headroom

//! headroom control-protocol types and framing. spec: `IPC.md` (repo root); this is its rust binding.

#![forbid(unsafe_code)]

#![warn(missing_docs)]

mod codec;

mod error;

mod proto;

pub use codec::{Codec, DEFAULT_MAX_FRAME_BYTES, MIN_MAX_FRAME_BYTES};

pub use error::{Error, ErrorCode, ProtoError};

pub use proto::{

    DaemonEvent, Event, HelloData, LayerALevel, LayerASnapshot, MeterTick, Op, ProfileEvent,

    ProfileInfo, Request, Response, ResponsePayload, Route, RouteList, RouteRule, RouteRuleMatch,

    RoutingEvent, ServerFrame, SinkInfo, Sinks, Status, StreamRoute, Topic,

};

/// wire version; bumped only on incompatible changes.

pub const PROTOCOL_VERSION: u32 = 1;

/// socket dir stem; full path `${XDG_RUNTIME_DIR}/headroom/control.sock`, falling back to `/run/user/$UID/...`.

pub const DEFAULT_SOCKET_DIR: &str = "headroom";

pub const DEFAULT_SOCKET_NAME: &str = "control.sock";

/// honours `XDG_RUNTIME_DIR`, else falls back to `/run/user/$UID/...`. `None` when neither is determinable.

#[must_use]

pub fn default_socket_path() -> Option<std::path::PathBuf> {

    use std::path::PathBuf;

    if let Ok(dir) = std::env::var("XDG_RUNTIME_DIR") {

        if !dir.is_empty() {

            return Some(

                PathBuf::from(dir)

                    .join(DEFAULT_SOCKET_DIR)

                    .join(DEFAULT_SOCKET_NAME),

            );

        }

    }

    // uid from /proc/self/status: nix-free, dependency-light

    let uid = read_self_uid()?;

    Some(

        PathBuf::from(format!("/run/user/{uid}"))

            .join(DEFAULT_SOCKET_DIR)

            .join(DEFAULT_SOCKET_NAME),

    )

}

fn read_self_uid() -> Option<u32> {

    let s = std::fs::read_to_string("/proc/self/status").ok()?;

    for line in s.lines() {

        if let Some(rest) = line.strip_prefix("Uid:") {

            let first = rest.split_whitespace().next()?;

            return first.parse().ok();

        }

    }

    None

}