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 an internal library crate for the yash shell. Currently, **this
18//! crate is not intended to be used as a library by other crates. No part of
19//! this crate is covered by semantic versioning.**
20//!
21//! The entry point for the shell is the [`main`] function, which is to be used
22//! as the `main` function in the binary crate. The function sets up the shell
23//! environment and runs the main read-eval loop.
24
25pub mod startup;
26// mod runner;
27
28use self::startup::args::Parse;
29use self::startup::init_file::run_rcfile;
30use self::startup::input::prepare_input;
31use std::cell::RefCell;
32use std::ops::ControlFlow::{Break, Continue};
33use yash_env::Env;
34use yash_env::RealSystem;
35use yash_env::option::{Interactive, On};
36use yash_env::semantics::{Divert, ExitStatus, exit_or_raise};
37use yash_env::system::resource::GetRlimit;
38use yash_env::system::{
39    Chdir, Disposition, Errno, Fcntl, GetCwd, GetUid, Isatty, Sigaction, Signals, Sysconf,
40    TcGetPgrp, Times, Umask, Write,
41};
42use yash_executor::Executor;
43use yash_semantics::trap::run_exit_trap;
44use yash_semantics::{Runtime, interactive_read_eval_loop, read_eval_loop};
45
46async fn print_version<S>(env: &mut Env<S>)
47where
48    S: Fcntl + Isatty + Write,
49{
50    let version = env!("CARGO_PKG_VERSION");
51    let result = yash_builtin::common::output(env, &format!("yash {version}\n")).await;
52    env.exit_status = result.exit_status();
53}
54
55// The RefCell is local to this function, so it is safe to keep borrows across await points.
56#[allow(clippy::await_holding_refcell_ref)]
57async fn run_as_shell_process<S>(env: &mut Env<S>)
58where
59    S: Chdir
60        + GetCwd
61        + GetRlimit
62        + GetUid
63        + Runtime
64        + Sysconf
65        + TcGetPgrp
66        + Times
67        + Umask
68        + 'static,
69{
70    // Parse the command-line arguments
71    let run = match self::startup::args::parse(std::env::args()) {
72        Ok(Parse::Help) => todo!("print help"),
73        Ok(Parse::Version) => return print_version(env).await,
74        Ok(Parse::Run(run)) => run,
75        Err(e) => {
76            let arg0 = std::env::args().next().unwrap_or_else(|| "yash".to_owned());
77            env.system.print_error(&format!("{arg0}: {e}\n")).await;
78            env.exit_status = ExitStatus::ERROR;
79            return;
80        }
81    };
82
83    // Import environment variables
84    env.variables.extend_env(std::env::vars());
85
86    let work = self::startup::configure_environment(env, run).await;
87
88    let is_interactive = env.options.get(Interactive) == On;
89
90    // Run initialization files
91    // TODO run profile if login
92    run_rcfile(env, work.rcfile).await;
93
94    // Prepare the input for the main read-eval loop
95    let ref_env = RefCell::new(env);
96    let lexer = match prepare_input(&ref_env, &work.source) {
97        Ok(lexer) => lexer,
98        Err(e) => {
99            let arg0 = std::env::args().next().unwrap_or_else(|| "yash".to_owned());
100            let message = format!("{arg0}: {e}\n");
101            // The borrow checker of Rust 1.79.0 is not smart enough to reason
102            // about the lifetime of `e` here, so we re-borrow from `ref_env`
103            // instead of taking `env` out of `ref_env`.
104            // let mut env = ref_env.into_inner();
105            let mut env = ref_env.borrow_mut();
106            env.system.print_error(&message).await;
107            env.exit_status = match e.errno {
108                Errno::ENOENT | Errno::ENOTDIR | Errno::EILSEQ => ExitStatus::NOT_FOUND,
109                _ => ExitStatus::NOEXEC,
110            };
111            return;
112        }
113    };
114
115    // Run the read-eval loop
116    let result = if is_interactive {
117        interactive_read_eval_loop(&ref_env, &mut { lexer }).await
118    } else {
119        read_eval_loop(&ref_env, &mut { lexer }).await
120    };
121
122    let env = ref_env.into_inner();
123    env.apply_result(result);
124
125    match result {
126        Continue(())
127        | Break(Divert::Continue { .. })
128        | Break(Divert::Break { .. })
129        | Break(Divert::Return(_))
130        | Break(Divert::Interrupt(_))
131        | Break(Divert::Exit(_)) => run_exit_trap(env).await,
132        Break(Divert::Abort(_)) => (),
133    }
134}
135
136pub fn main() -> ! {
137    // SAFETY: This is the only instance of RealSystem we create in the whole
138    // process.
139    let system = unsafe { RealSystem::new() };
140    let mut env = Env::with_system(system);
141
142    // Rust by default sets SIGPIPE to SIG_IGN, which is not desired.
143    // As an imperfect workaround, we set SIGPIPE to SIG_DFL here.
144    // TODO Use unix_sigpipe: https://github.com/rust-lang/rust/issues/97889
145    env.system
146        .sigaction(RealSystem::SIGPIPE, Disposition::Default)
147        .ok();
148
149    let system = env.system.clone();
150    let executor = Executor::new();
151    let task = Box::pin(async {
152        run_as_shell_process(&mut env).await;
153        exit_or_raise(&env.system, env.exit_status).await
154    });
155    // SAFETY: We never create new threads in the whole process, so wakers are
156    // never shared between threads.
157    unsafe { executor.spawn_pinned(task) }
158    loop {
159        executor.run_until_stalled();
160        system.select(false).ok();
161    }
162}
yash_cli/lib.rs

yash_cli/
lib.rs
