continuwuity/src/main.rs

use std::{
    fs::Permissions, future::Future, io, net::SocketAddr, os::unix::fs::PermissionsExt,
    sync::atomic, time::Duration,
};

use axum::{
    extract::{DefaultBodyLimit, FromRequestParts, MatchedPath},
    response::IntoResponse,
    routing::{get, on, MethodFilter},
    Router,
};
use axum_server::{bind, bind_rustls, tls_rustls::RustlsConfig, Handle as ServerHandle};
use conduit::api::{client_server, server_server};
use figment::{
    providers::{Env, Format, Toml},
    Figment,
};
use http::{
    header::{self, HeaderName},
    Method, StatusCode, Uri,
};
use hyper::Server;
use hyperlocal::SocketIncoming;
use ruma::api::{
    client::{
        error::{Error as RumaError, ErrorBody, ErrorKind},
        uiaa::UiaaResponse,
    },
    IncomingRequest,
};
use tokio::{net::UnixListener, signal, sync::oneshot};
use tower::ServiceBuilder;
use tower_http::{
    cors::{self, CorsLayer},
    trace::TraceLayer,
    ServiceBuilderExt as _,
};
use tracing::{debug, error, info, warn};
use tracing_subscriber::{prelude::*, EnvFilter};

use tokio::sync::oneshot::Sender;

use clap::Parser;

pub use conduit::*; // Re-export everything from the library crate

#[cfg(all(not(target_env = "msvc"), feature = "jemalloc"))]
use tikv_jemallocator::Jemalloc;

#[cfg(all(not(target_env = "msvc"), feature = "jemalloc"))]
#[global_allocator]
static GLOBAL: Jemalloc = Jemalloc;

#[derive(Parser)]
#[clap(version, about, long_about = None)]
struct Args {}

#[tokio::main]
async fn main() {
    Args::parse();
    // Initialize config
    let raw_config =
        Figment::new()
            .merge(
                Toml::file(Env::var("CONDUIT_CONFIG").expect(
                    "The CONDUIT_CONFIG env var needs to be set. Example: /etc/conduit.toml",
                ))
                .nested(),
            )
            .merge(Env::prefixed("CONDUIT_").global());

    let config = match raw_config.extract::<Config>() {
        Ok(s) => s,
        Err(e) => {
            eprintln!("It looks like your config is invalid. The following error occurred: {e}");
            return;
        }
    };

    if config.allow_jaeger {
        opentelemetry::global::set_text_map_propagator(opentelemetry_jaeger::Propagator::new());
        let tracer = opentelemetry_jaeger::new_agent_pipeline()
            .with_auto_split_batch(true)
            .with_service_name("conduit")
            .install_batch(opentelemetry_sdk::runtime::Tokio)
            .unwrap();
        let telemetry = tracing_opentelemetry::layer().with_tracer(tracer);

        let filter_layer = match EnvFilter::try_new(&config.log) {
            Ok(s) => s,
            Err(e) => {
                eprintln!(
                    "It looks like your log config is invalid. The following error occurred: {e}"
                );
                EnvFilter::try_new("warn").unwrap()
            }
        };

        let subscriber = tracing_subscriber::Registry::default()
            .with(filter_layer)
            .with(telemetry);
        tracing::subscriber::set_global_default(subscriber).unwrap();
    } else if config.tracing_flame {
        let registry = tracing_subscriber::Registry::default();
        let (flame_layer, _guard) =
            tracing_flame::FlameLayer::with_file("./tracing.folded").unwrap();
        let flame_layer = flame_layer.with_empty_samples(false);

        let filter_layer = EnvFilter::new("trace,h2=off");

        let subscriber = registry.with(filter_layer).with(flame_layer);
        tracing::subscriber::set_global_default(subscriber).unwrap();
    } else {
        let registry = tracing_subscriber::Registry::default();
        let fmt_layer = tracing_subscriber::fmt::Layer::new();
        let filter_layer = match EnvFilter::try_new(&config.log) {
            Ok(s) => s,
            Err(e) => {
                eprintln!("It looks like your config is invalid. The following error occured while parsing it: {e}");
                EnvFilter::try_new("warn").unwrap()
            }
        };

        let subscriber = registry.with(filter_layer).with(fmt_layer);
        tracing::subscriber::set_global_default(subscriber).unwrap();
    }

