view rust/chg/src/uihandler.rs @ 51809:45270e286bdc default tip

typing: hide the interface version of `dirstate` during type checking

As noted in the previous commit, the `dirstate` type is still inferred as `Any`
by pytype, including where it is used as a base class for the largefiles
dirstate.  That effectively disables most type checking.  The problems fixed two
commits ago were flagged by this change.

I'm not at all clear what the benefit of the original type is, but that was what
was used at runtime, so I don't want to change the largefiles base class to the
raw class.  Having both a lowercase and camelcase name for the same thing isn't
great, but given that this trivially finds problems without worrying about which
symbol clients may be using, and the non-raw type is useless to pytype anyway,
I'm not going to worry about it.

// Copyright 2018 Yuya Nishihara <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

use async_trait::async_trait;
use std::io;
use std::os::unix::io::AsRawFd;
use std::os::unix::process::ExitStatusExt;
use std::process::Stdio;
use tokio;
use tokio::process::{Child, ChildStdin, Command};

use crate::message::CommandSpec;
use crate::procutil;

/// Callback to process shell command requests received from server.
#[async_trait]
pub trait SystemHandler {
    type PagerStdin: AsRawFd;

    /// Handles pager command request.
    ///
    /// Returns the pipe to be attached to the server if the pager is spawned.
    async fn spawn_pager(
        &mut self,
        spec: &CommandSpec,
    ) -> io::Result<Self::PagerStdin>;

    /// Handles system command request.
    ///
    /// Returns command exit code (positive) or signal number (negative).
    async fn run_system(&mut self, spec: &CommandSpec) -> io::Result<i32>;
}

/// Default cHg implementation to process requests received from server.
pub struct ChgUiHandler {
    pager: Option<Child>,
}

impl ChgUiHandler {
    pub fn new() -> ChgUiHandler {
        ChgUiHandler { pager: None }
    }

    /// Waits until the pager process exits.
    pub async fn wait_pager(&mut self) -> io::Result<()> {
        if let Some(p) = self.pager.take() {
            p.await?;
        }
        Ok(())
    }
}

#[async_trait]
impl SystemHandler for ChgUiHandler {
    type PagerStdin = ChildStdin;

    async fn spawn_pager(
        &mut self,
        spec: &CommandSpec,
    ) -> io::Result<Self::PagerStdin> {
        let mut pager =
            new_shell_command(&spec).stdin(Stdio::piped()).spawn()?;
        let pin = pager.stdin.take().unwrap();
        procutil::set_blocking_fd(pin.as_raw_fd())?;
        // TODO: if pager exits, notify the server with SIGPIPE immediately.
        // otherwise the server won't get SIGPIPE if it does not write
        // anything. (issue5278)
        // kill(peerpid, SIGPIPE);
        self.pager = Some(pager);
        Ok(pin)
    }

    async fn run_system(&mut self, spec: &CommandSpec) -> io::Result<i32> {
        let status = new_shell_command(&spec).spawn()?.await?;
        let code = status
            .code()
            .or_else(|| status.signal().map(|n| -n))
            .expect("either exit code or signal should be set");
        Ok(code)
    }
}

fn new_shell_command(spec: &CommandSpec) -> Command {
    let mut builder = Command::new("/bin/sh");
    builder
        .arg("-c")
        .arg(&spec.command)
        .current_dir(&spec.current_dir)
        .env_clear()
        .envs(spec.envs.iter().cloned());
    builder
}