult<R>,
) -> NetResult<R> {
    match UNIX_NS.get() {
        Some(ns) => f(&**ns),
        None => Err(NetError::Unsupported),
    }
}