//! Listening on a Unix socket: the directory at 0700, a stale socket removed, the socket at 0600
//! (M5a spec, section 7). The same steps as `brokerd`'s; no crate depends on another role's.

use std::fs::{DirBuilder, Permissions};
use std::io;
use std::os::unix::fs::{DirBuilderExt, PermissionsExt};
use std::os::unix::net::UnixListener;
use std::path::Path;

/// Bind one socket: prepare its directory at 0700, make it private, remove any stale socket,
/// bind, then make the socket itself private at 0600. The error names the path.
pub fn listen(socket: &Path) -> Result<UnixListener, String> {
    // The same five steps as `listen` in brokerd/src/serve.rs. Every error is a String naming its
    // path: format!("{}: {e}", path.display()).
    // 1. The directory is `socket.parent()`; when that is None, empty, or `/` itself (its own
    //    parent() is None): Err(format!("{}: a socket needs a directory of its own, not / or none",
    //    socket.display())).
    // 2. `DirBuilder::new().recursive(true).mode(0o700).create(dir)`.
    // 3. `std::fs::symlink_metadata(dir)`; when its file_type() is not a directory:
    //    Err(format!("{}: is a symbolic link or not a directory; memoryd will not change its mode",
    //    dir.display())). Then `set_permissions(dir, Permissions::from_mode(0o700))`.
    // 4. Remove a stale socket: `remove_file(socket)`; NotFound is fine, any other error is
    //    returned.
    // 5. `UnixListener::bind(socket)`, then `set_permissions(socket,
    //    Permissions::from_mode(0o600))`. Ok(listener).
    todo!()
}