    // This is needed for opening lots of file descriptors, which tends to
    // happen more often when using RocksDB and making lots of federation
    // connections at startup. The soft limit is usually 1024, and the hard
    // limit is usually 512000; I've personally seen it hit >2000.
    //
    // * https://www.freedesktop.org/software/systemd/man/systemd.exec.html#id-1.12.2.1.17.6
    // * https://github.com/systemd/systemd/commit/0abf94923b4a95a7d89bc526efc84e7ca2b71741
    #[cfg(unix)]
    maximize_fd_limit().expect("Unable to increase maximum soft and hard file descriptor limit");

    config.warn_deprecated();
    if config.is_dual_listening(raw_config) {
        return;
    };

    info!("Loading database");
    if let Err(error) = KeyValueDatabase::load_or_create(config).await {
        error!(?error, "The database couldn't be loaded or created");
        return;
    };
    let config = &services().globals.config;

    if config.allow_registration
        && !config.yes_i_am_very_very_sure_i_want_an_open_registration_server_prone_to_abuse
    {
        error!("!! You have `allow_registration` enabled in your config which means you are allowing ANYONE to register on your conduwuit instance without any 2nd-step (e.g. registration token).\n
        If this is not the intended behaviour, please disable `allow_registration` and set a registration token.\n
        For security and safety reasons, conduwuit will shut down. If you are extra sure this is the desired behaviour you want, please set the following config option to true:
        `yes_i_am_very_very_sure_i_want_an_open_registration_server_prone_to_abuse`");
        return;
    }

    if config.allow_registration
        && config.yes_i_am_very_very_sure_i_want_an_open_registration_server_prone_to_abuse
    {
        warn!("Open registration is enabled via setting `yes_i_am_very_very_sure_i_want_an_open_registration_server_prone_to_abuse` and `allow_registration` to true. You are expected to be aware of the risks now.\n
        If this is not the desired behaviour, please disable `allow_registration` and set a registration token.");
    }

    info!("Starting server");
    if let Err(e) = run_server().await {
        error!("Critical error running server: {}", e);
    };

    // if server runs into critical error and shuts down, shut down the tracer provider if jaegar is used.
    // awaiting run_server() is a blocking call so putting this after is fine, but not the other options above.
    if config.allow_jaeger {
        opentelemetry::global::shutdown_tracer_provider();
    }
}

async fn run_server() -> io::Result<()> {
    let config = &services().globals.config;
    let addr = SocketAddr::from((config.address, config.port));

    let x_requested_with = HeaderName::from_static("x-requested-with");

    let middlewares = ServiceBuilder::new()
        .sensitive_headers([header::AUTHORIZATION])
        .layer(axum::middleware::from_fn(spawn_task))
        .layer(
            TraceLayer::new_for_http().make_span_with(|request: &http::Request<_>| {
                let path = if let Some(path) = request.extensions().get::<MatchedPath>() {
                    path.as_str()
                } else {
                    request.uri().path()
                };

                tracing::info_span!("http_request", %path)
            }),
        )
        .layer(axum::middleware::from_fn(unrecognized_method))
        .layer(
            CorsLayer::new()
                .allow_origin(cors::Any)
                .allow_methods([
                    Method::GET,
                    Method::HEAD,
                    Method::POST,
                    Method::PUT,
                    Method::DELETE,
                    Method::OPTIONS,
                ])
                .allow_headers([
                    header::ORIGIN,
                    x_requested_with,
                    header::CONTENT_TYPE,
                    header::ACCEPT,
                    header::AUTHORIZATION,
                ])
                .max_age(Duration::from_secs(86400)),
        )
        .layer(DefaultBodyLimit::max(
            config
                .max_request_size
                .try_into()
                .expect("failed to convert max request size"),
        ));

    let app = if cfg!(feature = "zstd_compression") && config.zstd_compression {
        debug!("zstd body compression is enabled");
        routes()
            .layer(middlewares.compression())
            .into_make_service()
    } else {
        routes().layer(middlewares).into_make_service()
    };

    let handle = ServerHandle::new();
    let (tx, rx) = oneshot::channel::<()>();

    tokio::spawn(shutdown_signal(handle.clone(), tx));

    if let Some(path) = &config.unix_socket_path {
        if path.exists() {
            warn!(
                "UNIX socket path {:#?} already exists (unclean shutdown?), attempting to remove it.",
                path.display()
            );
            tokio::fs::remove_file(&path).await?;
        }

        tokio::fs::create_dir_all(path.parent().unwrap()).await?;

        let socket_perms = config.unix_socket_perms.to_string();
        let octal_perms = u32::from_str_radix(&socket_perms, 8).unwrap();

        let listener = UnixListener::bind(path.clone()).unwrap();
        tokio::fs::set_permissions(path, Permissions::from_mode(octal_perms))
            .await
            .unwrap();
        let socket = SocketIncoming::from_listener(listener);

