yash-semantics 0.15.0

// This file is part of yash, an extended POSIX shell.
// Copyright (C) 2021 WATANABE Yuki
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

//! Command execution

mod and_or;
mod compound_command;
mod function_definition;
mod item;
mod pipeline;
pub mod simple_command;

use crate::Runtime;
use crate::trap::run_traps_for_caught_signals;
use std::ops::ControlFlow::{Break, Continue};
use yash_env::Env;
use yash_env::semantics::Result;
#[doc(no_inline)]
pub use yash_env::semantics::command::search;
use yash_syntax::syntax;

/// Syntactic construct that can be executed.
pub trait Command<S> {
    /// Executes this command.
    ///
    /// Implementations of this method is expected to update `env.exit_status`
    /// reflecting the result of the command execution.
    #[allow(async_fn_in_trait)] // We don't support Send
    async fn execute(&self, env: &mut Env<S>) -> Result;
}

/// Executes the command.
///
/// After executing the command body, the `execute` function [runs
/// traps](run_traps_for_caught_signals) if any caught signals are pending, and
/// [updates subshell statuses](Env::update_all_subshell_statuses).
impl<S: Runtime + 'static> Command<S> for syntax::Command {
    async fn execute(&self, env: &mut Env<S>) -> Result {
        use syntax::Command::*;
        let main_result = match self {
            Simple(command) => command.execute(env).await,
            Compound(command) => command.execute(env).await,
            Function(definition) => definition.execute(env).await,
        };

        let trap_result = run_traps_for_caught_signals(env).await;
        env.update_all_subshell_statuses();

        match (main_result, trap_result) {
            (_, Continue(())) => main_result,
            (Continue(()), _) => trap_result,
            (Break(main_divert), Break(trap_divert)) => Break(main_divert.max(trap_divert)),
        }
    }
}

/// Executes the list.
///
/// The list is executed by executing each item in sequence. If any item results
/// in a [`Divert`](yash_env::semantics::Divert), the remaining items are not
/// executed.
impl<S: Runtime + 'static> Command<S> for syntax::List {
    async fn execute(&self, env: &mut Env<S>) -> Result {
        // Boxing needed for recursion
        Box::pin(async move {
            for item in &self.0 {
                item.execute(env).await?
            }
            Continue(())
        })
        .await
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::tests::echo_builtin;
    use crate::tests::return_builtin;
    use futures_util::FutureExt;
    use yash_env::semantics::Divert;
    use yash_env::semantics::ExitStatus;
    use yash_env::system::r#virtual::SIGUSR1;
    use yash_env::system::r#virtual::VirtualSystem;
    use yash_env::test_helper::assert_stdout;
    use yash_env::trap::Action;
    use yash_syntax::source::Location;

    #[test]
    fn command_handles_traps() {
        let system = VirtualSystem::new();
        let mut env = Env::with_system(system.clone());
        env.builtins.insert("echo", echo_builtin());
        env.traps
            .set_action(
                &env.system,
                SIGUSR1,
                Action::Command("echo USR1".into()),
                Location::dummy(""),
                false,
            )
            .now_or_never()
            .unwrap()
            .unwrap();
        let _ = system
            .state
            .borrow_mut()
            .processes
            .get_mut(&system.process_id)
            .unwrap()
            .raise_signal(SIGUSR1);

        let command: syntax::Command = "echo main".parse().unwrap();
        let result = command.execute(&mut env).now_or_never().unwrap();
        assert_eq!(result, Continue(()));
        assert_eq!(env.exit_status, ExitStatus::SUCCESS);

        assert_stdout(&system.state, |stdout| assert_eq!(stdout, "main\nUSR1\n"));
    }

    #[test]
    fn list_execute_no_divert() {
        let mut env = Env::new_virtual();
        env.builtins.insert("return", return_builtin());
        let list: syntax::List = "return -n 1; return -n 2; return -n 4".parse().unwrap();
        let result = list.execute(&mut env).now_or_never().unwrap();
        assert_eq!(result, Continue(()));
        assert_eq!(env.exit_status, ExitStatus(4));
    }

    #[test]
    fn list_execute_divert() {
        let mut env = Env::new_virtual();
        env.builtins.insert("return", return_builtin());
        let list: syntax::List = "return -n 1; return 2; return -n 4".parse().unwrap();
        let result = list.execute(&mut env).now_or_never().unwrap();
        assert_eq!(result, Break(Divert::Return(Some(ExitStatus(2)))));
        assert_eq!(env.exit_status, ExitStatus(1));
    }
}