herdr/src/ipc.rs

use std::fs;
use std::io;
use std::os::unix::fs::MetadataExt;
use std::os::unix::fs::PermissionsExt;
use std::os::unix::net::UnixStream;
use std::path::Path;

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub(crate) struct SocketFileIdentity {
    dev: u64,
    ino: u64,
}

pub(crate) fn prepare_socket_path(
    path: &Path,
    busy_message: impl FnOnce(&Path) -> String,
) -> io::Result<()> {
    if let Some(parent) = path.parent() {
        fs::create_dir_all(parent)?;
    }

    if !path.exists() {
        return Ok(());
    }

    match UnixStream::connect(path) {
        Ok(_) => {
            return Err(io::Error::new(io::ErrorKind::AddrInUse, busy_message(path)));
        }
        Err(err)
            if matches!(
                err.kind(),
                io::ErrorKind::ConnectionRefused
                    | io::ErrorKind::NotFound
                    | io::ErrorKind::TimedOut
            ) => {}
        Err(err) => return Err(err),
    }

    if let Err(err) = fs::remove_file(path) {
        if err.kind() != io::ErrorKind::NotFound {
            return Err(err);
        }
    }

    Ok(())
}

pub(crate) fn socket_file_identity(path: &Path) -> io::Result<SocketFileIdentity> {
    let metadata = fs::metadata(path)?;
    Ok(SocketFileIdentity {
        dev: metadata.dev(),
        ino: metadata.ino(),
    })
}

pub(crate) fn remove_socket_file_if_owned(
    path: &Path,
    identity: SocketFileIdentity,
) -> io::Result<()> {
    let current = match socket_file_identity(path) {
        Ok(current) => current,
        Err(err) if err.kind() == io::ErrorKind::NotFound => return Ok(()),
        Err(err) => return Err(err),
    };

    if current != identity {
        return Ok(());
    }

    match fs::remove_file(path) {
        Ok(()) => Ok(()),
        Err(err) if err.kind() == io::ErrorKind::NotFound => Ok(()),
        Err(err) => Err(err),
    }
}

pub(crate) fn restrict_socket_permissions(path: &Path, mode: u32) -> io::Result<()> {
    let mut permissions = fs::metadata(path)?.permissions();
    permissions.set_mode(mode);
    fs::set_permissions(path, permissions)
}