        #[cfg(feature = "systemd")]
        let _ = sd_notify::notify(true, &[sd_notify::NotifyState::Ready]);

        info!("Listening at {:?}", path);
        let server = Server::builder(socket).serve(app);
        let graceful = server.with_graceful_shutdown(async {
            rx.await.ok();
        });

        if let Err(e) = graceful.await {
            error!("Server error: {:?}", e);
        }
    } else {
        match &config.tls {
            Some(tls) => {
                let conf = RustlsConfig::from_pem_file(&tls.certs, &tls.key).await?;
                let server = bind_rustls(addr, conf).handle(handle).serve(app);

                #[cfg(feature = "systemd")]
                let _ = sd_notify::notify(true, &[sd_notify::NotifyState::Ready]);

                info!("Listening on {}", addr);
                server.await?
            }
            None => {
                let server = bind(addr).handle(handle).serve(app);

                #[cfg(feature = "systemd")]
                let _ = sd_notify::notify(true, &[sd_notify::NotifyState::Ready]);

                info!("Listening on {}", addr);
                server.await?
            }
        }
    }

    Ok(())
}

async fn spawn_task<B: Send + 'static>(
    req: axum::http::Request<B>,
    next: axum::middleware::Next<B>,
) -> std::result::Result<axum::response::Response, StatusCode> {
    if services().globals.shutdown.load(atomic::Ordering::Relaxed) {
        return Err(StatusCode::SERVICE_UNAVAILABLE);
    }
    tokio::spawn(next.run(req))
        .await
        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)
}

async fn unrecognized_method<B: Send + 'static>(
    req: axum::http::Request<B>,
    next: axum::middleware::Next<B>,
) -> std::result::Result<axum::response::Response, StatusCode> {
    let method = req.method().clone();
    let uri = req.uri().clone();
    let inner = next.run(req).await;
    if inner.status() == axum::http::StatusCode::METHOD_NOT_ALLOWED {
        warn!("Method not allowed: {method} {uri}");
        return Ok(RumaResponse(UiaaResponse::MatrixError(RumaError {
            body: ErrorBody::Standard {
                kind: ErrorKind::Unrecognized,
                message: "M_UNRECOGNIZED: Unrecognized request".to_owned(),
            },
            status_code: StatusCode::METHOD_NOT_ALLOWED,
        }))
        .into_response());
    }
    Ok(inner)
}

