yash_cli/
lib.rs

1// This file is part of yash, an extended POSIX shell.
2// Copyright (C) 2021 WATANABE Yuki
3//
4// This program is free software: you can redistribute it and/or modify
5// it under the terms of the GNU General Public License as published by
6// the Free Software Foundation, either version 3 of the License, or
7// (at your option) any later version.
8//
9// This program is distributed in the hope that it will be useful,
10// but WITHOUT ANY WARRANTY; without even the implied warranty of
11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12// GNU General Public License for more details.
13//
14// You should have received a copy of the GNU General Public License
15// along with this program.  If not, see <https://www.gnu.org/licenses/>.
16
17//! This is a library crate that implements the command-line frontend for the
18//! yash shell. It is used by the `yash3` binary crate to provide the shell
19//! functionality. Currently, this crate is not intended to be used as a library
20//! by other crates.
21//!
22//! The entry point for the shell is the [`main`] function, which is to be used
23//! as the `main` function in the binary crate. The function sets up the shell
24//! environment and runs the main read-eval loop.
25
26pub mod startup;
27// mod runner;
28
29use self::startup::args::Parse;
30use self::startup::init_file::run_rcfile;
31use self::startup::input::prepare_input;
32use std::cell::RefCell;
33use std::ops::ControlFlow::{Break, Continue};
34use yash_env::Env;
35use yash_env::RealSystem;
36use yash_env::System;
37use yash_env::option::{Interactive, On};
38use yash_env::signal;
39use yash_env::system::{Disposition, Errno, SystemEx as _};
40use yash_executor::Executor;
41use yash_semantics::trap::run_exit_trap;
42use yash_semantics::{Divert, ExitStatus};
43use yash_semantics::{interactive_read_eval_loop, read_eval_loop};
44
45async fn print_version(env: &mut Env) {
46    let version = env!("CARGO_PKG_VERSION");
47    let result = yash_builtin::common::output(env, &format!("yash {}\n", version)).await;
48    env.exit_status = result.exit_status();
49}
50
51// The RefCell is local to this function, so it is safe to keep borrows across await points.
52#[allow(clippy::await_holding_refcell_ref)]
53async fn run_as_shell_process(env: &mut Env) {
54    // Parse the command-line arguments
55    let run = match self::startup::args::parse(std::env::args()) {
56        Ok(Parse::Help) => todo!("print help"),
57        Ok(Parse::Version) => return print_version(env).await,
58        Ok(Parse::Run(run)) => run,
59        Err(e) => {
60            let arg0 = std::env::args().next().unwrap_or_else(|| "yash".to_owned());
61            env.system.print_error(&format!("{}: {}\n", arg0, e)).await;
62            env.exit_status = ExitStatus::ERROR;
63            return;
64        }
65    };
66
67    // Import environment variables
68    env.variables.extend_env(std::env::vars());
69
70    let work = self::startup::configure_environment(env, run);
71
72    let is_interactive = env.options.get(Interactive) == On;
73
74    // Run initialization files
75    // TODO run profile if login
76    run_rcfile(env, work.rcfile).await;
77
78    // Prepare the input for the main read-eval loop
79    let ref_env = RefCell::new(env);
80    let lexer = match prepare_input(&ref_env, &work.source) {
81        Ok(lexer) => lexer,
82        Err(e) => {
83            let arg0 = std::env::args().next().unwrap_or_else(|| "yash".to_owned());
84            let message = format!("{}: {}\n", arg0, e);
85            // The borrow checker of Rust 1.79.0 is not smart enough to reason
86            // about the lifetime of `e` here, so we re-borrow from `ref_env`
87            // instead of taking `env` out of `ref_env`.
88            // let mut env = ref_env.into_inner();
89            let mut env = ref_env.borrow_mut();
90            env.system.print_error(&message).await;
91            env.exit_status = match e.errno {
92                Errno::ENOENT | Errno::ENOTDIR | Errno::EILSEQ => ExitStatus::NOT_FOUND,
93                _ => ExitStatus::NOEXEC,
94            };
95            return;
96        }
97    };
98
99    // Run the read-eval loop
100    let result = if is_interactive {
101        interactive_read_eval_loop(&ref_env, &mut { lexer }).await
102    } else {
103        read_eval_loop(&ref_env, &mut { lexer }).await
104    };
105
106    let env = ref_env.into_inner();
107    env.apply_result(result);
108
109    match result {
110        Continue(())
111        | Break(Divert::Continue { .. })
112        | Break(Divert::Break { .. })
113        | Break(Divert::Return(_))
114        | Break(Divert::Interrupt(_))
115        | Break(Divert::Exit(_)) => run_exit_trap(env).await,
116        Break(Divert::Abort(_)) => (),
117    }
118}
119
120pub fn main() -> ! {
121    // SAFETY: This is the only instance of RealSystem we create in the whole
122    // process.
123    let system = unsafe { RealSystem::new() };
124    let mut env = Env::with_system(Box::new(system));
125
126    // Rust by default sets SIGPIPE to SIG_IGN, which is not desired.
127    // As an imperfect workaround, we set SIGPIPE to SIG_DFL here.
128    // TODO Use unix_sigpipe: https://github.com/rust-lang/rust/issues/97889
129    let sigpipe = env
130        .system
131        .signal_number_from_name(signal::Name::Pipe)
132        .unwrap();
133    _ = env.system.sigaction(sigpipe, Disposition::Default);
134
135    let system = env.system.clone();
136    let executor = Executor::new();
137    let task = Box::pin(async {
138        run_as_shell_process(&mut env).await;
139        env.system.exit_or_raise(env.exit_status).await;
140    });
141    // SAFETY: We never create new threads in the whole process, so wakers are
142    // never shared between threads.
143    unsafe { executor.spawn_pinned(task) }
144    loop {
145        executor.run_until_stalled();
146        system.select(false).ok();
147    }
148}
yash_cli/lib.rs

yash_cli/
lib.rs
