boxmaker/docs/plans/M5b/files/crates/brokerd/tests/instance.rs

//! One `brokerd` per home (M5b spec, section 9a): a second `brokerd serve` against the same home is
//! refused with the lock's line, and the first keeps serving; once the first is killed, a new one
//! removes the stale sockets and serves. Every wait has a deadline, and every process is killed
//! and every path removed by a guard (tip T44). Do not edit.

#[path = "support/tmp.rs"]
mod tmp;

use std::os::unix::fs::PermissionsExt;
use std::os::unix::net::UnixStream;
use std::path::{Path, PathBuf};
use std::process::{Child, Command, Stdio};
use std::time::{Duration, Instant};

use bxcore::{Empty, Envelope, Message, PROTOCOL_VERSION, read_frame, write_frame};
use tmp::TempDir;

const POINTER: &str = "see docs/runbook.md#already-running";

struct Home {
    dir: TempDir,
    config: PathBuf,
}

impl Home {
    fn new(tag: &str) -> Home {
        let dir = TempDir::new(tag);
        std::fs::create_dir_all(dir.path().join("grants")).unwrap();
        let text = format!(
            "[paths]\nhome = \"{home}\"\ngrants = \"{home}/grants\"\n",
            home = dir.path().display()
        );
        let config = dir.write("brokerd.toml", &text);
        Home { dir, config }
    }

    fn path(&self, relative: &str) -> PathBuf {
        self.dir.path().join(relative)
    }

    fn command(&self) -> Command {
        let mut command = Command::new(env!("CARGO_BIN_EXE_brokerd"));
        command
            .args(["serve", "--config"])
            .arg(&self.config)
            .stdin(Stdio::null())
            .stdout(Stdio::null());
        command
    }

    /// `brokerd serve` with its stderr in `<home>/<name>.err`, for the messages of a failing test.
    fn start(&self, name: &str) -> Daemon {
        let err = std::fs::File::create(self.path(&format!("{name}.err"))).unwrap();
        Daemon(self.command().stderr(Stdio::from(err)).spawn().unwrap())
    }

    fn stderr_of(&self, name: &str) -> String {
        std::fs::read_to_string(self.path(&format!("{name}.err"))).unwrap_or_default()
    }

    /// Runs `brokerd serve` to its end, at most 10 s (then it is killed), and gives its exit code
    /// (`None` if it had to be killed) and its stderr.
    fn run_to_end(&self) -> (Option<i32>, String) {
        let mut child = Daemon(self.command().stderr(Stdio::piped()).spawn().unwrap());
        let deadline = Instant::now() + Duration::from_secs(10);
        let mut code = None;
        while Instant::now() < deadline {
            if let Ok(Some(status)) = child.0.try_wait() {
                code = status.code();
                break;
            }
            std::thread::sleep(Duration::from_millis(20));
        }
        let _ = child.0.kill();
        let _ = child.0.wait();
        let mut stderr = String::new();
        if let Some(mut pipe) = child.0.stderr.take() {
            let _ = std::io::Read::read_to_string(&mut pipe, &mut stderr);
        }
        (code, stderr)
    }

    fn tools(&self) -> PathBuf {
        self.path("run/loop-broker/broker.sock")
    }

    fn admin(&self) -> PathBuf {
        self.path("run/owner-broker/admin.sock")
    }
}

/// A running `brokerd serve`, killed and waited for when dropped. Declared after the `Home`, so it
/// drops first.
struct Daemon(Child);

impl Drop for Daemon {
    fn drop(&mut self) {
        let _ = self.0.kill();
        let _ = self.0.wait();
    }
}

impl Daemon {
    fn running(&mut self) -> bool {
        matches!(self.0.try_wait(), Ok(None))
    }
}

/// True when `brokerd` answers on its owner's socket: `approvals` gets the list of approvals. Any
/// other answer, or none within 5 s, is false.
fn answers(admin: &Path) -> bool {
    let Ok(mut stream) = UnixStream::connect(admin) else {
        return false;
    };
    let limit = Some(Duration::from_secs(5));
    if stream.set_read_timeout(limit).is_err() || stream.set_write_timeout(limit).is_err() {
        return false;
    }
    let ask = Envelope {
        v: PROTOCOL_VERSION,
        id: 1,
        r#final: true,
        msg: Message::Approvals(Empty {}),
    };
    if write_frame(&mut stream, &ask).is_err() {
        return false;
    }
    matches!(
        read_frame(&mut stream),
        Ok(Envelope {
            msg: Message::ApprovalList(_),
            ..
        })
    )
}

/// Waits up to 10 s for `brokerd` to answer on `admin` and to listen on `tools`.
fn wait_until_it_answers(home: &Home) -> bool {
    let deadline = Instant::now() + Duration::from_secs(10);
    while Instant::now() < deadline {
        if answers(&home.admin()) && UnixStream::connect(home.tools()).is_ok() {
            return true;
        }
        std::thread::sleep(Duration::from_millis(20));
    }
    false
}

fn inode(path: &Path) -> u64 {
    use std::os::unix::fs::MetadataExt;
    std::fs::symlink_metadata(path)
        .map(|m| m.ino())
        .unwrap_or(0)
}

#[test]
fn a_second_brokerd_on_the_same_home_is_refused_and_the_first_keeps_serving() {
    let home = Home::new("inst-twice");
    let mut first = home.start("first");
    assert!(
        wait_until_it_answers(&home),
        "the first brokerd never answered; stderr: {}",
        home.stderr_of("first")
    );
    let before = (inode(&home.tools()), inode(&home.admin()));

    let (code, stderr) = home.run_to_end();
    let line = format!(
        "brokerd: another brokerd is running (it holds {}); {POINTER}",
        home.path("run/brokerd.lock").display()
    );
    assert_eq!(code, Some(1), "the second brokerd: {stderr}");
    assert_eq!(
        stderr,
        format!("{line}\n"),
        "the lock's line, and nothing else"
    );

    assert!(first.running(), "the first brokerd is still running");
    assert_eq!(
        (inode(&home.tools()), inode(&home.admin())),
        before,
        "the first's sockets are still there"
    );
    assert!(
        answers(&home.admin()),
        "the first brokerd still answers; its stderr: {}",
        home.stderr_of("first")
    );
}

#[test]
fn after_the_first_is_killed_a_new_brokerd_removes_the_stale_sockets_and_serves() {
    let home = Home::new("inst-restart");
    let mut first = home.start("first");
    assert!(
        wait_until_it_answers(&home),
        "the first brokerd never answered; stderr: {}",
        home.stderr_of("first")
    );
    let _ = first.0.kill();
    let _ = first.0.wait();
    assert!(
        home.tools().exists() && home.admin().exists(),
        "a killed brokerd leaves its sockets"
    );
    assert!(!answers(&home.admin()), "nobody serves the stale socket");

    let _next = home.start("next");
    assert!(
        wait_until_it_answers(&home),
        "the new brokerd never answered; stderr: {}",
        home.stderr_of("next")
    );
    let lock = home.path("run/brokerd.lock");
    let mode = std::fs::metadata(&lock).map(|m| m.permissions().mode() & 0o777);
    assert_eq!(mode.ok(), Some(0o600), "the lock file, mode 0600");
}