fn routes() -> Router {
    Router::new()
        .ruma_route(client_server::get_supported_versions_route)
        .ruma_route(client_server::get_register_available_route)
        .ruma_route(client_server::register_route)
        .ruma_route(client_server::get_login_types_route)
        .ruma_route(client_server::login_route)
        .ruma_route(client_server::whoami_route)
        .ruma_route(client_server::logout_route)
        .ruma_route(client_server::logout_all_route)
        .ruma_route(client_server::change_password_route)
        .ruma_route(client_server::deactivate_route)
        .ruma_route(client_server::third_party_route)
        .ruma_route(client_server::request_3pid_management_token_via_email_route)
        .ruma_route(client_server::request_3pid_management_token_via_msisdn_route)
        .ruma_route(client_server::get_capabilities_route)
        .ruma_route(client_server::get_pushrules_all_route)
        .ruma_route(client_server::set_pushrule_route)
        .ruma_route(client_server::get_pushrule_route)
        .ruma_route(client_server::set_pushrule_enabled_route)
        .ruma_route(client_server::get_pushrule_enabled_route)
        .ruma_route(client_server::get_pushrule_actions_route)
        .ruma_route(client_server::set_pushrule_actions_route)
        .ruma_route(client_server::delete_pushrule_route)
        .ruma_route(client_server::get_room_event_route)
        .ruma_route(client_server::get_room_aliases_route)
        .ruma_route(client_server::get_filter_route)
        .ruma_route(client_server::create_filter_route)
        .ruma_route(client_server::set_global_account_data_route)
        .ruma_route(client_server::set_room_account_data_route)
        .ruma_route(client_server::get_global_account_data_route)
        .ruma_route(client_server::get_room_account_data_route)
        .ruma_route(client_server::set_displayname_route)
        .ruma_route(client_server::get_displayname_route)
        .ruma_route(client_server::set_avatar_url_route)
        .ruma_route(client_server::get_avatar_url_route)
        .ruma_route(client_server::get_profile_route)
        .ruma_route(client_server::set_presence_route)
        .ruma_route(client_server::get_presence_route)
        .ruma_route(client_server::upload_keys_route)
        .ruma_route(client_server::get_keys_route)
        .ruma_route(client_server::claim_keys_route)
        .ruma_route(client_server::create_backup_version_route)
        .ruma_route(client_server::update_backup_version_route)
        .ruma_route(client_server::delete_backup_version_route)
        .ruma_route(client_server::get_latest_backup_info_route)
        .ruma_route(client_server::get_backup_info_route)
        .ruma_route(client_server::add_backup_keys_route)
        .ruma_route(client_server::add_backup_keys_for_room_route)
        .ruma_route(client_server::add_backup_keys_for_session_route)
        .ruma_route(client_server::delete_backup_keys_for_room_route)
        .ruma_route(client_server::delete_backup_keys_for_session_route)
        .ruma_route(client_server::delete_backup_keys_route)
        .ruma_route(client_server::get_backup_keys_for_room_route)
        .ruma_route(client_server::get_backup_keys_for_session_route)
        .ruma_route(client_server::get_backup_keys_route)
        .ruma_route(client_server::set_read_marker_route)
        .ruma_route(client_server::create_receipt_route)
        .ruma_route(client_server::create_typing_event_route)
        .ruma_route(client_server::create_room_route)
        .ruma_route(client_server::redact_event_route)
        .ruma_route(client_server::report_event_route)
        .ruma_route(client_server::create_alias_route)
        .ruma_route(client_server::delete_alias_route)
        .ruma_route(client_server::get_alias_route)
        .ruma_route(client_server::join_room_by_id_route)
        .ruma_route(client_server::join_room_by_id_or_alias_route)
        .ruma_route(client_server::joined_members_route)
        .ruma_route(client_server::leave_room_route)
        .ruma_route(client_server::forget_room_route)
        .ruma_route(client_server::joined_rooms_route)
        .ruma_route(client_server::kick_user_route)
        .ruma_route(client_server::ban_user_route)
        .ruma_route(client_server::unban_user_route)
        .ruma_route(client_server::invite_user_route)
        .ruma_route(client_server::set_room_visibility_route)
        .ruma_route(client_server::get_room_visibility_route)
        .ruma_route(client_server::get_public_rooms_route)
        .ruma_route(client_server::get_public_rooms_filtered_route)
        .ruma_route(client_server::search_users_route)
        .ruma_route(client_server::get_member_events_route)
        .ruma_route(client_server::get_protocols_route)
        .ruma_route(client_server::send_message_event_route)
        .ruma_route(client_server::send_state_event_for_key_route)
        .ruma_route(client_server::get_state_events_route)
        .ruma_route(client_server::get_state_events_for_key_route)
        // Ruma doesn't have support for multiple paths for a single endpoint yet, and these routes
