schematics/src/symbols/systemd/user_service.rs

use crate::async_utils::sleep;
use crate::command_runner::{CommandRunner, SetuidCommandRunner};
use crate::symbols::Symbol;
use async_trait::async_trait;
use std::error::Error;
use std::ffi::OsStr;
use std::path::Path;
use std::time::Duration;

#[derive(Debug)]
pub struct UserService<'a, S: AsRef<Path>, U: AsRef<str>, R: CommandRunner> {
  socket_path: S,
  service_name: &'a str,
  command_runner: SetuidCommandRunner<'a, U, R>,
}

impl<S: AsRef<Path>, U: AsRef<str>, R: CommandRunner> UserService<'static, S, U, R> {
  pub fn new(
    socket_path: S,
    user_name: U,
    service_name: &'static str,
    command_runner: &'static R,
  ) -> Self {
    Self {
      socket_path,
      service_name,
      command_runner: SetuidCommandRunner::new(user_name, command_runner),
    }
  }
}

impl<S: AsRef<Path>, U: AsRef<str>, R: CommandRunner> UserService<'_, S, U, R> {
  async fn systemctl_wait_for_dbus(&self, args: &[&OsStr]) -> Result<String, Box<dyn Error>> {
    let mut tries = 5;
    loop {
      let result = self.command_runner.run_with_args("systemctl", args).await?;
      if result.status.success() {
        return Ok(String::from_utf8(result.stdout)?.trim_end().to_string());
      } else {
        let raw_stderr = String::from_utf8(result.stderr)?;
        let stderr = raw_stderr.trim_end();
        if stderr != "Failed to connect to bus: No such file or directory" {
          return Err(stderr.into());
        }
      }
      tries -= 1;
      if tries == 0 {
        return Err("Gave up waiting for dbus to appear".to_string().into());
      }
      sleep(Duration::from_millis(500)).await;
    }
  }

  async fn check_if_service(&self) -> Result<bool, Box<dyn Error>> {
    loop {
      let active_state = self
        .systemctl_wait_for_dbus(args![
          "--user",
          "show",
          "--property",
          "ActiveState",
          self.service_name,
        ])
        .await?;
      match active_state.as_ref() {
        "ActiveState=activating" => sleep(Duration::from_millis(500)).await,
        "ActiveState=active" => return Ok(true),
        "ActiveState=failed" => {
          return Err(
            String::from_utf8(
              self
                .command_runner
                .get_output(
                  "journalctl",
                  args!["--user", format!("--user-unit={}", self.service_name)],
                )
                .await?,
            )?
            .into(),
          )
        }
        _ => return Ok(false),
      }
    }
  }
}

#[async_trait(?Send)]
impl<S: AsRef<Path>, U: AsRef<str>, R: CommandRunner> Symbol for UserService<'_, S, U, R> {
  async fn target_reached(&self) -> Result<bool, Box<dyn Error>> {
    self.check_if_service().await
  }

  async fn execute(&self) -> Result<(), Box<dyn Error>> {
    self
      .systemctl_wait_for_dbus(args!["--user", "enable", self.service_name])
      .await?;
    self
      .systemctl_wait_for_dbus(args!["--user", "restart", self.service_name])
      .await?;

    loop {
      if !(self.check_if_service().await?) {
        return Err("Generic error".into());
      }

      if self.socket_path.as_ref().exists() {
        return Ok(());
      }
      sleep(Duration::from_millis(500)).await;
    }
  }
}