1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179
//! This crate allows cleanly exiting a program using a custom exit code,
//! without the drawbacks of [`process::exit`]. Destructors will be called as
//! usual, and the stack will be completely unwound.
//!
//! It is always required to attach [`#[main]`][attribute] to the main
//! function. Then, [`with_code`] can be called from almost anywhere in the
//! program. Restrictions are noted in the documentation for that function.
//!
//! # Implementation
//!
//! Internally, this crate uses panicking to unwind the stack. Thus, if
//! panicking were set to "abort" instead of the default "unwind", setting the
//! exit status would not work correctly. This crate will cause a compile error
//! in that case, to avoid silent incorrect behavior. Further information can
//! be found in the [Rustc Development Guide][panic_runtime].
//!
//! Additionally, the program will not exit if [`with_code`] is called from a
//! spawned thread, unless panics are propagated from that thread. However,
//! propagating panics is usually recommended regardless.
//!
//! # Examples
//!
//! ```
//! use std::env;
//!
//! fn read_args() {
//! if env::args_os().nth(1).is_some() {
//! eprintln!("too many arguments");
//! quit::with_code(1);
//! }
//! }
//!
//! #[quit::main]
//! fn main() {
//! read_args();
//! }
//! ```
//!
//! [attribute]: main
//! [panic_runtime]: https://rustc-dev-guide.rust-lang.org/panic-implementation.html#step-2-the-panic-runtime
#![forbid(unsafe_code)]
#![warn(unused_results)]
#[cfg(not(panic = "unwind"))]
compile_error!(
r#"Quit requires unwinding panics:
https://docs.rs/quit/latest/quit/#implementation"#
);
use std::panic;
use std::panic::UnwindSafe;
use std::process;
use std::process::Termination;
use std::sync::atomic;
use std::sync::atomic::AtomicBool;
#[cfg(all(feature = "__unstable_tests", not(quit_docs_rs)))]
#[doc(hidden)]
pub mod tests_common;
/// Modifies the main function to exit with the code passed to [`with_code`].
///
/// This attribute should always be attached to the main function. Otherwise,
/// the exit code of the program may be incorrect.
///
/// # Examples
///
/// ```
/// #[quit::main]
/// fn main() {}
/// ```
pub use quit_macros::main;
struct ExitCode(process::ExitCode);
enum ResultInner<T>
where
T: Termination,
{
Result(T),
ExitCode(process::ExitCode),
}
#[doc(hidden)]
pub struct __Result<T>(ResultInner<T>)
where
T: Termination;
impl<T> Termination for __Result<T>
where
T: Termination,
{
#[inline]
fn report(self) -> process::ExitCode {
use ResultInner as Inner;
match self.0 {
Inner::Result(result) => result.report(),
Inner::ExitCode(exit_code) => exit_code,
}
}
}
#[doc(hidden)]
#[inline]
pub fn __run<F, R>(main_fn: F) -> __Result<R>
where
F: FnOnce() -> R + UnwindSafe,
R: Termination,
{
panic::catch_unwind(main_fn)
.map(|x| __Result(ResultInner::Result(x)))
.unwrap_or_else(|payload| {
if let Some(&ExitCode(exit_code)) = payload.downcast_ref() {
__Result(ResultInner::ExitCode(exit_code))
} else {
panic::resume_unwind(payload);
}
})
}
#[doc(hidden)]
pub static __ATTACHED: AtomicBool = AtomicBool::new(false);
#[doc(hidden)]
#[macro_export]
macro_rules! __main {
(
( $($signature_token:tt)+ )
( $($args_token:tt)* ) -> $return_type:ty { $($body_token:tt)* }
) => {
$($signature_token)+ (
$($args_token)*
) -> $crate::__Result<$return_type> {
$crate::__ATTACHED.store(
true,
::std::sync::atomic::Ordering::Release,
);
$crate::__run(|| { $($body_token)* })
}
};
( $signature:tt $args:tt $body:tt ) => {
$crate::__main!($signature $args -> () $body);
}
}
/// Cleanly exits the program with an exit code.
///
/// Calling this function from within an FFI boundary invokes undefined
/// behavior. Because panics are used internally to unwind the stack, the exit
/// code cannot be passed safely. [`process::exit`] should be used instead in
/// that case.
///
/// This function will not behave as expected unless [`#[main]`][attribute] is
/// attached to the main function. Other implementation notes are mentioned in
/// [the module-level documentation][implementation].
///
/// # Examples
///
/// ```
/// fn exit() -> ! {
/// quit::with_code(1);
/// }
/// ```
///
/// [attribute]: main
/// [implementation]: self#implementation
#[inline]
pub fn with_code<T>(exit_code: T) -> !
where
T: Into<process::ExitCode>,
{
assert!(
__ATTACHED.load(atomic::Ordering::Acquire),
"`#[quit::main]` has not been attached to `main`",
);
panic::resume_unwind(Box::new(ExitCode(exit_code.into())));
}