        // share one Ruma request / response type pair with {get,send}_state_event_for_key_route
        .route(
            "/_matrix/client/r0/rooms/:room_id/state/:event_type",
            get(client_server::get_state_events_for_empty_key_route)
                .put(client_server::send_state_event_for_empty_key_route),
        )
        .route(
            "/_matrix/client/v3/rooms/:room_id/state/:event_type",
            get(client_server::get_state_events_for_empty_key_route)
                .put(client_server::send_state_event_for_empty_key_route),
        )
        // These two endpoints allow trailing slashes
        .route(
            "/_matrix/client/r0/rooms/:room_id/state/:event_type/",
            get(client_server::get_state_events_for_empty_key_route)
                .put(client_server::send_state_event_for_empty_key_route),
        )
        .route(
            "/_matrix/client/v3/rooms/:room_id/state/:event_type/",
            get(client_server::get_state_events_for_empty_key_route)
                .put(client_server::send_state_event_for_empty_key_route),
        )
        .ruma_route(client_server::sync_events_route)
        .ruma_route(client_server::sync_events_v4_route)
        .ruma_route(client_server::get_context_route)
        .ruma_route(client_server::get_message_events_route)
        .ruma_route(client_server::search_events_route)
        .ruma_route(client_server::turn_server_route)
        .ruma_route(client_server::send_event_to_device_route)
        .ruma_route(client_server::get_media_config_route)
        .ruma_route(client_server::create_content_route)
        .ruma_route(client_server::get_content_route)
        .ruma_route(client_server::get_content_as_filename_route)
        .ruma_route(client_server::get_content_thumbnail_route)
        .ruma_route(client_server::get_devices_route)
        .ruma_route(client_server::get_device_route)
        .ruma_route(client_server::update_device_route)
        .ruma_route(client_server::delete_device_route)
        .ruma_route(client_server::delete_devices_route)
        .ruma_route(client_server::get_tags_route)
        .ruma_route(client_server::update_tag_route)
        .ruma_route(client_server::delete_tag_route)
        .ruma_route(client_server::upload_signing_keys_route)
        .ruma_route(client_server::upload_signatures_route)
        .ruma_route(client_server::get_key_changes_route)
        .ruma_route(client_server::get_pushers_route)
        .ruma_route(client_server::set_pushers_route)
        // .ruma_route(client_server::third_party_route)
        .ruma_route(client_server::upgrade_room_route)
        .ruma_route(client_server::get_threads_route)
        .ruma_route(client_server::get_relating_events_with_rel_type_and_event_type_route)
        .ruma_route(client_server::get_relating_events_with_rel_type_route)
        .ruma_route(client_server::get_relating_events_route)
        .ruma_route(client_server::get_hierarchy_route)
        .ruma_route(server_server::get_server_version_route)
        .route(
            "/_matrix/key/v2/server",
            get(server_server::get_server_keys_route),
        )
        .route(
            "/_matrix/key/v2/server/:key_id",
            get(server_server::get_server_keys_deprecated_route),
        )
        .ruma_route(server_server::get_public_rooms_route)
        .ruma_route(server_server::get_public_rooms_filtered_route)
        .ruma_route(server_server::send_transaction_message_route)
        .ruma_route(server_server::get_event_route)
        .ruma_route(server_server::get_backfill_route)
        .ruma_route(server_server::get_missing_events_route)
        .ruma_route(server_server::get_event_authorization_route)
        .ruma_route(server_server::get_room_state_route)
        .ruma_route(server_server::get_room_state_ids_route)
        .ruma_route(server_server::create_join_event_template_route)
        .ruma_route(server_server::create_join_event_v1_route)
        .ruma_route(server_server::create_join_event_v2_route)
        .ruma_route(server_server::create_invite_route)
        .ruma_route(server_server::get_devices_route)
        .ruma_route(server_server::get_room_information_route)
        .ruma_route(server_server::get_profile_information_route)
        .ruma_route(server_server::get_keys_route)
        .ruma_route(server_server::claim_keys_route)
        .route(
            "/_matrix/client/r0/rooms/:room_id/initialSync",
            get(initial_sync),
        )
        .route(
            "/_matrix/client/v3/rooms/:room_id/initialSync",
            get(initial_sync),
        )
        .route(
            "/client/server.json",
            get(client_server::syncv3_client_server_json),
        )
        .route(
            "/.well-known/matrix/client",
            get(client_server::well_known_client_route),
        )
        .route(
            "/.well-known/matrix/server",
            get(server_server::well_known_server_route),
        )
        .route("/", get(it_works))
        .fallback(not_found)
}

async fn shutdown_signal(handle: ServerHandle, tx: Sender<()>) -> Result<()> {
    let ctrl_c = async {
        signal::ctrl_c()
            .await
            .expect("failed to install Ctrl+C handler");
    };

    #[cfg(unix)]
    let terminate = async {
        signal::unix::signal(signal::unix::SignalKind::terminate())
            .expect("failed to install signal handler")
            .recv()
            .await;
    };

    #[cfg(not(unix))]
    let terminate = std::future::pending::<()>();

    let sig: &str;

    tokio::select! {
        _ = ctrl_c => { sig = "Ctrl+C"; },
        _ = terminate => { sig = "SIGTERM"; },
    }

    warn!("Received {}, shutting down...", sig);
    handle.graceful_shutdown(Some(Duration::from_secs(60)));

    services().globals.shutdown();

    #[cfg(feature = "systemd")]
    let _ = sd_notify::notify(true, &[sd_notify::NotifyState::Stopping]);
    tx.send(()).unwrap();

    Ok(())
}

async fn not_found(uri: Uri) -> impl IntoResponse {
    warn!("Not found: {uri}");
    Error::BadRequest(ErrorKind::Unrecognized, "Unrecognized request")
}

async fn initial_sync(_uri: Uri) -> impl IntoResponse {
    Error::BadRequest(
        ErrorKind::GuestAccessForbidden,
        "Guest access not implemented",
    )
}

async fn it_works() -> &'static str {
    "hewwo from conduwuit woof!"
}

trait RouterExt {
    fn ruma_route<H, T>(self, handler: H) -> Self
    where
        H: RumaHandler<T>,
        T: 'static;
}

impl RouterExt for Router {
    fn ruma_route<H, T>(self, handler: H) -> Self
    where
        H: RumaHandler<T>,
        T: 'static,
    {
        handler.add_to_router(self)
    }
}

pub trait RumaHandler<T> {
    // Can't transform to a handler without boxing or relying on the nightly-only
    // impl-trait-in-traits feature. Moving a small amount of extra logic into the trait
    // allows bypassing both.
    fn add_to_router(self, router: Router) -> Router;
}

macro_rules! impl_ruma_handler {
    ( $($ty:ident),* $(,)? ) => {
        #[axum::async_trait]
        #[allow(non_snake_case)]
        impl<Req, E, F, Fut, $($ty,)*> RumaHandler<($($ty,)* Ruma<Req>,)> for F
        where
            Req: IncomingRequest + Send + 'static,
            F: FnOnce($($ty,)* Ruma<Req>) -> Fut + Clone + Send + 'static,
            Fut: Future<Output = Result<Req::OutgoingResponse, E>>
                + Send,
            E: IntoResponse,
            $( $ty: FromRequestParts<()> + Send + 'static, )*
        {
            fn add_to_router(self, mut router: Router) -> Router {
                let meta = Req::METADATA;
                let method_filter = method_to_filter(meta.method);

                for path in meta.history.all_paths() {
                    let handler = self.clone();

                    router = router.route(path, on(method_filter, |$( $ty: $ty, )* req| async move {
                        handler($($ty,)* req).await.map(RumaResponse)
                    }))
                }

                router
            }
        }
    };
}

impl_ruma_handler!();
impl_ruma_handler!(T1);
impl_ruma_handler!(T1, T2);
impl_ruma_handler!(T1, T2, T3);
impl_ruma_handler!(T1, T2, T3, T4);
impl_ruma_handler!(T1, T2, T3, T4, T5);
impl_ruma_handler!(T1, T2, T3, T4, T5, T6);
impl_ruma_handler!(T1, T2, T3, T4, T5, T6, T7);
impl_ruma_handler!(T1, T2, T3, T4, T5, T6, T7, T8);

fn method_to_filter(method: Method) -> MethodFilter {
    match method {
        Method::DELETE => MethodFilter::DELETE,
        Method::GET => MethodFilter::GET,
        Method::HEAD => MethodFilter::HEAD,
        Method::OPTIONS => MethodFilter::OPTIONS,
        Method::PATCH => MethodFilter::PATCH,
        Method::POST => MethodFilter::POST,
        Method::PUT => MethodFilter::PUT,
        Method::TRACE => MethodFilter::TRACE,
        m => panic!("Unsupported HTTP method: {m:?}"),
    }
}

#[cfg(unix)]
#[tracing::instrument(err)]
fn maximize_fd_limit() -> Result<(), nix::errno::Errno> {
    use nix::sys::resource::{getrlimit, setrlimit, Resource};

    let res = Resource::RLIMIT_NOFILE;

    let (soft_limit, hard_limit) = getrlimit(res)?;

    debug!("Current nofile soft limit: {soft_limit}");

    setrlimit(res, hard_limit, hard_limit)?;

    debug!("Increased nofile soft limit to {hard_limit}");

    Ok(())
}